Doepfer

Notes: This filter's unique feature is that different filter types are realized by injecting the audio signal at different points of the circuit. For this reason, the A-101-1 has three inputs with level control: one lowpass input which is normalized to the bandpass input, which itself is normalized to the highpass input. The level controls make it possible to mix the filters and to generate new filter types. e.g. with all three filter levels turned to maximum level you get a notch filter.

Furthermore, the cutoff frequency influences which filter type is "monitored". This way you can blend from LP over BP to HP with increasing cutoff, known as "frequency scanning". Interesting effects happen when three different audio signals are used because they are both morphed and filtered at the same time.

Notes: This filter's unique feature is that different filter types are realized by injecting the audio signal at different points of the circuit. For this reason, the A-101-1 has three inputs with level control: one lowpass input which is normalized to the bandpass input, which itself is normalized to the highpass input. The level controls make it possible to mix the filters and to generate new filter types. e.g. with all three filter levels turned to maximum level you get a notch filter.

Furthermore, the cutoff frequency influences which filter type is "monitored". This way you can blend from LP over BP to HP with increasing cutoff, known as "frequency scanning". Interesting effects happen when three different audio signals are used because they are both morphed and filtered at the same time.

Vintage edition with black faceplate and custom knobs.

Notes: A-101-6 is a new filter module that uses so-called opto FET's to control the filter frequency. Opto FET's are very similar to Vactrols, but use light dependent field effect transistors (FET's) instead of light dependent resistors (LDR's). An opto FET is a combination of a light-dependent FET and an LED, both put into a small light-proof case. The advantage, compared to vactrols, is a much faster response of opto FET's compared to LDR's - this allows much faster attack/decay times and even FM effects.

The variable resistors corresponds to the opto FET. The brightness of the Opto FET LED's, and consequently the filter frequency, can be adjusted manually (Frequ. control) and controlled by means of an external control voltage (CV) with attenuator. The LED at the front panel reflects the LED brightness inside the opto FET's.

The type of filter is chosen by jumpers on the PC board (factory setting: low pass). The type of filter determined by the jumpers positions can be marked by means of a water-resistant felt pen at the front panel.

The resonance is controlled by the Feedback control up to self-oscillation. By means of a trimming potentiometer the maximal feedback can be adjusted. High feedback values can be used mainly in the all-pass mode to obtain very extreme self-oscillation sounds. Even an external feedback signal can be used instead of the internal feedback connection (FB In socket). Whenever the filter type is changed by means of the jumpers the trimming potentiometer for the maximal feedback has to be re-adjusted.

The Mix control is used to pan between the original signal (CCW position) and the effect signal (CW position). In filter mode (LP/HP) this control is usually set fully CW. In the all-pass modes one obtains phasing sounds at centre position or "pure" all-pass sound in fully CW position.

Notes: Module A-101-8 is a 8-stage phase shifter which uses light-sensitive resistors (LDR) and is a replica of the Compact Phasing A manufactured by the company Schulte in the seventies. The actual phasing circuit is identical to the historic model. Only the illumination control of the LDRs is different: the A-101-8 uses LEDs to illuminate the LDRs, the historic model used incandescent miniature lamps. And the A-101-8 has no built-in LFO but can be controlled by any external control voltage source (e.g. LFO, ADSR, random, Theremin, ribbon controller, sequencer, midi). The phasing offset (i.e. the base value for the phase shifting) and the modulation depth of the external control signal can be adjusted separately. The Compact Phasing A had no offset control but only a depth control for the built-in LFO. Feedback and mixing ratio of the output signal are set by two controls. The audio input is equipped with an attenuator. The module has two audio outputs available (same as the historic model) and a visual display of the phase shifting.

The module has these controls and in/outputs available:

Control Man. : manual control of the phase shift offset (base value)

Control CV: attenuator for the signal applied to the CV socket

Control Feedb.: Feedback or Resonance (similar function as filter resonance/feedback/emphasis)

Control Mix: sets the mixing ratio between original and phase shift signal appearing at output 1

fully CCW: only the modified input signal appears at output 1 (see note below *)

center: a mixture between the modified input signal and the phase shift signal appears at output 1, that's the standard position for the classical phasing effect

fully CW: the pure phase shifted signal appears at output 1 (e.g. for vibrato effects)

Control Input Level: attenuator for signal applied to the In socket

Socket In: audio input

Socket CV: control voltage input

Socket Out 1: audio output 1 (mix signal)

Socket Out 2: audio output 2 (modified input signal)

LED: visual control of the phase shift

The module has some peculiarities (same as the historic model):

The input signal is processed at first by a pre-stage which outputs a "modified" input signal (*). This signal is not processed by the phase shift stages but is affected by the feedback setting. Only when feedback is set to zero this signal is identical to the input signal. Otherwise it contains feedback components.

This signal is output on socket Out 2.

When both output sockets Out 1 and Out 2 are used as stereo channels one obtains a spatial stereo sound effect.

The same signals is also used for the CCW position of the mix control. With mix control fully CCW the unmodified signal appears only if the feedback control is set to zero. Otherwise it contains feedback components.

The historic model had two audio inputs: one 5-pin DIN socket and a 1/4" jack socket. The DIN socket was intended for high-level line signals. When the 1/4" jack socket was used the amplification of the pre-stage increased by about 100. The 1/4" jack socket was intended for low level signals (e.g. electric guitars or microphones). For this feature the A-101-8 has an internal jumper that can be used to increase the amplification. As long as the module is used within the A-100 system usually the lower amplification is used to avoid distortion.

The 8 photo resistors and LEDs are assembled within an small lighproof box. In addition the pc boards are made of lighproof black material to avoid interfering light from other modules or the bus board.

Dimensions
4 HP
45 mm deep

Current Draw
30 mA +12V
30 mA -12V

Notes: ***B-STOCK: Box opened, but product is in excellent condition and in perfect working order***


Module A-101-8 is a 8-stage phase shifter which uses light-sensitive resistors (LDR) and is a replica of the Compact Phasing A manufactured by the company Schulte in the seventies. The actual phasing circuit is identical to the historic model. Only the illumination control of the LDRs is different: the A-101-8 uses LEDs to illuminate the LDRs, the historic model used incandescent miniature lamps. And the A-101-8 has no built-in LFO but can be controlled by any external control voltage source (e.g. LFO, ADSR, random, Theremin, ribbon controller, sequencer, midi). The phasing offset (i.e. the base value for the phase shifting) and the modulation depth of the external control signal can be adjusted separately. The Compact Phasing A had no offset control but only a depth control for the built-in LFO. Feedback and mixing ratio of the output signal are set by two controls. The audio input is equipped with an attenuator. The module has two audio outputs available (same as the historic model) and a visual display of the phase shifting.

The module has these controls and in/outputs available:

Control Man. : manual control of the phase shift offset (base value)

Control CV: attenuator for the signal applied to the CV socket

Control Feedb.: Feedback or Resonance (similar function as filter resonance/feedback/emphasis)

Control Mix: sets the mixing ratio between original and phase shift signal appearing at output 1

fully CCW: only the modified input signal appears at output 1 (see note below *)

center: a mixture between the modified input signal and the phase shift signal appears at output 1, that's the standard position for the classical phasing effect

fully CW: the pure phase shifted signal appears at output 1 (e.g. for vibrato effects)

Control Input Level: attenuator for signal applied to the In socket

Socket In: audio input

Socket CV: control voltage input

Socket Out 1: audio output 1 (mix signal)

Socket Out 2: audio output 2 (modified input signal)

LED: visual control of the phase shift

The module has some peculiarities (same as the historic model):

The input signal is processed at first by a pre-stage which outputs a "modified" input signal (*). This signal is not processed by the phase shift stages but is affected by the feedback setting. Only when feedback is set to zero this signal is identical to the input signal. Otherwise it contains feedback components.

This signal is output on socket Out 2.

When both output sockets Out 1 and Out 2 are used as stereo channels one obtains a spatial stereo sound effect.

The same signals is also used for the CCW position of the mix control. With mix control fully CCW the unmodified signal appears only if the feedback control is set to zero. Otherwise it contains feedback components.

The historic model had two audio inputs: one 5-pin DIN socket and a 1/4" jack socket. The DIN socket was intended for high-level line signals. When the 1/4" jack socket was used the amplification of the pre-stage increased by about 100. The 1/4" jack socket was intended for low level signals (e.g. electric guitars or microphones). For this feature the A-101-8 has an internal jumper that can be used to increase the amplification. As long as the module is used within the A-100 system usually the lower amplification is used to avoid distortion.

The 8 photo resistors and LEDs are assembled within an small lighproof box. In addition the pc boards are made of lighproof black material to avoid interfering light from other modules or the bus board.

Dimensions
4 HP
45 mm deep

Current Draw
30 mA +12V
30 mA -12V

Notes: Module A-101-8V is a 8-stage phase shifter which uses light-sensitive resistors (LDR) and is a replica of the Compact Phasing A manufactured by the company Schulte in the seventies. The actual phasing circuit is identical to the historic model. Only the illumination control of the LDRs is different: the A-101-8 uses LEDs to illuminate the LDRs, the historic model used incandescent miniature lamps. And the A-101-8 has no built-in LFO but can be controlled by any external control voltage source (e.g. LFO, ADSR, random, Theremin, ribbon controller, sequencer, midi). The phasing offset (i.e. the base value for the phase shifting) and the modulation depth of the external control signal can be adjusted separately. The Compact Phasing A had no offset control but only a depth control for the built-in LFO. Feedback and mixing ratio of the output signal are set by two controls. The audio input is equipped with an attenuator. The module has two audio outputs available (same as the historic model) and a visual display of the phase shifting.

The module has these controls and in/outputs available:

Control Man. : manual control of the phase shift offset (base value)
Control CV: attenuator for the signal applied to the CV socket
Control Feedb.: Feedback or Resonance (similar function as filter resonance/feedback/emphasis)
Control Mix: sets the mixing ratio between original and phase shift signal appearing at output 1
fully CCW: only the modified input signal appears at output 1 (see note below *)
center: a mixture between the modified input signal and the phase shift signal appears at output 1, that's the standard position for the classical phasing effect
fully CW: the pure phase shifted signal appears at output 1 (e.g. for vibrato effects)
Control Input Level: attenuator for signal applied to the In socket
Socket In: audio input
Socket CV: control voltage input
Socket Out 1: audio output 1 (mix signal)
Socket Out 2: audio output 2 (modified input signal)
LED: visual control of the phase shift
The module has some peculiarities (same as the historic model):

The input signal is processed at first by a pre-stage which outputs a "modified" input signal (*). This signal is not processed by the phase shift stages but is affected by the feedback setting. Only when feedback is set to zero this signal is identical to the input signal. Otherwise it contains feedback components.

This signal is output on socket Out 2.
When both output sockets Out 1 and Out 2 are used as stereo channels one obtains a spatial stereo sound effect.

