my focusrite scarlett 2i2 has started buzzing.

[ariadne@social.treehouse.systems]

@dadregga I think I also only notice the buzzing now because instead of reinstalling the passive monitors I brought to the $dayjob thingy, I elected to switch to the active monitors I was previously using with my Mac Studio (which I don't use anymore except as a server).

[ariadne@social.treehouse.systems]

@dadregga though you would think ASRock Rack boards would have clean power distribution... haha nevermind.

I probably wouldn't buy another ASRock Rack board after some of the weird shit my threadripper machine has done.

[ariadne@social.treehouse.systems]

adding a powered usb hub did not fix it. so i modified a usb cable to let me splice in power from an external 5v psu.

*that* fixed it.

[ariadne@social.treehouse.systems]

this is a *server motherboard* ASRock. what are you even doing. why is there noise on the USB power rails.

[gsuberland@chaos.social]

@ariadne asrock are terrible at this. every board I've had from them has noisy USB with audio frequency garbage coupled from the CPU power rails. my guess is they run 4 layer and let return currents flow right under the USB bucks and I2S DAC in most of their designs.

[ariadne@social.treehouse.systems]

@rpgwaiter scientific equipment? professional AV equipment?

[ariadne@social.treehouse.systems]

(it is this board: https://www.newegg.com/asrock-wrx90-ws-evo-eeb-form-factor-12-0-in-x-13-0-in-30-5-cm-x-33-0cm-14-layer-pcb-2oz-copper-pcb-motherboards-amd-amd-wrx90-strx5/p/N82E16813162155 if you want to avoid it)

[agowa338@chaos.social]

@ariadne

Get yourself an USB Opto-isolator. The latest ones out of china that I've seen ship with a DC-DC isolator making it unnecessary to splice in an external 5v and it is still isolated up to 10kV or something like that.

I use it for my CNC as the motor causes the USB to drop so low that the host circuit kept detecting it as a reconnect signal. (Also I had to find a 2.0 only host controller as all of the 3.0's when downgraded were not "lenient enough" for this thing...)

[gsuberland@chaos.social]

@jpm @ariadne true, but still, I've seen >400mVp-p audio frequency noise across VUSB/GND on one of their boards. no common mode filtering either. hot garbage.

[ariadne@social.treehouse.systems]

@agowa338 already done. it arrives later this week.

[ariadne@social.treehouse.systems]

2oz copper seems like a lot for a PCB, but maybe it isn't

[gsuberland@chaos.social]

@ariadne 2oz is generally the minimum for motherboards, has been since the late 2000s.

[agowa338@chaos.social]

@ariadne

the DC-DC isolator is basically a dc-ac converter + transformer + ac-dc converter but all in one small component. Hence it should be good enough to smooth out the unclean power.

And this one here is the cheap one I have. It is good up to 2.5kV (according to the seller): https://de.aliexpress.com/item/1005007254879252.html

[gsuberland@chaos.social]

@jpm @ariadne yeah I hate it

[be@floss.social]

@dadregga @ariadne using balanced audio connections tends to sidestep such issues