Delay when using Acoustic Timing Reference

_rcr

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Hi all, I am attempting to use an acousting timing reference for measurements but I am seeing some Delay (circa -270 msec) whenever I take measurements on my Mac (MacOS 12.5.1) running REW v5.20.9. I have tried a windows 10 tablet (same version of REW) and had the same issue, yet strangely enough when I dig up an old Macbook Pro running REW 5.20.9 on MacOS 10.15.7 I get very low delays (circa .2 msec).

Does anyone else see / hear this delay in taking measurements in this manner? Is there a know issue / fix?
 

John Mulcahy

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Do you hear the timing chirp before the sweep? Is the sample rate shown in Audio Midi Setup for the interface you are using the same as the rate in REW? What are you measuring? Some devices are slow to unmute themselves or switch sample rate or mode when they start to receive a signal.
 

_rcr

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Yes I hear the chirp before the signal and it trips the measurements to start. Audio midi is showing 48 kHz just like my settings in REW.

I'm measuring a test tone I got given by Mitch from Accurate Sound to build FIR filters for Roon.

I tried removing the MiniDSP Umik I was measuring with and used the onboard mic on my Macbook Pro (the M1 one above) and the same result occurred, circa 270 msec of delay.

I have a Mac laptop and a Windows tablet demonstrating the same problem while an old (circa 2013) Macbook Pro is just happy and fine. The fact that the Mac and the Windows machine are displaying nearly identical delays lends me to think something in REW isn't playing nice.
 

sm52

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I would think that there is something in Windows and the new Mac laptop that gives this result. I have a laptop with win 7-64, and there is no such thing.
 

_rcr

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No, the file is being played back in Roon.

The laptop is listening to the Roon playback of the sweep and recording that.

When I hit start in REW, it sits patiently waiting for the sweep. When I play the sweep in Roon it detects the initial blip then records the full sweep but the delay at the start is circa 270 msec. This does not happen on my other Mac laptop, just the new M1 and the Windows 10 tablet I attempted it on too.

I've tried removing microphone and usb hub for the Mac and the issue persists using the onboard mic.
 

John Mulcahy

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Please read the help section linked above. REW does not play the file, but it needs to see the file to make sure it has configured the same sweep details. Big delays can be a sign that the sweep in the file is a different length to the sweep settings in REW. The details of the sweep are in the file, loading it into REW allows REW to use the same settings.
 

sm52

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_rcr
Does this thread describe a similar problem?
 

sm52

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John Mulcahy,
when using acoustic timing reference from REW (not from a file), should the 5-20 kHz signal be alone, before the main sweep tone? Or should there be another 5-20 kHz after the main one?
 

John Mulcahy

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There will be a second tone at the end if the option to adjust the clock with acoustic timing reference is selected.
 

sm52

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If the clock adjustment option is not selected, then the tone is one, before the sweep, right?
 
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