The same signals is also used for the CCW position of the mix control. With mix control fully CCW the unmodified signal appears only if the feedback control is set to zero. Otherwise it contains feedback components.

The historic model had two audio inputs: one 5-pin DIN socket and a 1/4" jack socket. The DIN socket was intended for high-level line signals. When the 1/4" jack socket was used the amplification of the pre-stage increased by about 100. The 1/4" jack socket was intended for low level signals (e.g. electric guitars or microphones). For this feature the A-101-8 has an internal jumper that can be used to increase the amplification. As long as the module is used within the A-100 system usually the lower amplification is used to avoid distortion.

The 8 photo resistors and LEDs are assembled within an small lightproof box. In addition the pc boards are made of lightproof black material to avoid interfering light from other modules or the bus board.

Power consumption: 30mA at +12 V and 30mA at -12 V
Depth: 45mm
HP : 4

Notes: A-104 is a fourfold formant filter as used in the Mixtur Trautonium by Oskar Sala. It is made of four parallel resonance filters, each filter can be switched to low pass or band pass or off. Frequency, resonance and level are controlled for each filter separately (no voltage control). The frequency range for the filters is about 50Hz...5kHz. The filter audio inputs are very sensitive so that distortion may intentionally be used to create new sounds - if desired. The sketch below shows the basic layout of the A-104. The A-104 is a versatile module for sound modification. In the first place it is used for reproduction of resonances (e.g. the vocal-like effects known from the Trautonium). In combination with the subharmonic generator A-113, the Trautonium Manual A-198 and some other A-100 modules one obtains a Trautonium replica. More detailed information about the Trautonium can be found on our internet site.

Dimensions
20 HP
45 mm deep

Current Draw
30 mA +12V
10 mA -12V

Notes: Module A-105-2 is a voltage controlled low pass filter with 24dB/octave slope.

It is the successor of the A-105 which had to be discontinued because the obsolete SSM2044 filter circuit. The A-105-2 is based on the SSI2144 which is in turn the successor circuit of the SSM2044. The features of both modules are nearly the same. The main difference is the clearly reduced front panel width of the A-105-2 (4HP instead of 8HP) and the associated changes of the controls and sockets positions. In addition the A-105-2 is equipped with 2 audio inputs.

The module has these controls and in/outputs available:

Control Frequ: manual frequency control
Control FCV2: attenuator for the frequency control voltage applied to socket FCV2
Control Q: manual resonance control
Control QCV: attenuator for the resonance control voltage applied to socket QCV
Control Input 1 Level: attenuator for the audio input signal applied to socket Input 1
Socket Input 1: audio input 1 (with attenuator)
Socket Input 2: audio input 2 (without attenuator)
Socket FCV1: frequency control voltage 1 (without attenuator, about 1V/oct scale)
Socket FCV2: frequency control voltage 2 (with attenuator)
Socket QCV: resonance control voltage (with attenuator)
Socket Out: audio output
Technical notes:

Frequency range: about 15Hz ... 15 kHz
Resonance up to self oscillation
Max. input voltage at Input 2 without clipping/distortion: about 15Vpp
Max. output voltage without clipping/distortion: about 15Vpp
The signals of both inputs are mixed before they are processed by the filter. This saves an external mixer for small setups.
Depth: 45 mm

HP : 4

Notes: Module A-105-2V is a voltage controlled low pass filter with 24dB/octave slope.

It is the successor of the A-105 which had to be discontinued because the obsolete SSM2044 filter circuit. The A-105-2 is based on the SSI2144 which is in turn the successor circuit of the SSM2044. The features of both modules are nearly the same. The main difference is the clearly reduced front panel width of the A-105-2 (4HP instead of 8HP) and the associated changes of the controls and sockets positions. In addition the A-105-2 is equipped with 2 audio inputs.

The module has these controls and in/outputs available:

Control Frequ: manual frequency control
Control FCV2: attenuator for the frequency control voltage applied to socket FCV2
Control Q: manual resonance control
Control QCV: attenuator for the resonance control voltage applied to socket QCV
Control Input 1 Level: attenuator for the audio input signal applied to socket Input 1
Socket Input 1: audio input 1 (with attenuator)
Socket Input 2: audio input 2 (without attenuator)
Socket FCV1: frequency control voltage 1 (without attenuator, about 1V/oct scale)
Socket FCV2: frequency control voltage 2 (with attenuator)
Socket QCV: resonance control voltage (with attenuator)
Socket Out: audio output
Technical notes:

Frequency range: about 15Hz ... 15 kHz
Resonance up to self oscillation
Max. input voltage at Input 2 without clipping/distortion: about 15Vpp
Max. output voltage without clipping/distortion: about 15Vpp
The signals of both inputs are mixed before they are processed by the filter. This saves an external mixer for small setups.
Depth: 45 mm

HP : 4

Notes: Module A-106-1 is a unique low/high pass filter and has its origin in Doepfer's experiments to build an MS20 filter clone. In contrast to other filter designs, it has different audio inputs for low and high pass, but only one audio output. The type of filter (12dB low pass, 6dB high pass or any mix) is defined by the shares of the audio signal fed to the corresponding inputs. Even two different audio signals can be used as low and high pass input. A special feature is the polarizer at the high pass input that allows to add/subtract the high pass to/from the low pass share, leading to pseudo band pass and notch responses.

Another special feature is the clipping controls, which allow independent adjustment of the positive and negative clipping level. The resonance goes up to self-oscillation, but with a clearly different behaviour than on other filters. At certain resonance and clipping settings the self-oscillation generates rectangle or short sawtooth shaped pulses.

In general, the A-106-1 is a very strange and awesome filter and far away from being perfect (e.g non-linear control scale, self-oscillation with all sorts of waveforms except sine, a lot of roaring, rattling, noise or other unpredictable sounds at high distortion and resonance settings, high distortion or audio level overrides the resonance, significant CV feedthrough). But the A-106-1 has a lot of character - probably much more than any other filter of the A-100 - and is able to generate filter sweeps which are not possible with any other filter.

Notes: Module A-106-6 is a multimode filter that is based on the filter circuit of the Oberheim Xpander. The module features 15 different filter types (those filters of the A-107 that were available in the Xpander) with 8 filters available simultaneously. The toggle switch Filter Group is used to switch between 2 filter groups.

These filter types are available:

- 1L (6 dB low pass)
- 2L (12 dB low pass)
- 3L (18 dB low pass)
- 4L (24 dB low pass)
- 1H (6 dB high pass)
- 2H (12 dB high pass)
- 3H (18 dB high pass)
- 2B (6 dB band pass)
- 4B (12 dB bandpass)
- 2N (notch)
- 3A (allpass)
- 2H1L (asymmetrical band pass made of a 12 dB high pass and a 6 dB low pass)
- 3H1L (asymmetrical band pass made of a 18 dB high pass and a 6 dB low pass)
- 2N1L (combination of notch and 6 dB low pass)
- 3A1L (combination of allpass and 6 dB low pass)

The module features voltage-controlled resonance. For filter group 2 (2L, 4L, 2B ...) even self-oscillation is possible.

All standard VCF controls are available: manual filter frequency control Frq, one control voltage input with attenuator (FCV2) and one without attenuator (FCV1, ~ 1 V/octave). In addition, voltage-controlled resonance with manual control (Q) and a CV input with attenuator (QCV) are available.

The circuit is based on a 24dB lowpass filter. The outputs of the four internal filter stages (i.e. the 6, 12, 18 and 24dB outputs) are mixed together with different levels and polarities to obtain 15 different filters. Because of this special circuit the outputs have slightly different levels and noise floor. This is caused by the different internal amplifications and numbers of stages that are required to generate the filter in question. If e.g. a filter is derived by one stage only (e.g. the 6 dB, 12dB, 18dB and 24dB low pass) the noise floor is smaller compared to a filter that is derived by a combination of all four filter stages.

Notes: Module A-108 is a completely new voltage-controlled low pass filter based on the well-known transistor ladder (Moog ladder). The module has internally an 8-stage low pass filter with different slopes available: 6, 12, 18, 24, 30, 36, 42 and 48 dB per octave. In addition, it features a band pass output (i.e. band pass with transistor ladder). In the factory, the 4 low pass outputs of the A-108 are internally connected to the filter stages 6, 12, 24 and 48dB.

Resonance (Emphasis or Q) can be adjusted manually right up to self-oscillation, in which case the filter will behave like a sine wave oscillator. The A-108 features an external feedback input that enables the insertion of additional modules into the feedback path (e.g. VCA for voltage-controlled resonance or phaser/frequency shifter for phase/frequency shifting effects). The socket is normalized and internally connected to the 48dB low pass output if no cable is inserted into the feedback socket.

The frequency can be adjusted manually, or by voltage control. Three CV inputs (CV1, CV2, CV3) are available. CV2 and CV3 are equipped with attenuators.

The filter audio input is very sensitive so that distortion - if desired - is possible even with normal A-100 levels (e.g. VCO output). Self-oscillation will break off at high distortion levels as the internal feedback signal is drown out by the distorted audio signal. This feature may intentionally be used to create new sounds.

In combination with the Voltage Controlled Mixer A-135 and the Morphing Controller A-144 a filter with voltage-controlled slope can be realized (i.e. controlling the slope from 6dB to 48dB via CV).

Notes: Module A-110-1 is a voltage-controlled oscillator. This VCO's frequency range is about eight octaves (ca. 15Hz ... 8kHz). It can produce four waveforms simultaneously: rectangle, sawtooth, triangle, and sine wave (triangle and sine shapes are not perfect, see remark below). The output levels are typically 8Vpp for saw and rectangle, and 10Vpp for triangle and sine. The frequency or pitch of the VCO is determined by the position of the octave (Range) switch and tuning (Tune) knob, and by the voltage present at the CV inputs. Frequency modulation (FM) of the VCO is therefore a possibility. Footage (the octave of the fundamental) is set by the Range control in five steps, and Fine tuning controlled by the Tune knob by about +/-1 one semitone (can be modified for a wider range).

You can control the pulse width of the square wave either by hand, or by voltage control - Pulse Width Modulation or PWM.

For more detailed information please look at the user's manual A110_man.pdf. In addition, the A-110 service manual is available as an example for the A-100 service manual that is available at extra charges. This document describes also how to modify the sensitivity of the tune control, how to re-adjust the 1V/octave scale and the frequency offset (i.e. the absolute pitch). Such modifications should be carried out by experienced users only!

The core of the A-110-1 is a sawtooth oscillator (in contrast to the A-111-1, which is based on a triangle oscillator). The other waveforms are derived from the sawtooth by internal waveform converters. As the sawtooth reset (i.e. the back-to-zero slope) is not infinite fast but takes a little bit of time the derived waveforms triangle and sine are not perfect! At the top of the waveform they have a small glitch or notch that is caused by the sawtooth reset and cannot be eliminated by the waveform converters. The sine is derived from the triangle by a simple diode-based converter and the sine shape is not perfect (only a rounded triangle).

