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post #1 of 57 Old 07-16-2002, 04:01 AM - Thread Starter
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Hello Fellow addicts, My name is Curtis and I am a addict.::eek: :D I have a little question for my fellow addicts. I have a Yamaha RX-V1105 receiver. and want to go to 6.1 or maybe 7.1 using my 1105 and a Dolby pro-logic receiver. Yamaha has a few units with dual center channel out puts.If I go for 7.1 using the dual center output, do the pro-logic unit have equal power to both outputs (separate ) or one that feeds both???
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post #2 of 57 Old 07-16-2002, 04:44 AM
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I don't know the answer to that, Curtis. How come your pro-logic receiver has two center channel outputs at all?

Dual speakers is nice, though. If you have a nice projector system with a fairly big screen, then you may find that one center speaker is not enough even in DD5.1 material. Typically a center speaker is no wider than a typical 29" TV, and so that is (roughly) the 'width' of the sound image that it portrays. With a much bigger screen, you may find that that 'locks' the center sound to the very center of the picture, which is a bit unnatural.

Personally I deal with this problem in my system by having an 'indirect' center speaker - i.e. I bounce it off the wall. It is a shame to do that when my center speaker is acoustically superb, but there you go, I couldn't afford two!!!
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post #3 of 57 Old 07-16-2002, 07:44 AM
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I was thinking of running two centers as well (A pair of Totem Model One Signatures) and thought that there might be defraction/imaging/dispersion problems by having two tweeters side by side.

I was going to lay the speakers on there side with the tweeters in the center...Anyone think that this would have a negative impact on imaging? :(

Blu-ray and HD DVD supporter.
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post #4 of 57 Old 07-16-2002, 09:08 AM
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I am planning on doing this same thing with my speakers, which are full range 5-way speakers. I doubt that it will be a problem, but I cannot test it out in my current room, as I don't have the width to handle the two center speakers and my mains and they are just entirely too large to move to another area to test out the theory. If anybody has some good evidence, I would like to know also.

Mike
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post #5 of 57 Old 07-16-2002, 12:14 PM
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Dual center channel speakers in the front soundstage is not an idea you want to pursue. Phase errors and cancellation create many more problems than they cure. Position the speaker so the tweeter is focused on the correct plane and you'll be better off. It is not true that the dispersion of the speaker is limited to the size of the speaker cabinet. Regards.
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post #6 of 57 Old 07-16-2002, 01:05 PM
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Bill,

How would two speakers next to eachother have phase errors, but one speaker with 2 tweeters next to eachother not have that problem?

Each of my mains has 24 tweeters and I doubt that they have more problems created with the array than they would have had with one tweeter per tower.

I just don't see your explanation as viable.

Mike
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post #7 of 57 Old 07-16-2002, 02:08 PM
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Bill Lucas is correct. The only advantage of dual center channel speakers is an additional 3 dB of potential output. But you also add a plethora of comb-filtering, lobing, cancellations, difference in arrival times, phase problems.

Mike, not only would two speakers next to each other for center be wrong, a single speaker with two tweeters next to each other is wrong, too, but maybe to a lesser extend because of the tweeter's proximity to each other. When you have arrival time differences of 6"-12" in the treble where the wavelength may be less than that causes many sonic problems. Vertically-aligned tweeters (a line array) doesn't have the serious problems of adjacent tweeters.

Believe me, I sell speakers, and if I thought it were better to sell TWO centers, I'd be all for it. But the physics doesn't bear it out.

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post #8 of 57 Old 07-16-2002, 05:00 PM
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Quote:
...you also add a plethora of comb-filtering, lobing, cancellations, difference in arrival times, phase problems.
Yup! And the main reason for this is because centre channel info is mono. If the two centre speakers were not being fed the same material, these problems wouldn't be an issue.

