TempoTec Variations V1: LibusbExclusive playback corruption on Lenovo Y700, while Aune Yuki is clean

Support
1

App version

Beta

Issue description

App version
Beta — 15.0.0B9 (build 127779)

Issue description
TempoTec Variations V1 produces audible ticks/static, distortion, and occasional apparent tempo or pitch instability when using Symfonium USB exclusive / LibusbExclusive output.

The DAC enumerates normally and playback starts normally. Android standard USB audio routing is clean with the same V1. UAPP direct USB exclusive is also clean with the same V1, cable, port, and music files.

The problem reproduces with both 44.1 kHz PCM16 and 44.1 kHz PCM32 output. This is therefore not limited to one bit depth or one PCM altsetting.

I tested the same 44.1 kHz / 16-bit FLAC through the same Symfonium LibusbExclusive path using an Aune Yuki DAC. Yuki plays cleanly.

Expected behavior:
Clean bit-perfect USB exclusive playback with TempoTec Variations V1.

Actual behavior:
Ticks/static, audible distortion, and occasional apparent tempo/pitch instability with TempoTec Variations V1 only.

Device type

Phone

Media provider

Navidrome

Steps to reproduce

Connect TempoTec Variations V1 to a Lenovo Legion Y700 TB320FC running Android 15.
Open Symfonium and enable USB exclusive / LibusbExclusive playback.
Play a 44.1 kHz, 16-bit FLAC from Navidrome.
Observe audible ticks/static, distortion, and occasional apparent tempo or pitch instability.
Keep the same tablet, USB port, cable, Symfonium settings, and FLAC file.
Replace TempoTec Variations V1 with Aune Yuki USB DAC.
Replay the same track.
Observe that Yuki playback is clean.

Additional information

The attached log contains a direct A/B comparison using the same 44.1 kHz / 16-bit FLAC.

TempoTec Variations V1:

VID 22e1
PCM16, stereo, 44.1 kHz
Interface 1, altsetting 2
Async feedback enabled
4,000 packets/s
160 ms pipeline
655,360-byte queue
Correct clock programming and readback at 44.1 kHz
No reported underrun, fallback, or restart

Aune Yuki USB DAC:

PCM16, stereo, 44.1 kHz
Interface 1, altsetting 3
Async feedback enabled
8,000 packets/s
80 ms pipeline
248,320-byte queue
Clean audio with the same app, file, cable, port, and device

Both devices show correct average PCM throughput. The reproducible difference appears to be specific to the TempoTec V1 transport profile, likely around async-feedback handling, packet pacing, endpoint interval, or per-packet completion handling.

Could you inspect raw feedback values, feedback filtering/clamping, per-packet transfer completion status, and packet-size distribution for VID 22e1?

I searched existing issues first

on

I understand that logs are mandatory

on

Log upload name / description

symfonium-y700-tempotec-v1-vs-yuki-44k1-pcm16.log

2

If you did not use and LLM for the report I’m impressed :wink:

Update to build 127781 and in all cases please provide logs with both dacs with that version.

3

Of course I use chatgpt to assist with investigations and report writing, but not to spam more posts :D.

I haven’t seen a download link for a newer beta build (127781) yet. Please guide me how to get it, I’m using the f-droid beta repo.

4

It is in the froid repo Symfonium Phone Beta

5

The latest beta appears to fix the original TempoTec V1 playback corruption issue on my Lenovo Y700.

I tested PCM16 and PCM32 playback with the same DAC and direct LibusbExclusive mode. Playback is now clean, and the new logs show stable audio completions, stable feedback handling, no underruns, no fallback, no restart, and no transfer errors.

I will keep testing longer playback and track switching, but the original audible ticking/distortion/tempo instability is no longer reproducible so far.