CHERRY AUDIO VM901 User manual

Voltage Modular: Cherry Audio MRB modules

This content was taken from the product pages on 28 October 2021.

Voltage Modular: Cherry Audio / MRB Modules User Manual

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Table of Contents

1 CP3 Console Panel Mixer.................................................................................................. 4

2 VM901 Voltage Controlled Oscillator............................................................................... 6

3 VM901ABBB Voltage Controlled Oscillator...................................................................... 8

4 VM902 Amplifier ............................................................................................................ 10

5 VM903 Random Signal Generator.................................................................................. 11

6 VM904A/B/C Filters........................................................................................................ 12

7 VM905 Reverb................................................................................................................ 16

8 VM907A Fixed Filter Bank .............................................................................................. 17

9 VM911 Envelope Generator........................................................................................... 18

10 VM911-A Dual Trigger Delay .......................................................................................... 21

11 VM912 Envelope Follower ............................................................................................. 22

12 VM914 Fixed Filter Bank................................................................................................. 24

13 VM921ABBB Oscillator Bank .......................................................................................... 25

14 VM921 Voltage Controlled Oscillator............................................................................. 25

15 VM923 Filters/Noise....................................................................................................... 29

16 VM927 Multiple.............................................................................................................. 31

17 VM928 Sample Hold....................................................................................................... 32

18 VM958 Keyboard/VCO Interface.................................................................................... 34

19 VM960 Sequencer .......................................................................................................... 37

20 VM962 Sequential Switch............................................................................................... 40

21 VM984 Four-Channel Matrix Mixer................................................................................ 41

22 VM995 Attenuators........................................................................................................ 42

23 VM1630 Frequency Shifter............................................................................................. 43

24 VM2500 Blank Panel Module 1001 ................................................................................ 45

25 VM2500 Clocked Sequential Control Module 1027 ....................................................... 46

26 VM2500 Dual Envelope Generator Module 1003 .......................................................... 51

27 VM2500 Dual Envelope Generator Module 1033 .......................................................... 54

28 VM2500 Dual Four-Channel Mixer Module 1051 .......................................................... 57

29 VM2500 Dual Noise/Random Voltage Generator Module 1016 oscillators .................. 58

30 VM2500 Dual Oscillator Module 1023 ........................................................................... 59

31 VM2500 Dual Reverberator Module 1025 ..................................................................... 61

32 VM2500 Filtamp Module 1006....................................................................................... 63

33 VM2500 Mix-Sequencer Module 1050 .......................................................................... 65

34 VM2500 Modamp Module 1005 .................................................................................... 68

35 VM2500 Multimode Filter Resonator Module 1047 ...................................................... 70

36 VM2500 Oscillator Module 1004-P ................................................................................ 73

37 VM2500 Oscillator Module 1004-R ................................................................................ 75

Voltage Modular: Cherry Audio / MRB Modules User Manual

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38 VM2500 Oscillator Module 1004-T ................................................................................ 77

39 VM2500 Oscilloscope Module 1019............................................................................... 79

40 VM2500 Preset Voltage Module 1026 ........................................................................... 81

41 VM2500 Quad Envelope Generator Module 1046......................................................... 83

42 VM2500 Sample & Hold Module 1036........................................................................... 86

43 VM2500 Synthesizer Voice Module 1045 ...................................................................... 88

44 VM2500 Triple VCA Module 1042 .................................................................................. 93

Voltage Modular: Cherry Audio / MRB Modules User Manual

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1CP3 Console Panel Mixer

The VM900 CP3 is a recreation of the classic Moog

"Console Panel Mixer." At high inputs levels, it had a

tendency to clip the tops and bottoms of waveforms for a

characteristic overdriven tone. We've also included a

switch that allows selection between the more overdriven

tone and the later, cleaner-sounding version.

Note that CP3 is DC-coupled and can be used to mix audio

or sub-audio CV signals.

1.1 Inputs, Outputs, and Controls

The four inputs are stacked vertically on the left side of the panel; we'll go over the

repeated controls just once.

Mixer Inputs jacks and level knobs- Plug inputs into the jacks and set volumes with the

knobs. Signals will tend to clip at higher input levels, particularly when the Model switch is

set to the Rev. 1 position.

Model- Selects the audio characteristics of the earlier or later production CP3 circuit. Rev. 1

has more of a tendency to clip waveforms, whereas Rev. 2 is less inclined to break up.

Click Filter- When engaged, this rounds of sharp waveform edges to reduce clicking - it's

intended for use with edgy control signals to reduce clicking when patched to something

such as a VCA CV. The Click Filter is generally not recommended for use with audio signals.

Master Gain- Sets overall output volume. While turning up the four input levels will increase

distortion (especially in rev1), Master Gain is pure output gain and has no effect on

distortion.

Voltage Modular: Cherry Audio / MRB Modules User Manual

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+/- Output jacks - Signal outputs for positive and inverted mixed signals. The (-) out, in

addition to being inverted from the (+) out, does not sound the same in Rev. 1 mode - the

distortion characteristics are very different between the two jacks. In fact, the outputs are

so different that there is quite a stereo image to be had between them. Rev. 2 mode is

purely clean and does not exhibit these quirks.

Voltage Modular: Cherry Audio / MRB Modules User Manual

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2VM901 Voltage Controlled Oscillator

The VM901 is a full-function oscillator

module. It can be used in the audio range,

or as a low-frequency modulation source.

2.1 Inputs, Outputs, and Controls

Fixed Voltage Control- Sets the range down five octaves or up six octaves.

