Doepfer A-156


Dual Quantiser

The A-156 Module is a dual control voltage quantiser. A quantiser converts a continuous input control voltage in the range of 0 ... 10V into a stepped output voltage in the same voltage range. The possible steps in the A-156 are not restricted to the usual half-tone grid (ie gradation in 1 / 12V steps) but also allows other scales of the grid such as the major scale, minor scale, major chord , Minor chord, fundamental fifth and the inclusion of sixth or seventh in the chords. The voltage values at the input are only converted into discrete voltages at the output, which meet the selection criterion for the permissible voltage grid (for example a minor seventh chord). The operating mode for Quantiser 1 is set with 3 tilt switches with center position. The Quantiser 2 is fixed to the half-tone grid.

For each of the two Quantisers there is a control input (CV In), a control output (CV Out), a trigger input (trig in) and a trigger output (trig. Out). If no signal is present at the trigger input (socket open), the quantisation is carried out continuously. If, however, a square-wave signal is applied there (from an LFO or the MIDI-SYNC interface for example), the quantisation is always performed only at the rising edge of the trigger signal. The quantisation process can thus be synchronised with other processes on demand. At the trigger output, a pulse appears whenever a quantisation (or a step change in the output voltage) occurs. For example, an envelope generator (ADSR) can be started.

In addition, the module has a common transpose input, which can be added to both quantisers and is quantised in a halftone grid. A typical application for this is to transpose a quantized sequence (generated by the A-155) with a second control voltage (from the MIDI CV interface for the example).

  • Quantisation of a tone sequence from the A-155 into a fixed grid (halftones, only major scale, minor scale only)
  • Quantise the control voltage of a Trautonium manual A-198, Theremin A-178 or Light-to-CV module A-179 to get always half-tones, scales, or chord sounds
  • Arpeggio-like sound sequences with LFO, Random, Noise, ADSR etc. as input voltage

Euro Rack Module

  • Bi-directional control voltage quantiser
  • Converts continuous input voltage into step output voltage
  • Euro rack format
  • Width: 8 HP
  • Depth: 55 mm
  • Power consumption: +50 mA (+ 12V)/ -10 mA (-12V)
Available since December 2004
Item number 176366
Sales Unit 1 piece(s)
Switch Modul No
CV-Editor/VC-Processor Yes
Tools No
Width 8 TE / HP
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51 Customer ratings

4.7 / 5

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30 Reviews

Doepfer A-156 Quantiser
Blair 04.04.2014
I have the Doepfer A-149 module which generates stored and quantised random voltages. This is great, but soon I found myself looking for a module which would take the output of the A-149 and restrict it to play notes from recognisable scales, such as major and minor ones. I also wanted to create arpeggios which included only notes from certain chords. Research showed that I needed to get a control voltage quantiser, which would select from the random collages only those values that would play notes from chords or scales I had selected.

I bought the A-156 Dual Quantiser after I had checked out much more expensive versions from other manufacturers. The A-156 does not have all the 'bells and whistles' of its more expensive competitors, such as programmable scales and memories. however these devices are at least twice as expensive as the A-156, and I was not looking for extra functionality. A key feature of the A-156 is that it is a dual quantiser - in effect two devices in one. However, the second quantiser defaults to generating semi-tone scales only. This can be changed by changing the position of a jumper on the main circuit board. After that, both quantisers offer the same features, such as notes from a chosen scale or arpeggio playing a certain chord.

The A-156 also includes trigger outputs, which will send a gate signal each time a new note value is generated. This is very useful for 'shaping' the sound, such as triggering a low pass gate to open each time a note is created by the A-156 and played by a VCO.

Are there any shortcomings? Not really. For the price this module performs incredibly well, and it easy to operate. My one suggestion is that the jumper that links or separates the two quantisers, should be replaced by a 2-way switch on the module's front panel.

Great module, highly recommended.


Incredibly useful module
Anonymous 21.07.2016
I use this module on nearly every patch I set up. It's incredibly good for turning an LFO or a noise source into note CV and trigger output, all in time with an incoming clock pulse to create surprising pseudo-random arppegios and sequences of notes. The control switches allow for all the random notes to be kept in a specified key or chord rather than being just an unconnected series of notes so this module really helps to fill out a patch with constantly surprising and pleasing flurries of notes.

One thing worth noting is that there is a jumper on the board to set both channels to the same harmonic settings. I found this vital as without it the module will simply default to random semitones which rapidly becomes tiresome. With the jumper set you get more useful root, optional third, fifth and selectable 6th or seventh on major or minor chords.

overall, five stars all the way. I'm expanding my modular all the time and will definitely buy another of these. Highly recommended.


simple, inexpensive and essential
Anonymous 31.10.2016
Soon after I started my modular system I realised that a quantizer was going to be essential.
Although this is a simple quantizer (compared with some on the market) it proved to be just what I needed and affordable ...and then I discovered how much more it could be.
Two quantisers in one module is great as you can produce a bassline and arpeggio and then transpose the whole thing playing notes from a keyboard.
The trigger functions can produce some interesting effects. For example send a sine LFO (offset to be in the positive range for the quantizer) to one of the inputs and take the trigger out and you get a speeding up and slowing down trigger sort of like the rhythm of a perpetually boucing ball.
I also often use the switches as performance controls shift your whole piece from minor to major or to introduce a 6th or 7th.
The only improvement I would suggest would be LEDs to show the state of the output triggers ...but I'm maybe too fond of flashing lights!


Essential for analogue sequencing
Anonymous 15.04.2014
Being new to modular synthesis, I didn't realise how essential a quantiser was when dealing with analogue sequencers until I purchased this.

Having two separate quantisers in a single module is great and really ups the flexibility. As all Eurorack owners know, when space is limited, having modules that perform multiple tasks in a small space is a godsend!

Was particularly impressed with the scale functions in the secondary quantiser that make it a breeze to get usable, melodic results.

The transpose CV in is something I need to delve a little deeper into, but you can use this to great effect to transpose a sequence up or down in pitch using an external keyboard.

A great little module!