Unpacking the MICRO B
Front Panel Description
Rear Panel Description
Using The MICRO B
Multi-timbral Mode
MIDI Controlled Effects

Manual Rev H1.3 (HTML version)


The MICRO B was designed for both the purist B3 organ player or people who just need a great organ sound. The MICRO B is real easy to use. It requires absolutely no programming. There are front panel rotary controls for volume, key click, and overdrive, plus controls for percussion volume and decay. It has a built-in rotating speaker effect (front panel and foot switch controlled) with a simulated upper and lower rotor which speeds up and slows down just like the real thing.

The MICRO B lets you select three levels of chorus or vibrato and comes with 36 of the most popular drawbar settings. The first 22 presets are selectable via the front panel: all 36 can be selected through MIDI. In addition, the MICRO B can operate in three part multi-timbral mode for any three adjacent channels as well as MIDI OMNI ON mode. There are high level stereo audio outputs, CH2 output may be used to drive stereo headphones. All this makes the MICRO B very easy and intuitive to use.

Unpacking the MICRO B

Inside the MICRO B you will find the following:
  1. MICRO B unit
  2. AC adapter
  3. user's manual
  4. MIDI implementation chart
  5. warranty card
  6. 4 - rubber feet
Please return the warranty card soon after your purchase. The information you provide will allow Voce to keep you informed about updates and new products.

Front Panel

  1. VOLUME - Rotary volume control. turn clockwise to increase volume level.
  2. MIDI - LED indicator lights up when MICRO B is turned on. The LED will flash off briefly when the MICRO B receives MIDI transmissions from a MIDI controller.
  3. OVERDRIVE- Rotary overdrive control. Turn clockwise to increase overdrive (distortion effect) level .
  4. KEY CLICK - Rotary key click control. Turn clockwise to adjust the MICRO B's key click (attack) volume level. Key click is an electrical noise generated in tone wheel organs by the mechanical bounce of nine key contacts. It will be necessary to re-strike a note on the keyboard to hear the change made to the sound.
  5. EFFECTS- Used to select any of three levels of chorus, vibrato, or the rotary speaker effect. Can also be controlled via MIDI, see the section on MIDI CONTROLLED EFFECTS for more details.
  6. RS FAST (Rotating Speaker FAST) - This push-button control and associated LED allows the setting of the rotating speaker speed. When the LED is lit, the rotating speaker effect is set to fast rotation. When the LED is off, the speaker's rotation is slow. The push-button toggles between the two states, and allows a gradual speed and slow down of rotation to occur. Can also be controlled via MIDI, see the section on MIDI CONTROLLED EFFECTS for more information.
  7. PERCUSSION - ON/OFF - When depressed, this push-button turns on the percussion effect. The Percussion effect is similar to the sound produced when a xylophone is struck. When the percussion effect is not on, the state of switches PERCUSSION 2nd/3rd, PERCUSSION VOLUME, and PERCUSSION DECAY, will not affect the sound produced by the MICRO B. Can also be controlled via MIDI, see the section on MIDI CONTROLLED EFFECTS for more information.
  8. PERCUSSION - 2nd/3rd - Toggles between two percussion waveforms for the percussion effect (2nd or 3rd harmonic of the fundamental). This switch will affect the sound produced by the MICRO B only if the PERCUSSION ON/OFF switch is in the ON position. Can also be controlled via MIDI, see the section on MIDI CONTROLLED EFFECTS for more information.
  9. PERCUSSION - VOLUME- Rotary percussion volume control. Turn clockwise to increase percussion volume.
  10. PERCUSSION - DECAY - Rotary percussion decay control. Turn clockwise to decrease percussion decay rate.
  11. PRESET - Rotary preset selector. Allows selection of any one of the first 22 presets as indicated by the positions marked 1 - 22. The position marked M selects multi-timbral mode (see page 11). The position marked P allows the MICRO B to accept program changes from a MIDI controller.
There are a total of 36 presets in the MICRO B. The first 22 are selected through the PRESET selector, the remaining 14 presets may be selected via program changes from a MIDI controller. 

Rear Panel

The MICRO B rear panel diagram is shown below. A description of each component follows:


  1. CH1 - Channel 1 audio output.
  2. CH2/PHONE - Channel 2 audio output. Can also be used to drive stereo headphones.
  3. MIDI THRU - 5-pin DIN MIDI thru output. This MIDI output may be used to send a "carbon copy" of the MIDI IN data to other modules.
  4. MIDI IN - 5-pin DIN MIDI input. This MIDI input accepts MIDI data from a MIDI controller (i.e. keyboard) or computer.
  5. FT SW - 1/4" phone jack foot switch input. A momentary foot pedal (such as a sustain pedal) may be connected to this input to toggle the rotating speaker effect between a fast or slow speed.
  6. MIDI CH - 16 position rotary switch. Selects basic MIDI channel (channel 1 - 15 only) by setting the switch to positions 1 - 15. MIDI OMNI ON mode is selected by setting the switch to position 0.
  7. TUNING - Rotary tuning control. Center detent is set to A440 standard tuning.
  8. POWER JACK - The AC wall adapter connects to the MICRO B via this jack.
  9. POWER SWITCH - push on / push off switch


Refer to the diagram above for setting up the MICRO B.