If a perfect triangle is required, the A-111-1 is recommended. For a perfect sine wave the quadrature LFO/VCO A-143-9 is recommended.

Notes: Module A-110-1 is a voltage-controlled oscillator. This VCO's frequency range is about eight octaves (ca. 15Hz ... 8kHz). It can produce four waveforms simultaneously: rectangle, sawtooth, triangle, and sine wave (triangle and sine shapes are not perfect, see remark below). The output levels are typically 8Vpp for saw and rectangle, and 10Vpp for triangle and sine. The frequency or pitch of the VCO is determined by the position of the octave (Range) switch and tuning (Tune) knob, and by the voltage present at the CV inputs. Frequency modulation (FM) of the VCO is therefore a possibility. Footage (the octave of the fundamental) is set by the Range control in five steps, and Fine tuning controlled by the Tune knob by about +/-1 one semitone (can be modified for a wider range).

You can control the pulse width of the square wave either by hand, or by voltage control - Pulse Width Modulation or PWM.

For more detailed information please look at the user's manual A110_man.pdf. In addition, the A-110 service manual is available as an example for the A-100 service manual that is available at extra charges. This document describes also how to modify the sensitivity of the tune control, how to re-adjust the 1V/octave scale and the frequency offset (i.e. the absolute pitch). Such modifications should be carried out by experienced users only!

The core of the A-110-1 is a sawtooth oscillator (in contrast to the A-111-1, which is based on a triangle oscillator). The other waveforms are derived from the sawtooth by internal waveform converters. As the sawtooth reset (i.e. the back-to-zero slope) is not infinite fast but takes a little bit of time the derived waveforms triangle and sine are not perfect! At the top of the waveform they have a small glitch or notch that is caused by the sawtooth reset and cannot be eliminated by the waveform converters. The sine is derived from the triangle by a simple diode-based converter and the sine shape is not perfect (only a rounded triangle).

If a perfect triangle is required, the A-111-1 is recommended. For a perfect sine wave the quadrature LFO/VCO A-143-9 is recommended.

Notes: Module A-110-2 is a low-cost voltage-controlled oscillator. It's a slightly reduced version of the standard VCO A-110-1. Compared to the A-110-1, the A-110-2 has no sine output and the (expensive) octave rotary switch is replaced by a 3-position toggle switch. In return, the A-110-2 is equipped with an additional linear FM input and a soft sync input. A jumper is used to select the range of the tune control between about 1/2 octave and about 4 octaves. The width of the module is only 8 HP compared to the 10 HP of the A-110-1.

All other features are essentially the same as for the A-110-1.

Explanation of the jumpers and trimming potentiometers:

- JP2: CV connection to A-100 bus
- JP3: range of Tune control (installed = about 4 octaves, not installed = about 1/2 octave)
- JP4: AC/DC coupling of the linear FM input (installed = DC coupling, not installed = AC coupling)
- P5: 1V/Oct scale
- P6: frequency offset
- P7: high-end trim
- P8: adjustment +1 Oct. range switch
- P9: adjustment -1 Oct. range switch
- P10: temperature VCO heater

The core of the A-110-2 is - like the A-110-1 - a sawtooth oscillator (in contrast to the A-111-1, which is based on a triangle oscillator). The other waveforms are derived from the sawtooth by waveform converters. As the sawtooth reset (i.e. the back-to-zero slope) is not infinitely fast but takes a little bit of time the triangle is not perfect! At the bottom of the waveform it has a small glitch or notch that is caused by the sawtooth reset and cannot be eliminated by the waveform converter. If a perfect triangle is required, the A-111-1 is recommended.

The sawtooth output of the A-110-21 has a falling (or negative) slope. The front panel shows erroneously a rising (or positive) slope. This has no influence on the sound but becomes important when the module is used as an LFO or is mixed with the sawtooth output of another VCO.

The control voltage applied to the socket 1V/Oct is added to the control voltage coming from the bus (interruptible by removing the jumper JP2). Connecting a cable to the socket 1V/Oct does not interrupt the bus CV connection!

Notes: Module A-110-2 is a low-cost voltage-controlled oscillator. It's a slightly reduced version of the standard VCO A-110-1. Compared to the A-110-1, the A-110-2 has no sine output and the (expensive) octave rotary switch is replaced by a 3-position toggle switch. In return, the A-110-2 is equipped with an additional linear FM input and a soft sync input. A jumper is used to select the range of the tune control between about 1/2 octave and about 4 octaves. The width of the module is only 8 HP compared to the 10 HP of the A-110-1.

All other features are essentially the same as for the A-110-1.

Explanation of the jumpers and trimming potentiometers:

- JP2: CV connection to A-100 bus
- JP3: range of Tune control (installed = about 4 octaves, not installed = about 1/2 octave)
- JP4: AC/DC coupling of the linear FM input (installed = DC coupling, not installed = AC coupling)
- P5: 1V/Oct scale
- P6: frequency offset
- P7: high-end trim
- P8: adjustment +1 Oct. range switch
- P9: adjustment -1 Oct. range switch
- P10: temperature VCO heater

The core of the A-110-2 is - like the A-110-1 - a sawtooth oscillator (in contrast to the A-111-1, which is based on a triangle oscillator). The other waveforms are derived from the sawtooth by waveform converters. As the sawtooth reset (i.e. the back-to-zero slope) is not infinitely fast but takes a little bit of time the triangle is not perfect! At the bottom of the waveform it has a small glitch or notch that is caused by the sawtooth reset and cannot be eliminated by the waveform converter. If a perfect triangle is required, the A-111-1 is recommended.

The sawtooth output of the A-110-21 has a falling (or negative) slope. The front panel shows erroneously a rising (or positive) slope. This has no influence on the sound but becomes important when the module is used as an LFO or is mixed with the sawtooth output of another VCO.

The control voltage applied to the socket 1V/Oct is added to the control voltage coming from the bus (interruptible by removing the jumper JP2). Connecting a cable to the socket 1V/Oct does not interrupt the bus CV connection!

Notes: This analogue VCO is well versed in the art of deep and beautiful thru-zero frequency modulation, allowing the frequency to stop when CVs with 0V are applied, and even to go backwards when modulated with negative CVs.

The term "quadrature" refers to simultaneously available sine and cosine waves at individual outputs. The VCO is sine based i.e. no waveshaping is used to derive the sine; for that reason, the sound is really clear and shows a minimum of distortion and overtones.

The module has two control sections:

The exponential section consists of the XTune control, the 1V/Oct input and the XFM input with the corresponding attenuator XFM.

The exponential control voltage is the sum of these three voltages. The linear section consists of the LTune control and the LFM input with the corresponding attenuator LFM. The linear control voltage is the sum of these two voltages.

The main advantage of the A-110-4 compared to other Thru Zero VCOs is that the design uses a sine/cosine core. The sine/cosine waves are not derived from other waveforms (e.g. sawtooth or triangle) by means of waveshaping. Rather the sine and cosine waves are the core of the VCO which results in very pure waves with a minimum of distortion and overtones.

With it's both control possibilities, linear and exponential, as well as it's thru-zero ability, the VCO is perfectly suited for all types of FM applications.

Notes: This analogue VCO is well versed in the art of deep and beautiful thru-zero frequency modulation, allowing the frequency to stop when CVs with 0V are applied, and even to go backwards when modulated with negative CVs.

The term "quadrature" refers to simultaneously available sine and cosine waves at individual outputs. The VCO is sine based i.e. no waveshaping is used to derive the sine; for that reason, the sound is really clear and shows a minimum of distortion and overtones.

The module has two control sections:

The exponential section consists of the XTune control, the 1V/Oct input and the XFM input with the corresponding attenuator XFM.

The exponential control voltage is the sum of these three voltages. The linear section consists of the LTune control and the LFM input with the corresponding attenuator LFM. The linear control voltage is the sum of these two voltages.

The main advantage of the A-110-4 compared to other Thru Zero VCOs is that the design uses a sine/cosine core. The sine/cosine waves are not derived from other waveforms (e.g. sawtooth or triangle) by means of waveshaping. Rather the sine and cosine waves are the core of the VCO which results in very pure waves with a minimum of distortion and overtones.

With it's both control possibilities, linear and exponential, as well as it's thru-zero ability, the VCO is perfectly suited for all types of FM applications.

Notes: Module A-112 is the combination of a voltage controlled 8 Bit Sampler and a wavetable oscillator. On top of it the module is able to generate some special effects. A-112 was designed as an additional sound source with the typical sounds of the early 8 bit samplers and is not comparable with the modern polyphonic MIDI samplers available on the market.

Sampling mode: 8 bit audio resolution, 128kB memory in 2 banks 64kB each (equivalent to 2 seconds of sampling time for each bank with 32 kHz sampling rate), audio input with attenuator, overload display in record mode (gate LED), possibility of MIDI Dump to store sounds in a computer via MIDI, non-volatile memory for the 2 samples in the module, manual tune control for adjustment of sampling rate for record and play, CV input (~ 1V/Oct), both manual tune and CV determine the sampling rate respectively the pitch (pitch range is 5 octaves), gate input (not a trigger: the sample starts at the positive edge of the gate signal and is played as long as gate is high or until the end of the sample is reached), manual Gate button, non-filtered audio output (thus quantizing noise can be used as an element of the sound intentionally).

Wavetable mode: special appearance of the sampling mode when playing a sample, the audio input is now used as a second control voltage input for moving through the sample in 256 byte wide loops (wavetables). The control voltage required to move through all wavetables applied to the input "Wave CV In" is in the range -2.5V (wavetable 1) ... 0V (wavetable 127) ... +2.5V (wavetable 256) when control "Atten." is set fully clockwise. To achieve the typical wavetable oscillator sounds the sampling memory must contain corresponding wavetable data (e.g. loaded via MIDI dump). These data contain a set of wavetables with different harmonic content (e.g. a filter sweep) to get the typical wavetable sound while moving through the tables via CV. But you may also use a "normal" sample and go through the sample with CV to obtain partially amazing sounds never heard before. You may use for example sampled speech and go with CV through the syllables or speech shreds to get really very extreme sounds. An ideal addition for this feature is the Offset/Attenuator module A-183-2 which can be used to adjust the position of the wavetable (Offset) and the modulation depth (Att.). The corresponding jumper of the A-183-2 has to be set to bipolar offset (as the A-112 requires -2.5V...+2.5V to pass through all 256 wavetables). As modulation source an LFO (A-145, A-146, A-147, A-143-3), ADSR (A-140, A-141, A-142, A-143-1/2) or a random voltage (A-118, A-149-1) may be used. Even a ribbon controller (A-198 or R2M), the Theremin module A-178, the Joystick A-174 or the Wheels module A-174-2 are useful to drive through the wavetables.

Effects: Additionally, the module offers - in a way free of charge - some effects like delay, reverse delay, pitch shifting or freeze. But it has to be pointed out that due to the 8 bit audio resolution these effects are not comparable to high quality effect units and should be understand as an extra for nothing. The A-112 is not an effects unit!

