CR-78 midi with uniPulse


  • Midi trigger of all CR-78 instruments, most fully velocity sensitive. Guiro pitch can be controlled slightly.
  • Midi controlled accent trigger (send max velocity 127 to trigger accent). Accent amount is still controllable via knob.
  • Instrument mixer on CR-78 will continue to work.
  • Sync via midi clock, switch between internal clock and midi clock via toggle switch.
  • Use CR-78 Rhythms and midi control simultaneously.
  • Not need to cut any traces, installation is completely reversible.

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Installation manual

The installation manual as PDF

Config file

Config file Download (Right click, save as)

TR606 UniPulse Installation

Buy uniPulse in our shop!

uniPulse TR-606 features

  • Full velocity control of all 7 voices
  • Six (6!) additional sounds (An 808ish deep clicky bassdrum and a higher pitched one, Only Snare Noise, Only Tom Noise, Each half of Cymbal (the hitting sound and the decaying sound))
  • Midi clock input. Clock is also sent to external din-sync devices.
  • Midi controlled Open hihat decay
  • Midi controlled hihat and cymbal length
  • You can install an additional midi socket, or use the existing DIN-Sync socket

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Hammond AutoVari 64 midi with uniPulse

Thanks to Jonas Olesen we now have a comprehensive uniPulse installation manual.
He also installed extra outputs and pitch mods which are of course optional, but recommended modifications.

Note from Tubbutec forum user Cyrano1 :
Note this is only for AV-64 MK-1 boards (->1979).
Auto-Vari 64 MK-2 board (1980) has completely redesigned unit on one single board with various ICs that is totally different.

The Hammond Auto vari 64 – Unipulse installation and modifications

By Jonas Olesen

some more info in this thread.


The power wire in the back goes directly to exposed solder joints besides the transformer, BEFORE they go
into the transformer. This means that 220v is completely exposed – be careful.
I glued a piece of plastic on top of these joints.
The service manual is extremely well written and explains almost all circuits in detail, and combined with
the fact that all connections in the machine are marked with their functions in plain English, makes the
machine very easy to work with.

Installation of the Unipulse:

Very straightforward – simply cut the wires in the voiceboard connector and solder on the unipulse triggers and power. Then reinsert the connector.
[Tubbutec: We believe there is a way to avoid cutting wires, but lacking a machine we can not test this. If you own a machine and want to test this, please get in touch]

I attached the unipulse board to a piece of wood glued and screwed to the chassis.
Trig outputs 1-9 triggers the sounds, except brush and sandblock.

On the front of the Autovari I have installed 10 additional outputs from the Unipulse, so these can be used
to trigger / synch other machines. Please note that the back panel is too thick to attach minijack outputs,
The fron panel is thin metal, and there is a lot of space for outputs and additional potmeters here.
Midi input installed on the back besides audio outputs.

Small corrections to the Tubbutech voice board trigger points:

Bassdrum trigger: differs from the drawing, has to be Bassdrum besides it (has a wire)
Brush has no wire in the connector, it will probably trigger if the trace is followed underneath the voice
board, but I did not implement it. Strangely the Brush plays in the internal rhytems, although no visible wire
is connected to it via the voiceboard main connector.


Low frequency output:

Seperate output for the low frequency content.
Main output contains both hugh and low content – the balance pot located on the back is moved to the
front – from here the balance can be set to only high frequency content.
This way there are a seperate output for low and hugh content.

Pitch mods:

Easy and a must do!
I found the resistors by poking with alligator clips – the online scanned service manual is so low resolution,that the resistor numbers can not be read.
1: Bassdrum: Replace R4 with a 50k log pot
2: Snare drum low frequency: Replace R65 and R55 with a stereo 50k log pot
3: Conga: Replace R14 with a 50k log pot
4: Bongo. Replace R23 with a 50k log pot
5: Claves: R33 + R32 50k log Stereo pot (to obtain a wider pitch range)
6: Rimshot: Replace R40 with a 50k log pot
Cowbell: The cowbell consists of two seperate sounds:
7: Cowbell 1: Replace R50 with a 50k log pot.
8: Cowbell 2: Replace R58 with a 50k log pot.

Not implemented:

Sandblock CV trigger.
Brush trigger.
Decay mods.
Sync clock:
Not tested

Download the config file (you need to extract the pconf file from the zip file).

Rhythm Ace FR6 uniPulse install

This manual describes how to add velocity sensitive midi to the Rhythm Ace FR6 using uniPulse.

Picture via Matrixsynth

This was not tested, the manual is only based on the schematics available. If you have installed this, please be so kind and send us pictures.

