I’ve noticed an excessive amount of noise on the audio output of my Gills when it’s powered by USB power from the PROG port, and has a USB MIDI controller connected to the other USB-C (host) port.
Most of the noise disappears when the controller (Novation Launchkey Mini Mk.3) is disconnected.
Is this expected behaviour, and if so, is there anything more that can be done to prevent USB-device-related noise breaking through to the Gill’s audio output?
Should I be powering Gills and/or the controller from an external power source, perhaps?
Powering Gills and/or the controller from an external power source is an option but may still not avoid ground loops.
If you are powering Gills from a laptop, as a test, run your laptop on battery (instead of AC) while Gills is connected and see if noise is reduced.
Which Gills version do you have? Noise has (arguably) been improved after users on Discord suggested some changes.
Some users reported noise from MIDI controllers with lots of LEDs, the noise even pulsing with the LEDs lighting up. An old Axoloti problem apparently. Some are using some sort of USB isolator between Axoloti and the MIDI controller, @Blindsmyth am I correct?
Here I can power the controller on a seperate outlet on my isolated power supply.
I did however notice a lot of noise on @karlosono’s gills when powered by the computer the other day. No external midi controller attached. This was something I never had with axoloti in that form.
This happens a lot with USB powered devices sadly. I’ve not noticed the problem with my Ksoloti build but it’s a nightmare with the Korg NTS-1, which I’m powering and controlling over USB MIDI.
What I’ve found knocks the noise right back to nothing is a massive ferrite core on the USB lead:
It sounds like black magic but it kills the noise while still allowing the essential USB functionality. You can get a load of them cheaply on Amazon - I think I paid about £6 for 10 of them, something like that - and I’ve added them to any of the USB leads I’m likely to use with audio gear.
I suspect it’s not a ground loop issue, but if it is you can get isolators to pass the audio through. Or you can build your own like I did
Interesting! Despite what some engineers say, I have found that ferrites on 5V AND ground lines of the USB connection seem to help reducing noise. The latest Cores and Big Genes have those added.
Gills does not have its own USB connectors, but it does have ferrites on the external DC power input.
Incidentally, here is a screenshot from a member post in the Synth DIY group on Facebook:
The worst of the noise I was experiencing was definitely related to the LEDs on the Launchkey Mini. It varied according to the pad LED lightshow. I wonder if there’s a setting in the Novation config app to keep the pad LEDs turned off.
I’ll get myself some of those ferrite rings. Neither of the cables I was using had them, I don’t think.
That’s intriguing, but don’t those coils pick up loads of additional noise from ambient RF?
Not in my experience. They’re standard audio transformers, used for decades in all sorts of things including telecommunications. This is where I got the circuit from: https://solorb.com/elect/musiccirc/stereoiso/index.html
If you don’t have a ground loop issue I wouldn’t use an isolator though, because you inevitably lose some of the volume. The big ferrites are much more likely to help you out, from my experience at least.
Really try to run the launchpad on a seperate power supply with the isolator. I’ve had these irritating LED noises with all of my midi controllers, launchpad, launchcontrol XL, launchkey mini etc and this really got rid of it completely!
Good point here! I’ve been putting these on all connectors with my axolotis, but somehow forgot about this option with my ksolotis. This is a good reminder to get a few of these.
Yeah this also helped me sometimes. You can also buy this in different format:
I’m just revisiting this because I found I needed a USB isolator when I added a couple more USB-powered things to the hub. I picked up one of these on AliExpress and it works really well: https://www.aliexpress.com/item/1005007593501630.html
It works at USB 1.1 speed, not USB 2.0 and definitely not USB 3.0. If you’re only really doing MIDI over USB that’s not a problem in the slightest. Audio can be done at that speed as well (my Behringer mixer is USB 1.1) but you’re not going to be wanting to drag around massive files.
The only other thing to note is that there’s a slight voltage drop when going through it, so you want short, high quality cables. (My hacked up solution was not high quality, which is how I discovered this.)
