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Notes: Module A-145 is a low frequency oscillator, which produces cyclical control voltages in a very wide range of frequencies.

Five waveforms are available: sawtooth, inverted sawtooth, triangle, sine and square wave. The LFO can be used as a modulation source for any number of modules - for instance modulating the pulse width or frequency of a VCO, modulation of the cut-off frequency of a VCF, or amplitude modulation with a VCA.

A three-way switch lets you select three frequency ranges, spanning from one cycle every several minutes at the lowest, to moderate audio frequency at the highest (about 4-5 kHz).

The LFO signal can also be synchronised, via the reset input.

Identical to the A-145-1, but only 4 HP wide and with additional LEDs for the square wave and the sawtooth signal.

Power consumption: 30mA at +12V and 20mA at -12V
Depth: 45mm
4 HP

Notes: Module A-119-2 is a Dual external input amplifiers with only 4HP module width. The module contains two amplifiers with separately adjustable amplification levels. Each channel is equipped with an overload display. The module can also be used for stereo signals, e.g. the stereo output of a smartphone.

Controls and displays:

Level 1/2: manual control of the amplification in the range 0 - about 45.
Overload 1/2: overload LED, begins to light up for output levels beyond about 10Vpp (+/-5V)
In 1: audio input 1 (monophonic or stereophonic, see technical details)
In 2: audio input 2 (monophonic)
Out 1/2: audio output (monophonic)

Technical Details:

For higher amplifications the two amplifiers can be daisy-chained
Different normallling options are available via the rear of the modules with jumpers.
All inputs and outputs are DC coupled. Thus the module can be used also for the amplifications of control voltages.

Power consumption: 20mA at +12V and 20mA at -12V
Depth: 30mm
4 HP

Notes: A-149-3 is the third module of the A-149-x range. In this group, this module present several functions of Don Buchla's "Source of Uncertainty 265/266" (SOU) modules that cannot be realized with existing A-100 modules. Some functions of Buchla's 265 and 266 SOU can be realized with existing A-100 modules.

Module A-149-3 is based on the homonymous "Fluctuating Random Voltages" by Buchla. Compared to the historic original, a lot of functions have been added. For example the user has access to virtually all internal signals (e.g. Noisy Triangle or S&H) and there are a lot of adjustable parameters which were fixed in the original.

For example, the frequency and noisiness of the internal triangle oscillator, the correlation of the S&H and manual or automatic frequency control of the S&H clock oscillator. The fixed internal connections of the original are wired to sockets in the A-149-3 and can be used also individually as the connections of the original are realized as normalled sockets. That way e.g. the S&H or slew unit can be used independent from the other units.

The functions in detail:

As in the original a digital noise signal is filtered in three different ways. The three "noise flavours" are available at three sockets and can be used for all kind of noise applications:

+3db (+3dB per octave, a bright noise, also called blue noise)
-3dB (-3dB per octave, a dark noise, also called red or brown noise, Allan Strange calls it "reciprocal white noise")
Flat (flat spectrum, also called pink noise)

In the original the -3dB output is used add some noise to an internal triangle oscillator with fixed frequency (~ 100 Hz) and fixed "noisiness". The result is called "noisy triangle". In the A-149-3 the frequency of the triangle oscillator and the level of the noisiness can be adjusted. The frequency is adusted by means of the Frq. control and the Range switch (~ 110Hz ... 5 seconds period in position high). In addition one can select between the -3dB and Flat output as noisiness source by means of an internal jumper. When Noisiness control is fully CCW one obtains a clean undisturbed triangle signal. With Noisiness control fully CW the result is a triangle signal with a lot of noise or randomness. The noisy triangle signal is available at the socket "N Tri" and is displayed with a dual colour LED.

The "N Tri" signal is normalled to the signal input of the subsequent Sample&Hold unit (S&H). The clock signal for the S&H is generated by an internal rectangle oscillator. This signal is normalled to the S&H clock socket and is displayed by an LED. One can select between manual and automatic control of the clock period by means of a toggle switch. In position "man." the period is controlled manually by the "Period" control. With control "Period" fully CCW one obtains the shortest period or highest frequency. Turning the control up increases the period or lowers the frequency. In position "auto" of the switch the period is controlled by the slew unit.

In this position a vactrol is used to define the frequency of the S&H clock. This vactrol is controlled in the same way as the vactrols of the slew unit, i.e. the period of the S&H clock changes simultaneously with the slew time. In the historic original only the auto mode was available. There was no manual control available.

The S&H has another special feature: the Correllation control. It's a feedback function where shares of the S&H output are fed back to the S&H signal input and mixed with the actual S&H input signal. The result is slurring the signal like a sub-audio lowpass filter, kind of a "digital slew function" because the gradation of the signal persists.

The S&H output is availabe at the corresponding socket and is displayed with a dual colour LED.

The S&H output is normalled to the signal input of the subsequent Slew Limiter unit (SL). The core of the slew limiter are two vactrols (vactrol = combination of a light emitting diode/LED and a light dependent resistor/LDR built into lightproof case). The brightness of the vactrol LEDs can be controlled manually (control "Man." of the slew unit) and by an external control voltage (socket "SL CV" with associated attenuator "CV" of the slew unit). The brightness of the vactrol LEDs is displayed at the top of the front planel. As already mentioned a third vactrol can be used to control the frequency of the S&H clock oscillator simultaneously to the slew limiter. The SL output is availabe at the corresponding socket and is displayed with a dual colour LED.

