Tags: Low pass gate module

Notes: The Meng Qi DPLPG is a Dual Passive 1-pole vactrol based Low Pass Gate/VCA in modest 2 HP. No power is required as the design is completely passive.

Handpicked components ensure that the modules will be musical.

Feed it a trigger and enjoy the natural smooth decay of a vactrol.

Notes: Tiny little low-pass gate in Intellijel's compact 1U format. Great value approach to this west coast classic module, based on a vactrol for that natural, organic sound.

Supplier's Notes:

Drop this module (or a few of them) into your 1U row, patch in some sound sources, and then ping them with gates and CV to get some instantly pleasing results. So simple and fun!

Natural dynamics with the magic of vactrols.

In general, low pass gates (LPGs) control the amplitude and timbre of a signal by opening and closing a low pass filter. When the gate is closed, no frequencies are allowed to pass through (and no output is heard). As the gate begins to open, the lowest frequencies pass through to the output. As the gate opens further, the output grows louder and its high frequency content increases.

Traditional Low Pass Gates use vactrols to control the opening and closing of the filter. Encased within a vactrol is both a light source and a light detector. Applying a control voltage to the vactrol lights its internal LED i the brightness of which is measured by its detector. What makes vactrols particularly unique (and well-suited to musical applications) is their non-linear response to voltage - in particular, the way in which the internal LED slowly dims (rather than shutting off instantly) when the control voltage is removed. This sonic coupling of timbre and volume, along with the circuit's natural decay, makes the low pass gate particularly adept at producing tones associated with struck objects, like hand drums or marimbas. Indeed, low pass gates are the main ingredient of the so-called Buchla Bongo sound.

The Intellijel Passive Low Pass Gate 1U is a simple, vactrol based, 1-pole, passive low pass gate, which is controlled by an external CV input. Without positive control voltage, the gate is completely closed and none of the LPG's input signal is passed through to the output. Increasing amounts of positive CV open the gate i making the output signal both louder and brighter. At +5V, the gate is fully open and the input signal is passed through to the output.
This makes LPGs sound very different (and more acoustic) than the traditional complement of envelopes, VCFs and VCAs that are employed in most subtractive synthesizers. Exciting the vactrol (via the CV input) with a trigger, noise blast, or short envelope will result in a very natural sounding filtered envelope that's reminiscent of the sonic characterics of struck objects, which are allowed to decay naturally.

In addition, because this is a passive circuit (no power is applied to it), its sonic characteristics are somewhat dependent upon the audio signal you feed into it, making it a very natural and organic way to shape a signal's volume and tone.

Pairs very well with the intellijel Shifty module to derive polyphony out of a only a few HP of modules.

Width: 6HP
Depth: 19mm

Notes: A Low Pass Gate (LPG) can be a low pass filter, a VCA or a combination of both. This means both the harmonic content and volume can be controlled simultaneously which resembles the behaviour of many instruments: the louder, the more harmonics.

The A-101-2's mode of operation is set with a switch: left position is low pass, right is VCA and the combo mode is in the centre. Alternatively, you can activate the modes with gate signals which is the reason for two gate inputs; this is very interesting in combination with clock dividers or trigger sequencers.

- Gate 1 high & gate 2 low = low pass mode
- Gate 1 low & gate 2 high = VCA mode
- Both Gate 1 & 2 high = combo mode

The A-101-2 has an aggressive sound, compared to other LPGs and its resonance goes up to self-oscillation which not many LPGs offer. The oscillation is rather dirty and far from being a sine wave.

3U Eurorack module, 8HP wide, 50mm deep.

Notes: The Dual Stereo Gate (DXG) music synthesizer module is a Dual Stereo Low Pass Gate and Mixer. It follows in the footsteps of the QMMG, Optomix, RxMx, DynaMix, and LxD. Unlike its predecessors, the DXG is specifically oriented around mixing stereo signals, making it an important addition to any system containing modules like XPO, QPAS, Morphagene, Mimeophon, and other stereo modules by Make Noise or others.

Unique to the DXG is a new low pass gate circuit that does not use vactrols. This circuit is 100% analogue and its response was arrived at after many months tailoring it to meet or exceed the expectations that have been set by all the vactrol low pass gates that Make Noise has created over the years.

In the past, Make Noise produced the Dynamix module and Dynamics circuit in the 0-COAST, both of which are vactrolless LPGs; however, the DXG is a completely new approach which better implements the gentle single pole filtering of a low pass gate, while also emulating the slow decay and memory of the vactrol based low pass gate. This new circuit makes possible the consistency of response necessary for versatile stereo use, while also keeping the module small and affordable so that it can be a key part of just about any modular system.

As on all of Make Noise's low pass gates, the DXG's Control parameter is used to set both the amplitude and the frequency content of the sound that passes through it. The control parameter tends to open faster than it closes, imparting a subtle decay phase onto any envelope shape that is used to modulate it.

Unlike previous low pass gates made by Make Noise, all the DXG's inputs and outputs are stereo. Each set of inputs is normalled so that the left input can be used for a mono signal, sending a copy to both left and right outputs. The Auxiliary inputs are also a stereo pair with mono normalization. These normalizations allow for the DXG to be used as a simple three channel stereo mixer, with one or two of the channels additionally being used for dynamics control and note event generation. The Aux inputs can be used to chain together larger decentralized mixes using additional DXG modules, or X-PAN, Optomix, modDemix etc.