Best,
Sanjay

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post #9 of 57 Old 07-16-2002, 05:12 PM
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Jumping in here behind Paul. There are many problems with dual center channels when you want to have any more than a single seating location, and even then it isn't easy. The thing to remember about sound and acoustics is that "close" or "far" is always dependent on what frequencies we are talking about. Vertical line arrays of tweeters can be made to work only IF the tweeters are close enough. The same problem occurs with woofers used in a horizontal MTM center channel if the crossover is not low enough and the drivers are not close enough. Once two drivers are "close enough" for the frequencies they are reproducing, they do indeed behave as one.

Check out the following link. While the simulation is for subwoofers at 9' spacing, the EXACT same thing happens at 9" spacing but at frequencies 12x as high. The effect is scalable. Two separated center channels will be fighting some nasty effects from this case.

Speaker Spacing

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post #10 of 57 Old 07-16-2002, 05:44 PM
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Well, this just shoots my theory about how to run my center channel to hell. I am not going to be running a perf. screen, so I don't know what I would do about my center channel if I cannot run a pair of towers on their sides. I have them, and now I am to hear that my plan just won't work.

What I don't understand is how a 12" wide x 1" high ribbon driver would be OK, but 2 6" wide x 1" high drivers side by side would not be OK. Call me crazy, but when we are talking about tweeters, isn't even 1 foot apart a miniscule amount when compared to the really high frequencies they are playing?

I know the theoretical physics says that the ideal source is a point that plays all frequencies, but with the technology we have, that isn't possible. Multiple drivers is the rule. Some speakers offer multiple drivers in a given frequency range. Super high end speakers like the Infinity IRS V and the Genesis 1.1 have as many as 72 tweeters. Are you saying that they would sound better with only one driver? As I have a pair of IRS V right next to a pair of IRS Gammas, which only have one driver for any frequency range, other than bass, I can tell you that the multiple drivers doesn't detract from the sound, but rather the IRS V sound better, even with the exact same amps.

I have seen center channels with a tweeter in the center and midrange on EACH side. This is not considered a problem, but if they are in different cabinets, suddenly, we are to talk about how the plethora of comb-filtering, lobing, cancellations, difference in arrival times, phase problems starts to kick in?

Paul, I see on your platinum center channel speaker you sell, there is a horn tweeter in the center, with a midrange above and below that. There is a bass speaker to the left and the right of it. Taking your theory as fact that 6" to 12" side to side is a problem, what about the Martin Logan electrostatic center channel, which has a driver that is much larger than 12" wide?

I am not saying that this is a perfect solution, but I think that the problems are overblown. I bought a center channel once (kappa video to go with my Infinity Kappa 9 about 10 years ago) because I bought into the whole arguement that my speakers I wanted to use, kappa 6 speakers on their sides, would have the wrong dispersion patterns and wouldn't work as a center channel. I never enjoyed the center channel I got, which was VASTLY inferior to my mains and I just left it up on my TV for the last 5 years, unplugged, just for looks. I would hate to pass on having wonderful sounding center speakers because of a comb-filtering speech unless it was proven to me a little better.

Oh, and the tweeters on the top of the in my mains at seven feet away from the tweeters in the bottoms. I still do not seem to find the single tweeter in my Gammas to be comperable, even at lower volume levels where it should remove the multi-driver advantage. Very large Martin Logan, Apogee, Magnapan and other planar speakers are in a similar situation, yet there is not a concensus that they are inferior to dome/horn tweeters and cone midranges.

Paul, I do not believe people just because of their position or their incentive to want things to be my way. You market speakers, but you don't know everything. Neither do I. As there has yet to be a perfect speaker made, I can only surmise that nobody knows everything, but rather that we are all trying to find perfection. We haven't found the way yet, but many different paths have gotten us a good distance. When implemented properly, multiple drivers have, in my experience, been more benefit than harm.

I really don't want to have to set this thing up to test it, but that will be the only way for it to be put to rest in my mind. Perhaps I will do that when I get a chance in a couple of weeks. Until then, I have only to go by what I am told, which is different than what I have heard. Given the choice, I would either wait to test it out for myself, or go by my personal experience.

