Ariadne Conill 🐰Mar 3
my focusrite scarlett 2i2 has started buzzing. grr.
Show threadAriadne Conill 🐰
i am powering it via probably the shittiest possible usb-c cable. i wonder if getting a better cable would fix it.
Mar 3 at 12:13amWeb
Show threadAriadne Conill 🐰Mar 3

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.

Show threadAriadne Conill 🐰Mar 3
this is a *server motherboard* ASRock. what are you even doing. why is there noise on the USB power rails.
Show threadAriadne Conill 🐰Mar 3
(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)
Show threadAriadne Conill 🐰Mar 3
2oz copper seems like a lot for a PCB, but maybe it isn't
Show threadGraham Sutherland / PolynomialMar 3
@ariadne 2oz is generally the minimum for motherboards, has been since the late 2000s.
Show threadI love this, so IMar 3

@gsuberland @ariadne ah yes, the single-worst unit in electronics.

2 ounces (weight) of copper (volume) per square foot (area) - it's a linear dimension, approximately 70um

Show threadGraham Sutherland / PolynomialMar 3
@jpm @ariadne yeah I hate it
Show threadClifton RoystonMar 3

@ariadne

My experience is that ASRock sucks, generally speaking, and if they put out any actually good mobo it is by accident.

Show threadGraham Sutherland / PolynomialMar 3
@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.
Show threadI love this, so IMar 3
@gsuberland @ariadne that, and USB VBUS is the second-worst voltage source that most people will use - the worst being automotive “12” volt
Show threadGraham Sutherland / PolynomialMar 3
@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.
Show threadI love this, so IMar 3
@gsuberland @ariadne USB VBUS go eeeeeeeeeeeeeeeeeeee
Show threadI love this, so IMar 3
@gsuberland @ariadne and I'm still seriously considering designing and building a USB VBUS fixer (as big an input cap as I can get away with, a 1MHz-class buck-boost converter in the middle, and as big an output capacitor as I can afford)
Show threads0 Is Not A SysadminMar 3
@jpm @gsuberland @ariadne the irony is we have this issue specifically with the server motherboards that a certain high end audio console manufacturer uses in their consoles (no actual USB audio devices, but issues with USB HID and MIDI devices due to noisy/saggy VBUS)
Show threadI love this, so IMar 3
@s0 @gsuberland @ariadne speaking of your $DAYJOB, do you reckon they’d pay for a device called “The USB Power Unfuckenator” or should I workshop some more names?
Show threadDuncan BayneMar 3
@jpm @s0 @gsuberland @ariadne In a heartbeat. But my $DAYJOB folks are unusual (in a good way).
Show threadPaul_IPv6Mar 4

@jpm @s0 @gsuberland @ariadne

LOL.

depends. if you're selling directly to the engineering folks, it's perfect. if you're trying to get to a company big enough to have a purchasing department, you might need something a bit more... polished? :)

Show threadrpgwaiterMar 3
@ariadne to be fair, I think most servers will use USB for initial os install and like.. that's it? Not sure what else you'd use it for, kvm?
Show threadAriadne Conill 🐰Mar 3
@rpgwaiter scientific equipment? professional AV equipment?
Show threadKlaus FrankMar 3

@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...)

Show threadAriadne Conill 🐰Mar 3
@agowa338 already done. it arrives later this week.
Show threadKlaus FrankMar 3

@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

1pcs 1500v adum3160 digitales Signal Audio-Leistungs isolator USB zu USB-Audiosignal isolator 12 MBit/s 1,5 MBit/s - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

aliexpress.
Show threadtheodoraMar 3
@ariadne You sure it wasn't a ground loop ? :0
Show threadAriadne Conill 🐰Mar 3
@theodora yes. 100% positive. my power is clean, i have three-phase service
Show threadRandom Damage 🌻Mar 3

@ariadne Maybe

It's a pretty simple device, and cables do seem to wear out faster than you'd expect

Show threadBen LeggettMar 3

@ariadne

USB power sucks ass for ground loop isolation/noise, genuinely.

It took me weeks to get buzzing out of my computer audio stack.

Show threadAriadne Conill 🐰Mar 3
@dadregga yeah I bought a powered USB hub. that should fix it, I think that there is ripple current on the USB power rail
Show threadAriadne Conill 🐰Mar 3
@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).
Show threadAriadne Conill 🐰Mar 3

@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.