Best setup for two subwoofers.

If this is indeed Dr. Toole's position, then I disagree with him:

"...the best choice if budget allows... is FOUR subs each in a corner.... They will provide the smoothest bass for the most listeners in room."

I question whether that's really what he said, because Todd Welti's investigation showed that four subs with one at the midpoint of each wall in a rectangular room was smoother than one in each corner.

In the paper mentioned in my second post above, Dr. Geddes compared four subs each in a corner against three subs in a specific asymmetrical configuration (one in a corner, one along an opposite wall, and one closer to the ceiling than to the floor). The three subs asymmetrical were not only smoother, they also had less frequency response variation from one listening location to another.

I have been manufacturing four-piece multisub systems since 2006, and my experience plus my customers' supports the argument for asymmetrical positioning even if it's confined to the horizontal plane. I am unaware how many of my customers tried a symmetrical configuration, but to the best of my knowledge all of them have chosen to use an asymmetrical one.

Regarding the relative phase of widely-spaced subs, it is far less critical than intuition would lead us to believe. The reason is, we cannot even detect the pitch of a bass note before several cycles have reached our ears. By then the room's effects have totally swamped the first-arrival sound. For all practical purposes, in the size rooms we listen in at home there is no such thing as "direct sound" in the bass region. By the time we hear it, it's all reverberant sound. This is precisely why a distributed multisub system offers such a significant improvement in perceived bass clarity and smoothness, instead of sounding like mud: The only place a multisub system offers improvement is in the reverberant field, but from a perceptual standpoint that's all there is in our rooms anyway.

Duke

Duke,

The best thing I can suggest to you is to log on to Scott's Home Theatre Geeks. Look up the Episode with Dr. Toole and enjoy listening to one of the most respected men audio reproduction of sound, how humans perceive sound and speaker R&D.

http://twit.tv/htg16

You will find his assertion that 4 subs placed in each corner of the room will give the most efficient and likely best sound of sub bass for multiple listeners in room. Four subs placed mid way on the 4 walls may give better general fidelity but are not as efficient in bass output to power input.

Dr. Toole is also fine with two subs placed generally midway on walls if costs are an issue.

Thank you very much for the link, Les creative edge.

In the first half of the interview, I didn't hear anything on the subject of speakers, rooms, subwoofers, subwoofer placement, or psychoacoustics that I didn't already know. Not trying to be a smartass, but those are topics I have studied. Now I did learn some of the "why" behind limitations at the microphone end of the chain, and behind the fallacy of pursuing "ideal" room dimensions.

Much of the surround-sound discussion in the second half was EXTREMELY educational to me, as historically I've been a two-channel guy. Toole obviously can teach me a great deal about multichannel, so a few minutes ago I ordered his book. I have you to thank, Les creative edge, for making me aware that Toole's book contains a lot of valuable information I am not familiar with.

Back to the first half of the interview. Fascinating that Todd Welti, whose work I'm familiar with, was actually commissioned by Toole to investigate multisubs. I hadn't appreciated that it was Toole's idea first.

As far as subwoofer configuration goals, Toole apparently places top priority on bass efficiency rather than smoothness, as he prefers four in the corners over four at the wall midpoints. My top priority is smoothness, which comes at the expense of efficiency because destructive interference is the mechanism by which maximum smoothness is achieved.

The comparison I would like to see, but which I don't think anyone has made, is four subs at the midwall locations vs four subs in a thought-out asymmetrical configuration. I bet they both would sound pretty darn good.

Again thank you very much for this discussion and the link, without which I would have continued in my mistaken belief that there probably wasn't much in the book that would be new to me. At some point I wish to become competitive in the home theater sound system marketplace, and Toole's book will be a primary resource.

Duke

Duke,

Thanks and I'm glad posts like we've put here can be informative for each of us and others here. This is to be a fun hobby for us audio/video geeks as Scott Wilkenson would likely say. Too often, too many of us fret needlessly over things that can just take the fun out of the hobby.

I remember first hearing and reading about Dr. Toole back when I was a young kid in the early 80's. We had a KICK A$$ audio magazine here in Canada back then called Sound Canada and it was quite simply one of the finest audio magazines at the time and guys like Ian Masters, Dr. Toole and others wrote cool stuff in it often. Even though much of Dr. Toole's stuff was over my head then, today as a hobbiest and one who tries to keep an open mind I've learned things from him and other respected persons in the field.

If I may, I was very much anti-multi channel for music until recently. I got my Oppo BDP-83 with the AIR Record sampler Blu-ray and that was an aural revelation for me in how good properly engineered multi-channel sound can be. Mark Waldrep was also on Scott's podcast a while back, check it out to get his ideology on AIX Records and their efforts at making superior quality, hi rez multi-channel sound.

For me when listening by myself with a stereo LP, CD or tape, well I think that sounds the best if you can sit in the stereo sweet spot and you play back a good stereo recording. But a proper, hi rez multi-channel recording on good consumer gear that is properly setup and calibrated KICKS REGULAR STEREO'S A$$! 1-2-3 years ago I'd never admit to that. But having heard hi rez multi-channel sound on an AIX Blu-ray sampler disc with my modest but well setup system BLEW ME AWAY!

Well I sided tracked things bad enough, back to your regularly scheduled programming, LOL!

Thankyou all for the help. You really helped me understand the question I had and took me to a level beyond what I knew existed. I will try my best to experiment with the methods mentioned. Ill post results as to what other sub I pickup and how well everything is working together, as well as my placements. Thx again.