Allo USBridge - Dragonfly Red - MQA horrible buzz

Hi, I had a raspberry pi 3 running Volumio, with Roon Bridge installed on it, using Dragonfly Red which is updated to the latest MQA firmware. That worked perfectly. I have just received an Allo USBridge and it didn’t work at all to begin with, but followed their instructions to get USB1.1 mode working, and now anything that is not MQA seems to work perfectly, and sounds better than using the Raspberry Pi as a transport. However, any MQA track has a horrible buzzing sound, this happens whether I have MQA decoding turned on or off, and whether sample rate conversion is on or off. The buzzing will go away after a minute or so of listening but then starts again with the next track.

EDIT: With MQA core decoder turned off, there is no buzz.

Is there any known way to fix this?

Hi @Nathan_Scrivener,

Can you share a screenshot of Device Setup for this device as well as a screenshot of the Signal Path when playing MQA content to it?


Dropbox link to a recording taken from my phone:

You can hear the buzzing clearly, it clears up starting around the 50 second mark.


Update - There is no buzz when:

  1. MQA core decoder is switched off
  2. switch max playback rate to 48khz with core decoder on,
  3. switch max bitdepth to 16 bit with core decoder on.
  4. any other file playback format

OK after some more extensive testing on a variety of file formats, I have found that it’s any file that is output at 96khz that has this problem. It is not MQA specific, it’s just that is the ‘first unfold’ sample rate.

Hi @Nathan_Scrivener,

I think the next step here is to enable some diagnostics on your account so our technical staff can get some more insight into what’s going on here.

However, before I enable this feature, I’d like to ask for your help ensuring we gather the right information.

First, can you please reproduce the issue once more and note the time at which the buzz occurs. Then respond here with that time, and I’ll make sure we review the diagnostics related to that timestamp.

Hi Dylan,

8:45am New Zealand time. Playing back “Anna” by “Howe Gelb” on Tidal, upsampled to 96khz.

The buzz starts on commencement of playback at that sample rate.

Thank you.

Hi @Nathan_Scrivener,

Now that I have the timestamps, diagnostics have been enabled on your account. The next time your Core is active a diagnostics report will automatically be generated and uploaded directly to our servers

Once that’s been received, I’ll be sure to update this thread and pass the diagnostics over to the team for further analysis.

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