USB audio output error

Bug description (state clearly and simply): Audio output has loud high frequency digital noise every every few minutes. It starts with a single sample click, and then builds exponentially until the high frequency clicks are almost the entire signal. Then it reverses in the same way back to a single click and then it is clean for a few minutes. I’ve taken a quick video of FabFilter’s response so you can see and hear it happening. Let me know if you want me to upload it.

Steps to reproduce (use numbered list):

  1. I am running a USB cable directly into my Macbook Pro’s USB-C port listening with ProTools.
  2. Set sample rate at 48k.
  3. Load preset “buszzzz Celine” (or any other preset, but this is a good demo)
  4. Wait.

Software version (blank if unknown): 04092018 (today’s version) same thing was happening on the previous version.

Type (major or minor): Major

any video is helpful to figure out what’s going on, and please also post version numbers of everything.

I don’t have protools here so I cannot exactly reproduce your setup. I typically test with audacity.

Did you set the 48kHz sample rate in the Audio/MIDI Device Setup application in Mac OSX? You have to set the sample rate there to be the same sample rate you are using on the SSP. Otherwise you will get garbage. Make sure that protools doesn’t change the sample rate of the percussa device behind your back and that it matches the audio/midi setup settings as well as those of the SSP.

Also, please test with a simple patch of one LFO (sine output) patched to the OUT module. Nothing else in the patcher grid, and verify that the patch works through the output jacks of the SSP.

I would also test with audacity to make sure this is not something protools related. Make sure to set the correct project sample rate before you record. Audacity is a free download.

I downloaded Audacity and tried. The same behavior happens.

The same behavior happens with every preset. I chose Celine’s recent preset since that is just an LFO through the bus to the output and so the problem is really clear with it and you could eliminate any mistake on my part patching up a preset. Also, you can easily reproduce my test setup WRT the Percussa.

I am currently on the road, so I only have a limited testing environment. However, If I go out of the Percussa analog outputs and into an iRig Duo and then use the USB audio input from the iRig, the problem does not occur.

The Percussa is set to 48K. The AudioMidi Setup app in the Mac recognizes it as a 48k device and both Audacity and Protools recognize the Percussa 2x2 interface at 48k.

It sounds to me like either a buffer overrun or a mismatch in sampling rates at either end of the MIDI interface. I have the Percussa set as the clock source. I haven’t tested with the Mac as the clock source.

I am running the most recent OS X 10.13.6 on a 2.9 GHz 2018 15 inch MacBook Pro.

Let me know how you want me to send the video.

try setting the mac as the clock source? I am not sure that this is the cause of your problems but we’ll see.

I am testing on El capitan, I don’t have the latest version of Mac OSX yet so I have no idea what the behaviour is with their most recent USB audio class drivers.

what I would also try is to quit audacity if you have a problem, restart it, restart the recording and then see if you still have the problem. This might give us some additional info.

I’ve been planning an OS update for the SSP which would extend the USB audio streaming to 8 channels, maybe I can get this issue fixed in the same update.

Hi Bert- I sent you a recording to let you know what it sounds like. The way the noise starts and stops is always the same. Quitting and restarting Audacity didn’t help. Trying a different AudioMidi setup didn’t help. Looking forward to an update. If I can help test, let me know. In the mean time, I’m just running through an external AD converter since the analog output of Percussa works fine.

OK thanks. I’ll look into this and get back to you when I know more.

Hi Bert, any update on this issue?

I am on version 22042019 and have been encountering what sounds like the same problem - My unit’s noise does not ramp up exponentially, but rather seems to jump in quanta. Other than that this sounds like the exact same problem.

I’m on a 2014 Mac Mini, running Sierra 10.12.6 and using Logic/Ableton. My sample rate is 48k on the SSP, in AMS, and in the Logic session.

I get the noise even when just an LFO sine wave is patched to the output like you suggested. I have recorded short sample clips of the noise both entering and leaving the signal; let me know if you would like me to send them your way.

I have been using the analog out workaround as well, but it would be great to get a fix for this - also 8ch USB audio would be really cool! :ok_hand:


there will be an update tomorrow for the multichannel USB audio streaming, which solves all of these problems. See this announcement - Multichannel USB audio streaming update - exclusive live stream tomorrow 7pm UK time

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