SURROUND SPEAKERS - Bipole, Dipole, Quadpole, Omnipole... WHICH ONE? - Page 2

In most cases, no. The only cure would be to invert the phase of the 7.1 surrounds, and that would most likely cause greater problems under 300 Hz. So much of the surround information is out of phase anyway (by the time it reaches your ears), it doesn't make a lot of difference.

Incidentally, do an A/B of Dolby Digital and Pro Logic II (movie mode) and you may not hear that big a difference. Jim Fosgate nailed analog surround pretty good.

I have to stop reading this stuff at work, people are starting to wonder what I am laughing at!

But for my $.02 I just recently purchased QS8's from Axiom. They are what is referred to as quad-pole speakers. I have 4 of them in a 7.1 system. They replaced 4 direct radiators. They sound ABSOLUTELY FANTASTIC!!!! Music, dialog, and especially sound effects are more lively than ever before. Again, just my $.02

Is it true you're closing your store?

SOMEONE get this man a cookie.
To simplify it more, Mono seems best for Music, Di/Bi for movies, and both are fine for other types of sounds unless your a stickler (Like the lonly guy with 5 speakers in the exact distances setup for just 1 person to enjoy at a time).

Others keep referencing the mixer's studio as the goal. If I was a mixer or sound designer I would want my artistic intention to be most accurately portrayed in a first-run/high-end commercial theater. Why? Because that's who we're making the movie for and that's where they'll see it! I don't understand why I would want my work to be appreciated only by one lonely, pathetic guy in a small room sitting equidistant from 5 identical speakers. Until Gary Rydstrom chimes in, we'll just agree to disagree.

I think you may have missinterpreted the intent of that statement. It wasn't about who the mixer of the sound track should mix it for, home or theater. But just that theaters has limitation in their ability to provide the best surround sound experience based on their inherent design to satisfy a large number of individuals. Therefore, from a home theater perspective to argue a point of best configuration for sound reproduction by trying to emulate how it would sound in a commercial theater is flawed since we should be able to do better.

I actually use four M&K 200s for the sides and back, which are based on a Tripole configuration. A tweeter and woofer in the front and a pair of mid-tweeters on each side.

So long it is done acoustically, not electrically.

A DIPLOLE is assigned as either Left or Right, and when 4 are used in a 7.1 system, there are phase errors between LS/LBR and RS/RBS if the two left and the two right speakers are positioned according to their Left and Right assignment.

To fix the problem, simply tuning the LBS and RBS up side down will correct the phase error. The other way is to swap the Left Right assignment of the two speakers.

The incorrect way would be to reverse the polarity of the wiring.

I honestly believe that THX adopted a dual monopole for their back surrounds based on the easier set up rather than a better set up...

Mark

So, for those of us that are not lonely and don't selfishly dwell within some multi-channel monopole cocoon (or passionately debate the advantages of di/bipole speakers on speaker forums ) what are we to make of this in practical terms?

If I interpret your post correctly the tendencies are as follows:
Small room = Dipoles
Acoustically dead = Dipoles
Multiple seats = Dipoles

Large room = Direct (Monopole)
Acoustically alive = Direct (Monopole)
One or "less" seating = Direct (Monopole)
Seating not close to speaker = Direct (Monopole)

Ok, assuming I've interpreted you somewhat accurately please indulge me and clarify a few things for this neophyte. What constitutes a small or large room? Would a 23' x 19' room be considered large?

What constitutes acoustic "life" and how does it die? I didn't realize it could live.

As far as seating goes are you talking about rows of seating or absolute numbers? Would a sofa sectional (with a single row) in a HT be considered multiple seats?

Finally, what happens if you have conflicting tendencies? For example a very large room with just a Lazy Boy in it... which characteristic trumps the others?


That sounds very reasonable but then how do we really ever make intelligent decisions? If buying speakers depends almost exclusively on personal preference (as seems to be the consensus) and every room has unique sound characteristics then how can we possibly choose a speaker brand (especially without auditioning in our own room) much less know what type?

Should I just go buy a Bose cube system and call it a day? Or maybe just a Bose wave? Never mind, I know the answer to that question.... buy a Triad system and call it a day!

All kidding aside, thanks for the information and I look forward to some enlightenment - I wish to achieve HT Nirvana!!

That's not how it works. All you're doing, effectively, is using 4 monopoles, but locating them badly and aiming them improperly. You can do this more easily and often for less money with two pairs of speakers.

