CorOS Version: 3.1.0
Describe your issue:
When I apply FX to tracks in my DAW (REAPER) recorded with QC, i experience robotic playback/clipping/distortion.
Steps to reproduce your issue:
- Record audio into REAPER using Input 1, Input 2, or USB Out 3 (from Grid) using either a guitar with 1/4" instrument cable, or SM57 microphone with standard XLR cable
- Apply any combination of FabFilter Pro-C, Pro-Q, or Pro-R
- Hit Play on DAW, and experience robotic playback/clipping
I expected this to happen:
When I apply FX on my audio tracks recorded with QC, i expect clean, accurate playback.
I have tried the following things:
- I have tried changing the buffer size in my DAW as high as possible
- I have tried lowering the I/O input volume of the relevant inputs on the QC
- I have tried changing USB cables
- I have tried changing USB POrts
- I have tried Toggling Safe Mode in the Audio Driver Settings
- I have tried monitoring with headphones and speakers
Note that before really messing with all the I/O levels, i was experiencing this issue with no FX loaded on the DAW tracks. I have been using these plugins for years with no issues on my previous audio interface (Axe FX II). That said this seems like an issue in playback with the QC and not an issue with my plugins/DAW.
My full email to neural support:
Hello,
I purchased a brand-new quad cortex from Sweetwater that i received on 3/8/25. I installed Cortex Control and the latest USB Driver from the neural downloads page and connected the unit to my PC which has an i7-14700KF 3.4 GHz processor with 32 GB RAM running Windows 11.
Using the latest version of REAPER as my DAW (monitoring with my headphones and speakers turned off), i selected the ASIO audio driver and Neural DSP USB device option. I set the project sample rate to 48k. I plugged an SM57 mic into Input 2 of the QC with a standard XLR cable.
I selected a blank preset on the QC. After selecting Input 2 as my input for the Grid and setting reasonable levels for input 2 on the I/O page, i was able to hear my voice in my headphones. I even experimented and added a reverb and compression block on the QC grid and everything sounded great. I disabled the QC reverb and compression, reverting back to a blank preset as i had planned to add these effects using fabfilter compression and reverb on a track in my DAW.
I created a new track and selected Input 2 as the track input. I record armed the track with record monitoring enabled. I noticed that if i started to sing loudly into the mic the playback would begin to have distortion/clipping/robotic playback that would âlatchâ until i either restarted the unit or changed the buffer size in my DAW. I reduced the signal level of input 2 and increased the buffer size in my DAW to the maximum setting and tried again. The results initially seemed better. I recorded a vocal sample. I then tried to apply the Fabfilter reverb and compression, and the distorted playback immediately returned. I have never experienced this issue with these plugins or with any previous audio interfaces.
I was unable to fix the issue with any of the following methods:
1.) Changing the buffer size as high as possible
2.) Reducing input 2 level
3.) Using Input 2 â USB Out 3 (from Grid) with a blank preset
4.) Changing USB cables
5.) Changing USB Ports
6.) Toggling Safe Mode in the Audio Driver Settings
7.) Monitoring via my speakers instead of headphones
Thus, i tried to record some guitars via Input 1 using a 5150 preset i dialed in. There is absolutely no clipping anywhere in the chain. Initially, things were sounding good, until i opened an instance of Fabfilter Pro Q 3 on the track. Immediately, the robotic playback returned on the guitars this time.
My last test was keeping all plugin windows closed and recording to what my ears sounded like a âcleanâ take with respect to the distortion and clipping issue. I thought i had succeeded in this, because during track and playback the guitars sounded good to my ears. Feeling confident the signal was clean, i then attempted to add the Fab Filter Pro Q and immediately the clipping returned.
I tried the same experiment with the SM57 in input 2, this time applying reverb and compression after tracking what sounded like a âcleanâ vocal take, and the clipping returned.
Initially i thought there was a problem with just having the plugins open while recording, but it seems like there is an issue with playback when applying these FX post tracking, which is a massive issue for me.
Do you have any suggestions for me? Are there known issues being worked in the audio driver? This problem basically renders my unit useless, as i bought it primarily as an audio interface/recording device.
Please help, i really like everything else about the QC. I dont want to have to return it.
Thanks,
-Rick
Edit:
I did some additional testing with the USB Statistics diagnostics.
With an SM57 plugged into Input 2, monitoring on my headphones, with a blank preset, and with Input 2 routed into a track in REAPER that is record armed with record monitoring enabled and also has the FabFilter plugins instantiated; I yell into the microphone until i experience the audio transition into robotic playback. The USBAudioRdWrDistanceAverage turns red. After i see this occur, playback becomes robotic in my DAW on the audio track until i change the buffer size.
It seems like the USBAudioRdWrDistanceAverage variable is reducing to a low number when this happens, although i have seen it turn red and be as high as 500. It looks like it is also turning red periodically on the diagnostic page even when i just let the unit sit without passing audio in or out of it.
Additionally, i noticed that when the tracks recorded with the QC are experiencing the latched robotic playback, i am able to playback other tracks that were recorded with my axe FX II that have FabFilter Pro-Q on them within the same project with no issues!