Features

- Make Noise's first Stereo Low Pass Gate

- Vactrol-free design for classic Low Pass Gate sounds, but with the balance and consistency needed for true Stereo

- Fully Stereo i/o for easy integration into a Stereo-equipped modular synthesizer

- All Left inputs normalled for easy use with Mono signals

- STRIKE Input allows use of Gate signal to trigger Low Pass Gate circuit, creating "plucking" or "pinging" sound from any Gate

- Summing stage with Stereo AUXiliary IN allows for chaining of multiple units, creating larger mixes

- Part of a decentralized mix console integrated throughout the system along with X-PAN, Optomix, XOH, etc.

- Pairs well with XPO, QPAS, Morphagene, Mimeophon, Spectraphon etc.

Width: 8hp
Power:
74mA @ +12V
86mA @ -12V
Module Depth (incl power cable): 43mm

Notes: Tiptop bring the iconic low-pass gate to their range of Buchla reissues. The 292t offers four channels which can be mixed or treated individually, with adjustable modes for low-pass filtering, VCA or the classic low-pass gate combo.

Supplier's Notes:
The 292t is a reissue of Don Buchla's low-pass gate from the 1970s, adapted for the Eurorack modular format. The module consists of four independent low-pass gates (LPGs) and retains the natural, percussive sounds of the original, all of which can be manipulated in real time using control voltages. The 292t allows you to mix up to four sounds from their individual outputs or through a summed output, functioning as a mixdown. Each channel can operate in one of three modes: a low-pass filter with a variable cutoff, a VCA with controllable gain, or a combination of both, producing Buchla's classic low-pass gate effect.

Notes: *** Updated to v3 in February 2024 with improved hardware and circuitry ***

The Omen is a dual LPG with a bit more than you might be used to. This module was born out of the realisation that it was possible to make far more interesting LPG designs than the standard we've become so accustomed to.

In a convergence of old-school LPG design and more modern components, the Omen boasts two -6dB resonant filters, custom built vactrols, built in CV attenuation and no less than three cutoff modes per filter. Filter 1 is soft and light, imparting a gentle, naturally gated touch of filtering on your sound, while Filter 2 is darker and more resonant, and can turn downright growly and distorted when left wide open.

Designed to give you as many creative options as possible, the Omen has the unique ability to function as either two discrete LPG, or as one 4-pole resonant LPG. When plugging a signal in to Input 1, and with no signal plugged into Input 2, the output will be present at both Output 1 and Output 2, with Output 2 producing the signal as it passes through both filters. Tweaking both filters independently will generate a wide array of soft and sometimes harsh tones, ranging from Buchla bongos to early synthesis brass and organ sounds. There is much to love here.

CV is similarly handled, by plugging in only one CV source, it will act on both channels - this is useful for creating musically similar outputs as well as when using the dual filter operation. However, the dual filter mode greatly benefits from having two CV inputs: use an envelope in CV1 to act as a VCA, and an LFO in CV2 to create tremolo, for instance.

Using custom designed, hand built vactrols, care has been taken to mitigate the less desirable aspects of passive LPGs - in most modules, the user can expect zero bleed through on the LPG channels, and signal attenuation is minimal even with the 4-pole filter settings engaged. Of course, many of the natural features of vactrols remain, such as subtle memory effect when engaging the vactrol for long periods.

Finally, you receive maximum blinkenlights as LED's on the front panel simulate the action of the vactrols, so you'll always know what's going on under the hood. No collection of fancy LPG's is complete without the Omen.

Dimensions
4 HP
36 mm deep

Current Draw
Module does not draw current

Notes: This versatile dual-function Eurorack module offers both a Low Pass Gate (LPG) and a Voltage-Controlled Amplifier (VCA), inspired by two iconic designs in synthesiser history.

Low Pass Gate (LPG)

The LPG is modeled after the classic Buchla design, delivering a rich, organic sound that blends amplitude control with low-pass filtering. Ideal for producing natural-sounding dynamics, the LPG responds to control voltages to create plucky, percussive tones and smooth, woody textures. Its distinctive vactrol-based architecture provides a warm and unique character, adding depth and nuance to your patches.

Voltage-Controlled Amplifier (VCA)

The VCA draws its inspiration from the legendary Minimoog, ensuring a clean, dynamic, and responsive performance. Known for its iconic smoothness and headroom, this design is perfect for traditional amplitude shaping, allowing precise control over audio signals with minimal distortion. The VCA section excels in both subtle modulation and aggressive signal sculpting, making it a versatile choice for any patch.

Power consumption: 30mA at +12V and 47mA at -12V

Depth: 27mm

6 HP

Notes: Have some noisy modules in your case? Or maybe you're just looking to attenuate your sound for a different vibe. Whatever your case, Lopas is a great, compact solution for your passive filtering needs. Lopas has 5 passive low-pass filters each with a different cutoff frequency (10k, 5k, 1k, 500, 100) at -6dB/octave. Lopas has NO resonance making it great for reducing unwanted harsh frequencies without sacrificing a VCF.

Technical specs:

3U x 4HP x 20 mm deep.
Passive Module -- No power required!

What's in the box:

1x Lopas Module
2x Mounting Screws