OP-1 and OP-Z connected together with MIDI and Sound output creates strong sound interference

I just got an OP-Z. And wanted to use it with OP-1 : the sequencer would be driving the music, while the OP-1 could alow me to add additional layers on the 4 tracks recorder.
For this I needed:

  • to mix both of their output to the same output : using a mixing table
  • to connect them together with MIDI so that they are synchronized
    Everything worked almost perfectly… except that… connecting the audio output together while both are connected for MIDI leads to a very noisy sound interference.
    This noise is so strong that it prevents any decent recording or work when connected together…

Here is a video that shows the issue:

Did anyone experience the same ?
This problem is a typical accidental amplification of some CPU/Microcontroller noise. It probably comes from the fact that one of these 2 devices are improperly shielded.
It’s frustrating because both come from the same brand and are impossible to work together.
As a side note: If you connected one of them to a power supply with ground, the noise gets lower… but still unacceptable…

Any experienced the same ?

This could be USB noise. You can get around it by either disabling USB charging for one or both devices, or by using a filter on either the usb connections, or on the audio cables.

Turning off USB charging on both devices can help, but it didn’t completely get rid of the noise for me. I bought a ground loop isolator off amazon and it cleaned up the noise perfectly.

That sounds great ! Thanks for sharing
Now: how to you turn-off the USB charging feature :

  • On OP1 ?
  • On OPZ ?

I am not sure how you filter things here : do you need a special USB Hub that shields signals properly ?
I tried a better mixing table (with ground power cable)… it kinda helped but still getting interferences in background…

u can turn off usb charging on both op1 and opz.

if that doesn’t work, what u need is a ground loop isolator
some come in the form of a usb device.
others are audio.

the audio ones are cheaper than the usb. both should work fine.

Thanks ! I will check these ‘loop isolators’ !
Does anyone know do we turn USB charging option in OP-Z and OP-1 ?

its in the guide for both of them

for op1 is in the shift+com menu

for opz is some button combo that i dont know off the top of my head

look it up

opz its hold screen+ note E2

Cool. Thanks! I surprisingly missed these details in the Doc. while reading…

I think my issue on the buzz sound is resolved. And yes : I had to cancel the USB power on OP-1 and OP-Z (“Screen” button + E2 Note).

Now, looks like I can’t put the OP-Z back to USB powering… “Screen” button + E2 Note doesn’t seem to toggle it back… but it’s another story

Thanks for your help, guys!

Usb powering is probably switched on again after turning poweroff and on?