I'm just setting up a Denon x2000 with an HSU VTF2 sub and just 2 fronts )no other speakers except the sub).
The Denon manual days to set up Odyssey I should set the sub to the max crossover freq and the volume dial to 12 o'clock before running Odyssey. Shouldn't the sub crossover be set to "off" if it's going to be set by Odyssey anyway?
You can turn the XO off on the sub or turn it all the way up which may be as high as 200 Hz. Make sure the speakers are set to small in the setup menu.
Audyssey ignores all the pre-Audyssey settings, so it doesn't matter if the speakers are set to Large or Small before running Audyssey. It will measure the in-room roll-off of the speakers and send that info to the receiver, which will then use it to set the speakers' size, and, if set to Small, the crossover frequencies.
If, afterrunning Audyssey, the speakers are set to Large, they can be changed to Small. When making that change, the default crossover frequency selected will be the next higher crossover above the F3, (the -3 dB roll-off point of the speakers.) If that crossover frequency is low, it can be raised. However, if it's high, say 100 to 150 Hz, it probably should not be lowered. Audyssey doesn't provide any correction below the F3, so there would be no correction provided below that point if the crossovers are lowered.
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