Due to the access facilities to many of the internal signals and connections it's possible to use the sub-units also for other applications. E.g. the noisy triangle signal, the S&H unit (incl. correlation) or the SL unit can be used for other signals. The S&H clock can be applied also from outside to synchronize the S&H to other signals.

If required, the internal clock signal is available at a pin header of the pc board.

Controls, Switches and Displays:

Slew Unit

Man.: manual adjustment of the slew time

CV: attenuator for the SL CV input

LED: display of the slew function (bright = short slew lime, dark = long slew time), identical to the brightmess of the vactrol LEDs

Triangle LFO

Frq.: LFO frequency, range ~ 110 Hz ... 5 seconds period

Noise: adjustment of noisiness (= perturbance of the triangle signal)

+3dB/-3dB: switch for the source of noisiness

LED: display of the noisy triangle signal, dual color LED (rot = positive / yellow = negative output voltage)

Sample&Hold (S&H)

Period: period of the internal clock signal for the S&H unit, fully CCW = shortest period or highest frequency, fully CW = longest period or lowest frequency

LED: display of the internal clock signal

Correl.: adjustment of the correllation of the S&H unit

Man./Auto: switching between manual and automatic control of the clock frequency, when auto is selected the clock frequency is controlled by the slew unit

LED: display of S&H output, dual color LED (rot = positive / yellow = negative output voltage)

Slew Limiter (SL)

LED: display of SK output, dual color LED (rot = positive / yellow = negative output voltage)

Sockets:

+3dB : filtered digital noise with +3dB per octave (output)

-3dB : filtered digital noise with -3dB per octave (output)

Flat : flat noise output

N Tri : Noisy Triangle output, about 10Vpp (-5V ... +5V)

S&H In: S&H signal input, normalled to N Tri

S&H Out : S&H signal output

SL CV: control voltage of the slew limiter unit, connected to the corresponding attenuator "CV" of the slew unit

S&H Clk: clock input of the S&H unit, normalled to the internal clock oscillator

SL In: slew limiter input, normalled to S&H Out

SL Out : slew limiter output

The arrow symbols indicate the normalling of sockets. Outputs are inverse labelled.

Technical details:

Frequency range of the triangle LFO: about 110 Hz ... 5 seconds period
Output level of the triangle LFO: ~ 10 Vss (-5 V...+5 V)
Frequency range of the internal clock oscillator: about 3 seconds ... 30Hz
Output level of the internal clock oscillator: ~ 10 Vss (0 V...+10 V)
Required input level of the S&H clock input: +5V

Depth: 45mm
8 HP

Notes: Blank panel, 4HP, constructed from anodised aluminium, silver.

Notes: - High-grade patch cable designed for modular units
- 3.5mm mono jack plugs
- Length: 15cm
- Yellow finish

Notes: Patch cable for ultra short connections in the modular synthesiser 8.5 cm, white mono jack plugs 3.5 mm at both ends

Notes: Blank panel, 42HP, constructed from anodised aluminium, silver.

Notes: - High-grade patch cable designed for modular units
- 3.5mm mono jack plugs
- Length: 80cm
- Red finish

Notes: - High-grade patch cable designed for modular units
- 3.5mm mono jack plugs
- Length: 200cm
- Green finish

Notes: - 6.3 mm jack male mono to 3.5 mm jack male mono
- Length: 1.5 metres

Notes: Blank panel, 8HP, constructed from anodised aluminium, silver.

Notes: - High-grade patch cable designed for modular units
- 3.5mm mono jack plugs
- Length: 30cm
- Black finish

Notes: - High-grade patch cable designed for modular units
- 3.5mm mono jack plugs
- Length: 50cm
- Angled connector on one end
- Orange finish

Notes: - 6.3 mm jack male mono to 3.5 mm jack male mono
- Length: 3 metres

Notes: Module A-124 is a special 12dB multimode filter using the "strange" filter circuit of the "EDP Wasp" (an analog synthesizer with black/yellow case built end of the seventies, manufactured by the UK company "Electronic Dream Plant" with Chris Huggett und Adrian Wagner). This design "abuses" digital inverters as analog operational amplifiers leading to distortions and other "dirty" effects that generate the specific sound of this filter. The filter is equipped with a band pass output and a combined low/notch/high pass output. For this output a control knob defines the relation between low and high pass signal. If both signals appear at the same level (i.e. middle position of the Mix knob) one obtains a notch filter. Otherwise the low or high pass signal predominates. The module does not feature self-oscillation in contrast to most of the other filters of the A-100 system.

Inputs: Audio In, CV In (2x)
Outputs: Bandpass Out, Low/Highpass Mix-Out
Controls: Audio and CV attenuator, Frequency, Resonance, LP/HP Mix

The function and operation of this module is very similar to the module SEM VCF A-106-5. But the sound of both filters is very different! The only functional difference is the position of the sockets and controls, and the function of the controls CV2 (A-124: normal attenuator, A-106-5: polarizer).

- 3U Eurorack module, 8HP wide, 45mm deep
- Current draw 30mA

Notes: Module A-160-2V is an enhanced version of the standard clock divider A-160. The module is a frequency divider for clock/trigger/gate signals, designed to be a source of lower frequencies, particularly for rhythm uses.

