EP - 133 + OP1 Field sync

Hey fam, looking for some help syncing these two devices. I’d like to use the EP 133 to start and stop the Field, but the kicker is that Im trying to do this over 3.5mm since I need the USB C port open to plug my Apogee Jam into for my guitar. Pretty easy to get the sync going over USB C, not so much over 3.5mm, I was trying for a minute last night and couldn’t figure out which settings I needed to have configured to make this happen. Any help is appreciated!


one possible workaround for the short term is to remove the apogee jam. i personally plug my telecaster right into my op1f and it sounds crisp, clear, and signal strength is great. just a thought.


Nice! :+1: ^

Yeah do this or maybe check out getting a usb-c hub (like the Kenton Nucleus/nucleum? Something like that, te recommends)
This was you may be able to use both (you’d set the settings in the midi settings menu if it recognized both devices.

Just using an adapter from 1/4 to 3.5mm?

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correct. monster cable brand has an adapter and amazon sells a cable that is 1/4 on one end and 3.5mm on the other. just make sure to change op1f input to mono by turning ochre encoder in mic menu.

have you read this page carefully? especially the end? im not an expert but i think this might be helpful info that possibly maybe you have not explored yet. hope it helps.

fwiw the SYNC works slightly different on the EP than say the PO or the OP1

sync pulse on the TIP of the cable does not start/stop the EP sequencer like it does on the others

rather start and stop pulse is on the RING of the cable instead

likewise the EP sends this start and stop pulse on the RING of the sync out as well


ah just re-read your original post
if u trying to send the sync pulse from the EP to the OP1
then i think u are gunna have a bad time regardless
pretty sure the OP1 only sends sync pulses
and does NOT receive them

Dammit. Well thanks for clearing that up!

TE got back to me and said OP1F only receives midi over usb c


I really wish the op-1 field had an op-lab built in

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Best solution is probably using a Retrokit RK-006 and also get a USB-hub from them that is proven to work.

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Heyo guys.
And first, lemme say sorry for the crossposting (posted this in the EP133 thread on the Elektronauts forum).

Got some Sync question for you.

One of my customers (and dear friend, I might add) just sent me a bunch of tracks he recorded on his set-up.
Namely, an OP1 Field, a SP404mk2, an EP-133 and a Digitakt.

Upon mixing these tracks, I noticed a noise, spread across multiple frequencies, on the tracks labeled as EP133.
When asked, he told me he simply connected the EP133 to the op1 Field and recorded patterns from the EP to the OP. Connections went as follows :
EP133 out to OP1f audio in via 3,5mm stereo cable (to get the audio signal)
EP133 usb to OP1f usb via Apple USB-C cable (to get the MIDI sync)

He lended me his EP133 so I could help him troubleshoot what went wrong.
And when trying to replicate the issue, quick enough, I got that same parasite hum.

Upon closer inspection, it appears that the hum is probably due to some USB-C charging ground loop.
When disconnecting the USB-C, the noise goes away.
Trying to turn off the USB-C charging doesn’t work on the op1 Field.
Tried many variations : with or without fresh batteries in the EP133, various cables either direct in or through many hubs. But the noise persists. As long as there’s charging, there’s noise.
And the issue here is that the op1f only takes MIDI sync via USB-C (as per TE support feedback).

I tried to use PO sync mode to maintain the Sync in between, but after an hour worth of plugin/unplugin stereo cables and setups, nothing worked in between the two.

I tried his op1 Field and mine - this changes nothing.
His EP133 doesn’t produce noise when connected to an iPad, an audio interface or my SP404mk2.

I can salvage about 70 to 80% of that noise using RX10. He agreed on being charged for the audio repair, since there is no backup tool and he deleted all projects to free up space on the EP133.

So here goes my questions :

  • is there absolutely no way to turn off USB-C charging on the op1F when connected via USB-C to the EP133?
  • has anyone been able to work out PO sync mode in between the op1f and the EP133? I tried about 5 different ways based on reddit threads and OP Forums answers, but nothing works. I have enough cables and splitters to make this happen, but I can’t figure it out.
  • Has anybody noticed that same noise?

I included a screenshot from RX10 showing the horrendous noise in spectral mode (look out for continuous horizontal lines throughout the audio file : that’s our culprit caught red-handed!). I couldn’t get the video to upload. But tried to describe it to the best I could.

Thanks for any feedback. I’m out of options, for now. TE has the weirdest ecosystem of all.

Thanks for your time!

usb noise is super common when plugging both audio and usb between two devices
something about sharing audio and data grounds i believe?
from what i’ve read its a usb thing. like the way it was designed.

u can try a ground loop isolator either audio style or usb style
both should work. i’ve had success with both. u only should need one or the other.

i’ve never ever had success with turning the charging off
i also tried using DI boxes and lifting the ground without success either

as for the sync pulses.
the EP133 works a little differently than OP1 or the POs
OP1 // POs only need one signal. pulse starts and keeps timing
EP133 uses two signals (TRS cable is needed). it does the timing pulse on one (i think tip?)
and the start / stop on the other (i think ring? maybe these are flipped?)
also further, the OP1 can only SEND sync pulse. it does NOT receive it.
so u can’t really start stop the EP with the OP1. via the pulses.

a third thing (this may not be relevant to the field i’m not sure, but def is relevant to the OG or POs)
is that the sync pulse from the PO and the OG is really low.
like 1V. whereas most devices are looking for atleast 3v or 5v pulses.
so some other devices do not reliably detect these low pulses
so either no sync or erratic sync.

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Thanks a lot for all these clarifications.
Means a lot, helps even more.

I was, indeed, trying to start/stop the EP from the OP1f. And it never worked.

I may be short of one cable, tho - a dual 3.5 TRS to a single 3.5 TRS.

I’ll update this thread if I ever find anything. Or if TE has some insights.

The weirdest thing, tho, is that even if I do get some ground loop when using the MicroFreak and the EP, the MicroFreak ground loop is actually way quieter than the one from the EP.
And I still don’t understand how TE keeps designing thing around its ecosystem and not within.

Thanks a lot.
Dunno if you ever got the EP and the op1f to actually sync together - but I really appreciate your answer.

I was about to spend an hour tonight in between mixes and masters. Now I just need to spend 5 minutes finding the best ground loop isolator I can find!