10 kHz noise / spike when recording synthesizers

[michat]

Hey guys,

I hope you can help.
I've got several analog synthesizers connected into a 24 channel soundcraft mixer.
All of them produce a 10 kHz noise / spike whether they are played or not. As soon as I pull up the fader on the desk, it's there permanently.
The synths are a Prophet rev2, Dreadbox Medusa, Behringer Neutron, TD3, and some drumcomputers as well.
The thing they have in common is that they are all hooked up via USB on a powered external hub.

Could that be the problem - and if not - what could it be?

Thanks in advance.

[vurt]

can you unplug all the synths, then power one only from the same place as the mixer?

see if that has the same spike.

[Synthman2000]

void

[michat]

Yeah, unfortunately I need to wait some days to test it.
I always wanted to post some pictures of my studio but haven't done it yet, it's an absolute mess down there when it comes to cables and power cords

But I will try when I'm back, thanks for the advice.

There's no test generator in it afaik, it's a LX7II mixer.
And it only occurs when using external synthesizers. I also got 8 channels coming from my soundcard and some outboard fx but none of them got this noise in it.

[foosnark]

USB can definitely create some noise like that, that'd be my first suspect.

I had a Reface CS which was super noisy until I got a USB noise isolator, which helped immensely.

[thecontrolcentre]

Yeah, unfortunately I need to wait some days to test it.
it's an absolute mess down there when it comes to cables and power cords

I tend to keep my audio, midi & USB cables as seperate from one another as possible. I got a new USB Hub yesterday, then spent the afternoon un-tangling power & usb cables.

[michat]

USB can definitely create some noise like that, that'd be my first suspect.

I had a Reface CS which was super noisy until I got a USB noise isolator, which helped immensely.

Never heard of those. Do I need to place one after the hub or would it also work when placed between computer and hub? They seem to be quite expensive and that noise is on all synths hooked up via usb.

[foosnark]

Never heard of those. Do I need to place one after the hub or would it also work when placed between computer and hub? They seem to be quite expensive and that noise is on all synths hooked up via usb.

Not sure, I only needed the one and I put it between the hub and keyboard (didn't try it the other way). I don't have the Reface anymore to try it now.

[thecontrolcentre]

... that noise is on all synths hooked up via usb.

Are they all doing audio, power and MIDI over USB? I have quite a few analog synths, including a Medusa, connected via a Yamaha 01V98i mixer and I'm not getting any noticable noise (with audio and midi cables, rather than USB). I use USB mainly to connect my midi controllers & back-up drives.

[michat]

... that noise is on all synths hooked up via usb.

Are they all doing audio, power and MIDI over USB? I have quite a few analog synths, including a Medusa, connected via a Yamaha 01V98i mixer and I'm not getting any noticable noise (with audio and midi cables, rather than USB). I use USB mainly to connect my midi controllers & back-up drives.

They are all doing MIDI over USB. I also got an Erebus from Dreadbox and an Access Virus 2, both having no USB and both without the noise.
Having so much equipment is probelmatic in various ways - too much MIDI and audio ports plus waaaayyy too much power cords needed. I've got two Focusrite 18i20 interfaces in daisy chain mode, two USB hubs, one MIDI interface (plus the ones in the audio interface), 32 audio channels on the mixer AND a submixer for the RD-8/RD-9 but still - not enough ports to hook everything up simultaneously.

[kritikon]

The USB sounds most likely the culprit. Try running some of the synths via MIDI cables instead and see if the noise goes. Can't remember the details exactly but I'm sure I remember a few synth manuals telling me hubs are not good and that they should be connected direct if using USB. Personally, I still use old-fashioned MIDI cables. It doesn't have to be difficult - MIDI patchbays still exist and are just as useful as audio patchbays. I have an old 7-way MIDI patchbay that is probably easier than some of the modern ones - just 7 in/out/thru at the back and 7 in/out/thru at the front. Modern ones seem to get all electronic and fiddly, but can patch more units than mine admittedly. MOTU spring to mind as the most accessible ones. It's definitely doable - I run maybe 10 synths and there's certainly room for more, though obvs I can't have them all via the patchbay (but I never need to have all 10 running simultaneously anyway). Even in the old days I had up to 11 units MIDI daisy-chained and the only one that ran into any problems was the OSCar (didn't like being last in the chain for some reason) - and I never noticed any obvious lags or hold-ups in MIDI (and I used to do a lot of CC/wheel data etc)

[michat]

