Curiouser and curiouser. Is it like a radio-frequency noise, the way sometimes your FM radio would pick up the fact that your cell phone was about to ring? What module is the noise coming out of? Just the one oscillator? Does the Mother 32 do the same thing when you run it as CV out of the Keystep?
Yeah, any module I’ve tried listening to as well as the M-32. As noted, it doesn’t depend on synth output level settings so I think it’s just the fact the ground loop exists or something of that sort. Sounds like digital switching noise plus low frequency, maybe 60 Hz although there’s definitely more frequencies and structure than just the usual 60 Hz.
M-32, synth PS, and computer all are plugged into the same UPS.
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Does the frequency of the noise appear to change when you play different notes on the mother? Can you measure the frequency of the noise?
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Have you tried on laptop battery as suggested…
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Does the sound change if you open a window, or move one or in general move the computer’s mouse? I’m experiencing that with my macbook and usb audio-interface-output + mixing desk + usb audio-interface-input. There is definitely a loop here.
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I tried the simplest setup I could think of:
- Mother-32 plugged into AC
- Audio interface USB plugged into laptop (running on battery)
- KeyStep USB plugged into laptop
- KeyStep CV Out plugged into M-32 VCO CV in
and the noise is present.
The higher frequency switching type noise is reduced if I plug a 9V wall wart into the KeyStep. It’s not eliminated and the lower frequency noise stays the same.
The noise DOES depend on activity on the KeyStep. For instance, switching between Seq and Arp changes the high frequency noise by about a semitone. So it seems I’m picking up noise from the KeyStep circuitry.
The noise does not depend on mousing, window opening, etc. on the laptop.
The noise disappears if the audio interface USB is moved to the desktop computer while the KeyStep USB stays on the laptop.
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Is the KeyStep’s USB required to do anything (other than, presumably, firmware updates) it can’t do with MIDI DIN?
Not that I have a MIDI DIN interface. I mean, I used to, but it’s nowhere to be found, and anyway it was ancient. Don’t know if it’d work with my current setup.
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BY doing that you have broken the loop. It seems that you have found your way of recording audio. But, seriously, this is a right mess, this USB interference thing. I used to be able to make the most noise free recordings in my studio!
B.t.w. if you had changed to midi that might have broken the loop as well as long as there is no GND connected in the midi cable (otherwise that would introduce a loop, and midi loops are no big deal, but the USB noise the midi cable picks up is).
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You can back up saved sequences to the Arturia Midi Control Center software and set various running features of the Keystep, but otherwise if you don’t need to use the Keystep as a midi or DAW-CV box and as a stand-alone sequencer/controller it works for you then it sounds like you’re set. If you have another less noisy USB to midi solution then there’s no reason you couldn’t use the Keystep’s 5pin midi out tot that input.
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Desktop machines can be really noisy, more so than laptops. Get a USB isolator… It will probably solve your noisy PC issue.
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Noise exists even plugged into a battery powered Chromebook with the desktop machine off. And as indicated changing controls on the KeyStep changes the noise, suggesting that’s where it’s at least in part coming from, though I don’t have a powered USB hub to try with no computer involved at all. Jos has previously reported “some limited success” using a USB isolator in a similar situation.
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That will only work if the USB device is not very demanding data speed wise. I could not keep my audio device from stuttering with the USB-isolator.
I think the best bet is to use ground loop isolators in the analog domain to break the loop.
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Would that have unity gain though?
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They are supposed to. In loopop’s video they are mentioned and BigClive also has a video on them.
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Sorry, I’m being stupid. I was thinking of the analog connections from the BeatStep to the synth, which would require multiple isolators operating at DC at unity gain which isn’t what these things are necessarily designed for. But I’m sure you meant the connection from the synth to the audio interface, which makes more sense. Guess I’ll look into it.
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FWIW, the audio isolators did nothing for the USB noise coming from my Roland Boutiques.
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Maybe it’s just faulty? Laptops have DC DC converters that still make a noise. Maybe the noise is coming from the keystep. It’s really tricky chasing down noise in a system!
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Oh, that’s a bit rubbish! Analogue loop isolators work really well, I’ve got a few of them between the digital domain and the analogue. My Raid disk packs make a lot of noise, they have rather cheap power supplies. Shame for things that cost nearly a grand a piece.
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Why do you think that is so? Please explain.
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If I knew what it was, I’d have said. It’s rubbish to have a noise problem… just clarifying.
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