The sampling time of the A-112 is about 1...30 seconds corresponding to a sampling frequency range of about 60kHz...2kHz (64kB@60kHz ~ 1 s, 64kB@2kHz ~ 30 s).

Technical note: the module uses a battery for the non-volatile storage of the sampling data. Batteries have a limited lifespan and have to be inspected at least every two years. For details please refer to the FAQ page of our website: Lifespan of rechargeable batteries (used for memory backup).

Notes: Module A-120 is a voltage controlled low-pass filter, which filters out the higher parts of the sound spectrum, and lets lower frequencies pass through. The Cut-Off Frequency determines the point at which filtering takes effect. You can control this manually, or by voltage control (filter modulation, for instance by an LFO). Three CV inputs are available, and the sum of the voltages from these affects the filter cut-off.

The module is based on a so-called "transistor ladder" design, with a cut-off slope of -24 dB/octave, as in various Moog synthesizers. That's what gives it its classic, legendary Moog sound.

Resonance (or Emphasis) is adjustable all the way up to self-oscillation - in which case the filter behaves like a sine wave oscillator.

Notes: Module A-121 is a voltage-controlled multi-mode filter with a cut-off slope of -12 dB / octave. Four simultaneous outputs are available, each with different characteristics: low-pass, band-pass, high-pass and notch (or band reject). The cut-off frequency determines the point at which the respective filter effects appear. The frequency can be adjusted manually, or by voltage control (Filter modulation, for instance by an LFO or ADSR). Two CV inputs are available, whose control voltages are summed. Resonance (Emphasis or Q) can be adjusted manually, or by voltage control, right up to self-oscillation, in which case it will behave like a sine wave oscillator.

Technical notes: Module A-121-2 is the successor of the obsolete module A-121. But the circuitry is totally different from the A-121 which used the obsolete CEM3320 filter circuit. The sound of the new module A-121-2 is identical to filter of the Dark Energy II but has been expanded by the voltage-controlled resonance feature.

Notes: Module A-121 is a voltage-controlled multi-mode filter with a cut-off slope of -12 dB / octave. Four simultaneous outputs are available, each with different characteristics: low-pass, band-pass, high-pass and notch (or band reject). The cut-off frequency determines the point at which the respective filter effects appear. The frequency can be adjusted manually, or by voltage control (Filter modulation, for instance by an LFO or ADSR). Two CV inputs are available, whose control voltages are summed. Resonance (Emphasis or Q) can be adjusted manually, or by voltage control, right up to self-oscillation, in which case it will behave like a sine wave oscillator.

Technical notes: Module A-121-2 is the successor of the obsolete module A-121. But the circuitry is totally different from the A-121 which used the obsolete CEM3320 filter circuit. The sound of the new module A-121-2 is identical to filter of the Dark Energy II but has been expanded by the voltage-controlled resonance feature.

Notes: A-123-2 is a voltage controlled high-pass filter with four filter outputs (6, 12, 18 and 24dB slope). It also features voltage control of the resonance.

These controls and in/outputs are available:

- Audio In with attenuator (Lev)
- Manual Frequency control (Frq)
- FCV1: Frequency control input (~ 1V/oct)
- FCV2: Frequency control input with polarizer
- QCV: Resonance control input with attenuator
- Manual Resonance control (Q)
- 6dB Output
- 12dB Output
- 18dB Output
- 24dB Output

Notes: Module A-130-8 contains eight linear voltage controlled amplifiers (VCAs). Each VCA features a control voltage input (CV), a signal input (In) and a signal output (Out). In addition three mixers are included: the socket labelled "1-4" outputs the sum of the VCAs 1-4, the socket labelled "5-8" outputs the sum of the VCAs 5-8, the socket labelled "1-8" outputs the sum of all eight VCAs.

The signal inputs are able to process levels up to 10Vpp without clipping. Each CV input is equipped with a trimming potentiometer that is used to adjust the sensitivity of the CV input in question. In the factory the module is adjusted for the CV range 1...+5V but can be re-adjusted by the user for other control voltage ranges (e.g. 0...+10V).

The amplification range for each single VCA is 0...1. The signals of the sum outputs have a lower amplification to avoid distortion.

The VCAs and mixers are fully DC coupled, i.e. the module can be used for the processing of both audio and control voltage signals. The control voltage and signal inputs can be normalled by means of small solder pads (e.g. 1 > 2 > 3 > 4 and so on, or 1 > 5, 2 > 6, 3 > 7, 4 > 8 for the stereo application mentioned below).

Typical applications:

Any kind of VCA application (e.g. voltage controlled attenuation of audio or control voltage signals)
Two voltage controlled mixers with four channels each
Voltage controlled stereo mixer with four channels each, for this the control voltage inputs have to be correspondingly patched or internally normalled: CV1=CV5 / CV2=CV6 / CV3=CV7 / CV4=CV8
Voltage controlled mixer with eight channels
Add-on for the planned Joystick module A-174-4

Dimensions
6 HP
40 mm deep

Current Draw
50 mA +12V
50 mA -12V
0 mA 5V

Notes: Module A-132-3 is composed of two identical voltage controlled amplifiers (VCA). Each VCA has a manual gain control and a control voltage input with attenuator.

The character of the control scale can be switched to linear or exponential.

All inputs and outputs are DC coupled. Consequently the VCAs can be used to process both audio and control voltages.

The input has no attenuator available but is capable to process up to 16Vss signals (i.e. -8V...+8V) without distortion.

Notes: A-132-8 is an octal VCA and primarily planned for polyphonic applications. The module contains four VCA pairs. Each pair includes two daisy-chained VCAs. One VCA has a linear control scale, for the second VCA linear or exponential control scale can be chosen by means of jumpers. We decided to provide two VCAs for each voice because usually one VCA is required for loudness envelope and a second one for velocity (or other functions like individual voltage-controlled loudness of each voice, amplitude modulation and so on).

These controls and in/outputs are available:

- Default Gain 1 (GL)
- Default Gain 2 (GX)
- CV Input VCA 1
- CV Input VCA 2
- Audio Input
- Audio Output

In addition, an Audio Sum Output is also available.

The module features two Default Gain controls (GL, GX), that enable the opening of the first VCAs (L) and/or second VCAs (X). For this the controls GL and GX generate two internal control voltages 0...+10V which are connected to the switching contacts of the sockets 1L...4L (control GL) and 1X...4X (control GX). As long as no patch cable is inserted into the socket in question the internal default control voltage (GL or GX) is used to control the corresponding VCA. This is necessary when the VCA in question is not in use (i.e. no external CV available). Otherwise the VCA would close and there would be no output signal even if the other VCA in the chain is open. The controls GL and GX are also useful for testing polyphonic patches (e.g. for tuning the VCOs).

In the factory the CV inputs are adjusted for a CV range 0...+10V - matching to the polyphonic ADSR module A-141-4. But the sensitivity of each CV input can be adjusted by means of a trimming potentiometer to adapt the CVs even to other control voltage ranges.

Notes: Module A-135-1 is a quad voltage controlled mixer. It is made of 4 independent linear VCA's. The VCA outputs are mixed to a common output. For each VCA the following inputs and controls are available: audio input with attenuator, control voltage input with attenuator, gain (pre-amplification). The VCA's are realized with high-quality CEM VCA's (CEM3381 for version 1 and SSM2164 for version 2).

Applications: voltage controlled mixing of up to 4 audio signals with separate control voltages (e.g. delivered by LFO's, ADSR's, Random, Shepard generator, MIDI-to-CV interface or other control voltage sources). In connection with the Morphing-Controller A-144 the soft fade-over of 4 audio signals with only one control voltage is possible.

Inputs: 4 x Signal in, 4 x CV In
Output: Signal Out, Version 2 in addition: 4 x Single Out
Controls: 4 x Signal In Attenuator, 4 x CV Attenuator, 4 x Initial Gain

Notes: A-135-2 is a miniature version of the A-135-1. Behind a front panel with 8 HP only four linear VCAs (voltage controlled amplifiers) and a voltage controlled mixer based on the VCAs are available.

Controls, In/Outputs and Functions of each VCA:

- Level (manual control of the VCA amplification), small rubberized knob (L1...L4)
- Control voltage input with associated attenuator (CV1...CV4), for the full VCA control range about 0...+5V control voltage are required (attenuator fully clockwise), for higher control voltages the attenuator is used, the attenuators are without knobs, just plastic shafts with white marker
- Signal Input
- Signal Output
- All inputs and outputs are DC coupled. Consequently the VCAs can be used to process both audio and control voltages (e.g. to control the level of LFOs or envelopes)
- The signal input is not equipped with an attenuator. But the VCAs can process all signals up to 15Vpp / -7.5...+7.5V without clipping. In case of higher levels an external attenuator is required (e.g. A-183-1).
- The available amplification range is 0...1, the maximal amplification is 1 (i.e. it "clips" and remains at 1 even if the control voltage goes beyond the value that corresponds to amplification 1)

Functions of the voltage controlled mixers:

- Two outputs ("Selected" and "All")
- Selected output: the ouput if a VCA is removed from this sum signal when a plug is inserted into the corresponding VCA output.
- All output: sum of all VCA outputs, regardless of inserted plugs into the VCA outputs
- The maximal amplification is about 0.6 to avoid clipping at the mixer outputs (otherwise the outputs may distort with 15Vpp signals at each signal input and full amplifications)

Special functions of the voltage controlled mixers (selectable by internal jumpers):

- Dual Stereo VCA: In this case the control unit of VCA1 (L1 + CV1) affects also VCA3 and the control unit of VCA2 (L2 + CV2) affects also VCA4, the control units of VCA2 and VCA4 are out of operation
- Quad VCA: In this case the control unit of VCA1 (L1 + CV1) affects all four VCAs. The control units of VCA2, VCA3 and VCA4 are out of operation. In this mode the module has the same function as module A-132-2. That's why module A-132-2 will be discontinued.
- Normalling of the signal inputs: by means of internal jumpers signal input 1 can be normalled to signal input 2, signal input 2 to signal input 3 and signal input 3 to signal input In 4. That way the same input signal can be distributed to four different channels by means of control voltages (e.g. quadrophonic distribution of audio signals). Suitable control voltage sources are e.g. A-144 (Morphing Controller) or A-143-9 (Quadrature LFO).

Notes: A-135-2 is a miniature version of the A-135-1. Behind a front panel with 8 HP only four linear VCAs (voltage controlled amplifiers) and a voltage controlled mixer based on the VCAs are available.

Controls, In/Outputs and Functions of each VCA:

Level (manual control of the VCA amplification), small rubberized knob (L1...L4)

Control voltage input with associated attenuator (CV1...CV4), for the full VCA control range about 0...+5V control voltage are required (attenuator fully clockwise), for higher control voltages the attenuator is used, the attenuators are without knobs, just plastic shafts with white marker

Signal Input

Signal Output

All inputs and outputs are DC coupled. Consequently the VCAs can be used to process both audio and control voltages (e.g. to control the level of LFOs or envelopes)

The signal input is not equipped with an attenuator. But the VCAs can process all signals up to 15Vpp / -7.5...+7.5V without clipping. In case of higher levels an external attenuator is required (e.g. A-183-1).