Has anybody here honestly run multiple center channels? As my speakers are no longer made, I have no other way to get a center channel with matching drivers other than taking my full range speakers and having them made into a single center channel, which would look almost exactly the same as they do right now, which is what i find so confusing.

Mike
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post #11 of 57 Old 07-16-2002, 06:30 PM
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Quote:
Paul, I do not believe people just because of their position or their incentive to want things to be my way. You market speakers, but you don't know everything. Neither do I.
Agreed. But...I know more than you about this. The information I gave you was not "marketing" as you stated. If I were a shameless sales whore, I would have given you bad information and suggested you buy FOUR center channel speakers...ALL TRIAD! But I was honest with you, and technical whiz Mark Seaton backed me up. I wish for your sake we were wrong, but we're not. Your setup will probably sound acceptable, though. It just isn't right.

The higher you go in frequency, the more desireable vertically-aligned drivers are. That's why the Triad InRoom Platinum Center has a vertical mid/tweet/mid array. As the wavelengths get longer at lower frequencies, drivers can be horizontal, but there is still some comb-filtering. This is a concession made for placement reasons with center channel speakers. And remember that even with vertically-aligned drivers, the distance between the axes of the two drivers cannot exceed the wavelength at the crossover frequency.

That's not "marketing" and I am out of this thread.

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post #12 of 57 Old 07-17-2002, 02:06 PM
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I have very large mains & rears (polk SRS SDA's 2.1)

I can only speak from experience, I'm not an expert but I've found that in
my case one center channel was not enough. So I use 3 centers each
powered by the internal amps of my 3090 (80w/ch). One center was above
my rptv and the remaining 2 were mounted at head height inside my av cabinets. Now the center section matches the other channels, although
they have significantly more power (375w/ch)..

You may want to experiment w/ 2 centers, if you don't like the results,
you can always return the 2nd center.

Good Luck
Jose
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post #13 of 57 Old 07-17-2002, 06:17 PM
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I just happened to read the owner's manual for the Onix Rockets and it has recommendations for speaker placement. It states that if you are using a projector screen, you may want to try two center speakers...one on top and one on bottom to center the sound in the middle of the screen.

Brian

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post #14 of 57 Old 07-18-2002, 04:04 PM
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Hello again guys,

I went back to fix the link above which was confused in submitting it. Please check out the graphs now that it works properly.

Now for some other comments and posts made...

Quote:
Originally posted by Mr.Poindexter
Well, this just shoots my theory about how to run my center channel to hell. I am not going to be running a perf. screen, so I don't know what I would do about my center channel if I cannot run a pair of towers on their sides. I have them, and now I am to hear that my plan just won't work.

What I don't understand is how a 12" wide x 1" high ribbon driver would be OK, but 2 6" wide x 1" high drivers side by side would not be OK. Call me crazy, but when we are talking about tweeters, isn't even 1 foot apart a miniscule amount when compared to the really high frequencies they are playing?
"Not work" is a matter of debate. They will provide sound, and they will play louder, cleaner than a single version. What they won't do is provide smooth frequency response over any significant area, resulting in a sound that warbles in and out with position. As for the 12" wide by 1" high ribbon, you would not want to use this for a center channel, as the high frequencies would be very directional, rolling off quickly past the 12" dimension. Placed such that it is tall rather than wide would work much better to cover a comfortable listening area because it is then narrow relative to the frequencies, allowing for wider dispersion. This is what is called a line source. As I mentioned in my previous post, in all things audio, size only has relevance to the frequencies covered. What is large for high frequencies, can be miniscule for low frequencies. So in fact 12" is a huge distance to the sounds coming from most tweeters. Even supposed line sources only behave down to some lower frequency where the line is still more than 2-3 wavelengths long. Below that frequency, it behaves more like a point source, and eventually exactly like a point source.

