Which means that it isn't a constant volume level.
That is why it is important to set your volume control to your "normal" listening level before you auto calibrate.

I'm missing something here. As far as I know, auto calibrate does not let you set the volume of the test tone.

Old post reopened. Has anyone used a different microphone to calibrate their 990. I seem to have misplaced mine, but I have two Audyssey mikes from my Onkyos. Will they work? Anyone got an opinion?

I don't see any reason that they shouldn't.These mics are pretty much commodities.

Don't do it. These processors are matched up to the microphones. The differences are likely to be less of a problem for basic calibration than for room correction, but it still may not be ideal.

I would think it should work, but I would want to check the technical specs of each microphone to make sure they are somewhat compatible. You don't want to saturate the mic input.

The more I think about it the more I think it should work as all the measurements being taken are relative and the microphone should cancel itself out.

You could always try it and not commit the results if they look like garbage. I take it that you have a pretty good idea what the results should be for your setup already? I don't think there's much risk of physically damaging the mic input of the 990.

I will keep lookin for my microphone, thanks guys.