The available amplification range is 0...1, the maximal amplification is 1 (i.e. it "clips" and remains at 1 even if the control voltage goes beyond the value that corresponds to amplification 1)

Functions of the voltage controlled mixers:

two outputs ("Selected" and "All")

Selected output: the ouput if a VCA is removed from this sum signal when a plug is inserted into the corresponding VCA output.

All output: sum of all VCA outputs, regardless of inserted plugs into the VCA outputs

The maximal amplification is about 0.6 to avoid clipping at the mixer outputs (otherwise the outputs may distort with 15Vpp signals at each signal input and full amplifications)

Special functions of the voltage controlled mixer (selectable by internal jumpers)

Dual Stereo VCA: In this case the control unit of VCA1 (L1 + CV1) affects also VCA3 and the control unit of VCA2 (L2 + CV2) affects also VCA4. The control units of VCA3 (L3 + CV3) and VCA4 (L4 +CV4) are out of operation.

Quad VCA: In this case the control unit of VCA1 (L1 + CV1) affects all four VCAs. The control units of VCA2, VCA3 and VCA4 are out of operation. In this mode the module has the same function as module A-132-2. That's why module A-132-2 will be discontinued.

Normalling of the signal inputs: by means of internal jumpers signal input 1 can be normalled to signal input 2, signal input 2 to signal input 3 and signal input 3 to signal input In 4. That way the same input signal can be distributed to four different channels by means of control voltages (e.g. quadrophonic distribution of audio signals). Suitable control voltage sources are e.g. A-144 (Morphing Controller) or A-143-9 (Quadrature LFO).

Additional technical specification for each VCA (based on the specifications of the VCA circuits CEM3360/AS3360 used in the module):

Crosstalk between VCAs: typ. - 80dB

Signal attenuation at 0V CV: typ. -70dB

Total harmonic distortion: typ. 1%

Control voltage feedthrough: max. 15mV

Width: 8 HP / 40.3 mm
Depth: 45 mm (measured from the rear side of the front panel)
Current: +40mA (+12V) / -40mA (-12V)

Notes: Mix four stereo signals with CV control over levels. Doepfer's usual great value and user-friendly approach make this a great choice at an excellent price point.

Supplier notes:
A-135-3 is a is a voltage controlled stereo mixer with four inputs. Behind a front panel with 8 HP only eight linear VCAs (voltage controlled amplifiers) and the mixer based on the VCAs are available.

Controls, Inputs and Functions of each input:

Level (manual control of the VCA amplification), small rubberized knob (L1...L4)

Control voltage input with associated attenuator (CV 1...4), for the full VCA control range about 0...+5V control voltage are required (attenuator fully clockwise), for higher control voltages the attenuator is used, the attenuators are without knobs, just plastic shafts with white marker

Signal Input left/right (InL 1...4 / InR 1...4)

The signal inputs are not equipped with an attenuator. But the VCAs can process all signals up to 15Vpp / -7.5...+7.5V without clipping. In case of higher levels an external attenuator is required (e.g. A-183-1).

The sum of the left and right signals appear at the sockets Out L and Out R. The maximal amplification is about 0.5 to avoid clipping at the mixer outputs (otherwise the outputs may distort with 15Vpp signals at each signal input and full amplifications). If another maximal amplification (e.g. 1) is required two resistors have to be replaced.

All inputs and outputs are DC coupled. Consequently the module can be used to process both audio and control voltages.

Additional technical specification for each VCA (based on the specifications of the VCA circuits CEM3360/AS3360 used in the module):
Crosstalk between two channels: better than - 80dB
Signal attenuation at 0V CV: better than -80dB
Total harmonic distortion: typ. 1%
Control voltage feedthrough: max. 15mV

HP : 8

Notes: Module A-135-5 is a combination of a voltage controlled polyphonic mixer and a polyphonic suboctave generator. It is made of 12 voltage controlled amplifiers (VCAs) which are arranged in form of a 4x3 matrix. Herewith up to three four-voice polyphonic signals (e.g. the outputs of three polyphonic VCOs A-111-4) can be mixed. The level of each of the three polyphonic channels (A, B, C) with four voices each can be controlled manually or by means of an external control voltage with associated attenuators.

In addition the module features four frequency dividers which derive the suboctaves from the four input signals of channel A. The suboctave signals are wired to the switching contacts of the sockets of channel B. As long as the sockets of channel B are not patched the suboctave signals of channel A are used as inputs for channel B. The suboctaves are symmetrical rectangle waves with half the frequency of the corresponding signal A. For example two polyphonic VCOs A-111-4) can be used and patched to the channels A and C. Channel B then provides the suboctaves of channel A.

As the module is fully DC coupled it can be used also for the mixing of control voltages in a polyphonic environment (e.g. for envelopes, LFOs or other control voltages).

The switching contacts of the 12 input sockets and the four outputs are internally connected to pin headers. That way the module can be internally pre-patched to other polyphonic modules (e.g. the four inputs A to an A-111-4, the four inputs C to another A-111-4 and the outputs to the polyphonic filter A-105-4). As the switching contacts of the sockets are used for the internal pre-patching the internal patch can be overridden by using the sockets at the front panel.

The module has these controls and in/outputs available:

Controls Lev.A, Lev.B, Lev.C: manual level adjustment of the channels A, B and C

Controls CV A, CV B, CV C: attenuators for the corresponding control voltage inputs

Sockets A1...4: inputs channel A

Sockets B1...4: inputs channel B (if the sockets are not patched the suboctave signals are used for the inputs B)

Sockets C1...4: inputs channel C

Sockets CV A. CV B, CV C: control voltage inputs for the channels A, B and C

Sockets Out 1...4: outputs

Dimensions
10 HP
55 mm deep

Notes: A-137 is a voltage controlled Wave Multiplier. The basic idea of a wave multiplier is to multiply the waveform of an incoming signal (e.g. triangle/saw/sine from a VCO) within one period of the waveform. This leads to additional harmonics of the incoming signal. The period and consequently the pitch of the signals remains unchanged (in contrast to frequency multiplication e.g. with the PLL module A-196).

The A-137 works as a kind of "inverse low pass filter", i.e. it adds a lot of harmonics to a signal that contains none or only a few harmonics (e.g. sine or triangle waveform). In contrast to that a low pass filter (e.g. A-120) removes harmonics from a signal that contains a lot of harmonics (e.g. saw or rectangle waveform). Consequently the best results are obtained in combination with input signals poor in harmonics (e.g. sine or triangle). The A-137 can be used with signals rich in harmonics too (e.g. saw) but the effect is not as remarkable as for triangle or sine waves. For rectangle signals none or only little effects are obtained.

The A-137 is a very sophisticated wave multiplier that offers much more features, more controls and more waveform manipulations than other wave multipliers available so far. In addition all parameters are both manually adjusted and controlled by external voltages. These are the features of the module:

Controls:

- Input Level (to adjust the input level for best effect of the succeeding controls)
- Multiples (number of waveform multiplications, manual control)
- Harmonics (additional effect that adds more harmonics similar to the resonance/emphasis control of filters, manual control)
- Folding Level (controls upper and lower folding level, manual control)
- Symmetry (controls symmetry between upper and lower folding level, manual control)

Inputs/Outputs:

- Audio In (also suitable for control signals)
- Multiples CV In (with attenuator)
- Harmonics CV In (with attenuator)
- Folding Level CV In (with attenuator)
- Symmetry CV In (with attenuator)
- Audio Out (resp. processed control signal output)

The Multiples parameter (manual and ext. CV) defines the number of basic wave multiplications within one period. With the Folding Level and Symmetry parameter (both manual and ext. CV) the upper and lower clipping levels of the wave folder units are controlled. The Harmonics parameter (manual and ext. CV) adds some harmonic content by sharpening the waveform edges and adding overshoot peaks. It works a little bit like the resonance control of a VCF. The module is fully DC coupled, i.e. even control signal can be processed with the modules.

Notes: Module A-138j is a four channel mixer with an additional polarity/mute switch for each input. In the upper position of the corresponding switch the inverted signal is used. In the center position the input in question is turned off (mute) and in the lower position the "normal" (i.e. non-inverted) signal is used. The inverting of signals is used especially for control voltage signals (e.g. LFO, ADSR). But even for corellated audio signals this feature is useful. For example for feedback applications or the mixing of original and processed signals (e.g. original and filtered signal to obtain new filter types).
Channel 1 features in addition an Offset function: provided that no plug is inserted into socket Input 1 control Lev.1 generates an adjustable DC voltage (positive or negative depending upon the position of the polarity switch).
On top of that the module is equipped with two types of single outputs and a dual mix output. All inputs and outputs are DC coupled. Consequently the VCAs can be used to mix both audio and control voltages.
Each input is - apart from the polarity/mute switch - equipped with a linear attenuator. The amplification range is 0....1.
The single outputs offer the attenuated and possibly inverted/muted signal of the channel in question. Two version of single outputs are available:

Single Output A: If a plug is inserted into the single output "A" socket the channel in question is removed from the sum signal.
Single Output B: If a plug is inserted into the single output "B" socket the channel in question is not removed from the sum signal. This type of single outputs is available only for the channels 1 and 2.
Based on this flexible structure each channel can be used also individually as attenuator or inverter (i.e. without mixer function).

The output is twice available (two sockets, hard-wired like a multiple).

The distances between the controls and sockets are smaller as for the standard A-100 modules and rubberized small-sized knobs are used. In return the front panel has 6 HP width only. The module is primarily planned for applications where only limited space is available.

Power consumption: 20mA at +12 V and 20mA at -12 V

Depth: 40mm

HP : 6

Notes: Module A-138m is a 4 x 4 matrix mixer with switches for unipolar/bipolar mode for each column. Unipolar means that the controls work as attenuators. Bipolar means that the controls work as polarizers. In this mode the amplification is zero in the middle position of the corresponding control. Turning the knob counterclockwise from the center position the signal is subtracted from the output sum with increasing amount (i.e. negative). Turning the knob clockwise from the center position the signal is added to the output sum with increasing amount. The module is DC-coupled and can be used for both audio and control voltage mixing.

By means of an internal jumper one can select if the four upper controls work as DC offset generators - provided that no patch cord is plugged into the upper input socket. If this feature is not required it can be deactivated by removing the jumper on top left of the pc board. The function is identical to the A-138a/b.

Dimensions
20 HP
20 mm deep

Current Draw
30 mA +12V
30 mA -12V

Notes: Modules A-138p/o are used to built a simple performance mixer (instead of an external stand-alone mixer). Module A-138p is the 4-fold input module, A-138o is the output module that can be combined with one or more A-138p.

