[PROBLEM] Brief 'buzz' when skipping to next track

[TheOldPresbyope]

@dr.diem

I'm curious whether you've tried driving your Schiit DAC from moOde installed on a standard RPi rather than the USBridge? Have you tried driving it from MPD installed on your laptop?

Regards,
Kent

[dr.diem]

Hi Kent,

Unfortunately I don't have a standard RPi to test with. It did occur to me that using MPD on my laptop would be a useful test; I'll have to install it and a client to see how that goes.

Ian

[TheOldPresbyope]

Hi Kent,

Unfortunately I don't have a standard RPi to test with. It did occur to me that using MPD on my laptop would be a useful test; I'll have to install it and a client to see how that goes.

Ian

Pity about not having a Pi on hand to test with. I admit it's pure speculation on my part that the Allo USB subsystem is implicated somehow (and perhaps only with the Schiit Unison USB input) but an A/B test would be a quick way to test that. 

The RPF seems to think their supply chain will be working again in 2023 and their existing backorders fulfilled

Fortunately my projects-box is well stocked with most of the Pi models.

Regards,
Kent

[dr.diem]

I got around to installing mpd/ncmpcpp on my laptop and tried it out feeding the DAC directly via ALSA (i.e. Pulseaudio disabled). No surprise the track  skipping was flawless with no 'buzz'. This test, in combination with Geojanitor experiencing the same issue between an rPi and another Schiit DAC with their Unison USB, is I think adequate evidence that the 'next track buzz' is down to a hardware issue between the rPi USB output and Schiit's Unison USB input.

Ah well, at least I now know the cause. Ironically of course the whole point of the Allo USBridge is the low-noise USB output, so it doesn't have S/PDIF, and there's no way I'm replacing the DAC, so I guess I'll just have to put up with it

Thanks all for your troubleshooting input even though we didn't arrive at a solution,


Ian

[Geojanitor]

I got around to installing mpd/ncmpcpp on my laptop and tried it out feeding the DAC directly via ALSA (i.e. Pulseaudio disabled). No surprise the track  skipping was flawless with no 'buzz'. This test, in combination with Geojanitor experiencing the same issue between an rPi and another Schiit DAC with their Unison USB, is I think adequate evidence that the 'next track buzz' is down to a hardware issue between the rPi USB output and Schiit's Unison USB input.

Ah well, at least I now know the cause. Ironically of course the whole point of the Allo USBridge is the low-noise USB output, so it doesn't have S/PDIF, and there's no way I'm replacing the DAC, so I guess I'll just have to put up with it

Thanks all for your troubleshooting input even though we didn't arrive at a solution,


Ian

Ian
I hate to suggest this on this forum but have you tried other software on your USBridge? When this issue appeared with me a while back I tried Volumio and I did not have the issue with buzz. I don't especially like Volumio and so went back to Moode with the S/PDIF hat on my pi. I can't explain why the issue seemed to be software specific since both implementations use MPD. It's only my 2-bits, good luck.

[dr.diem]

Thanks Geojanitor, that's a crucial data point ! Could you let me know which release of Moode you're running (i.e. is it v8.x or a lower release?) and did you definitely experience the buzz on 8.x? The one thing I didn't do yet is reflash the SD card from the last v7 release to an 8.x, so it'd be really useful to know whether you've effectively already performed that test.

Thanks again for following up,

Ian

[dr.diem]

@Tim Curtis I have now finally got around to testing this issue with moode v8.2.0 and unfortunately it still occurs. I tested with a 'vanilla' install, that's to say I burnt the SD card, plugged it in, chose the correct output device, set up the library and ran tests immediately.

As I mentioned earlier in the thread I could not reproduce the issue from my laptop running mpd on Gentoo Linux (4.19.184 kernel).

Geojanitor's input has also been useful - he also experienced the issue when using a Schiit DAC that has their Unison USB implementation, and in his case with a stock rPi. This is of course helpful since it factors out the Allo USBridge as being implicated. Even more usefully, he discovered that the issue is unique to USB (it didn't occur for him when using S/PDIF), and that it did not occur on USB when running Volumio.

All this to say that the issue seems to be related to Schiit DACs/USB output/Moode. I am more than happy to run beta builds to run testing if this is something you're prepared to work on; it seems as though it will affect all users with Schiit DACs.

Cheers,

Ian

[Tim Curtis]

The symptom suggests some sort of incompatibility in that combination of hardware and software. I have a USBridge SIG and Revolution DAC and playback is totally glitch free with any method of navigating among tracks. The Rev DAC uses an XMOS U208 USB chipset.

Have you checked to see if the vendor has a firmware update for their USB chipset?

[dr.diem]

Schiit have developed their own USB chipset, and no there's no updates posted for my DAC. I'll reach out to their support channel to see if they're aware of the issue.

As I say the USBridge is not implicated since the issue was replicated with a stock rPi. However, according to @Geojanitor who did that test, the issue does not occur when running Volumio. Nor did it from mpc/mpd on my laptop.

I think I'll try installing a terminal-based mpd client on the USBridge to see if files played that way are affected. Unless you don't think that's worthwhile?

[TheOldPresbyope]

@dr.diem

Have you asked Schiit about this behavior?

Regards,
Kent