The Clock input will take any digital signal from, eg., an LFO, MIDI sync, or the gate from a MIDI-CV interface. At the outputs, you have access to three sets of seven different sub-divided clock signals, from half the clock frequency down to 1/128. The low/high levels of the output signals are 0V and about +10V.

The A-160-2V also has a reset input. Whenever a reset signal is sensed, all outputs are set to certain levels which depend upon the selected mode.

HP : 4

Notes: A-138s is a simple but useful 4-in-2 mixing tool. It has four inputs available. Each input is equipped with an attenuator (Level) and a panning control that is used to distribute the signal to the left and right output. Beyond stereo mixing it is equally suited to create variable parallel routings. For example: Any of the four inputs may be routed in variable intensity to feed two filters.

You may regard the A-138s as a smaller version of the A-138m Matrix Mixer.

Inputs and outputs are DC coupled, i.e. the module can be used for the mixing of control signals too.

- 3U Eurorack module, 8 HP wide, 30 mm in depth
- Power consumption: 10 mA at +12 V and 10 mA at -12 V

Notes: - High-grade patch cable designed for modular units
- 3.5mm mono jack plugs
- Length: 120cm
- Blue finish

Notes: Module A-130-2 is the slim version of module A-132-3 and offers essentially the same features. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is half the width of the A-132-3. The module is primarily planned for applications where only limited space is available.

The module is composed of two identical voltage controlled amplifiers (VCA). Each VCA has a manual gain control (also named Initial Gain) 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 (e.g. for voltage control of the level of LFO or envelope signals). The signal input has no attenuator available but is capable to process up to 16Vpp signals (i.e. -8V...+8V) without distortion. For the processing of higher levels an external attenuator (e.g. A-183-1) is recommended.

The amplification range is 0...1. Even with a higher external control voltage the amplification remains at 1 (kind of "amplification clipping" at 1).

Controls (for each of both units):

- Gain: manual gain control (Initial Gain) in the range 0...1
- CV: attenuator for the CV input
- Lin/Exp: switches the VCA characteristic to linear or exponential, in center position the VCA is off (mute function)

Inputs and outputs (for each of both units):

- CV: control voltage input, min. +5V required for max. amplification (1) with CV control fully CW and Gain fully CCW
- In: signal input, max. 16Vpp (+8V...-8V) without distortion
- Out: signal output

Notes: Blank panel, 2HP, constructed from anodised aluminium, silver.

Notes: - High-grade patch cable designed for modular units
- 3.5mm mono jack plugs
- Length: 50cm
- Grey finish

Notes: - High-grade patch cable designed for modular units
- 3.5mm mono jack plugs
- Length: 50cm
- Transparent cabling

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: A-182-2 is a simple passive module that contains four changeover switches, which are used to connect or disconnect the sockets of the corresponding socket triplet:

- In the upper position of the switch the upper socket of the corresponding socket triplet is connected to the centre socket
- In the lower position of the switch the lower socket of the corresponding socket triplet is connected to the centre socket
- In the centre position of the switch the sockets are not connected

Each unit of the module can be used to switch between two signals or to interrupt/connect a signal. In the last case the third socket of the triplet is not used.

The module is fully passive and both audio or control signals can be switched.

Notes: Module A-185-2 is a precision control voltage adder/buffer. Precision means that the amplification of the inputs without attenuators is exactly 1.00 and is suitable to add control voltages for the pitch control of VCOs (e.g. from keyboard + sequencer 1 + sequencer 2). Summing resistors matched to 0.1% are used to obtain an accuracy of 0.1% for the added voltages.

The module is equipped with four CV inputs: one with attenuator and three without attenuator. Each input is normalled to +1 V (i.e. if no plug is inserted the input contributes 1 V to the sum appearing at the output).

The input with attenuator can be used for common modulations (e.g. from an LFO, ADSR, Theremin, Pitch-Bender) for all VCOs connected to the output. The Lev.1 control is used to adjust the depth of the modulation, the first switch selects the polarity of the modulation. If no signal is connected to the first socket the attenuator works as a (fine) tuning knob because a voltage in the range 0...+1V (right position of the switch) or 0...-1V (left position of the switch) is added to the CV output.

The inputs without attenuators are planned to add control voltages coming out of keyboards, sequencers, Midi-to-CV interfaces, ribbon controllers or other CV sources that follow the 1V/oct standard. For example the CV of a keyboard can be used to transpose the CV coming from a sequencer, or the CV of a slow sequencer can be used to transpose the CV from a fast sequencer.

Each input is equipped with a three-position switch that determines if the corresponding voltage is added (right position), subtracted (left position) or if the input has no effect (centre position). If no plug is inserted the corresponding switch works as an octave switch for the lower three sections as the default 1 V are added or subtracted to the output voltage according to the switch position. The first switch can be used to add a variable voltage to the sum output. The variable voltage is adjusted with the Lev.1 control and the knob works then as kind of a (fine) tuning control.

The module is equipped with 4 outputs: three non-inverting and one inverting ouput. An internal jumper can be used to connect the non-inverted or inverted output to the CV line of the A-100 bus. That way the module can used to control several VCOs that are connected to the same bus board as the A-185-2 (same functionality as A-185-1).

Notes: Compact and simple four-input mixer module from Uncle Dieter. Linear pots make it suited to mixing CV signals but it can also handle audio. Mixed signal hard-wired to two sockets.