I wonder if more than 1% of the population of the AVS forum has ever heard a well setup HT system.

My first response would be an attempt at sarcasm and say "No John, only you have." However, you would probably just follow it up with something like "that appears obvious" and I don't particularly want to feed into your arrogance.

As a result, I will take the more straight forward approach. Based on some of the designed systems we have all seen in this forum I would say that there are quite a few that have well designed and setup systems. Based on response I would also say there are some very knowledgeable and experienced members here. From past threads as well as this one, some agree with you and some don't.

It amazes me at times how some around here like to impose their opinions as if they are hardcore facts. Everyone talks about how subjective it is to choose a speaker because of individual preferences. Why should this topic be any different? Why is this one suppose to be thought of as an absolute?

Just curious John, you did not respond in anyway to my argument that both concepts are flawed to some degree because of the different types of effects we are trying to simulate. Therefore, it is all a compromise regardless of choice. Do you have any OPINION on that or was it just FACTUALLY wrong and not worth commenting on?

You obviously have plenty of knowledge and experience to share like others here, but why does it usually come off as "your way or the highway" so to speak? Just curious.

Rooms below 3000 cubic feet should be considered as "small" and rooms above 3000 cubic feet should be considered large. To answer your question you also need a ceiling height. If I was to Ass-U-Me 8 feet, then your room is over the 3000 cubic feet, [3496] so to be considered as "large".

This does not automatically state that you have to use either type of speaker though...

Mark

I have four Triad Onwall Gold (Di-pole) Surrounds in my treated demo-room which is about 22Lx17.5Wx8H with two rows of theater seating leaving about 2.5 feet to the sides and back wall. They are close to 2 feet above the listening position. I also have Def Tech's BPVX bi-polar surround speakers. The room has seen its share of direct radiating /monopole surrounds and the resulting theater experience between the two approaches is significant.

Both the di-pole or bi-pole set-up practically disappear to yield a remarkable surround sound immersive experience as the front soundstage appears to extend above and all around the listeners, and you feel like you are in much bigger venue. I have never been able to create that sense of spaciousness with monopole speakers which simply do not work well when you are a couple of feet from the drivers resulting in a muddled experience at times. I do callibrate the surrounds about 2 dBs higher than the front soundstage which is something you wouldn't want to do with mono-poles.

This is not the audio gospel according to Rudman, but simply my personal subjective experience in trying to grapple with this issue.

Approximately 4 years ago and after some input from one of the respondents here, S Durani (thanks), I decided to conduct my own experimentation with various rear and surround speaker configurations. This lasted for more than a year and as a result I have come to the conclusions below.

The opinions of various listeners were consulted throughout this period. Speakers used were Magneplanar M1.4s, B&W 603s, Mission 735s, B&W DS6s, M&K LCR55s all driven by 200W per channel Rotel, Musical Fidelity and NAD amplifiers using a Lexicon DC1v3 processor in all its surround modes, but mostly Logic 7. M&K 150THX LCR were used as mains with eventually six M&K LCR55s as surrounds. Low pass was 80 Hz. Yamaha and Kenwood THX receivers were also used. This was not a proper scientific study. Speakers similar to the Axiom QS8 or Paradigm 590s were never tested. I had no access to such. BUT > I don't think my conclusions would have differed.

In the end the shape of the room was the most important factor as it determined the speaker distances from the listener ear and influenced every listener's preferences. This was determined by moving the main speakers from the narrow width wall onto the wide sidewall in a 24 by 16 ft room, and repositioning surrounds and rears accordingly.

As soon as the point source became within 7 feet of the listener ear for sides and rears, dipoles would be most preferred with bipoles a close second and monopoles would be almost objectionable. As soon as the 7 feet distances were increased, the results became subjective and inconclusive with monopoles perhaps the most preferred.

What was interesting is that a small monopole was clearly second to one with a large woofer. So much so that placing large fullrange floorstanders in place of monopole surrounds were often preferred. This indicates much support for an Axiom QS8 type speaker. A large woofer area that moves more air than standard small surrounds is definitely preferred.

When the bipoles and dipoles were placed at ear level they were not liked. 2 feet minimum above ear level was preferred. In the case of monopoles the firing direction was of interest. With a 8 foot ceiling and more than 7 feet away from the ear aiming the speakers down to the floor 3 feet to the side of the listener was preferred. Playing into the ceiling was next, then aiming them at the sidewall next with playing directly over the head of the listener being the least preferred! (the position in which most monopoles are used!!)