The USB sounds most likely the culprit. Try running some of the synths via MIDI cables instead and see if the noise goes. Can't remember the details exactly but I'm sure I remember a few synth manuals telling me hubs are not good and that they should be connected direct if using USB. Personally, I still use old-fashioned MIDI cables. It doesn't have to be difficult - MIDI patchbays still exist and are just as useful as audio patchbays. I have an old 7-way MIDI patchbay that is probably easier than some of the modern ones - just 7 in/out/thru at the back and 7 in/out/thru at the front. Modern ones seem to get all electronic and fiddly, but can patch more units than mine admittedly. MOTU spring to mind as the most accessible ones. It's definitely doable - I run maybe 10 synths and there's certainly room for more, though obvs I can't have them all via the patchbay (but I never need to have all 10 running simultaneously anyway). Even in the old days I had up to 11 units MIDI daisy-chained and the only one that ran into any problems was the OSCar (didn't like being last in the chain for some reason) - and I never noticed any obvious lags or hold-ups in MIDI (and I used to do a lot of CC/wheel data etc)

I need to test that for sure. USB is the easy way because almost all devices have a port and we need them for firmware updates etc. It should be doable as I definitely need only one MIDI channel per instrument.
I need to take some photos of my room as you will directly see that it will be pita to change the setup in whatever way...

[lfm]

As said many times above, usb is not galvanic separation like din midi is with optocouplers and stuff.
- so ground loops with usb is common
- audio has ground, and so does usb, and soon problems having ground two ways
- midi over din midi, and sound from synths no problem anymore

And din midi cables you can have really long, 10m is no problem.

Other things that can affect is also how many different wall outlets are gear using. Do one and star connection to everything synths.

If phase of mains power is different on outlets, ground need to go back to fusebox and out again between gear. Loooong ground cable.

[kritikon]

I need to test that for sure. USB is the easy way because almost all devices have a port and we need them for firmware updates etc. It should be doable as I definitely need only one MIDI channel per instrument.
I need to take some photos of my room as you will directly see that it will be pita to change the setup in whatever way...

Firmware updates are rare enough not to be an issue. I have several synths that get updates but it's easy enough to just connect up USB as and when needed.
I feel your pain with setup - usually no quick way around that. I recently bought a mixer, having been mixerless for years. Took me over a day to completely redo the patchbay, incorporate the mixer properly, add in outboard gear. A real PITA, but worth it and only needs doing once. And if your setup is that complicated...do you use patchbays? Probably should IMO. They're incredibly useful but not obvious until you use them.

Distance between gear is more an issue with USB than MIDI. USB doesn't like long cables. As mentioned, MIDI is far more tolerant. Maybe that’s part of your problem - USB cables too long? I only found that out on a thread here at KvR...there's a finite limit to USB cable length (can't remember the exact details) but something like 1.5m or something. Too short to be useful as a studio connection method anyway...

[kritikon]

I did a quick check on that Bing A.I. thingy, so whether it's correct or not, who knows?

"USB cables have a maximum length that varies based on the version of the USB cable. The recommended cable length for getting the maximum speeds and available power for each type of USB cable is shown in the table below 1:

Mode Name Recommended Cable Length Bandwidth
USB 1.1 (Full Speed) 3 m (9 ft) 12 Mbps
USB 2.0 (High Speed) 5 m (16 ft) 480 Mbps
USB 3.2 Gen 1 2–3 m (6–9 ft) 5 Gbps
USB 3.2 Gen 2 3 m (9 ft) 10 Gbps
USB 3.2 Gen 2x2 (USB-C) 3 m (9 ft) 20 Gbps
USB4 (USB-C) 0.8 m (31 in) 40 Gbps
USB cables are made of copper, which limits the cable’s length because it loses signal strength the farther it reaches. This signal loss is measured in decibels per distance—the greater the distance, the more signal loss 1. With an increased transfer rate, such as those supported by USB 3.x and USB4, the USB communication becomes more susceptible to interference as the cable length increases 1. Engineers use shorter USB cables to overcome this problem and ensure a high data transfer rate 2."

So my guess of 1.5 m was not entirely bollocks.
But it seems that the more you transfer via USB, the shorter they should be, depending on which USB protocol, though most USB synths etc are USB2, I thought? So 5m might work.

And from Sweetwater guides: "USB CONNECTION TIP: We highly recommend connecting your interface directly to your computer, preferably a USB 2.0 port. USB hubs may not provide enough power to your interface, resulting in connectivity issues, and connecting to a USB 3.0 port may result in connectivity issues."

That seems to be a general advice for any and every USB synth