I have two questions about speaker setup before running Dirac.

System (5.1.4): Invisa SPS x2 and SuperCenter reference in the front, Invisa MPX x2 in the rear, HTR7000 x4 in the ceiling, SuperSubXL x2 (one front, one in the back) all run by an NAD T778 with Dirac Live 3 (full frequency).

Question 1: In Sandy's tips for Invisa install, he suggests leaving the frequency switch in the "up" position. Should I leave it there when I run the room correction, or put it in the neutral position? Or does it matter?

Question 2: The software suggests setting speaker distances and SPL levels before starting. No problem with the individual speakers, but what about the subs?

From what I've read, I need to set the amp to 0dB and adjust each sub separately using the sub output knob, not the amp. For two (or more) subs it says put the SPL meter equidistant, not necessarily at the listening position. My concern is that one sub is in the front of the room and the other behind a couch (the room is open, so there is plenty of space behind and to the side of the couch). Will that make a difference? Would it be better to use the main listening position?

Finally, I'll be interested to see how much boost I get when both subs are running. I've read the explanations for +3 to +6 increase in SPL, but I also understand the vagaries and effects of walls, corners, furniture, etc. on the final result.

"If I only understood everything I know about this stuff..."

Thanks for your help,
Doctor J

Hi Doctor J, #1 - I would recommend setting the frequency switch on the Invisa SPS speakers to the position that you prefer - before running the Dirac Room Correction system. For example, if you prefer a bit brighter sound from your system, I would suggest setting the frequency switch to the high position - then running the Dirac Room Correction. (If you prefer a smoother sound, I would recommend setting the frequency switch to the low or medium position - then running the Dirac Room Correction.)

#2 - As you've mentioned, I would recommend adjusting the volume controls on each of the subwoofers separately (as opposed adjusting the channel level on your NAD T778). When adjusting the level of each subwoofer, I would be included to use the main listening position as the point of reference or measuring location.

#3 - I would expect you to hear roughly 4-5 db more bass when using two subwoofers.... Happy Listening!

Thank you for the advice! I'll try to post the before and after results.

Quick follow-up

1) Since I am using the full-frequency version of Dirac 3 Live, I ended up with the switch set to neutral since the software was going to set a target curve anyway and equalize out any boosts or cuts to the upper bands. The MLP is a corner sofa so I used the wide setup with 17 measurements and I set up the speaker settings manually with a SPL meter before running the software.

The SPS fronts and MPX rears were actually very flat above 500 Hz (uncorrected) while the HTR7000 showed a bump at the high end despite the switch being in neutral, but all four were consistent in the room.

2) I set each sub separately to 75 dB (C-weighted) at the MLP. With both enabled, I got between 80 and 81 dB, as expected.

3) I'll try to upload some screenshots.