How to get Koala sequencer and OP1 field tape to sync over midi?

Hey everyone,
I am looking for a solution to a problem that I have been trying to solve for days:
Background is that I’ve had some success syncing my SP404MK2 and the OP1 field tape over USB-C so that I can program drum sequences on the SP and play them in sync with synth parts I have looped on the OP1 field tape. It’s a bit wonky but works for all intents and purposes.

Now, given the expected increase in portability, I tried to do the same thing with Koala on an iPhone 15 Pro and the OP1 field, but no such luck. I set the OP1f to send midi clock and Koala to receive it, but when I start the tape, Koala doesn’t start alongside (yet the play button is greyed out and says that Koala is syncing to external clock).
What’s even more weird: I want to process Koala audio through the OP1 and I can see from the recording meter that audio is incoming when I hit individual buttons. But I don’t hear anything. And yes, I have activated the “audio over USB setting”.

How can I get the two to talk together, preferably without going through another app? Any advice is welcome!

Great question and something that is useful to figure out. I was able to get most of the way there using Koala on an iPhone 13 Pro Max. By most of the way, I mean that I could not get the clocks to sync. I had Koala set to 110bpm and the OP-1 Field set to 65bpm and they did not auto-sync tempos. Other than that, and if I had to I could manually override the bpm as needed, I was able to push play on the OP-1 Field tape and it auto-played a Koala sequence. Not the reverse (Koala activating the OP-1 tape). I, too, had issues like you described at first. I was able to trace it not working to the connection via the USB cable was not fully recognized on the OP-1 Field—no apparent reason why, just wonkiness?I needed to unplug and re-plug the cable back into the iPhone and then I got the red connected icon within the USB connection icon. Then, everything started working. I did not do anything unique with the midi settings within the OP-1. In fact, I left it on “Both” for all of the midi options. In Koala, I needed to turn off the “External Midi clock sync” option and rely exclusively on the “Ableton Link” option, meaning I turned that setting on. Hope this helps. It is a bit fiddly, though. Lately, I have been finding the USB cable connection/handshake between OP-1 Field and other USB devices to not always be “on” and ready. Instead, needing to unplug/re-plug them to get everything to fully connect. Happy to answer any additional questions that may come up with this—I will do my best to add any more useful details as needed.


Thank you so much for your input. I have found out that weirdly I can get them to start and stop and keep sync including bpm when NOT using midi sync and toggling between po sync (which is obviously bad because it sends a timecode signal) and I think it’s called beat sync.
Another problem with my approach turns out to be that I cannot separate the audio input from my phone from the internal audio routing, so whenever I want to record something on the op1f to tape it also records the phone input. This is sort of ok when just recording synths to drums from the phone (I can just record with the phone input muted) but obviously poses a problem when trying to layer melodies and a bassline onto sample chops playing on the phone.

Finally, straw that broke the camel’s back, I have abandoned the project when I noticed that the OP1f won’t stop drawing power from my phone even when that setting is disabled.

I have weirdness problems with the SP 404 MK2 as well. At first I thought it was the SP but I am now convinced that it’s the OP1f. I hope for an update that really fixes midi on the op1f (I am not going to but an Ep133 just for that, and it’s not even clear that this would solve anything), allows for better audio routing, and also really disables charging. I am not holding my breath.

Thanks for the additional thoughts, experiences, and challenges. That is wild that using the PO SYNC option worked, for the most part, for what you are looking to do. Inspires me to mess with the bpm sync settings on the OP-1 Field to see the pros and cons of each option.

I totally share your frustration with the power drain of the OP-1 when connected to a mobile device via USB-C—the inability to permanently shut off the recharging of the Op-1’s battery. I do seem to find that once the OP-1 is fully charged, the power drain is significantly less on the mobile device—for whatever that’s worth (not much!). One workaround might be to use the 1/8” connector/cable and pass sound that way (no power charging involved). Depending on what model of phone you have, you might need to get a lightning to 1/8” adaptor to accept the cable coming from the OP-1.

An additional thought: have you considered using AUM on your mobile device as an intermediary interface between the OP-1 and Koala (or any other AU apps you might want to connect the OP-1 to. I know you are looking to keep it all light, streamlined, and simple…but AUM opens up so many possible routings and signal flow options between the OP-1 and your mobile device. You can set/customize which direction you want audio to go: from the OP-1 to the Phone via AUM and have AUM manage Koala; and also pass audio back and forth between the two—sending audio from Koala (via AUM) back to OP-1 either as a sample (synth or drum) -or- direct to the tape recorder. Pretty flexible and powerful. A lot of mobile music makers use AUM, or another is apeMatrix, that can manage signal customized signal flows. Both also support Bluetooth midi, if that has any use for you.

One last thing, and I am not sure this is applicable to your issue and use needs, but one way to stop the sound coming from the OP-1, when it is unwanted, might be to create a silent synth—save a synth slot with no sound. That way, the only sound that can come from the OP-1 is from the recorded tape, if that is preferred. Just something to think about, if it has a use case for you. Let me know if you have any additional questions.

Thanks for your reply, sorry for being so late to answer.
It think I will give AUM a try if TE ever figure out the charging thing (or Apple puts in toggle to disable reverse charging because it’s pointless most of the time anyway). I don’t want to spend time setting it up as a proof of concept without actually using it because my phone is dead after having it connected to the op1f for an hour.

about the sound routing: the problem for me is specifically that I want to disable sound recording over usb-c so as to be able to play Koala through the op1 master bus without it recording to tape.
There’s a nice diagram for the signal path in the op1 but it’s just eye candy as far as I can tell and provides no way to manipulate the internal routing…

Again, thank you for your help. If anything changes on the firmware side of things, I will try this again and report (I still believe this would be a really neat ultra portable setup)

I wonder if the charging - which device charges which and so on - isn’t wrapped up in the USB specification. There might not be much choice if you’re going to be plug and play compliant.

Yeah that’s possible. But I think it’s also possible to prevent it with software modifications. There’s even an option in the op1 firmware. It just doesn’t do anything…