Supplier notes:
Module A-138n is a simple four channel mixer, which can be used with either control voltages or audio signals. Each of the four inputs has an attenuator available. The output is twice available (two sockets, hard-wired like a multiple).

HP : 4

Notes: Module A-188-9 is a so-called high speed VCO that tracks perfectly to the 1V/oct scale in the frequency range of about 15kHz ... 500 kHz. The main application is the exact drive of BBD modules (A-188-1/2) to generate sounds realized by means of the so-called Karplus-Strong synthesis. But even in cooperation with other modules featuring high speed inputs (e.g. digital noise, delay, frequency divider) the A-188-9 makes sense. In principle the module is made of a precision audio VCO followed by a PLL (phase locked loop) unit that multiplies the frequency of the audio VCO by 32. Thus the module can be used also as an audio VCO as it features the standard waveforms sawtooth, triangle and rectangle with adjustable pulse width.

Controls:
Frq: frequency control (coarse)
CV: attenuator for the frequency control input CV
Fine: frequency control (fine), small control without knob
PW: pulsewidth control for the rectangle output of the audio VCO, in HSVCO mode this control has to be in the range marked "HSVO", small control without knob

Sockets:
1V: frequency control input 1V/oct scale
CV: frequency control input with attenuator CV
socket with rectangle symbol: rectangle output of the audio VCO, the pulse width of this output is adjusted by means of the control PW, output level ~ 7Vpp (~ -3.5V/+3.5V)
socket with sawtooth symbol: sawtooth output of the audio VCO, output level ~ 7Vpp (~ -3.5V ... +3.5V)
socket with triangle symbol: triangle output of the audio VCO, output level ~ 7Vpp (~ -3.5V ... +3.5V)
socket with inverted comb symbol: high speed VCO output, waveform rectangle, output level ~ 5Vpp (~ -2.5V/+2.5V)

Switches:
Range
upper position: audio VCO mode (frequency range of the audio VCO about 15 Hz to 6 kHz, the high speed output is not usable in this mode! )
lower position: High Speed VCO mode (frequency range of the high-speed output about 15 kHz ... 500 kHz, frequency range of the audio VCO about 500 Hz ... 15 kHz), in this mode the audio VCO and the high speed VCO can be used simultaneously

Slew
upper position: medium slew time
centre position: short slew time
lower position: long slew time
Technical Note regarding the Slew parameter:

Besides the audio VCO the module contains a so-called PLL circuit (Phase Locked Loop) and a 1:32 frequency divider. A slew limiter is part of the PLL. It defines how fast the frequency of the PLL follows the frequency of the VCO. The PLL cannot follow the VCO without any delay. Rather one has to find a compromise between the residual ripple of the PLL frequency and the frequency follow rate. That is the job of the slew limiter (works in principle like a glide or portamento unit). For this the module is equipped with a 3-position switch that is used to switch the slew time in 3 ranges. When mostly higher frequencies are used ((~ 100kHz ... 500 kHz) a short slew time can be chosen. When also lower frequencies are required (< 100kHz) a longer slew time may be used to reduce the residual frequency ripple. More details about the working principle of a PLL can be found in the information about module A-196. Module A-188-9 is in principle an A-196 combined with an audio VCO and a 1:32 frequency divider.

Width: 4HP / 20.0 mm
Depth: 45 mm (measured from the rear side of the front panel)
Current: +30 mA (+12V) / -15 mA (-12V)

Notes: Module A-192-2 contains two independent CV/Gate-to-Midi/USB interfaces. For each of the two sub-units these inputs are available:

- Gate Input (min. +5V)
- CVN Input (defines the Midi note number), 1V/octave standard, range 0...+10V (i.e. 10 octaves)
- CVV Input (defines the velocity value assigned to the Midi note message), can be used alternatively for Midi volume (CC#7), range 0...+5V
- CVC Input (free assignable to any Midi control change number), range 0...+5V

For both sub-units a common CV Transpose input is available (1V/octave, range 0...+10V). The voltage applied to this input is added internally to CVN before the Midi note number is generated. It can be used e.g. to transpose two sequences simultaneously by one voltage.

How it works:

Whenever the rising edge of the Gate input is recognized a Midi note on message is generated. The note number corresponds to the sum of the voltages applied to the CVN input and the common CV Transpose Input that is present at the rising edge of the gate signal.

Notes: Module A-196 contains a so-called phase locked loop (PLL). The basic PLL system is shown in the sketch at the bottom of this page. A PLL consists of three parts: voltage-controlled oscillator (VCO), phase comparator (PC), and low-pass filter (LPF). All parts are normally connected to form a closed-loop frequency-feedback system.

This is how a PLL works: The output of the internal VCO (linear CV control, rectangle output) is compared with an external signal (e.g. the rectangle output of a A-110 VCO) in the so-called phase comparator (PC). The output of the phase comparator is a digital signal (low/high/tristate) that indicates if the frequency resp. phase difference of the two input signals is negative, zero or positive. The output of the phase comparator is processed by a low pass filter (LPF) to generate a smooth voltage that is used to control the frequency of the internal VCO. The 3 units VCO, PC and LPF form a feedback loop that works like this: The control voltage (output of the LPF) increases as long as the external frequency is higher than the frequency of the internal VCO und stops increasing when both frequencies become identical. The control voltage decreases as long as the external frequency is lower than the frequency of the internal VCO und stops decreasing when both frequencies become identical.

