USB audio device no longer showing up

[Dr. Jennifer Nussbaum]

I've been using a Schiit Modi 3 D/A converter for my main desktop audio for a year or two. In the last week, it's been sporadically vanishing from PulseAudio.

It's normally plugged into a USB port on my monitor, which has several such ports, all of which work with other devices. When I plug it in, dmesg shows me:

[2126764.183346] usb 3-3.4: new full-speed USB device number 75 using xhci_hcd

[2126765.035388] usb 3-3-port4: Cannot enable. Maybe the USB cable is bad?

[2126765.887389] usb 3-3-port4: Cannot enable. Maybe the USB cable is bad?

[2126765.887461] usb 3-3-port4: attempt power cycle

[2126768.319399] usb 3-3-port4: Cannot enable. Maybe the USB cable is bad?

[2126769.171424] usb 3-3-port4: Cannot enable. Maybe the USB cable is bad?

[2126769.171483] usb 3-3-port4: unable to enumerate USB device

I get similar messages from other ports; other devices show up fine. This port is successfully providing power to the Schiit.

Though "Maybe the USB cable is bad?" is a dubious-sounding message, I did swap out the existing random cable with a brand-new good-quality one, with no difference.

I also tried to plug the Schiit into a Debian laptop, with the same results as above. Confoundingly, after this test, I re-plugged it into my monitor and it magically started to work -- it showed up in dmesg, it started to play audio.

However, hoping it magically works isn't a good long-term solution. Is there any way to figure out what's causing this? Could it be a hardware problem with the Schiit? If so, how do I report it to them?

[Thomas Amm]

Hi,

according to my long and sometimes painful experience with USB-audio
interfaces I suspect that it is the internal USB connector in your
external interface that's failing. So hardware problem, indeed.
These connectors are 50¢ apiece, but unfortunately they are usually SMC
parts soldered directy on the print circuit board so they provide very
little resistance against the shearing tension implied by the USB
cable. I've just luckily been able to repair a € 500.- desktop
synthesizer from exactly that kind of damage. That was hard enough
despite the usage of a full-size connector on the extarnal side and
probably much more space to work than inside a portable audio
interface.
I've seen this kind of damage a lot in USB interfaces and usually
there's little hope of repair unless you put a lot of time and skill in
it.

[Tom Yates]

On Thu, 22 Jul 2021, Thomas Amm wrote:

> according to my long and sometimes painful experience with USB-audio
> interfaces I suspect that it is the internal USB connector in your
> external interface that's failing. So hardware problem, indeed.
> These connectors are 50¢ apiece, but unfortunately they are usually SMC
> parts soldered directy on the print circuit board so they provide very
> little resistance against the shearing tension implied by the USB
> cable. I've just luckily been able to repair a € 500.- desktop
> synthesizer from exactly that kind of damage.

i note in passing this is another great use for USB hubs. recently when i
started having serious video camera problems, and having diagnosed a USB
socket on its way out, i ended up replacing a £20 hub with another £20
hub, instead of having to try, as you say, to repair a multi-hundred-euro
motherboard.

use a cheap hub for all your day-to-day connection and disconnection
needs, and save wear and tear on your fragile motherboard connectors.



--

Tom Yates - https://www.teaparty.net

[Thomas Amm]

On Thu, 2021-07-22 at 16:25 +0100, Tom Yates wrote:


> i note in passing this is another great use for USB hubs.  recently
> when i
> started having serious video camera problems, and having diagnosed a
> USB
> socket on its way out, i ended up replacing a £20 hub with another
> £20
> hub, instead of having to try, as you say, to repair a multi-hundred-
> euro
> motherboard.
>
> use a cheap hub for all your day-to-day connection and disconnection
> needs, and save wear and tear on your fragile motherboard connectors.
>

...and before the hub use a short USB-3 extension to keep your laptop
from being torn apart whenever you trip over the USB cable. But use a
hub - no matter what the vendor of your audio hardware say. They all
want their precious device to be directly connected - to avoid support
tickets by people using shitty hubs. So I can't agree to your "cheap"
argument. Not that I recommend expensive hubs in particular but they
should at least be based on a reliable chipset, bring a solid PSU and
no tacky connectors.

[Nicholas Geovanis]

On Fri, Jul 23, 2021 at 7:41 AM Thomas Amm <deb...@open-email.net> wrote:

...and before the hub use a short USB-3 extension to keep your laptop
from being torn apart whenever you trip over the USB cable. But use a
hub - no matter what the vendor of your audio hardware say. They all
want their precious device to be directly connected - to avoid support
tickets by people using shitty hubs. So I can't agree to your "cheap"
argument. Not that I recommend expensive hubs in particular but they
should at least be based on a reliable chipset, bring a solid PSU and
no tacky connectors.

Thomas which USB chipsets do you prefer for audio?
And are you doing MIDI over USB to the synth?

Viel Glueck .....Nick Geovanis

[Thomas Amm]

On Fri, 2021-07-23 at 08:11 -0500, Nicholas Geovanis wrote:
> >
> > Thomas which USB chipsets do you prefer for audio?
> > And are you doing MIDI over USB to the synth?
> >
> > Viel Glueck .....Nick Geovanis
> >

Mostly Realtek for now. I rember a faulty chipset in the early days of
USB3 causing lots of headaches but wasn't personally affected. No
actual USB-3 chipset has let me down so far, however. 
I am actually doing MIDI over USB with all my synths but one, a 1989
KORG Polysix with MIDI retrofit via DIN. This means I've got four
synths and three controllers communicating duplex over the same active
USB-3 hub without problems even when sequencing three of them and
recording + monitoring the master keyboard simultaneously. No miracle
comparing MIDI's very small bandwith and timing requirements with USB-3
specs.

[Nicholas Geovanis]

Thanks so much Thomas, that was a big question for me. Not so much USB-3 bandwidth but latency and timing. 

I have a Casio DMW, CSound under wintel (embarrassed silence ;-) and working on an Arduino-based sequencer. Arduino's have a base MIDI library and speak it directly.

[Thomas Amm]

OT now, but if you're intending to run more than a single MIDI in our
out on Arduino things might get somewhat more complicated than they
seem. Arduinos I/O is fine for a single MIDI channel (hence the
countless Arduino monophone MIDI synth projects) but will quickly get
to its limits with more demanding stuff. Expect nasty jitter and timing
problems unless using a dedicated UART.