A-138p features:

- 4 channels
- Controls and inputs for each channel
- Input (3.5 mm mono socket)
- Signal LED (as a coarse monitor of the incoming level, the level is measured after the gain control)
- Mute switch
- Gain (control to adapt different audio levels)
- Level (the main volume control)
- Aux
- Pan
- Internal jumper for each channel to choose between Aux pre/post main Level control
- Internal connection to the output module and to other A-138p modules

Doepfer A-138p requires A-138o (no stand-alone use).

Notes: ***B-STOCK: Box opened, product in perfect working order***


Module A-140-2 contains two ADSR type envelope generators behind a front panel with 8 HP only.

Each ADSR provides these controls and in/outputs:

- LED (displays the envelope output)
- A: manual Attack control
- D: manual Decay control
- S: manual Sustain control
- R: manual Release control
- Gate Input
- Retrigger Input
- CVT Input with attenuator (CVT = CV Time)
- Envelope Output 1
- Envelope Output 2

The output voltage range for each envelope is 0 - 10V. The time range of Attack/Decay/Release is about 1ms to 30s.

By means of internal jumpers one can select which time parameters are controlled by the CVT input (e.g. D only or D+R or A+D+R) and in which direction (i.e. if an increasing CVT shortens or stretches the time parameter in question).

Socket CVT can be normalled to an internal fixed voltage (i.e. the switching contact is connected to an internal fixed voltage). That way it's possible to change all time parameters simultaneously by means of the CVT control.

Another jumper is used to set output 2 to normal or inverted envelope.

And another jumper is used for the normalling of Gate 2 to Gate 1 (i.e. ADSR#2 is also triggered by Gate 1).

Two more jumpers are used for the optional bus access to the gate signal of the bus for each ADSR. Changing the positions of the mentioned jumpers allows to modify the factory settings.

Notes: Module A-140-2 contains two ADSR type envelope generators behind a front panel with 8 HP only.

Each ADSR provides these controls and in/outputs:

- LED (displays the envelope output)
- A: manual Attack control
- D: manual Decay control
- S: manual Sustain control
- R: manual Release control
- Gate Input
- Retrigger Input
- CVT Input with attenuator (CVT = CV Time)
- Envelope Output 1
- Envelope Output 2

The output voltage range for each envelope is 0 - 10V. The time range of Attack/Decay/Release is about 1ms to 30s.

By means of internal jumpers one can select which time parameters are controlled by the CVT input (e.g. D only or D+R or A+D+R) and in which direction (i.e. if an increasing CVT shortens or stretches the time parameter in question).

Socket CVT can be normalled to an internal fixed voltage (i.e. the switching contact is connected to an internal fixed voltage). That way it's possible to change all time parameters simultaneously by means of the CVT control.

Another jumper is used to set output 2 to normal or inverted envelope.

And another jumper is used for the normalling of Gate 2 to Gate 1 (i.e. ADSR#2 is also triggered by Gate 1).

Two more jumpers are used for the optional bus access to the gate signal of the bus for each ADSR. Changing the positions of the mentioned jumpers allows to modify the factory settings.

Notes: The module contains two ADSR type voltage controlled envelope generators with exponential curve shapes (charge/discharge curves of a capacitor) behind a front panel with 8 HP only.

Each ADSR provides these controls and in/outputs:

- LED (displays the envelope output)
- A: manual Attack control
- D: manual Decay control
- S: manual Sustain control
- R: manual Release control
- Gate Input
- Retrigger Input
- CVT Input with attenuator (CVT = CV Time)
- Envelope Output 1
- Envelope Output 2

The output voltage range for each envelope is 0 - 10V (10V = attack peak).

The time range of Attack/Decay/Release is about 1ms to 30s.

By means of internal jumpers one can select which time parameters are controlled by the CVT input (e.g. D only or D+R or A+D+R) and in which direction (i.e. if an increasing CVT shortens or stretches the time parameter in question).

Socket CVT can be normalled to an internal fixed voltage (i.e. the switching contact is connected to an internal fixed voltage). That way it's possible to change all time parameters simultaneously by means of the CVT control.

Another jumper is used to set output 2 to normal or inverted envelope.

And another jumper is used for the normalling of Gate 2 to Gate 1 (i.e. ADSR#2 is also triggered by Gate 1).

Two more jumpers are used for the optional bus access to the gate signal of the bus for each ADSR.

Notes: The A-141-2 module is an ADSR envelope generator with voltage controlled attack, decay, sustain and release parameters. Other features include LFO functionality as well as digital end-of-attack and end-of-release outputs. Besides positive and inverted outputs there is an output with voltage controlled amplitude available.

Attack, Decay, Sustain and Release parameters of the A-141-2 can be adjusted manually as well as via control voltages. The CV inputs come equipped with attenuators. In addition, a Comm-CV socket was implemented. Control voltages fed to this input influence all time parameters (A, D and R) simultaneously. Thus, it is possible to make high pitched notes shorter and more percussive. - Just like the behaviour of many acoustic instruments. The time range of the envelope goes from 50 microseconds to six seconds. Using a toggle switch, it is possible to increase these values by a factor of ten (500 us to 60 s) or a factor of hundred (5 ms to 10 min). To activate the envelope, there are gate and retrigger inputs.

The A-141-2 is equipped with a normal and an inverted output. Both connectors work with a fixed level. Furthermore, there is a third, variable output. Here, before reaching the out socket, the envelope signal is fed to a voltage controlled VCA. - Perfect for velocity CV signals. A jumper on the circuit board allows you to choose between a unipolar and a bipolar mode of operation. Other jumpers make it possible to normalize the CV inputs.

Last but not least, there are two digital outputs called EOA and EOR, which emit a gate signal after the attack respectively release phase. This is useful for delayed triggering of other envelopes. By connecting EOA or EOR output to the gate input, you can make the A-141-2 oscillate like a LFO. Adjustments to the envelope times change the frequency and waveform. If you connect the Attack CV input to the inverted output or the Decay respectively Release CV input to the normal output, you can alter the curve characteristics.

Notes: ***B-STOCK: Box opened, product in perfect working order***


The A-141-2 module is an ADSR envelope generator with voltage controlled attack, decay, sustain and release parameters. Other features include LFO functionality as well as digital end-of-attack and end-of-release outputs. Besides positive and inverted outputs there is an output with voltage controlled amplitude available.

Attack, Decay, Sustain and Release parameters of the A-141-2 can be adjusted manually as well as via control voltages. The CV inputs come equipped with attenuators. In addition, a Comm-CV socket was implemented. Control voltages fed to this input influence all time parameters (A, D and R) simultaneously. Thus, it is possible to make high pitched notes shorter and more percussive. - Just like the behaviour of many acoustic instruments. The time range of the envelope goes from 50 microseconds to six seconds. Using a toggle switch, it is possible to increase these values by a factor of ten (500 us to 60 s) or a factor of hundred (5 ms to 10 min). To activate the envelope, there are gate and retrigger inputs.

The A-141-2 is equipped with a normal and an inverted output. Both connectors work with a fixed level. Furthermore, there is a third, variable output. Here, before reaching the out socket, the envelope signal is fed to a voltage controlled VCA. - Perfect for velocity CV signals. A jumper on the circuit board allows you to choose between a unipolar and a bipolar mode of operation. Other jumpers make it possible to normalize the CV inputs.

Last but not least, there are two digital outputs called EOA and EOR, which emit a gate signal after the attack respectively release phase. This is useful for delayed triggering of other envelopes. By connecting EOA or EOR output to the gate input, you can make the A-141-2 oscillate like a LFO. Adjustments to the envelope times change the frequency and waveform. If you connect the Attack CV input to the inverted output or the Decay respectively Release CV input to the normal output, you can alter the curve characteristics.

Notes: The A-141-2 module is an ADSR envelope generator with voltage controlled attack, decay, sustain and release parameters. Other features include LFO functionality as well as digital end-of-attack and end-of-release outputs. Besides positive and inverted outputs there is an output with voltage controlled amplitude available.

Attack, Decay, Sustain and Release parameters of the A-141-2 can be adjusted manually as well as via control voltages. The CV inputs come equipped with attenuators. In addition, a Comm-CV socket was implemented. Control voltages fed to this input influence all time parameters (A, D and R) simultaneously. Thus, it is possible to make high pitched notes shorter and more percussive. - Just like the behaviour of many acoustic instruments. The time range of the envelope goes from 50 microseconds to six seconds. Using a toggle switch, it is possible to increase these values by a factor of ten (500 us to 60 s) or a factor of hundred (5 ms to 10 min). To activate the envelope, there are gate and retrigger inputs.

The A-141-2 is equipped with a normal and an inverted output. Both connectors work with a fixed level. Furthermore, there is a third, variable output. Here, before reaching the out socket, the envelope signal is fed to a voltage controlled VCA. - Perfect for velocity CV signals. A jumper on the circuit board allows you to choose between a unipolar and a bipolar mode of operation. Other jumpers make it possible to normalize the CV inputs.

Last but not least, there are two digital outputs called EOA and EOR, which emit a gate signal after the attack respectively release phase. This is useful for delayed triggering of other envelopes. By connecting EOA or EOR output to the gate input, you can make the A-141-2 oscillate like a LFO. Adjustments to the envelope times change the frequency and waveform. If you connect the Attack CV input to the inverted output or the Decay respectively Release CV input to the normal output, you can alter the curve characteristics.

Notes: Module A-143-3 is a low-cost four-fold modulation oscillator, often called LFO (low frequency oscillator). Like the other modules of the A-143 series (A-143-1 and A-143-2) not a very "exciting" module, just a bread-and-butter device and a simple demon for work. The module contains four simple LFOs. Each LFO is equipped with three waveform outputs: triangle, rectangle and rising sawtooth. The frequency of the sawtooth output is twice the frequency of the other outputs. A three-way switch is used to select one of three frequency ranges mid-low-high, spanning from about two cycles per minute at the lowest, to moderate audio frequency at the highest (about 5 kHz).

If other waveforms or additional LFO features are required (e.g. reset input, adjustable waveform, voltage controlled frequency) the LFO modules A-145, A-146 and A-147 are available.

Notes: Module A-147-2 is the successor of the VCLFO A-147 but offers much more features than the predecessor. The module is made of these sub-units:

- VCLFO: voltage controlled low frequency oscillator
- VCA: voltage controlled amplifier, switchable to voltage controlled polarizer
- VC delay unit: voltage controlled linear attack envelope (only one parameter: attack) for delayed LFO operation in combination with the VCA (e.g. delayed vibrato/tremolo)

LFO: The voltage controlled LFO has the waveforms Triangle, Sine, Sawtooth and Rectangle available and features a Reset/Sync input. Triangle/Sine and Rectangle are displayed by means of dual-colour LEDs (probably red/green), Sawtooth has a unicolor LED available (probably blue). The output levels are about -4V...+4V for Triangle, Sine and Rectangle. The Sawtooth level is about 0...+8V.