But there are some stumbling blocks: Different types of phase comparators with advantages and disadvantages can be made. Some phase comparators e.g. even lock at harmonics, i.e. if the two frequencies to be compared are integer multiples. But for some applications this can be used to create interesting effects. The A-196 contains 3 different types of phase comparators: PC1 is a simple exclusive OR, that even locks at harmonics. PC2 is a so-called RS flipflop and PC3 a more complex digital memory network. The user can select one of the three phase comparators with a 3-position switch. When PC2 is used a LED displays the "locked" state, i.e. when the frequency of the internal VCO is identical to the external frequency.

Special attention has to be directed to the frequency of the LPF. To obtain a smooth control voltage for the VCO the frequency of the LPF has to be much smaller than the lowest frequency of the internal or external audio signal. Otherwise the frequency of the internal VCO will jitter or wobble around the correct frequency. But for special effects this frequency jitter can be used intentionally. Example: frequencies in the range 50Hz...1kHz have to be processed with the PLL. Therefore the frequency of the LPF has to be about 10Hz or even less. Such a low frequency of the LPF causes a noticeable slew of the internal VCO. When the frequency of the external signal jumps e.g. between 500Hz and 1kHz it takes about 0.1 second until the internal VCO reaches the new frequency (like portamento). So one has to find a compromise between frequency jitter and portamento. But these remarks are valid only for the "ideal" working PLL. As the A-196 is used in a musical environment the "problems" and disadvantages with jitter and slew time lead to additional musical applications like portamento effects, wobbling frequencies or harmonic locking according to the type of frequency comparator and time constant of the PLL low pass filter. Instead of the internal manually controlled low pass filter the voltage controlled slew limiter A-171 can be used to obtain voltage control of this parameter. Normal audio filters (e.g. A-120, A-121) cannot be used for this job as the minimum frequency is to high (down to a few Hz or even less necessary) and the signal has to be DC coupled due to the low frequencies. Audio filters are normally AC coupled.

Another very important application of a PLL is frequency multiplication in combination with an external frequency divider. For this the output of the PLL-VCO is processed through an external frequency divider (e.g. A-163, A-160, A-161, A-115) before it is fed to In1 of the phase comparator. In this case the frequency of the PLL-VCO will be a multiple of the master frequency. E.g. if the A-163 is used and adjusted to dividing factor 5 the frequency of the PLL-VCO will be 5 times the frequency of the master VCO. Consequently, frequency division (A-163) leads to frequency multiplication with the PLL circuit. In combination with the PLL low pass frequency several effects can be realized (frequency multiplication with portamento or wobbling). The frequency multiplication can even be used to drive a graphic VCO. If your graphic VCO e.g. has 8 steps (e.g. A-155) and you use a frequency divider with factor 8 in the PLL feedback the output of the graphic VCO has the same frequency as the master VCO. Another application is the generation of pseudo-harmonics (not real harmonics as only rectangle waves are available) or clock generation for switched-capacitor filters.

Notes: 2HP narrow version of the A-180 multiples module. It is a passive signal splitter suitable for audio or CVs. Two sets of four jacks are interconnected, by placing a solder bridge you can connect all eight jacks.

Dimensions
2 HP
18 mm deep

Current Draw
Module does not draw current

Notes: Module A-138n is a simple four channel mixer, which can be used with either control voltages or audio signals. Each of the four inputs has an attenuator available. The output is twice available (two sockets, hard-wired like a multiple).

The module is the slim version of module A-138a and offers nearly the same features. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is half the width of the A-138a. The module is primarily planned for applications where only limited space is available. The only functional difference compared to the A-138a is the missing attenuator for the (dual) output.

Width: 4HP / 20.0 mm
Depth: 30 mm (measured from the rear side of the front panel)
Current: +10mA (+12V) / -10mA (-12V)

Notes: Module A-156 is a Dual Control Voltage Quantizer. A quantizer converts a continuous control voltage in the range 0...+10V into a stepped output voltage in the same voltage range (i.e. only certain voltages occur). Normally 1/12 V steps are used to obtain semitone steps. Quantizer 2 of the A-156 allows has more sophisticated quantizing modes like major scale (i.e. only voltages corresponding to the major scale), minor scale, major chord, minor chord, fundamental + fifth and addition of seventh or sixth when chords are selected. Only those voltages appear at the CV output which comply with the selection rule (e.g. minor chord with seventh). The mode setting of quantizer 2 is done with 3 switches (1-0-1 type with middle position). From the factory quantizer 1 is working in the semitone mode. But there is a jumper on the pc board that can be changed so that even quantizer 1 uses the same scale as quantizer 2.

For each quantizer the following in/outputs are available:

- Control voltage input (CV In): The input for the continuous voltage to be quantized
- Control voltage output (CV Out): The output of the quantized voltage
- Trigger input (Trig.In): If this jack is left open the quantizer is working permanently. If a rectangle voltage is applied quantisation happens only at the rising edge of the signal (e.g. from an LFO or MIDI-to-Sync interface). Thus the quantizing can be synchronized with other events
- Trigger output (Trig.Out): Whenever a quantisation happens (i.e. a new voltage is generated at the CV Out) a positive pulse occurs at this output. It may be used to trigger an envelope generator (ADSR) or for triggering other modules (sequential switch A-151, trigger divider/sequencer A-160/161, trigger delay A-162, ...). If none of these functions are used the jack is left open

On top of that the A-156 is provided with a common transpose CV input having an additive effect on both quantizers. This input is quantized in semitone steps. A typical application is the transposition of a sequence generated by the A-155 by a second control voltage (e.g. coming from the MIDI-CV interface A-190).

