I'm a new OA customer. I recently purchases a 975 with a 7125. I'm new to all this and never really setup a system before or at least never really knew what I was doing. I have a couple questions. This may be obvious but when calibrating the speakers using an SPL meter (I downloaded an app for my phone), do I want all 7 speakers to have the exact same dB level? What does the speaker distance setting do? Does the distance and calibration work together somehow or are these two completely different things? My sub didn't register on my SPL meter app. How should that be calibrated? The actual speakers I have are Polk Audio Monitor 4 bookshelfs. I have 6 of those and a Polk Audio 5jr as a center channel. Old stuff, may not be the best but I have always liked the old Polk Audio speakers. The frequency range on the M4 speakers is 35Hz to 25KHz. Should I set the crossover down to 40Hz since the speakers can go down to 35 or should I use a higher value? The manual says to use 60 to 80 for a bookshelf speaker.

That's it for now.

Thanks,
Don

Yes you want all your speakers to be at the same level. The level allows the surround system to provide the right volume of sound and in some instances it can be as loud as the mains. The distance setting allows the surround processor to actuate each speaker at the proper time to give you the surround experience by allowing the sound to get to your ears at the right time. Since sound travels about 1100 feet per second the difference in distance of the speakers to your prime seating position is important. For the best experience set the distances first then the levels. Although the Polks go down to 35hz your sub is much more capable than the Polks down low. I would start with the setting at 80 hz and work from there. I usually set the sub distance with a tape measure and the volume using a meter from Radioshack and then by ear using some sources that have great bass effects. It is likely that the small microphone on your phone is not sensitive the LFE and doesn't see it.