The CV control can be switched to attenuator or polarizer ("CV Mode" switch). In polarizer mode the CV inputs affects the frequency in the reverse manner when the CV control is left from the centre position. In the centre position CV has no effect and right from the centre the control works like a normal attenuator. The frequency range (without external CV) is from about 0,005 Hz (i.e. about 3 minutes per period) to 200 Hz (with external CV max. frequency about 1kHz). In addition a ultra-low mode can be activated by means of an internal jumper. When the ultra-low jumper is set a fixed voltage is connected to the switching contact of the "LFO CV" socket. In polarizer mode of the CV control that way extremely low frequencies (up to one hour period and more) are possible. For this a jumper has to be installed on the pin header JP6. In the factory a dummy jumper is installed on the pin header JP7 "Dummy". JP7 has no function and is used only for "parking" of the jumper. Simply remove the jumper from JP7 and plug it on JP6. JP6 is located behind the CV control.

VCA: This is a linear VCA that can be switched to "normal" VCA (i.e. kind of a voltage controlled attenuator) or voltage controlled polarizer ("VCA Mode" switch). In the "normal" VCA mode amplification +1 is achieved with about +5V control voltage. In polarizer mode the amplification ranges from about -0.5 (i.e. inverted signal with about 50% level) with 0V CV to +0.5 (i.e. non-inverted signal with about 50% level) with +5V CV. With about +2.5V CV the signal is suppressed. Details about the functioning of a voltage controlled polarizer can be found in the description of the module A-133. In this mode the VCA can be treated also a DC coupled ring modulator (similar to A-114).

The VCA of the A-147-2 has three sockets available: "In" (signal input), "Out" (signal output) and "CV" (control voltage input).

The Triangle Output of the LFO is normalled to the VCA signal input by means of the switching contact of the "VCA In" socket. If another LFO waveform (or any other signal) should be processed by the VCA the corresponding signal has to be patched to the "VCA In" socket. The VCA can be used also independently from the LFO and the Delay CV. In this case the VCA sockets In, Out and CV have to be patched accordingly. The VCA can be used also as waveshaper for the LFO signals (e.g. by patching VCA In and VCA CV to different LFO signals, if necessary via attenuator A-183-1 or offset generator/attenuator A-183-2).

Attack/Delay: The third sub-unit of the module is a simple, voltage controlled envelope generator that has only the parameter "Delay" (or Attack) available. This unit generates a linear increasing voltage that starts from 0V after each Delay Reset until it reaches about +5V. Then the voltage remains at +5V until the next Delay Reset occurs. The inclination or gradient is controlled by the manual Delay control and the Delay control voltage ("Delay CV" input). The waveform is linear, the control scale is exponential. The output voltage is displayed by a green LED and available at the "Delay Out" socket.

The manual Delay control ranges - without external "Delay CV" - from about 5ms (fully CW) up to 2 minutes (fully CCW). By means of an external voltage applied to the "Delay CV" socket this range can be extended. A rising CV shortens the delay time (behaviour like a VCO)!

The Delay output voltage ranges from about 0V to +5V. The rising edge of the gate, clock or trigger signal applied to the "Delay Reset" sockets resets the Delay output voltage to 0 V.

"Delay Out" is normalled to the VCA CV input by means of the switching contact of the "VCA CV" socket and consequently controls the Triangle level provided that no other patch is made. A typical example is the usage of a Gate signal (e.g. from a USB/Midi-to-CV/Gate interface) as Delay Reset. That way a delayed vibrato or tremolo can be realized if the VCA output is patched to the frequency CV input of a VCO (or VCF), or the CV input of a VCA.

Notes: Module A-147-2 is the successor of the VCLFO A-147 but offers much more features than the predecessor. The module is made of these sub-units:

- VCLFO: voltage controlled low frequency oscillator
- VCA: voltage controlled amplifier, switchable to voltage controlled polarizer
- VC delay unit: voltage controlled linear attack envelope (only one parameter: attack) for delayed LFO operation in combination with the VCA (e.g. delayed vibrato/tremolo)

LFO: The voltage controlled LFO has the waveforms Triangle, Sine, Sawtooth and Rectangle available and features a Reset/Sync input. Triangle/Sine and Rectangle are displayed by means of dual-colour LEDs (probably red/green), Sawtooth has a unicolor LED available (probably blue). The output levels are about -4V...+4V for Triangle, Sine and Rectangle. The Sawtooth level is about 0...+8V. The CV control can be switched to attenuator or polarizer ("CV Mode" switch). In polarizer mode the CV inputs affects the frequency in the reverse manner when the CV control is left from the centre position. In the centre position CV has no effect and right from the centre the control works like a normal attenuator. The frequency range (without external CV) is from about 0,005 Hz (i.e. about 3 minutes per period) to 200 Hz (with external CV max. frequency about 1kHz). In addition a ultra-low mode can be activated by means of an internal jumper. When the ultra-low jumper is set a fixed voltage is connected to the switching contact of the "LFO CV" socket. In polarizer mode of the CV control that way extremely low frequencies (up to one hour period and more) are possible. For this a jumper has to be installed on the pin header JP6. In the factory a dummy jumper is installed on the pin header JP7 "Dummy". JP7 has no function and is used only for "parking" of the jumper. Simply remove the jumper from JP7 and plug it on JP6. JP6 is located behind the CV control.

VCA: This is a linear VCA that can be switched to "normal" VCA (i.e. kind of a voltage controlled attenuator) or voltage controlled polarizer ("VCA Mode" switch). In the "normal" VCA mode amplification +1 is achieved with about +5V control voltage. In polarizer mode the amplification ranges from about -0.5 (i.e. inverted signal with about 50% level) with 0V CV to +0.5 (i.e. non-inverted signal with about 50% level) with +5V CV. With about +2.5V CV the signal is suppressed. Details about the functioning of a voltage controlled polarizer can be found in the description of the module A-133. In this mode the VCA can be treated also a DC coupled ring modulator (similar to A-114).

The VCA of the A-147-2 has three sockets available: "In" (signal input), "Out" (signal output) and "CV" (control voltage input).

The Triangle Output of the LFO is normalled to the VCA signal input by means of the switching contact of the "VCA In" socket. If another LFO waveform (or any other signal) should be processed by the VCA the corresponding signal has to be patched to the "VCA In" socket. The VCA can be used also independently from the LFO and the Delay CV. In this case the VCA sockets In, Out and CV have to be patched accordingly. The VCA can be used also as waveshaper for the LFO signals (e.g. by patching VCA In and VCA CV to different LFO signals, if necessary via attenuator A-183-1 or offset generator/attenuator A-183-2).

Attack/Delay: The third sub-unit of the module is a simple, voltage controlled envelope generator that has only the parameter "Delay" (or Attack) available. This unit generates a linear increasing voltage that starts from 0V after each Delay Reset until it reaches about +5V. Then the voltage remains at +5V until the next Delay Reset occurs. The inclination or gradient is controlled by the manual Delay control and the Delay control voltage ("Delay CV" input). The waveform is linear, the control scale is exponential. The output voltage is displayed by a green LED and available at the "Delay Out" socket.

Notes: Module A-147-2 is the successor of the VCLFO A-147 but offers much more features than the predecessor. The module is made of these sub-units:

- VCLFO: voltage controlled low frequency oscillator
- VCA: voltage controlled amplifier, switchable to voltage controlled polarizer
- VC delay unit: voltage controlled linear attack envelope (only one parameter: attack) for delayed LFO operation in combination with the VCA (e.g. delayed vibrato/tremolo)

LFO: The voltage controlled LFO has the waveforms Triangle, Sine, Sawtooth and Rectangle available and features a Reset/Sync input. Triangle/Sine and Rectangle are displayed by means of dual-colour LEDs (probably red/green), Sawtooth has a unicolor LED available (probably blue). The output levels are about -4V...+4V for Triangle, Sine and Rectangle. The Sawtooth level is about 0...+8V. The CV control can be switched to attenuator or polarizer ("CV Mode" switch). In polarizer mode the CV inputs affects the frequency in the reverse manner when the CV control is left from the centre position. In the centre position CV has no effect and right from the centre the control works like a normal attenuator. The frequency range (without external CV) is from about 0,005 Hz (i.e. about 3 minutes per period) to 200 Hz (with external CV max. frequency about 1kHz). In addition a ultra-low mode can be activated by means of an internal jumper. When the ultra-low jumper is set a fixed voltage is connected to the switching contact of the "LFO CV" socket. In polarizer mode of the CV control that way extremely low frequencies (up to one hour period and more) are possible. For this a jumper has to be installed on the pin header JP6. In the factory a dummy jumper is installed on the pin header JP7 "Dummy". JP7 has no function and is used only for "parking" of the jumper. Simply remove the jumper from JP7 and plug it on JP6. JP6 is located behind the CV control.

VCA: This is a linear VCA that can be switched to "normal" VCA (i.e. kind of a voltage controlled attenuator) or voltage controlled polarizer ("VCA Mode" switch). In the "normal" VCA mode amplification +1 is achieved with about +5V control voltage. In polarizer mode the amplification ranges from about -0.5 (i.e. inverted signal with about 50% level) with 0V CV to +0.5 (i.e. non-inverted signal with about 50% level) with +5V CV. With about +2.5V CV the signal is suppressed. Details about the functioning of a voltage controlled polarizer can be found in the description of the module A-133. In this mode the VCA can be treated also a DC coupled ring modulator (similar to A-114).

The VCA of the A-147-2 has three sockets available: "In" (signal input), "Out" (signal output) and "CV" (control voltage input).

The Triangle Output of the LFO is normalled to the VCA signal input by means of the switching contact of the "VCA In" socket. If another LFO waveform (or any other signal) should be processed by the VCA the corresponding signal has to be patched to the "VCA In" socket. The VCA can be used also independently from the LFO and the Delay CV. In this case the VCA sockets In, Out and CV have to be patched accordingly. The VCA can be used also as waveshaper for the LFO signals (e.g. by patching VCA In and VCA CV to different LFO signals, if necessary via attenuator A-183-1 or offset generator/attenuator A-183-2).

Attack/Delay: The third sub-unit of the module is a simple, voltage controlled envelope generator that has only the parameter "Delay" (or Attack) available. This unit generates a linear increasing voltage that starts from 0V after each Delay Reset until it reaches about +5V. Then the voltage remains at +5V until the next Delay Reset occurs. The inclination or gradient is controlled by the manual Delay control and the Delay control voltage ("Delay CV" input). The waveform is linear, the control scale is exponential. The output voltage is displayed by a green LED and available at the "Delay Out" socket.

Notes: Module A-147-5v contains four voltage controlled low frequency oscillators (VCLFO) with triangle waveform outputs. All LFOs share a common frequency control. Each of the LFOs 2, 3 features a Delta control which is used to shift the frequency of the LFO in question up or down. With the Delta controls at center positions the frequencies of all LFOs are roughly the same. To control the frequencies by external control voltages four CV inputs are available which follow roughly the 1V/oct standard.