Typical applications:

- Quantizing the CV sequence generated by an A-155 (semitone, only major scale, only minor scale and so on)
- Quantizing the voltage coming from the Trautonium Manual / Ribbon Controller A-198, Theremin A-178 or Light-to-CV module A-179 to get accurate semitones or major/minor scale tones
- Arpeggio-like effects with LFO, random, noise, envelope generators as CV sources (for negative or symmetrical voltages an offset must be added, e.g. with the offset/attenuator module A-129-3, to obtain positive voltages for the A-156 input)

Notes: Module A-119 (External Input / Envelope Follower) is designed to allow external audio signals to be integrated into the System A-100. It comprises a pre-amp, envelope follower, and comparator.

The pre-amp has two inputs: an unbalanced input for line level signals, with a gain factor of from 0 to 20, and a balanced input with a gain factor of from 0 to 500, for insertion of low level signals, for instance from a microphone or electric guitar.

The Envelope Follower reads the signal level of the input, and puts out a proportional voltage as an envelope at its own output.

The comparator generates a gate signal whenever the input goes above an adjustable trigger threshold.

Three LED's help you keep track of overload, the envelope, and the gate signal.

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: MCV4 is a budget-priced MIDI-to-CV-Interface to control vintage monophonic synthesizers via MIDI. MCV4 is provided with 4 analogue control voltage outputs (CV1...4) and one Gate/Trigger output.

These are the most important MCV4 features:
4 analogue control voltages CV1...CV4
Voltage range for CV1...4: 0...+5V, 8 Bit resolution (equivalent to 1/4 semitone resolution)
CV1 for pitch control (normally VCO CV)
CV2...4 for voltage control of other functions (e.g. VCF frequency, loudness, modulation)

MIDI control of CV1..4:
CV1: note on/off with pitch-bend, 1V/octave characteristic
CV2 monophic after-touch
CV3 velocity and/or volumen (controller #7)
CV4 velocity and/or any controller (setting of the controller number via learn button)

Pitch-bend is used for CV1 generation with 1/4 semitone resolution
Gate output type can be selected via jumper inside the device between voltage trigger (+5V or power supply voltage) and S-trigger (switched trigger)
MIDI channel and reference note for CV1=0V adjustable via learn button
Different assign modes for CV1 (highest note, last note, reference note)
Retrigger on/off while playing legato
Gate/trigger polarity normal/inverted
Two 1/4" stereo jack sockets for CV1/2 and CV3/4
1/4" mono jack socket for gate/trigger
Learn button with LED for adjusting MIDI channel, reference note for CV1, controller for CV4
Optical display of gate/trigger via LED
MIDI-In, MIDI-Thru
Non-volatile memory for parameter settings
Stable metal case (about 95x75x35 mm, 1mm sheet steel)

External AC adapter for power supply
AC adapter for 230V AC and European type of mains connector is included within Europe
7...12V/100mA DC required, DC connector with 5.5 mm outer diameter and 2.1 or 2.5 mm inner diameter, polarity: plus = center, minus = ring

*** Adapters for other parts of the world have to be purchased separately. ***

Suitable accessories:

MCV4 special cable (1/4" stereo jack plug -> 2 x 1/4" mono jack plug, length about 90cm, also called "insert cable")

MIDI channel, reference note for CV1 (this is the MIDI note corresponding to 0V of CV1 and thus the lowest possible note of the analogue synthesizer connected to MCV4) and the controller no. for CV4 are adjusted via learn function. For this, the learn button must be pressed and the required MIDI messages sent from the MIDI controlling device (MIDI synthesizer, keyboard, sequencer ...). The other parameters (retrigger, trigger polarity, assign mode ...) are adjusted in learn mode via program-change messages.
The Hz/V mode available in the predecessor model MCV1 is not available with the MCV4 because of the many problems occurring with the non-linear Hz/V characteristic. But some synthesizers normally using Hz/V can be controlled with V/Oct (e.g. Korg MS10/MS20, details you may find in the MCV4 user's guide).

If you want to use all 4 analogue control voltages, you need 2 special cables with a stereo 1/4" jack plug on one end (MCV4 side) and two mono 1/4" jack plugs on the other (synthesizer side). Cables like this can be purchase elsewhere. If you need it, it is recommended to order it together with the MCV4.

Notes: Economically priced module for connecting one foot controller and one double foot switch for control A-100 functions by means of the feet. For example, the frequency of a filter or the loudness can be controlled by a foot controller, but even other parameters like LFO frequency, modulation depth, phasing, pitch or any other voltage controlled parameter. The gate outputs controlled by the double foot switch can be used e.g. to trigger an envelope generator or to start/stop a sequencer. Even a single foot switch can be used if only one gate signal is required.

A special application of the A-177-2 is the usage within a Trautonium replica. The foot switches can be used to switch the mixtures of the subharmonic oscillator A-113. The foot controller can be used to control the overall loudness in combination with a VCA.

A-177 is compatible with the foot controllers FP5 and double foot switch VFP2. The Foot controller and double foot switch are not included with the module. If you want to use another foot controller or foot switch it has to be compatible to FP5 or VFP2.

