Thought I'd share this. Comparison of 1 vs 2 subs. No EQ, no Audyssey, no crossover in place.
I'm going to remeasure this weekend. One of my mdat files with post-Audyssey measurements got corrupted somehow.
I posted this graph earlier - this is pre and post Audyssey when I had just the first sub. There is way too much <15hz boost in my opinion. Here's my question - if I apply an HPF before I run Audyssey to discourage it from boosting so aggressively in the ULF, would I potentially have phase issues if I disable the HP afterward? Second scenario being I start with a steep 4th order and change to 2nd order after Audyssey.
I've read that HPF's can influence phase in the passed region. If Audyssey does it's job right with my distances and whatever time-domain stuff it does, I could potentially throw it out of wack by disabling the HP. Is that a correct understanding? My Onkyo has MultEQ XT. My goal is not to kill all the LF stuff, but rather let the sealed boxes do their rolloff job to protect the drivers. Audyssey wants none of that and thinks I should be flat to 5hz or lower.
I always EQ over Audyssey as I find it gets close but I can do better.
Just apply a 1st order butterworth where you want it to start rolling off after the Audyssey does its thing. The "phase" issue introduced should be unimportant, especially since your interested in decreasing output.
You can see the phase implications by looking at the group delay plot. Anywhere you apply significant eq prob indroduces some GD.
I had to go with a new placement. I had originally placed the speakers on the outside of the subs. There were some nasty dips between 50 and 90 hz from the mains as a result. Swapping the placement with the mains took care of it. The subs are now seeing a dip at around 65 hz, but it is narrower. I may experiment a little more with placement of the subs, but I don't have a lot of options. It sounds darn good though.