REW Measurement issue with external output

[paradis]

Hi, I've been trying REW few times without any issues, and i was using an USB DAC and UMIK both connected to a Macbook, so output and input are within the laptop itself.

Due to some new setup i'd love to measure the actual Pi-based streamer + Roon DSP mode, i no longer have the capability to have the output on the Macbook.

After some rounds of reading:
- I exported the measurement sweep file (44.1khz, 24bit, with acoustic timing reference of Left)
- I too exported the PinkNoise for speaker calibration file (44.1khz, 24bit)
- These two files I imported into my Roon server, and the Pi-based streamer (acts as a roon bridge) will stream from the Roon Server

I've the laptop connected to the UMIK-1, and under the measurement, i added the option to wait for timing reference, and muted the laptop speaker.
- From here on, I'll start the measurement as usual, but wait till the status shown "waiting for timing reference", then I hit the play of the sweep in my roon so it start playing
- Its a heavy hit and miss, most of the time it won't trigger the start of the measurement, and even it trigger the measurement, the results are quite a gap
- The measurement result i've got mostly are the follow
a. minimal or non exist 600hz and below, it's like nothing much being measured there
b. sometime the measured frequency its really just at the 10khz and above and nothing much below it

Any idea/comment/guidance of anything wrong steps that I did? Thanks

 

[John Mulcahy]

Sounds like the timing reference isn't being reproduced, do you hear it? Probably worth updating to the latest build and using the file playback option in any case, you will need to re-export the sweep.

 

[paradis]

Hi John, i did hear it, but it doesn't seems to easily trigger the measurement. I'm on 5.19 which is the latest stable release but i'll perhaps try the latest build.

but the method of what i described, am i heading on the right path?

 

[paradis]

I upgraded to latest build, the trigger of the timing reference is spot on, i did a quick measurement it seems to be good.

One thing i do not understand, if I am playing the sweep file from an external source, but why i have to select the exported wav file of the sweep in the measurement window?

 

[John Mulcahy]

Because the file contains information about the frequency span, sample rate and length of the sweep which REW needs to know.

 

[paradis]

Because the file contains information about the frequency span, sample rate and length of the sweep which REW needs to know.

Thanks John, it's working so I will find some time to test the measurement and correction, thanks