Follow up from John re: his recent calibration.
"I used the standard MiniDSP 2x4 ($99) to do what I describe below, but need to upgrade to the MiniDSP HD to put in the SFM values. I hope to do that next week. Here is a description of what I did to get everything to blend well using Dirac in the Lexicon MC-10.
I used the MiniDSP to match all the subs in volume and to manipulate phase so I had the flattest response at the MLP. It was easy to do the tweaking in the MiniDSP in terms of volume, mute, and phase vs. running around the room and adjusting everything. Problem I was having was that my two JBL S2S-EX subs (with SDA4600 amp) were being run out of the Lexicon MC10’s balanced outs and my two JBL HTPS400 subs were being run via the RCA out (Y’d). The Lexicon outputs the same signal to both at the same time, but I could not get them to match in volume while running Dirac. After I ran Dirac it always ended up sounding bass anemic and the smaller HTPS400 subs were playing louder than the S2S-EX subs (which would explain the reduced output and extension). With the MiniDSP, I came out of the single RCA sub output and split that out four ways via RCA – two to my HTPS400 subs and two via an RCA to Phoenix adapter to the SDA Synthesis amp that powered the S2S-EXs. The MiniDSP software allowed me to properly match the subs volume and adjust phase at the MLP while measuring the response and output with REW (and my ears). I didn’t do any filtering in the MiniDSP. The guys at Harman suggested, until I do SFM (hopefully next week), it’s best to level match the subs and do all EQ in Dirac. Doing EQ in the subs before using Dirac could stress the subs, especially if applying any boost. The other thing they said to not do, was EQ the subs individually, they should only be EQ’d as a system, all run together (after level and phase matching). They suggested leaving everything mono and level matched before running room correction. Once I have the right numbers from SFM, I will be entering the properly delays and levels. Now I have very flat bass at the MLP. Once I have SFM, I will have much better seat to seat consistency. It’s fairly consistent seat to seat now, but I know SFM will make it much better."
Please direct question to me so John does not have to field multiple PM's. He is very busy and I'm trying to help him minimize the time he dedicates to the AVS Forum. I'm happy to help in any way I can!