Quote:

I know the theoretical physics says that the ideal source is a point that plays all frequencies, but with the technology we have, that isn't possible.
Well, it isn't impossible, but I don't sell inexpensive, nor small solutions to the problem yet. ;) Until then, we must then seek to minimize the problems.

Quote:

Multiple drivers is the rule. Some speakers offer multiple drivers in a given frequency range. Super high end speakers like the Infinity IRS V and the Genesis 1.1 have as many as 72 tweeters. Are you saying that they would sound better with only one driver? As I have a pair of IRS V right next to a pair of IRS Gammas, which only have one driver for any frequency range, other than bass, I can tell you that the multiple drivers doesn't detract from the sound, but rather the IRS V sound better, even with the exact same amps.
Now consider what I mentioned about distances and frequency. In the IRS the design keeps the tweeters as close as possible. When the drivers are acoustically close, they behave as one, and in this case they act somewhat like a tall, thin ribbon of sound. Note that they still need the narrow horizontal dimension to get wide horizontal response. Since the "line" is tall enough to cover the listening area, the limited vertical dispersion is not an issue.

Quote:

I have seen center channels with a tweeter in the center and midrange on EACH side. This is not considered a problem, but if they are in different cabinets, suddenly, we are to talk about how the plethora of comb-filtering, lobing, cancellations, difference in arrival times, phase problems starts to kick in?

Paul, I see on your platinum center channel speaker you sell, there is a horn tweeter in the center, with a midrange above and below that. There is a bass speaker to the left and the right of it. Taking your theory as fact that 6" to 12" side to side is a problem, what about the Martin Logan electrostatic center channel, which has a driver that is much larger than 12" wide?
Spaced drivers do have definite problems.... above a frequency proportional to the distance between them. Below some frequency, the two drivers are acoustically close and behave mostly as one. This is where going with a 3 or more way speaker makes it easier to meet this criteria. Follow the link I fixed in my last post to see a visual representation of this. As for the large midrange ESL panel in the Martin Logans, there is a reason they need to make them curved, so that they still maintain wider coverage as frequency increases.

More later...

Mark Seaton
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post #15 of 57 Old 07-18-2002, 07:30 PM
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I tried two centre channel speakers with a Pioneer Pro-Logic reciever in the early 90's and the dialog was muddy. It's a bad idea IMO. Best wishes!

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post #16 of 57 Old 07-22-2002, 11:44 AM - Thread Starter
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Hey fella's maybe I did not explain it right or been misunderstood. My post was for dual (rear) for 7.1 or 6.1 using my Yamaha RX-V1105 5.1 DD and DTS. and for examble the Yamaha R-V730 Dolby Pro Logic which has dual center channel outputs.Using these two to create a 6.1 or tha dual output for the 7.1 effect.
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post #17 of 57 Old 07-22-2002, 12:14 PM
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AAAAAAHHAA... you meant Dual REAR centers!

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post #18 of 57 Old 07-26-2002, 10:22 AM
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If you would like an explanation of the comb filtering effect go to this web link:

Comb Filtering

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post #19 of 57 Old 07-26-2002, 02:16 PM
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Quote:
Originally posted by chim
I just happened to read the owner's manual for the Onix Rockets and it has recommendations for speaker placement. It states that if you are using a projector screen, you may want to try two center speakers...one on top and one on bottom to center the sound in the middle of the screen.

Brian

Boy, that really had me scratching my head as I've always read and believed that dual centers were inherently evil for the reasons listed in this thread.

Being curious, I sent an inquiring e-mail to Onix Rocket designer Dick Pierce and received one of his typically pragmatic replies which I found very interesting. (warning, his style is direct and geared toward the rec.audio newgroups he frequents)

-----------------------------------------------------------------------------------------------
(Slightly edited for non-specifity toward my inquiry)

The ONLY way possible to avoid comb filtering effects is to have a
single loudspeaker placed in an anechoic chamber.