While doing this a lady remarked the obvious. Why are there fewer speakers on the short walls than the long walls? Why only 1 speaker to create the sound field on the longest wall (side wall) with 2 over the short rear wall and 3 across the short front wall? Even applicable to Mr Scarpelli's man without friends.

Well I split the outputs from processor to power amp for the side surrounds and added a side surround so that there were 2 on the ceiling next to the side wall firing down. This has been preferred by +/- 80% of all listeners to the system when doing any type of A/B comparison involving surrounds. I wanted to add a 3rd side surround by running them into a pro-logic pre and then into additional power amps as well as add a center back, but time and resources put an end to this. For me departing from only one side surround to two monopoles was the major improvement.

Consequently I cannot understand why 3 fronts, 2 side and 2 rear speakers are the point of departure while it is so easy to have more than one speaker on the sidewalls, if you really wish to improve.

Would be wonderful if an Audio journal would attempt a more scientific test of this theory.

To summarise:

1) IF surrounds are within 7 feet, then dipoles and bipoles are preferred.
2) IF more than 7 feet away, then monopoles are at least equal.
3) Any full range surround that moves much air such as a floorstander is preferred (even if you have to mount them on the roof or up on the sidewall! - just how serious are you about your sound?)
4) Multiple side monopole speakers offer by far the most improvement. More than moving from monopole to dipole or bipole.
5) Positioning side (not rear) monopoles firing over the head of listeners were considered inferior.
6) Dipoles have a narrow edge over bipoles. This appears to be material dependent. If explosions, rain etc. If single voice, then the other way round.
7) Having to switch speaker mode depending on material - not for me.
8) Using different speaker brands for main LCR > disliked.
9) Using different speaker brands for surrounds > hardly noticed, unless mixing point source and electrostatics.

I am not likely to repeat this exercise. Drove me up the wall!

My 2c >> Spurge

ADZ523 and Rudman have saved me a lot of typing -- that's exactly the experience I've had.

One consequense of this on room design is that the rear end of the room needs to be left relatively reflective -- if you at all subscribe to the 'Live End - Dead End' theory of acoustic design more large panel suppression needs to be ahead of the first reflection point than to the rear of it.

Adding just a little of my own experience, the main problem I have with direct radiators is the mixing problem. I have many current mixes where a sound is suddenly 'sent' to a channel, and the localization with direct radiators makes such lazy mixing very distracting. Unfortunately I find such mixing very common, even on the most recent format soundtracks.

Whereas I hope all readers here agree that 'dumbing down' audio equipment to mask recording errors like FR, low sample rate, poor mic placement etc. is wrong, when it comes to spacial cues I'm forced to say that until the art improves most folks are better off with something other than monopoles for surrounds for movie soundtrack reproduction. Of course the larger and more varied (and older) your catalog, the more this is true.

What the OP is getting at (I think) and what Rudman commented on is that mutipole speakers usually suck at bass. I've also seen them suck at >10kHz treble, probably to reduce localization cues.

The Axiom QS8 needs to be crossed to at 100Hz. Most folks working in this area know a 60Hz global x-o is desireable -- all it would take is Axiom upsizing the QS8 to double the internal volume of the M3, using the M3's 6 1/2" woofers and front porting it, to solve this problem, but Axiom, like most manufacturers, still assumes that over 100Hz performance is all thats required of surrounds.

There are a few, but many of the "show" theaters certainly aren't among them.
I don't believe in the "it's all subjective" BS. There is better and there is worse. Speakers, setup, whatever. "it's all subjective" is an excuse for making poor, highly colored products or doing things badly.
I can if you'd like, I've just been *really* busy, so haven't had a lot of time.
Because it's not "my way", it's *the* way (for the most part). The goal should be to do it right, once you can't do it properly, you have to make your own compromises, but people want to muddy the waters with "it's all good" and it's not "all good". People should know the right way to do this stuff and back off as they need to, but this whole "this bad speaker worked for my bad setup" isn't exactly helpful from a real educational standpoint.

One thing isn't disputable. Dipoles seriously color the sound of the rear channels, almost to the point of unintelligibility. Put on a music disc and play through the rears and then realize it does that to everything you put on your speakers.

90-95% of our customers can't or won't do things ideally and we work to make it close. BUT, all of them walk away knowing what they could have done better too and they're glad they know because if they ever can do a more ideal room, they'll likely do it that way (wife permitting).

