Unwritten rule that all speakers can't be the same?

Rob Babcock

Rob Babcock

Moderator
Nick never said it was HT did he? I don't see him specifying whether the system will play mostly movies, mostly music, or what ratio. All systems are compromises, to borrow a cliche, and obviously it would be tough for a single system to be constructed to meet all the published recommendations (ie direct radiators for music, dipole surrounds for HT). If one system must perform both roles, then you'll have to decide which one you're going to optimize for. Without specifying what he wants to use them for it's hard to tell what to suggest.

Maybe Nick Danger can chime in with some clarification, plhart- he uses the phase "full-range floor-standers" once, but I don't know he's asking if they must be run rull range. If you're correctly interpretting his question, then he still may wish to consider floorstanders. There is one big advantage to using 5 towers, if you can- no speaker stands. I hate 'em, and the cost of bookshelves vs towers is often a wash once you factor in the stands. Given the only gear he lists by name is pretty cheap, I gather he wants to keep the budget low.

That said, the 5 identical speakers definately needn't be floorstanders. If he doesn't mind stands he might try 5 or 6 bookshelves. While many advocate dipoles or even bipoles as surrounds, that's never been universally preferred by all the experts. In fact, there are a few pretty knowledgeable writers who champion "monopoles" for HT.

IMO, dipoles pretty much suck for MC music. Especially "true dipoles" that operate out of phase over the entire freq range. If only the tweeters are out of phase the sound isn't so bad, but I hate the crappy upper bass/lower mids you get when the woofs cancel each other at the bottom. I personally think 5 "monopoles" is a better all around compromise (assuming 50/50 MC music/HT) than going with dipoles, although bipoles can be a great compromise.

The interview with Toole stated point blank that the very flattest, smoothest bass he could get was with multiple subs, and the best repeatable, practical setup was 4 subs pulled out well from the corners. The gain you get with trihedral corners is nice, but can engage room modes erratically. Either you misunderstood me or I didn't state it clearly- "best" in this case was my definition, not his. He just said the flattest & smoothest response was achieved that way. To me the flattest response is the best, but I have the luxury of not needing the corner gain. [Irrelevant FYI: pro installer & magazine contributor Russ Herchellman is also dead set against corner placement for subs, and backs it up with measurements.] I use parametric EQ, but even so it's easier to get smooth response if you need less equalization. JMOHO, but huge peaks are worse to me than losing extreme extension. Bear in mind, this is irrelevant to what speaker models he chooses. Whether 5 towers or a mix of speakers, setting them to small is still likely the way to go. Subs can then be placed wherever they work best, regardless of what type of mains you choose.

The main issue to me is that a conventional horizontal D'Appolito center basically sucks ( a "revelation," also mentioned elsewhere). If a person can accomodate it, going with 3 identical speakers across the front would be perfect. You could then choose your surrounds based on what you wanted to do with your rig, but MC music or HT, it's still great to have the same front speakers. If you have a Denon receiver (other brands may allow this, too) you can have dipoles & monopoles both connected and switch on the basis of which material you're using.

If the system is primarily for MC music (a longshot, since it seems like Peter Wilson & are are about the only guys here that own much) then definately go with 5 identical speakers.

I hope this helps.
 
WmAx

WmAx

Audioholic Samurai
Practical to have 4 subs pulled well out from every corner into a room? I'm not sure in what average situations this is practical -- sounds like jsut the opposite. I will have to assume this is the 1/4 symmetrcial 4 corner method mentioned in the Todd Welti AES paper I referenced. This was a Harmon Kardon research project -- and is probably on what Toole was basing his statements. I stand by my original posts -- as the original poster specficially mentioned full-range speakers for mains and surround positions -- and that is what I am addressing.

Refer to the informational research papers I mentioned if you want to know exactly what was found in attempts to model average room conditions.

-Chris

Rob Babcock said:
The interview with Toole stated point blank that the very flattest, smoothest bass he could get was with multiple subs, and the best repeatable, practical setup was 4 subs pulled out well from the corners. The gain you get with trihedral corners is nice, but can engage room modes erratically. Either you misunderstood me or I didn't state it clearly- "best" in this case was my definition, not his. He just said the flattest & smoothest response was achieved that way. To me the flattest response is the best, but I have the luxury of not needing the corner gain. [Irrelevant FYI: pro installer & magazine contributor Russ Herchellman is also dead set against corner placement for subs, and backs it up with measurements.] I use parametric EQ, but even so it's easier to get smooth response if you need less equalization. JMOHO, but huge peaks are worse to me than losing extreme extension. Bear in mind, this is irrelevant to what speaker models he chooses. Whether 5 towers or a mix of speakers, setting them to small is still likely the way to go. Subs can then be placed wherever they work best, regardless of what type of mains you choose.
 
Rip Van Woofer

Rip Van Woofer

Audioholic General
plhart: Thanks for correcting my careless assumption in your point (2) above. Somehow, somewhere I got the idea that multiple woofers (not necessarily subs) would somehow excite different room modes that would more or less cancel each other out to help smooth out the bass response. I shoulda figured it wasn't that simple! Live and learn. I have got to read those CEDIA acoustics articles here, and the other articles cited above.
 
WmAx

WmAx

Audioholic Samurai
Rip Van Woofer said:
Somehow, somewhere I got the idea that multiple woofers (not necessarily subs) would somehow excite different room modes that would more or less cancel each other out to help smooth out the bass response. I shoulda figured it wasn't that simple! Live and learn. I have got to read those CEDIA acoustics articles here, and the other articles cited above.
Uhm....you were pretty much right the first time. I believe you misinterpreted him. Multiple simultaneous bass sources within the room will fill in/cancel and smooth total average deviation(s), but only when stratigically placed for the specific room dimensions and features, or if you have a huge a number of sources(say 50 for example) then you can place randomly and they will cause a smooth response average.

