DIY looper Midi Sync (Beat Buddy to RC-30 looper)

[knight of ni]

I recently bought a beat buddy and use it quite a lot when practicing. I got interested in using its MIDI sync feature to sync a looper, but my Boss RC-30 doesn’t support MIDI sync. As a matter of fact, only expensive loopers has this feature... (except the Ditto 4X, but really I would see no reason for spending any more money)

Searching the internet pointed out an Arduino based pedal which would feed signal to a JamMan looper which can be driven though a cable. The Boss RC-30 doesn’t have such a feature, but I could open it and solder two wires out of each switch and trigger them with an Arduino.

Electronics is not my best skill (Im more into programming) but it was good enough to start a DIY project. Here’s how it works :

-I opened the Boss RC-30 and soldered 5 wires, 2 for each switch and 1 for the RC-30 3V power. This allows the looper switches to be triggered by the Arduino micro controller using optocouplers. This way electronics are totally separated and if lightning strikes the Arduino, well, the RC-30 is intact. More seriously it protects each device from a mishap on the other one.
A hole has to be drilled to let the wires out of the RC-30 either as is or using a plug.
Apart from that all RC-30 functionality is retained, original switches operate as before.

-A midi cable is connected to Beat Buddy MIDI out, and it is in turn connected to the Arduino through an optocoupler. This again decouples the Beat Buddy from the Arduino electronics.

-A pedal with two momentary switches is connected to the Arduino as well

The controller+electronic components, switches etc. is well under 50$/€.

When the Beat Buddy is playing, the Arduino gets the clock signals through the MIDI interface. When the left switch on the pedal it is connected to is pressed, it waits the next beat “one” to trigger recording on the RC-30. When the switch is pressed again , the Arduino again waits for beat “one” to stop recording. As the beat buddy sends time signature MIDI messages, the Arduino knows which beat is the “one” regardless of time signature. This way the loop and beat buddy are in sync.

The crucial point is timing. The looper will repeat endlessly the loop it has recorded while the beat buddy keeps playing. If the bars aren’t exactly the same duration, then the looper will drift away from the MIDI clock as the loop repeats.

The first successful tests show a difference of 60 microseconds on a 2.4 s loop. This is about 0.1 s difference after an hour of playing the loop against the beat buddy (1500 loops). After 10 minutes, the difference would be 15 milliseconds and I guess it’s hard to notice. Perhaps some optimisation will decrease this delay to 30 microseconds or who knows maybe even a few microsecs, but for the moment it’s good enough for me.

If anyone is interested I can post pics, diagrams and the Arduino code. It’s only a prototype at the moment but I intend to incorporate all that in a pedal. It can probably be adapted to any device that broadcasts a MIDI clock / any looper one is ready to open and solder wires inside.

Given the fact that you have to solder electronic components and open a looper to solder wires in it, the post audience is probably restricted a few people. Nevertheless, if anyone is interested/willing to participate, just ask me.

 

[Adamixoye]

Alternatively you could have bought my Pigtronix Infinity that I'm planning to sell, LOL.

But this is a cool project, subbed out of interest.

 

[Kahootz]

I created an account specifically to comment on this thread - I too have recently acquired a Beatbuddy and I’m trying to figure out how to make it work with my RC-30... things weren’t looking promising until I came across this. I would love to hear more about your project!

 

[jdh3000]

I run both instrument and drum machine into my Boss RC 20(neither have midi capabilities), then loop at whatever point, and stop the drums as I start the looper, then switch back.
With the loop pedal side by side with the drum start/stop pedal this can be done with one foot.

This is only really effective with one loop and of course no fills or any changes can be made to the drums while the loop is playing, but it's a perfect "sync"

I have an RC 50 which I can do more with, but I like the simplicity of the RC 20.
I do this with guitar mainly, I can lay down a rhythm and play lead to it.

 

[knight of ni]

Well I think I've nailed it. The key is not to try to trigger start/stop recording upon BeatBuddy MIDI events. There is often some random lag in receiving those events and you just can't count on being lucky. A few milliseconds difference get very noticeable say after 50 loops. The way to go is to let the beatbuddy run at a given tempo and trigger tap tempo on the Boss. The randomness will even out and if you use record loop using tempo mode then the recording is well synced.
I still have some development to do but it could be very simple : each time the Arduino detects a tempo change on the beat buddy it waits for the tempo to stabilize then send a tap tempo sequence for some bars. The beatbuddy can be paused (silent) but still sending the MIDI beats, which makes the tap tempo sync a silent operation. So basically you'd use the RC-30 as usual except it would be kept in sync in the background. What I have also to figure out is what happens when it's not a 4/4 rythmn.

 

[oanao]

hey, you project sounds awesome
Are you still ok to post diagram or scheme of the electronics and the Arduino code ?
I'm super interested, I have a Boss RC-30 and I'd like to sync it with the rest of my set-up : sequencer, drum machine, etc. and that would be great for the looper to be able to receive external MIDI or clock signal.

 

[knight of ni]

After a lot of testing I came to the conclusion that the only way the RC-30 could be driven reliably is through the tap tempo function and not through start/stop loop record as I 1st thought. The MIDI beat signal would randomly be a few ms off, so if it happens at the start or end of a loop recording the difference increases loop after loop after loop until it's quite noticeable. So sometimes my setup would work, sometimes it wouldn't, despite all the "clever" correction functions I'd thought of.
It all evens out with the tap tempo feature and then you have to record the loop based on the tempo. If that's enough for you I can share some stuff although it was far from being finished. Basically what you need is an Arduino board (obviously), a MIDI connector and library (easy), some bits of code (esay too) and simulating the second pedal press which means soldering 3 wires on the boss pedal, 2 for pedal button and 1 for the 3.5V voltage supply somewhere inside the pedal (easy to find too). The 3.5V is needed to decouple voltage supply from the Arduino and voltage supply from the pedal so as to avoid any potential mess. "Button pressing" is done through an optocoupler (in fact the MIDI connector uses one too).
I say 'was far from being finished' using the past tense because in the mean time Boss released the RC-500 which is right at the price point I was willing to spend on a MIDI enabled looper. It does everything I need so I have no need to pursue the project.
Basically the RC-500 tracks the tempo from the beat-buddy (and possibly any other MIDI device) but of course it does whothout nedding to press the tap tempo button and that's obviously something I couldn't do with the RC-30...

 

[oanao]

Ok ok, I think I get it. Thank you for your very quick answer
For now that's more than enough for me, maybe later I will understand better what additional features I'll need but right now it looks exactly like what I need.
So if you're still ok to share what you've got, that would really help me.
Thank you so much for your time