An ideal theater system is when you have 5-7 identical wide dispersion speakers with well matched subs (preferably sealed), with all of the speakers placed at ear level, aimed at you and with the fronts 2.5-3' from any room surface and you 5' or more from any speaker.

Or, next less ideal for a smaller room is an all high quality inwall system such as Triad with identical speakers so that the bad placement issue is minimized.

7.1's *entire* purpose is to allow monopoles to also create a holographic experience *while* allowing for proper placement of surround effects. It is not to have what I call "discrete diffusion" where you put all 4 rear channels in a blender and scatter it to the winds.

Why aren't dipole fans using dipoles for front and center speakers on the walls in front? If it is better, than you should match your fronts to the better rears. Try it, see how good it sounds.

Here's unique solution from Energy the V2.0Ri. It appears to be a monopole with two side firing drivers that can be toggled between dipole or bipole modes. In addition the level of the two side drivers can be attenuated to control the direct/ambient mix.

http://www.energy-speakers.com/v2/pr...age.php?id=14#

Amen Brother......
As stated by a few others here... sometimes one has to allow the room setup decide... Every room is different, and you have to fight the battles you can win.

Alimentall, what is your HT like?

what brand/model speakers subs and equipment are you using?

any pics?

Kinda boring right now, in a way and certainly not ideal (that will have to wait for the next house). 5 NHT L5s wall mounted with a U1 sealed subwoofer and 110" screen in between. All the speakers about 3' off the ground with two L5s on the back wall.

I don't hear the rear speakers very often as point source, but when I do, it's because my couch is against the back wall. But, with well mixed stuff, it *almost* sounds like an ideal 7.1 system. Superman Returns was mindboggling on it (not that the plot was, mind you). I have had my system more ideal in the past, this one is temporary and only for movies.

Rudman,

Awesome post man! Yours is the most comprehensive surround speaker comparison i've read. Thank you.


Basically, even if monopoles are used, reflected sound is preferrable. The more on-axis, the more annoying it became. Even bipoles at ear-level is not liked.


You're describing a side array. My difficulty with this has always been volume control for each pair. It's like having two pre stages for each pair of side surrounds so that the furthest pair outputs the same level as the closest pair. How did you deal with it?


More than 7ft from a single chair in the middle is attainable by many. But how many HTs have "end" seats 7+ ft from the nearest side surround? Nobody. What I don't get is how people enjoy surrounds at both ends of the couch?!?!?!? I guess that what J6P sees at Best Buy.


That's been my experience too.

You seem to be firmly grounded in the ideal that the presentation/FR/Dispersion should be the same 360degs. That's cool, if you were wearing goggles with the LCD panels an inch from your eyes or in the future, when the entire perimeter is the screen. Otherwise, in 2007, the action is 14ft in front of you. The LCR anchor the action in front. The surrounds support the front and should never compete for attention. Their job is to immerse you so that you feel you're in the same area as the characters on-screen, but it's the LCRs that tell the story.

the same distraction problem could be had if you had a 15ft stereo separation but your screen is 32". L and R material won't match on screen activity.

I'm assuming 4 speakers? Were they all the same? How were they setup? Where were they setup? Where was the couch? What was the room like?

Then one would assume that movies are all mixed with dipole side speakers in the studio, right?

Also, you're making an assumption that the sound engineer never wants to localize a source or give it immediacy in the rear. That it's all just random noises for effect.

I used different scenes to prove that monopole was more accurate, more involving, more revealing of what the engineer was trying to accomplish, but I remember one particular scene where a plane takes off in front of you and flies off behind you. With matching monitors, the effect was achieved with no change of timbre and amazing realism. With dipoles, the sound when from intense to ghostly, more like the plane was going into the twilight zone, but not into the air space behind you. Not a single person ever preferred the dipoles. And it was an NHT setup with either SuperZeros or the HDP-1s based on the SuperZeros, so it was an even, matched fight. And this was in 5.1, before 6.1 and 7.1 existed. These formats simply cemented the performance differential to the point where no further demonstration was needed.

You may have missed this but I have been told you are closing your store?

Gee, most of us just switch wires on one of the tweeters

If you do this, label the speaker on the back which tweeter is reversed (voice of experience).

I've not heard the QS8s -- they would not work for me due to the aforementioned low frequency limitation. If you want more info on the QS8s, search the Axiom forum http://www.axiomaudio.com/boards/ubbthreads.php on QS8.