Dr. Floyde Tool has demonstrated through years of research that sub placement in a rectangular room (Mine is 25 X 15 X 10) is most efficient and smooth response when subs are placed at the mid point of each wall. After hours of measuring and moving subs all around my room I have found that five subs across the front of the room (25') has the smoothest measured response. I'm certainly no one who could hold a candle to Dr. Toole's long career and knowledge in audio acoustics. I've read all the FAQ's on the website here and all of the threads regarding sub placement. I was wondering if anybody has done extensive multiple sub placement in a room prior to installing IBS's? I have the luxury the way my house is built that I can install IBS's (Single or multiple) in any location in the floor.
Hey guess what?!? I'm one of those idiots that actually did design my entire house around the Audio/Video room!!! The width of the room was supposed to be 24' but some how my tape measure measured 25'! Stupid tape meaure!!! The shape and size of the room was based on software by the late great Roy Allison (not Orbison, though he's cool too). Currently I am using five of Seigfried Linkwitz's "Thor" subwoofers. I'm curious why 5 sub woofers across the front of the room have a smoother response than 4 sub at the mid point of each wall. Does anyone have any idea why this appears to be better than what Dr. Toole has to say?
There's an academic paper available as well, but I haven't read that yet.
The conclusion seemed to be that the recommended number of subwoofers worked best to reduce the standard deviation between the different seats in the listening area, and thus gave the best result after equalisation, not that it gave the smoothest response before equalisation.
There was a simulation of 5 subs across the front wall. That gave one of the worst min-max and std.deviation variations between seats.
Are you saying that 5 subs gives you the best unequalised result for a single listening position, that it gives you the best equalised result over a range of positions, or something else?
Thanks for putting me onto Floyd Toole's work, it's fascinating.
Okay folks, after weeks of measuring and running sweeps using REW, I have some results. After measuring for five listening positions with 12 different sub placements (60 measurements), I sent all the measurements to Todd Welti at Harmon International for optimizing the best locations for the least amount of spatial variance per listening position. The point of this was not for the maximum SPL for the subs.
This first image is a rendering of the audio room (seating placements and room dimension).
And here is the data Todd sent back (I believe he used Matlab). Thanks, Todd for all your help with this exercise.
Very cool, thanks for sharing. And I'm impressed Todd did the analysis.
Based on my reading of Floyd's work and Todd's research as well as Sean Olive's writing, I've decided to pursue a dual manifold setup in my dedicated HT.
I already have an IB centered on the front wall, and will be adding another IB centered on the opposite wall.
This is one of the 'ideal' configurations from their research.
I'll then let my Denon AVP-A1, which handles multiple subs (independently) plus Audyssey Pro handle getting it tuned just right.
The primary benefit will be smoother seat-to-seat response as well as mitigating a slight null at the main listening position (even though this was a custom room design designed to minimize that stuff).