The module has these controls and in/outputs available:

Control F: manual control of the frequency for all four LFOs
Control Delta F2, F3 and F4: manual control of the frequency shift up/down for the LFO in question
Sockets CV 1...4: Frequency control voltage inputs (normalled from top to bottom)
Sockets with triangle symbol 1...4: triangle outputs
LEDs: visual displays of the triangle outputs (red = positive, yellow = negative output voltage)

Application examples:

Generation of four triangle modulation signals with a common frequency control for all LFOs and individual controls for the frequency deviation of each LFO, manually adjustable and controllable by external control voltages
Generation of modulation signals for polyphonic FM/PWM applications. For this the four CV inputs are connected to the same control voltages which are used to control the frequencies of the corresponding VCOs. That way each LFO follows the frequency of the associated VCO with the possibility to control the frequency of all VCOs (control F) and the frequency deviations (Delta F controls). For the simultaneous modulation depth control the Quad VCA module A-130-4 is recommended.
Generation of complex modulation signals by summing up the outputs (e.g. by means of a mixer module A-138n / A-138i / A-138j)

Technical notes:

The level of the triangle outputs is about +/-5V (10Vpp)
The manually adjustable frequency ranges from about 0.025 Hz (about 40 seconds) to about 50 Hz with the delta controls of LFOs 2, 3 and 4 about center position
The frequency deviations adjusted by the delta controls are about +/-1:5. Example: with 1 Hz in center position the frequency shift ranges from about 0.2 Hz in position -5 to about 5 Hz in position +5 (1 Hz/5 = 0.2 Hz, 1 Hz*5 = 5 Hz).
The manual frequency controls and the control voltage inputs have an exponential control behavior
With external control voltage the max. frequency is about 150 Hz, the minimum frequency
The scale of the CV inputs is roughly 1V/oct (not adjustable)
The CV inputs are normalled from top to bottom. Provided that only socket CV1 is patched CV1 controls the frequencies of all four LFOs.
When each CV input is patched to it's own control voltage each LFO is controlled individually by it's own CV. In this case CV1 controls only the frequency of LFO1.
Internally the rectangle outputs are available at four terminals (typ level +/-10V or 20Vpp). If required they can be wired to four sockets of a DIY breakout module made by the user, 1k protection resistors are recommended to avoid short circuits. If lower levels are required passive attenuators (voltage dividers) may be used.
Internally is even an (unbufferd) triangle sum signal available. For this each of the four triangle outputs is simply connected to the sum output terminal via a 47k resistor. This output has high impedance and should be buffered or amplified to avoid level drop when the load changes (e.g. by means of an A-180-3 or A-180-4 or A-183-3).

By changing the values of the capacitors in the LFO circuits even other frequency ranges are possible (e.g. Quad VCO to form kind of a cloud VCO). Pay attention that the accuracy of the CV input scales is not sufficient for precise 1V/oct VCO applications. The 1V/Oct scales cannot be adjusted and the circuits are not temperature compensated.

Dimensions
4 HP
45 mm deep

Notes: Module A-149-1 is the first module of the A-149-x range. In this group we present by popular request several functions of Don Buchla's "Source of Uncertainty 265/266" (SOU) modules that cannot be realized with existing A-100 modules. Many functions of Buchla's 265 and 266 SOU can be realized with existing A-100 modules. For details please refer to A-100 patch examples.

Module A-149-1 has available four different analogue random control voltages that are generated in different ways.

The "Quantized Random Voltages" section has available 2 CV outputs: "N+1 states" and "2N states". N is an integer number in the range 1...6 that can be adjusted with the manual control (Man N) and an external control voltage CVN with attenuator. Whenever the rising edge of the input clock signal (Clk In) appears a new random voltage is generated at the N+1 resp. 2N output. The N+1 output is capable to generate N+1 different voltage levels (or states), the 2N output up to 2N different states. If for example N is set to 4 the N+1 output generates up to 5, the 2N output 16 different states. The voltage steps of the 2N output are adjusted to 1/12 V in the factory. Consequently, exact semitones can be obtained in combination with a VCO. The voltage steps of the n+1 output are adjusted to 1.0 V in the factory corresponding to octave intervals in combination with a VCO. For each output a trimming potentiometer is available on the pc board that enables the user to select other voltage steps for the output in question.

Even the "Stored Random Voltages" section has 2 stepped CV outputs available: one with even voltage distribution of the max. 256 output states and second one with adjustable voltage distribution probability. The distribution probability is adjusted by a manual control (Man D) and an external control voltage CVD with attenuator. With the control set fully counter-clockwise most of the random voltages will be low magnitude but even medium and high magnitude voltages may appear but with smaller probability. As the control is turned to the right (or a positive control voltage appears at the CVD input) the distribution moves through medium to high magnitude voltage probability. The symbol at the lower jack socket shows this coherence graphically. The voltage range is 0...+5V for both outputs of the "Stored Random Voltages" section. For each output a trimming potentiometer is available on the pc board that enables the user to select another voltage range for the output in question.

The A-149-1 can be extended by 8 random digital voltages with the A-149-2 Digital Random Voltages module.

Dimensions
12 HP
60 mm deep

Current draw
40 mA +12V
10 mA -12V

Notes: Module A-149-4 generates four triggered random voltages which meet the criteria choosen by several controls.

Manual controls for the criteria selection:

Octave range (manual control "Oct."): this parameter defines how many octaves are covered by the random voltages (0 ... +5V, with "Oct." control fully CCW only 0V are generated)

Grid (6 illuminated radio buttons): this parameter defines the grid of the random voltages:

Octaves (Oct)

Octaves + Quin (Quint)

Chords

Scale

Semitones

continuous (i.e. stepless)

Minor / Major (2 illuminated radio buttons): this parameter defines in case of chords or scales if they are minor or major. For all other grids this parameter has no meaning

Sixth / Seventh (2 illuminated separate buttons): these parameters defines if the sixth or seventh is added. Valid only if Oct, Quint, Chord or Scale is chosen as grid.

The output voltages follow the 1V/octave standard with exception of the Continuous mode. The voltages in this mode are totally random and do not follow the 1V/oct standard (i.e. not a multiple of 1/12V).
The generation of a new random voltage at the output (CV Out 1...4) is triggered by the corresponding trigger input (Trig. In 1...4). The trigger inputs are normalled top down. The minimum trigger level is +2.5V (up to max. +12V).

Applications:

random polyphonic structures (in combination with the polyphonic modules A-111-4, A-105-4, A-132-8, A-141-4 and e.g. A-157 as trigger source and A-173-1/2 for transposition of the polyphonic structures)

any application that requires several random voltages

Width: 4 HP / 20.0 mm
Depth: 45mm (measured from the rear side of the front panel)

Notes: Module A-150-8 contains eight manually/voltage controlled switches. Each of the eight switches has a manual control button (Man.), a control voltage input (CV), a common Out / Input (O/I), and two In / Outputs (I/O1, I/O2). The switches are bi-directional, i.e. they can work in both directions, so can connect one input to either of two outputs, or either of two inputs to one output. Two LEDs show which in / output is active (i.e. which is connected to the common out / input). In addition, the LEDs are used for the programming of the module:

For each unit the operating mode can be selected: Toggle or Level controlled. In Toggle mode the rising edge of the CV input or operating the manual control button changes the state of the switch. In Level mode the switch state is defined by the voltage applied to the CV input (low voltage = I/O1, high voltage = I/O2) or by the state of the manual control button (not pressed = I/O1, pressed = I/O2). The modes are programmed very easily: Operating the Toggle/Level button of the program section displays the current state of each switch with the LEDs: left LED on = Toggle mode, right LED on = Level mode. Operating the manual control button of the switch in question changes the toggle/level mode while the Toggle/Level button of the program section is operated. During the programming patched CV signals may have to be removed as the CV signals would interfere with the manual operating buttons during the programming process.

In addition, it's possible to define master/slave groups. In such a group the upper unit (= master) controls also the state of the following switches provided that they are defined as slaves. Master/slave programming is also very simple: Operating the Master/Slave button of the program section displays the current state of each switch with the LEDs: left LED on = Master, right LED on = Slave.

When all 8 units are defined as master all switches are independent from each other. If for example the sequence is MSSSMSMS the control unit of the first switch also controls the switches 2, 3 and 4. The control unit of switch 5 also controls the switch 6, and the control unit of switch 7 also controls the switch 8. The current states of the slave switches are overwritten by the state of the master switch.

Technical note: To protect the electronic switches in case of an unsuitable patch (e.g. connection of two outputs) a 1k protection resistor is inserted into the O/I line of each switch. If control voltages used for VCOs are switched this may cause a small voltage drop and lead to undesired audible detuning. For this application we recommend to insert a CV buffer between A-150-8 and the VCO(s), e.g. the Buffered Multiple A-180-3 or the Precision Adder A-185-2. Integrating the buffers into the module A-150-8 was not possible because this would ruin the bidirectionality of the switches.

Notes: Module A152 is a very useful switching and T&H module. It combines a voltage addressed 1-to-8 multiplexer and 8 fold T&H that can be used as kind of an analogue shift register too. The active in/output is displayed by a LED. The digital output of the currently addressed step outputs "high". The remaining digital outputs are low.

Instead of voltage control even clock/reset controlled addressing of the active step is possible. The rising edge of each clock signal causes an advance to the next state. The rising edge of the reset signal resets to step 1.

The sum of the voltages coming from the manual Address control and the CV input define the currently addressed step of the 3 sub-devices. If the module is controlled by clock and reset the control voltage has to remain unchanged as the CV control has priority over the clock/reset control (e.g. simply turn the CV control fully counter-clockwise and do not touch the Address control knob).

Sub-device #1 is the bidirectional 8-fold multiplexer (kind of an electronical 8-fold rotary switch). Bidirectional means that it works into both directions like a mechanical rotary switch: the common socket may work as an output that is connected to one of the 8 inputs that are e.g. connected to modulation or audio sources. But the common socket may even function as input. In this case the signal applied to the common socket is output to the currently addressed single socket. The voltage range of the in/outputs to be switched is the full A-100 voltage range -12V....+12V. All A-100 signals can be switched without any restrictions.

Sub-device #2 is the addressed 8-fold T&H. The signal at the common T&H input is connected to the addressed T&H output. As soon as a new output is addressed the last voltage is stored at the output (Track&Hold function). The T&H section of the A-152 allows the emulation of the "toggling T&H" function of the Buchla module 266 "Source of Uncertainty". Only the first two T&H outputs of the A-152 are required for this application. This unit can be used also as kind of an analogue (shift) register. The difference to a "real" analogue shift register is that the sampled output voltages are not shifted to the next output but remain allocated to the same output. But in some cases (e.g. controlling the pitch of 3 VCOs by 3 output voltages of the A-152) the result is the same.

Sub-device #3 is the digital output section. The digital output of the currently addressed turns to "high". All other digital outputs are low. The digital outputs can be used to trigger e.g. envelope generators or to control the reset input in the clocked mode to reduce the number of addressed stages.