To use your MICRO B, please follow these easy steps:

1. Connect to MIDI device

The MICRO B requires a MIDI input from a MIDI device such as a MIDI keyboard, digital piano, or computer in order for it to be played.

2. Connect audio outputs to amplifier

The MICRO B provides two audio outputs for a stereo rotating speaker effect. Both CH1 and CH2 outputs should be connected for stereo operation to suitable audio system (i.e. digital piano audio inputs, stereo mixer / sound system line level inputs). If mono audio operation is desired, connect the instrument amplifier (mixer etc.) to CH1.

A set of stereo headphones may be connected to the CH2 output. Depending on the type of headphones used, it may be necessary to raise the level of the front panel volume control.

3. MIDI THRU Output

Useful in connecting more than one MIDI module in a daisy chain configuration. Use this output for sending a "carbon copy" of the MIDI data appearing at the MIDI IN connector to other MIDI devices.

4. Foot Switch

A momentary foot pedal (such as a sustain pedal) may be connected to this input to toggle the rotating speaker effect between a fast or slow state. The front panel FAST LED indicator will toggle on or off when the foot switch is operated.

5. AC Adapter

The MICRO B requires an external AC adapter. Make sure that you first connect the small barrel connector on the rear panel of the MICRO B before connecting the AC adapter to the wall outlet.

6. Select the Basic MIDI Channel

Set the basic MIDI channel on the MIDI channel selector located on the rear panel of the MICRO B. The basic MIDI channel should be the same as the channel that your MIDI controller uses to transmit MIDI note on/note off and program change information to the MICRO B. Refer to the MIDI channel selection table on page 12 for a list of all valid MIDI channel combinations.

7. Tuning

A rotary control is provided in the event that it is necessary to change the tuning of the MICRO B. The center detent position is A440 standard tuning. The pitch may be raised or lowered by one semitone.

Using the MICRO B

1. Built-in Demo

A built-in demonstration sequencer will demonstrate some of the various sounds and effects the MICRO B is capable of performing. It may be activated by holding in the fast button and simultaneously turning the preset selector to the M position. Some of the units controls will remain active during the demonstration. They are VOLUME, OVERDRIVE, KEYCLICK, PERCUSSION VOLUME, and PERCUSSION DECAY. To exit the demonstration mode, turn the preset selector to another position.

2. Playing

After hooking up the MICRO B as explained in the Set-Up section, you will be ready to begin playing. The MICRO B was designed to be very easy and intuitive to use. The following is a brief description of the MICRO B's controls together with an explanation of their usage.

Volume - Before powering up the MICRO B, make sure that the volume level is turned all the way down (volume control turned full counter clock-wise). Power up the MICRO B, the MIDI LED should light up, then play some notes on your keyboard and gradually turn up the volume to a comfortable listening level.

Key Click - Some of the controls which are provided on the MICRO B set the level of defects present in the sound of the original organs the MICRO B simulates. KEYCLICK is the best example of this type of control. Originally key click was thought to be a defect in tone-wheel organs. Gradually people became accustomed to the sound as new musical styles developed around the playing of the electric organ. Many styles of jazz organ depend on some level of key click being used in the sound.

To adjust the key click, repeatedly strike some notes and gradually turn the key click knob clockwise. Notice the key-click effect increases as you turn the knob. Adjust to taste.

Overdrive - Overdrive may be used to simulate the sound of an amplifier driven into clipping. It realistically simulates the organ sound used by many "R & B" and rock bands.

To adjust the amount of overdrive, simply play some notes and gradually turn the overdrive knob clock wise. Notice how the amount of overdrive increases as you turn the knob. Adjust to taste.

Effects - The MICRO B comes with built-in chorus and vibrato effects as well as a rotating speaker effect. You can select any of three levels of chorus or vibrato, or the rotating speaker effect. If you select rotating speaker (RS), the rotation speed will be indicated by the LED next to the button labeled FAST. If the LED is off, the rotating speaker velocity is slow: if the LED is lit, the rotating speaker speed is fast. You will hear the gradual acceleration or deceleration after FAST button is pressed. The rotating speaker effect will only be heard when the rotary selector is in the RS position.

Percussion - The percussion effect is enabled by pressing the PERCUSSION - ON/OFF push-button switch so it is left in an "in" position. With the percussion effect on, you can select between the 2nd and 3rd harmonic, and adjust the percussion volume and decay. Note that the percussion effect must first be turned on in order for any of these controls to have any effect.

The percussion effect is very useful for jazz style settings. A standard one would be preset 1 with percussion on 3rd harmonic and the PERCUSSION - VOLUME and PERCUSSION - DECAY settings adjusted to taste.

Presets - The MICRO B comes with 36 drawbar presets. The first 22 presets can be accessed through the preset selector on the front panel; to access all 36 presets you must use a MIDI controller capable of sending least program changes 0 to 35. Set the preset selector to P when using your MIDI controller to send program changes. This tells the MICRO B that all program changes will now be set by your MIDI controller. See the chart on the next page for a list of preset drawbar settings.

