Experiencing aliasing in sweep signal

[aanon]

I am experiencing something that sounds like severe aliasing when I play sweeps from REW for measurement.

Some background and explanations:

Signal path goes PC->Cambridge Audio DacMagic->MOTU 828mk3->amplifier
Connections are: USB to DacMagic, S/PDIF from DacMagic to MOTU, analog from MOTU to amplifier
Explanation: the reason I have DacMagic in the chain at all is so I can run my audio into the S/PDIF input of the MOTU, which in turn allows me to use the MOTU's parametric EQ on left and right input channels separately for my room correction purposes.

Testing/troubleshooting:

If I connect PC->MOTU directly over USB the sweeps are fine.
Using the same signal chain, I've also tested 1) playing sweeps through Focus Fidelity Impala and 2) exporting the REW sweeps as wav and playing them through JRiver. I don't hear any aliasing issues in either of those cases.

I believe this has to be an issue with my settings in REW but I'm not sure what. The sound I describe as aliasing is evident even from the initial chirp before measurement. It sounds like a short wave radio struggling to tune to a frequency, and near the end of the sweep sounds like a battle of light sabres. Haha..for want of better descriptions!

Any tips on how to resolve this issue would be much appreciated.

Aanon

 

[John Mulcahy]

Usually means parts of the replay chain are running at different sample rates. REW can only control sample rate on Windows if you are using ASIO or WASAPI exclusive drivers, if you are using the non-exclusive Java device entries the default format in the Windows properties for the device will set the rate. In either case devices later in the chain might be changing the rate.

 

[aanon]

Usually means parts of the replay chain are running at different sample rates. REW can only control sample rate on Windows if you are using ASIO or WASAPI exclusive drivers, if you are using the non-exclusive Java device entries the default format in the Windows properties for the device will set the rate. In either case devices later in the chain might be changing the rate.

Thank you John for the helpful response. It seems at this stage like I've been able to solve the issue by setting the DacMagic to 48kHz (previously was 44.1) in the Windows properties (default format). Back on track!