I've been using some time the last days to try out my new receiver and to try to find why I can't generate the digital output (SPDIF) and the SPL meter at the same time in REW. Sounds like a Windows and/or REW bug to me but I'll come back to that later on.
First, some subwoofer measurements. My sub is tuned to 15Hz, no PEQ used, crossover set to 80Hz on both receiver and sub. I thought that the most important was to get mains+sub right (even if measurement on mains or sub is incorrect). I see that many people measure sub first so I have to be wrong. Anybody has an explanation for it?
Subwoofer behind the left front speaker - Center seat:
sub_15hz_leftfront.jpg
Subwoofer behind the right front speaker - Center seat:
sub_15hz_rightfront_centerseat.jpg
Subwoofer behind the right front speaker - Left seat:
sub_15hz_rightfront_leftseat.jpg
Subwoofer behind the right front speaker - Right seat:
sub_15hz_rightfront_rightseat.jpg
Subwoofer behind the right front speaker - Left - Center - Right seats:
sub_15hz_rightfront.jpg
I took the measurements on the left and right seats to see how much the frequency curve varies across my sofa. My favorite is
Subwoofer behind the right front speaker - Right seat. I tried to get the same kind of curve on the center seat but I can't get rid of this 60Hz valley. Strangely, modifying the phase does not help so much. I just saw in the RX-V1800 manual that one of the manual EQ frequencies is 63Hz. Might help to improve the curve.
Generally, what do you think of the curves?
Now my problem with REW and the SPDIF output: because my PC generates a lot of high-frequency noise on the analog output when I move the mouse or when REW updates the screen, I am trying to use the digitial/SPDIF output.
I don't experience any problems when playing music (in Winamp) or generating test sounds in the REW generator window.
But sound output is stopped as soon as I click on the Record button in the SPL Meter window. Then I hear that some kind of high frequency sound comes from my main speakers, first very low then increase slowly until becoming loud. It's not like getting an external loop between a speaker and a microphone because it stops when the sound becomes loud.
Stopping the recording makes the digital output work again, high frequency noise disappears. As expected, I experience the same problem when running a full measurement.
I experience this problem even if I disconnect the RadioShack. I don't have any built-in microphone. My laptop is an old Dell Inspirion 8100. I tried to reboot but that did not help either.
Anybody know what could be wrong here?