Here is a list of all 36 MICRO B presets and their tone-wheel organ equivalents:
Preset # Drawbar equivalent  Preset # Drawbar equivalent 
1. 888000000 19.  888220000
2. 808808008 20.  888000000
split / (505000000 +2 oct.)
below middle C 
3. 888888888 21.  888000000
split / 848000000
below middle C 
4. 888473256 22.  888000008
split / 848000000
below middle C 
5. 832000003 23.  848000000
6. 800800008 24.  878420000
7. 888000008 25.  888070340
8. 888800000 26.  808104000
9. 800800000 27.  887340060
10. 800000005 28.  864321110
11. 880070080 29.  800370000
12. 800000544 30.  800000008
13. 088800002 31.  888800008
14. 888800003 32.  800008678
15. 008703004 33.  505000000
16. 888000030 34.  888000000 split / 848000000 +3 oct.) below middle C 
17. 828030001 35.  Farfisa Compact
18. 831000025 36.  Vox Continental

Notice that split presets are provided to make better use of single manual operation. Split presets 21 and 22 provide a typical organ bass setting for the left hand, while presets 20 and 34 provide a suitable sound for left hand accompaniment. The percussion effect will only be triggered for the right-hand part of the split.

Two "combo" organ settings (35, 36) are provided: their sound is very different than the tone-wheel organ settings.


When the MICRO B is in MIDI OMNI ON mode, it will respond to all MIDI channels. Any NOTE ON/NOTE OFF information (within the note range utilized by the MICRO B) and program changes (if the PRESET selector is set to P) will be recognized by the MICRO B. To enable MIDI OMNI ON mode set the MIDI Channel selector on the rear panel to the "0" position.

Multi-timbral Mode

Multi-timbral Mode allows the MICRO B to accept MIDI information received on three (3) adjacent channels as determined by the basic channel selected on the rear panel MIDI channel selector. Program changes may be sent to the MICRO B to allow different presets to play on each of the three channels. The percussion effect will only be triggered on the basic MIDI channel.

To use Multi-timbral mode do the following:

1. Select the three adjacent channels to be enabled by first setting the MIDI channel selector to the basic MIDI channel. The basic MIDI channel and the next two higher channels will be enabled. If channel 15 is selected, channels 16 and 1 will also be enabled. See the chart on the next page.

2. Set the preset selector on the front panel to M . By doing this you are now telling the MICRO B to accept MIDI data on the three channels selected in step 1 above.

OMNI ON mode and multi-timbral mode are mutually exclusive. OMNI ON mode takes precedence over multi-timbral mode.

MIDI Channel Selection Table


MIDI Controlled Effects

The MICRO B allows control of several of its effects via MIDI control changes. The following table lists the effects that can be controlled by MIDI, their MIDI control numbers, and the associated control values:
Rotating Speaker Fast/Slow
0 - 63 = Slow,
64+ = Fast
Rotating Speaker On/Off
0 - 63 = Off,
64+ = On
Percussion Harmonic 
0 - 63 = 2nd,
64+ = 3rd
Percussion On/Off
0 - 63 = Off,
64+ = On
Vibrato/Chorus On/Off
0 - 63 = Off,
64+ = On
Vibrato/Chorus Depth
0 - 18 = V1,
19 - 36 = V2, 
37 - 58 = V3, 
59 - 79 = C1, 
80 - 100 = C2, 
101 - 127 = C3, 

Note the MIDI control numbers are fixed, therefore to control the effects mentioned in the table you will need a programmable MIDI controller. The various buttons, wheels, sliders, or pedals of your MIDI controller must be assigned to the control number corresponding to the effect you wish to control.

Because of the wide variety of MIDI controllers (keyboards, computers, or sequencers) available on the market today, you will have to determine which MIDI controller is appropriate for this particular application. For example, you may elect to use the MOD wheel on your MIDI keyboard to control the rotating speaker FAST/SLOW rate or you may decide to use one of the push button controls on your MIDI controller to turn on the Percussion effect.


1. Controlling the rotating speaker fast/slow speed via a MOD wheel:

Program the MIDI keyboard's MOD wheel to send data on MIDI control number 68 instead of control number 1. Since the MOD wheel is a continuous controller, it will output a control value of 0 through 127 depending on what position it is set to. To select the rotating speaker FAST rate simply flip the MOD wheel all the way up (on most keyboards up means away from you) or all the way down (towards you) for the SLOW rate. The rotating speaker will begin changing speed after the MOD wheel crosses the midway point (when the control value switches between 63 and 64).

2. Using a push button to turn the Percussion effect on and off:

Lets say your MIDI controller has a push button control that can be assigned any MIDI control number. Set the MIDI control number of the push button control to 73. The MICRO B will interpret MIDI control number 73 as the Percussion ON/OFF control. Most push button MIDI controllers will output a value of 127 when in the "on" position and a value of 0 when in the "off" position. If your MIDI controller allows you to program the control value, then make sure you set it to a value between 0 through 63 for "off" and 64 through 127 for "on". Now you should be able to turn the Percussion effect on and off by pressing the push button.