Configuration file is here. (Right click, save-as)


The picture below shows the trigger point locations. Just solder uniPulse wires P1 – P8 to these points.

uniPulse power

Solder unipulse wire V+ to the V+ point shown in the picture below. Solder uniPulse GND to the V- point.

Clock and sync

It is not impossible to also sync the FR6 to midi clock. It is however rather complicated and involves quite a few extra parts. If you are interested please write us and we will provide instructions.

Rhythm Ace FR-1 uniPulse install

This manual shows how to connect uniPulse to the Ace Tone Rhythm Ace FR-1. It is possible to control all 10 drum voices via midi and they are velocity sensitive.
It is even possible to control the Brush sound in a velocity sensitive way.


Here you can see the voice board with the connections of uniPulse triggers P1-P10. The brush control needs a general purpose PNP transistor such as BC557 and a 56k resistor. Connect them them just the way it shown in the picture.
B, C, and E are the Base, Collector and Emitter of the transistor.
Connect the base to point B, the emitter to point E and the collector to uniPulse CV-out via a 56k resistor. The 56k resistor is not connected to the 470k resistor on the board, it only looks like that in the picture.

Continue reading

Maestro Rhythm King uniPulse install

Trigger the voices

Here you can see the trigger points for the Maestro Rhythm King.
In the upper right corner you can also see the +12V power supply for uniPulse.

Here is a picture of the voice board.A kind person from sent us this annotated version:

Interfacing the clock

The following created by our customer James Lo who did an awesome job interfacing the Maestro Rhythm Kings unusual clock circuit.

These instructions show a way to inject uniPulse sync clock and sync gate signals into a Maestro Rhythm King MRK-2. This is the MRK-2:

The MRK-2 has the unusual feature that it changes internal clock speed dependent on whether triplet or 16th note beats are selected. The circuit also encapsulates one of the more convenient clock injection points inside an RC network SIP, so we have to resort to unusual means. My solution parallels the transistors that comprise the “clock multivibrator” and selects the correct sync pulse based on the current beat. Here is a schematic-view of the points we will be attaching to:

Next is a component-view of those same points. The board containing the clock circuit is underneath the voice board, which can be easily removed to gain access.

To interface the uniPulse to the MRK-2, the uniPulse triplet and 16th note sync pulses are first level-shifted to the MRK-2’s v+ (~19V), and then one is selected by the triplet switch position (which is itself set by the current beat). The chosen pulse is used to drive a pair of BJTs that take over from the MRK-2’s clock multivibrator transistors. The MRK-2’s transistors are disabled by shorting their bases to ground via diodes, and the BJTs are enabled by shorting their sources to ground via diodes. Finally, the sync gate is used to switch v+ to the MRK-2’s start signal bus, mirroring the function of the start footswitch.

Here’s the uniPulse configuration:


The MRK-2’s clock multivibrator produces 15ms positive and negative pulses at all frequencies, so its duty cycle is frequency dependent. The uniPulse sync clock however is a square wave, but it doesn’t seem to matter. It’s possible to switch between duple and triplet beats while the machine is running, but you risk losing sync alignment. Note that the selection of active components isn’t particularly sensitive; you could, for instance, substitute a CD4011 for the CD4093. I just used garden variety small signal transistors I had left over from previous projects.

One known issue is that the clock rate is not quite right for the waltz and swing waltz beats.

Rhythm Ace FR2 uniPulse install

This manual describes how to install uniPulse in the Rhythm Ace FR2L

This is based on the schematics and has not been tested yet. Please let us know if you have installed it. Bonus points if you send us a video of the drum machine in action 🙂
Download the uniPulse Configurator file for Rhythm Ace FR2L

uniPulse power

In order to power the uniPulse, you need to install a few additonal components. Due to the high voltage after the transformer, an additional 15V regulator must be used (7815). The capacitors should have a voltage rating of at least 35V, more is ok. Connect the uniPulse V+ and V- wires as shown in the picture.


Trigger are very straight forward. Most triggers are soldered to the legs of diodes on the voice boards. Cymbal and Maracas triggers are simply connected to the solder points on the voice boards. It is also possible to control the Brush (B), but without testing it is hard to tell exactly how. This will be updated as soon as this information is available.

Clock sync

As always syncing the drum machine to the midi clock is optional and requires additional circuitry.
A level shifter is needed for the start/stop signal. Two pole switch (included in the kit) is used to switch between internal clock and midi clock. In order to access points A and B, desolder one leg of R12. A is connected to the resistor, B is connected to the board where the resistor was connected originally.
Point C can be directly connected to the Start/Stop switch.