I've been troubled by a perceived harshness in the high mids from my system for some time now.
I've tried moving the speakers (a bit, at least, my room isn't big enough to allow radical moves), eliminating toe in, and I've tried using makeshift sound absorbers at various points on the walls (heavy towels). I've gone back to stock everything in terms of cables, supports etc, I've done my best to ensure that no signal cables run too close or parallel to power cables. Basically all of the obvious stuff to try.
All to no avail.
So I picked up a Umik-1 and downloaded REW, in order to try to get to the bottom of things. And now I have a 20Hz-20KHz reading of the room taken from the listening position with a frequency response graph, a 'waterfall' plot and so on.
The thing is, I'm no expert at reading this kind of stuff. There's some wrongness going on at the bass end. But I don't have an immediate issue with the bass - I need to solve the high mid problem before worrying about that. Likewise there's an unexpected peak around 18KHz which is way too high to be the issue.
It's perfectly possible that the problem stems from not getting on with the speakers (S-400) and/or the source (usually a 172, but for this test an offboard DAC running into the 172's analogue input) rather than a problem with the room. Or from some other non-room related thing. But this measurement seemed a good place to start.
I've attached images of the SPL graph and the waterfall - does anyone fancy helping me to interpret them?