Frequency Range- Sets the coarse frequency range to sub-audio or standard audio ranges in

standard organ footages. Use the Lo setting when using VM901 as low-frequency

modulation source.

Fine Tuning (0/1/2)- Allows continuously variable tuning down (0) or up (2) one octave.

Width Of Pulse Waveform- Sets the width or "duty-cycle" of the rectangular (aka, pulse)

wave. It has no effect on any other waveform. Its default setting of 50% produces a perfect

square wave, rich in odd-order harmonics. Moving the knob left or right narrows its width as

well as the thickness of sound until it almost disappears at its extremes.

Control Inputs- These are 1V/octave exponential inputs. They're used for pitch CV as well as

modulating the oscillator frequency. All three jacks are the same and their incoming

voltages are summed.

Sine/Saw/Triangular/Pulse volume knobs- These set the volume of each waveform for each

respective output jack in the bottom row.

Voltage Modular: Cherry Audio / MRB Modules User Manual

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Fixed Level Outputs- These are outputs for the sine, sawtooth, triangular, and pulse waves,

respectively. They not affected by the Sine/Saw/Triangular/Pulse knobs and are always at

full output level.

Sine/Saw/Triangular/Pulse adjustable outputs- These are outputs for the sine, sawtooth,

triangular, and pulse waves, respectively. Their output level is set by the Sine, Sawtooth,

Triangular, and Pulse volume knobs.

Voltage Modular: Cherry Audio / MRB Modules User Manual

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3VM901ABBB Voltage Controlled Oscillator

The VM901ABBB is an

oscillator bank that

replicates the unique

oscillator controller/slave

arrangement of classic

Moog synthesizers.

The concept is that the

Oscillator Controller

module sets the overall

coarse tuning as well as

rectangular wave pulse

width for the three slave

oscillators.

In the original hardware

modular systems, the

oscillator controller and

slaves were connected

internally.

Any number of slave oscillators could be used, but the "one+three" combo was common,

and we felt it represented a good compromise of utility and size. Though these have the

appearance of four individual single-width modules, VM901ABBB is a single quad-width

module. If for you need something physically narrower, use the VM901 oscillator module.

3.1 901-A Oscillator Controller

The oscillator driver is the "master control" center; all of its control settings will affect the

three slave oscillators. Changing its Frequency setting will equally offset all three slave

oscillators, for example.

3.1.1 Inputs, Outputs, and Controls

Fixed Voltage Control- Sets the range down five octaves or up six octaves.

Frequency Range- Sets the coarse frequency range to sub-audio or standard audio ranges in

standard organ footages. Use the Lo setting when using VM901 as low-frequency

modulation source.

Fine Tuning (0/1/2)- Allows continuously variable tuning down (0) or up (2) one octave.

Voltage Modular: Cherry Audio / MRB Modules User Manual

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Width Of Pulse Waveform- Sets the width or "duty-cycle" of the rectangular (aka, pulse)

wave. It has no effect on any other waveform. Its default setting of 50% produces a perfect

square wave, rich in odd-order harmonics. Moving the knob left or right narrows its width as

well as the thickness of sound until it almost disappears at its extremes.

Control Inputs jacks- These are 1V/octave exponential inputs. They're used for pitch CV as

well as modulating the oscillator frequency. All three jacks are the same; signals received

will be summed and are multed to all three slave oscillators.

3.2 901-B Slave Oscillators

As mentioned, 901-A oscillator driver settings equally affect all three slave oscillators.

Conversely, settings on individual 901-B slave oscillators are independent and have no affect

on the adjacent oscillators.

3.2.1 Inputs, Outputs, and Controls

Frequency Range- Sets the coarse frequency range to sub-audio or standard audio ranges in

standard organ footages. Use the Lo setting when using VM901 as low-frequency

modulation source.

Frequency Vernier- Allows continuously variable tuning down or up by about one octave

and a major third.

Sine/Saw/Triangular/Pulse output jacks- Outputs for the sawtooth, sine, pulse, and

triangular waves, respectively.

Voltage Modular: Cherry Audio / MRB Modules User Manual

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4VM902 Amplifier

The idea of a voltage-controlled amplifier (VCA) is that an audio or control

signal is patched to its input, and externally controlled voltage controlled

via the Control Inputs jacks. This is useful for turning audio or control

signals on or off, applying envelope volume curves to sounds, regulating

the amount of modulation signals applied to audio signals, and more.

A simple analogy would be to think of a water faucet, with the control

voltage affecting how much the faucet is opened.

4.1 Inputs, Outputs, and Controls

Linear (Lin.)/Exponential (Exp.)- Selects the "curve" of the amplifier's response as the input

CV rises from 0 to 5V. Lin. or linear response curve is equally proportional across the voltage

input range, whereas Exp. or exponential curve is closer to how the human ear perceives

volume. You'll likely want to use the Lin. setting for modulation or control voltage situations,

and use the Exp. setting when an envelope generator is used to control an audio signal with

the amplifier. Or just use whatever sounds best, we won't tell.

Fixed Control voltage- Adds up to 5V of gain. This works in addition to incoming and Control

Inputs jack voltages. It's useful for manually "opening" the amplifier for drones.

Control Inputs jacks- Control signal inputs are patched in here. These have no attenuators

and are "wide open" all the time - typically these would be used to patch an envelope

generator. All three jacks are the same, and when more than one is used, incoming voltages

are summed.

Signal Inputs jacks- Use this jack to patch in audio or control signals to be controlled by the

VCA. Both inputs are summed.

Signal Outputs jacks- These carry the CV-modified version of input signals.

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