If the foot controller FP5 is used the CV output range is about 0...+8V. The gate output levels are 0/+12V in combination with the VFP2 (foot switch not operated = 0V, foot switch operated = +12V).

Notes: Module A-184-2 is the combination of two functions and planned primarily as an expansion module for VCOs or LFOs (e.g. A-110-1, A-110-2, A-145, A-147-2).

Triangle-to-Sine Waveshaper:

The upper section is a very precise triangle-to-sine converter (thanks to Tim Stinchcombe who recommended this circuit). It can be used to convert any triangle waveform into a (nearly) perfect sine. The converter is much better than the simple diode converter used in the A-110-1, A-111-1, A-145 and A-147-2. Two trimming potentiometers are used to optimize the sine shape. The converter should be assigned to one VCO or LFO because the trimming potentiometers have to be re-adjusted if the input level or DC offset of the input signal changes. If the trimming potentiometers are deliberately mis-adjusted it can be used also as a waveshaper for non-sine waveforms (e.g. sine-shaped at the top of the signal and a peak at the bottom, even voltage controlled by applying an additional voltage to the waveshaping circuit, "circuit-bending" notes will be available).

The waveform converter is DC coupled and can be used also for low frequencies (e.g. LFO triangle waves).

Voltage Controlled Crossfader:

The lower section is a voltage controlled crossfader. It has two inputs A and B. The two signals are mixed together with variable percentage. When the manual control CF is fully CCW only signal A appears at the CF Out socket. When the manual control CF is fully CW only signal B appears at the CF Out socket. In the centre position of the manual control both signal appear with the same level. In addition a control voltage input CV with attenuator is available to enable voltage control of the crossfade.

Two LEDs display the crossfading shares of input A and B.

The crossfader uses two high quality VCAs (SSM2164). Inputs and outputs are DC coupled. Consequently it can be used for audio signals and slowly varying control voltages as well.

The sockets of the upper section (triangle and sine) are normalled to the inputs A and B of the crossfader section. That way the crossfader is used to fade between triangle and sine of the VCO or LFO connected to the waveshaper. If other signals are plugged into the input sockets A and B these signals are used for crossfading.

The main application is to fade between two different waveforms of a VCO or LFO or two different VCF outputs. But the module can be used for any other signals too as the waveshaper and crossfader sections are independent apart from the normalled sockets.

Notes: Patch cable for modular synthesizer 80 cm, transparent, mono jack plug 3.5 mm at each end.

Notes: High quality rotary knob, for use with Doepfer or a wide range of modules. Robust design with indented edges. Green finish.

Notes: High quality rotary knob, for use with Doepfer or a wide range of modules. Robust design with indented edges. Yellow finish.

Notes: High quality rotary knob, for use with Doepfer or a wide range of modules. Robust design with indented edges. Retro style finish.

Notes: Module A-145-4 is a simple quad LFO (Low Frequency Oscillator). Not a very "exciting" module, just a bread-and-butter device and a simple demon for work. Virtually in every modular system several LFOs are required for modulation purposes. The module contains four simple LFOs with the waveforms triangle and rectangle. A dual colour LED (red = positive / yellow = negative output voltage) indicates the triangle output of each LFO. The frequency range can be chosen for each LFO individually by means of a jumper between about 50 Hz ... 0.04 Hz (about 20 seconds, jumper removed) and about 2Hz ... 0.002 (about 8 minutes, jumper installed).

The module can be treated as a slimmed version of the quad LFO A-143-3 as it has similar features available. But the distances between the controls are smaller and rubberized small-sized knobs are used. In return the front panel has 4 HP only which is less than one third of the A-143-3. The module is primarily planned for applications where only limited space is available. The functional difference compared to the A-143-3 are the missing sawtooth outputs and frequency range switches.

Notes: Module A-160-5 is a voltage controlled clock multiplier. The incoming clock signal (socket Clock In) is multiplied by a factor that depends upon the control voltage on socket CV In (0...+5V) and the position of the Mode switch. The multiplied clock signal is available at the socket Clock Out. According to the position of the Mode switch different clock multiplying factors are assigned to the control voltage. With 0V CV no clock output is generated. This state is indicated by "all LEDs off". With increasing CV integer factors (left position of the mode switch), power of two factors (middle position) or a mix of both (right position) are obtained. Nine LEDs are used to show the currently selected multiplying factor. In addition two LEDs are used to display the incoming and outgoing clock signal.

A manual control is used to adjust the clock multiplication factor manually without the need of an external control voltage. The voltage generated by this control ("Manual") is normalled to the CV In socket. As long as no plug is inserted into the CV In socket the clock multiplication factor is adjusted by means of the manual control knob and displayed by the LEDs. For dynamic applications (like the ratcheting function described below) the manually generated CV is overwritten by the external CV which has to be fed into the CV In socket.

The module can be used for all kind of clock multiplying applications. One important example is the generation of so-called ratcheting sequences. The band Tangerine Dream is famous for this kind of sequences. A normal sequencer generates only one gate signal per step. A ratcheting sequence may have also more than one gate pulses per step. This function can be obtained by using the A-160-5: one CV output of the sequencer is used to define the number of gate pulses per step. If the control of the step in question is fully CCW the generated CV is 0V and no gate signal is generated (mute of the step). When the control of the step in question is turned clockwise one, two or more gate pulses are generated depending upon the position of the mode switch and the voltage generated by the CV at this step.

