Norns midi clock noise

just got my 2host built which is super exciting, but I’m noticing that when I am sending midi clock from ableton into norns, I can hear it a bit. it’s definitely the clock as it is in ratio to the tempo transport set in live (a lot faster probably 12ppqn or whatever)

no clock, no noise:

clock going in, monitor at 0 in levels, low noise

change monitor to 100% in levels, higher noise

eng at 100% for reference when monitor is at 0% (if you turned your speakers up for the others, turn them to normal levels for this one)


Are there ways to mitigate noise from the clock going into the usb port? If not, what would be some other approaches of clocking norns from ableton?

ah I see that there is currently a beta of ableton link support, and some documentation and stuff coming in the next release of norns. I’ll keep my eyes peeled on that stuff Norns: clock

Consider this issue resolved pending that stuff (though if anyone does have ideas for ways of lessening noise getting its way over to the audio outs, still would be interested to know)

I’ll try a few tests and see if I can reproduce. Might be something tweakabke

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Sounds good, happy to help test anything too, just @ me. I raised gain on my interface to where awake (eng at 100%) was peaking close to 0dB. Audio outs at 100% in levels too

this is possibly an electrical/grounding issue with 2host

try with norns battery powered

try with a different usb midi solution as well, ie, usb midi on norns, din midi to audio interface on ableton, etc. din midi is optoisolated

but yes, much better: link support any day now

@okyeron @tehn I found some other micro usb cables that seemed to work better (noise still there but reduced in amplitude). It did not seem like power adapter plugged into norns vs. not changed the noise.

For a second there I was also getting noise from my (non-factory-issued) wifi adapter…norns audio out stopped working very briefly (maybe plugging in and out the wi-fi adapter caused norns to wig out?), I rebooted norns, and the additional wifi adapter noise stopped happening.

I’m doing some debug with @jlmitch5 in DM. Can’t reproduce on my setup, unfortunately.

FWIW - 2host midi signals are optoisolated

but this is all USB, right?

laptops + USB ground + audio = bleh

it’s USB to micro to MIDI (with optos) and back again.

Basically the same thing as 2 USB->DIN converters plugged together.

oh, apologies - my brain read that and thought about the ‘iconnect’ things.

but anyways… i do not see a schematic for 2host in the repo, but… from the layout it looks like the teensys are sharing a ground, no? therefore the norns and host USB shields are effectively connected? this is what i mean.

if that’s not the case then i can only imagine we are not giving enough current to the teensy that is supplied by norns host port. seems unlikely, LC consumption should peak at 50ma or less.

Yes - the 2 teensy’s are sharing ground. So that’s bad? Do the grounds need to be separate? (I did this awhile ago, so don’t remember if there was some rationale there, or just being dumb)

yes, it seems to me like a bad idea for noise issues, defeats one of the points of optoisolation (the other is protection against over-current / over-voltage,) and i can’t think of a great reason for it. (but it is hard to reason about it w/o schematic)