TR-77 Midi with Unipulse

This is how to add velocity sensitive midi to the Roland TR-77 drum machine using Tubbutec Unipulse.

Installation is very strait forward, you just need to solder some wires and drill holes for the Midi socket and learn button. To get a sound over midi, the machine needs to be started and no pattern selected.

Config file here: TR-77 config file
Alternative config file by Jacob Korn (thanks): TR-77 config file alternative version

This manual is just a brief description of how to install the uniPulse, for further information please check out the uniPulse page.

Trigger points

Trigger points are shown for all 13 instruments including Maracas:

trigger inputs 1-7

trigger inputs 1-7

trigger inputs 8-12

trigger inputs 8-12

Maracas CV input (Resistor is 75K)

Maracas CV input (Resistor is 75K)

This is where to get the supply voltage for the uniPulse:

Unipulse supply connections

Unipulse supply connections


It is possible to sync the TR-77 to midi clock, you will however need to start/stop the machine manually.

  1. Start the machine using the ‘button’.
  2. Start the midi clock

In order to add midi sync, you need to connect to the point shown in the picture below. Use one of the uniPulse digital output pins and configure it as ‘midi clock’. You also need to add a 4.7k resistor in series and a switch to select midi clock or internal clock.
The switch is included in the kit, the 4.7k resistor is included on request.

uniPulse D output –> 4.7k resistor —> switch —> point on the TR-77 board

Picture by Burnkit2600

The start stop method also shown in the picture will not work properly. it does not switch the machine between started and stopped state, but rather toggles between them on each start. That is somewhat usable but not perfect.

Installed board

And this is how the installed uniPulse board looks like (These pictures show the old MK1 version)

unipulsemount socket

11 thoughts on “TR-77 Midi with Unipulse

  1. Hey guys!

    got a Roland TR-77 and a couple of other drummies and was wondering if there is a place to share the presets?!

  2. Hi Jacob,
    so far the presets are linked in the installation manuals of the various machines. If you have config files for other machines it would of course be great if you shared them, at best together with a short description and pictures of the trigger points. You can send this directly to Tubbutec or register here and write a post yourself. See
    Thanks a lot 🙂

  3. Amazing! Is there a way to connect this so it can control the clock on the tr-77 so you can sync the patterns to other gear?

  4. Hi Thomas,
    unfortunately in case of the TR-77 we did not find a an easy solution to sync it to midi clock. But there certainly is some way to do it..

  5. Re: sync – any chance this makes sense, in the context of installing the Unipulse in a TR-77?

    From : ‘Simply connect the din sync line to the TR-77 resistor R4… It should sync best at 4 or 8 ppqn.’

    I see mention of clock outputs, midi dividers and DIN sync on the main Unipulse page, and (without being an electronics whiz myself – I will have a friend helping me with this) that makes me think that syncing a TR-77 is as simple as connecting one of the clock outputs to R4, and setting up the right division in the config – could that be the case, or do I misunderstand?

    Thank you!

  6. It is possible that this works, yes. It is however important to secure the uniPulse pins against high voltage by putting a resistor in series. 10k should do. The high voltage from the TR-77 might otherwise destroy the uniPulse.

  7. I’ve read the tr-77 is quite similar to the auto-vari. Would these instructions help me which the installion of the unipulse into my auto vari (since there isn’t instructions)

  8. Probably not. We can however provide you with an educated guess on how to do the installation based on the schematics. Best you write us a mail. Which drum machine is it exactly? Auto-vari 64?

  9. Hi guys, did someone finally found an easy solution to sync the tr77 ? if yes, can you please share your experience and explain us how to proceed ? thanks a lot in advance.

  10. Hey, quick question regarding the sync.
    I got it semi-working … It looks like if i stay above about 110BPM it sounds fine but under 110 it starts to sounds really weird , hard to say whats happening but its not what i would expect. Can you confirm (or not) if you have similar behaviors?

    Thank you <3

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