Technical note: Due to the nature of clock multiplying it takes a few input clock pulses until the clock output is stable. One has to average a few input clock pulses to generate the multiplied clock output signal. Even when the input clock frequency changes it will take a few cycles until the output clock signal is correct as the module cannot foresee the future of the clock input signal. The generated clock output signal is derived from the last few cycles of the clock input signal. Consequently the module should be driven only by a clock signal with constant or slowly changing frequency.

Notes: Module A-160-5 is a voltage controlled clock multiplier. The incoming clock signal (socket Clock In) is multiplied by a factor that depends upon the control voltage on socket CV In (0...+5V) and the position of the Mode switch. The multiplied clock signal is available at the socket Clock Out. According to the position of the Mode switch different clock multiplying factors are assigned to the control voltage. With 0V CV no clock output is generated. This state is indicated by "all LEDs off". With increasing CV integer factors (left position of the mode switch), power of two factors (middle position) or a mix of both (right position) are obtained. Nine LEDs are used to show the currently selected multiplying factor. In addition two LEDs are used to display the incoming and outgoing clock signal.

A manual control is used to adjust the clock multiplication factor manually without the need of an external control voltage. The voltage generated by this control ("Manual") is normalled to the CV In socket. As long as no plug is inserted into the CV In socket the clock multiplication factor is adjusted by means of the manual control knob and displayed by the LEDs. For dynamic applications (like the ratcheting function described below) the manually generated CV is overwritten by the external CV which has to be fed into the CV In socket.

The module can be used for all kind of clock multiplying applications. One important example is the generation of so-called ratcheting sequences. The band Tangerine Dream is famous for this kind of sequences. A normal sequencer generates only one gate signal per step. A ratcheting sequence may have also more than one gate pulses per step. This function can be obtained by using the A-160-5: one CV output of the sequencer is used to define the number of gate pulses per step. If the control of the step in question is fully CCW the generated CV is 0V and no gate signal is generated (mute of the step). When the control of the step in question is turned clockwise one, two or more gate pulses are generated depending upon the position of the mode switch and the voltage generated by the CV at this step.

Technical note: Due to the nature of clock multiplying it takes a few input clock pulses until the clock output is stable. One has to average a few input clock pulses to generate the multiplied clock output signal. Even when the input clock frequency changes it will take a few cycles until the output clock signal is correct as the module cannot foresee the future of the clock input signal. The generated clock output signal is derived from the last few cycles of the clock input signal. Consequently the module should be driven only by a clock signal with constant or slowly changing frequency.

Notes: Blank panel, 4HP, constructed from anodised aluminium, black.

Notes: Module A-148 (Dual S&H) has two identical sample & hold modules, designed to produce 'staircase' voltages. The signal present at the sample input is sampled at a rate set by the signal at the trigger input, and held at that voltage at the S&H output.

The exact shape of the staircase depends on the sort of waveform at the sample input: NOISE or RANDOM signals produce random patterns; an LFO produces rising or falling staircase patterns.

Two LEDs for each S&H indicate the voltage (positive or negative) of the sampled signal.

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: Blank panel, 1HP, constructed from anodised aluminium, silver.

Notes: Blank panel, 1.5 HP, constructed from anodised aluminium, silver.

Notes: Module A-165-2 includes six modification circuits for digital signals (clock, gate, trigger, start, stop etc.) which are derived from the two input signals Input 1 und 2:

inverted signal of Input 1 (labelled 1)
inverted signal of Input 2 (labelled 2)
T flipflop (toggle flipflop), controlled by Input 1, this output changes it's state whenever a the rising edge of Input 1 appears (labelled 1/2, as it works similar to a 1:2 frequency divider)
Set/Reset flipflop, this output changes it's state to "high" during the rising edge of Input 1 and turns "low" during the rising edge of Input 2 (labelled RS)
inverted output of the Set/Reset flipflop (labelled RS)
pulse output, during both the rising and falling edge of Input 1 a short trigger pulse with about 50 ms lenght is generated (labelled with the sign ± and a rectangle pulse symbol)
The outputs 2, 1/2, RS and the pulse output are equipped with LEDs that display the state of the output in question.
The output level for all six outputs can be set to 0/+5V or 0/+11V by means of a jumper on the pc board.

Voltage thresholds for the input voltages:

voltages below +0,8 V are treated as "low"
voltages above +3 V are treated as "high"
Typical applications

starting and/or stopping of events or switching operations with the RS or RS output (e.g. controlled by the trigger outputs of a sequencer, e.g. in combination with electronic switches)
generation of inverted digital signals
frequency division (1/2 output)
generation of short pulses during the rising and falling edge of a digital signal (e.g. triggering an envelope at both rising and falling edge of a gate signal).
Technical notes

The module cannot be used for bipolar signals! The negative share of the input signal will be clipped by means of a so-called clipping diode at the input of module A-165-2. This may affect the output circuitry of the module connected to the A-165-2 (depends upon the details of the output circuit and if it is protected against clipping). For the planned field of application that's normally no limitation because these signals (clock, gate, trigger) work usually only with positive voltages.
The module can be used for analog signals only to a limited extend! With analog signals the inputs of the module work as comparators and the negative share of the input signal is clipped (as mentioned above).

Width: 2HP / 10.0 mm
Depth: ? mm (measured from the rear side of the front panel)
Current: +?mA (+12V) / -?mA (-12V)