-Chris
 
Rob Babcock

Rob Babcock

Moderator
Toole didn't include pictures (I wish he would have! Dopes like me prefer crayon drawings to figurz! :p ). He explained placement as such: imagine shrinking your listening room by roughly 25%, centered from the middle. Then place the subs in the four virtual corners, well out from the real corners. The implication was that this wasn't so fussy that you needed a mathematically perfect windowless, doorless room to make it work.

Obviously, Martha Steward wouldn't approve of this, but it would be doable in any man-friendly larger room (not great WAF, I'll admit). Given, for example, a 20' x 26' room, that's really only a few feet out of the corners, probably closer to the corners than your main speakers. Hey, no one said the best sound will be the prettiest layout. Of course, four subs isn't practical to many people, but it's better than 50! He implied that the use of more subs was better even up to the dozens, but I'm sure he meant this in a research manner only. He got good results with 2.

I will have to find the source I'm referencing; I read so much crap that I can't always remember where I found it. :(

If you only have 1 sub, you likely would be better off with corner placement, especially if you need the extra room gain. Since SPL drops off with distance (and disregarding room gain for a moment), near field placement of a sub can work very well too, provided the x-over point is relatively low. Dr. Hsu advocates nearfield placement, and I can attest to the fact that it works well, but of course the WAF of that can be off the bottom of the chart.

Russ Herchellmen did have one of the best mainstream articles I've ever read on sub placement, along with a ton of measurements and some theory. I can't recall if he wrote for SGHT or Home Theater Magazine, though. I rarely throw away a mag, so maybe I can dig it up. Perhaps someone here has a link. He argues strenuously against corner placement and has a lot of in room measurements to back his assertions. YMMV, and of course many rules go out the window when you have irregular room shapes, arched doorways, bay windows, etc. Even some pretty potent acoustic software seems to get a little dicier when you have a goofy enough room. Trial and error is often the best answer. Many people of course are limited to very few potential locations.

At the risk of hijacking the original thread, many (if not most) audiophools use no sound theory at all when laying out their stuff. For instance, it seems that the vast majority of online photos of members rigs (not just at AH) have the listening couch right up smack against the rear wall! Yuck! That's a terrible spot. I've yet to see one picture with the couch against a wall where the person bothered to treat the spot behind his head in any way! I've also seen more pictures than I can count where the listening chair back extends well up over the top of the listeners head. Why would any intelligent person do this? You can easily hear the difference between the sound with your head against the headrest and leaning forward. The reason stuff like this is done is just simple ignorance & comfort (in the visual & physical sense).

My room isn't perfect, but I have a loveseat positioned well into the room (12 feet from the rear wall, give or take). I found that with test tones & an SPL meter, the bass varied by as much as 10dB moving the seating +/- one foot! It sits where the bass is pretty flat (esp after parametric EQ), the imagining is pretty good (imaging isn't one of my top fetishes) and the sightline is good. The backrest of the loveseat extends just over the top of my shoulders (I'm 5'9"-5'10"), and you get no bad reflections unless you slouch down. Room treatments are minimal and will be til I'm not so friggin' broke. :( My room has pretty damn low WAF, to be honest- I use it for HT, too, and I have full blackout for the projector. The front of the room is matted off with flat black fabric, as are a few strategic other points. It won't make Better Homes & Gardens, but it's laid out for performance, not looks.
 
Rob Babcock

Rob Babcock

Moderator
BTW, Chris, I wasn't trying to contradict you; certainly few people would find that practical from an aethetic sense, and 4 good subs wouldn't be cheap. Certainly it'd be no fun to try to EQ with my Behringer! :eek: :p "Practical" in a scientific sense isn't the same as practical in a regular home.

I hope one day to have a purpose built, dedicated room where I can go totally wild without regards to anything but the sound. My current room is a little longer than it would need to be and a little narrower than I'd like. It could use an extra 20 amp line, too (my sub amps have tripped the breakers a couple times :rolleyes: ).
 
Rip Van Woofer

Rip Van Woofer

Audioholic General
So I was right...then I was wrong...then I was right again?? Or just kinda sorta right? Ack!
:D
 
J

jmgillespie

Junior Audioholic
I just currently bought a pair of paradigm legends and now I'm going to buy rears to match. My struggle is between a pair of dipole (adp 170) and either a pair of floorstanding speakers (esprits or a matching pair of legends). I'm 20 years old and this is my second sound system and I need some help deciding which would be the best for me. I listen to about 75% movies on the system and 25% music. The movies are mostly action movies with a lot of sound coming from the rears (QT movies, war, sci-fi, ect.) and music is mostly rock and a little bit of hip hop.

One of the main reasons I'm looking at the esprits and legends for rears is becasue the dipoles drivers are smaller then the front legends. The legends have 6.5" mid-range and woofers and a 1" tweeters the dipoles have 5.5" mid-range and 3/4" tweeters. I had pretty much set my mind on the esprits or legends until I read this discussion. Any help would be appreciated.
 
Rob Babcock

Rob Babcock

Moderator
The last post bumping this up reminded me that a regular at AC (and dealer of VMPS) just set up 4 VMPS subs arranged in this configuration, with each one pulled out about 1/4 of the way from each corner. He reports that in 30+ years spent as a dealer and and hobnobbing with the audio gurus, he's finally acheived the best bass he's ever personally heard.

Might be something to this arrangement... ;)
 

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