As soon as you introduce multiple sources, whether real or virtual,
you WILL have comb filtering. (A "virtual" source is a reflection
of a real source. For example, place a loudspeaker 2 feet above the
floor: at frequencies where the floor is reflective, which is most
frequencies, there is an apparent or "virtual" source 2 feet BELOW
the floor, giving a doublet source with a separation of 4 feet).

That means that ALL stereo systems, ALL home theater system in ALL
rooms suffer from pretty massive amounts of comb filtering due to
path length differences to multiple coherent sources. It is completely
unavoidable in practice.

That being said, it can be argued that the more real sources you have,
especially sources that are placed different distances apart from room
boundaries and each other, the more evenly distributed the nulls of
the comb filtering will be and thus the smoother the overall response
due to comb filtering will be.

I think it can be argued, that, at its WORST, and additional center
channel speaker will NOT make things worse, and may potentially make
things better.

The arguments of the people you cite might be strictly true in a
first-order analysis but fail or at least loose much of their strength
when the entire boundary and multiple source considerations are taken.
One can further suggest that two competely coherent sources, placed
vertically, restrict radiation in the vertical plane, but not in the
horizontal plane, and thus can arguably REDUCE comb filtering effects
due to interference effects with the virtual sources under the floor
and above the ceiling.

Another point: the demon "comb filtering" itself is something of a red
herring in reality. Comb filtering can only occur if the size of the
radiating sources are very small compared to the wavelength while at
the same time the separation between them is large compared to the
wavelength. For something like the dual center-channel approach,
the ONLY frequencies where this is relevant is high frequencies, and,
within the listening window, the path length differences are simply
not big enough to cause the problem AND where they are big enough,
you're sufficiently far enough off axis that you don't care.

I believe the comb-filter argument against using dual center-channel speakers is specious and unsupportable.
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post #20 of 57 Old 07-26-2002, 03:49 PM
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Whoa, this thread's pretty wacky.

Dual center speakers is a dumb idea for reasons stated very clearly already. Don't wanna believe it. Ok. stay dim. But the truth has already been stated. I'm just adding that I back this up.

But then the poster meant dual rear centers -I think?? But never said REAR centers?

His actual question was -"If I go for 7.1 using the dual center output, do the pro-logic unit have equal power to both outputs (separate ) or one that feeds both???"

This question makes no sense. Please try it again.

IMO, most people don't even NEED a center chan. much less two if they sit fairly close to the center of the soundstage.

If you're way off center, then the nearer main speaker will shift the center image, but then you're seeing the screen on a bad off center angle too, and the levels of all your speakers are messed up also (center of none), so you must not really be very into good audio or video anyway. Leave those seats for children or guests who don't know any better.

Now I'm not saying -"DON'T BUY A CENTER SPEAKER!!" , but so many people use it as a "gap filler" for having mains that image like crap either because the speakers suck (usually not), and/or they have them set up poorly. -Often too far apart so the center image that 'could' be sharp, is more "cloud-like". Then they get a center chan. and say "Wow, the dialouge is soooo much clearer now! And 'locked' to the TV!"
The clearer part I already explained.
They 'locked to the TV' part is becuase of the horizontal arrangment of the woofers throwing more sound vertically than horizontally. Which is exactly what you DON'T want a speaker to do (=very un-open speaker).
Don't get me wrong -this still isn't horrible though. Why not you ask?
'Cuz your mains are overlapping the center so that it blends in even though it's poorly arranged to do so.

You'll fine some companies place the tweeter on top of the cabinet which allows them to place the woofers close together which helps out a lot. Probably phase corrects the tweeter too.

It's FREE for everyone reading this to experiment with a Phantom Center compared to using their center speaker. Every rec. can do it, and you lose none of the soundtrack.
You should find that the Phantom Center is more open, solid, and inherently 'perfectly matched' even more than the 'so-called' matching center is to your mains.

Like I said if the dialouge isn't as clear then you probably have your mains set up poorly. Sometimes you can't do anything about that though. Test it out though. Just TRY it.

I think this is part of why a TON of people say their systems sound really good for HT, but poor for Stereo.

If a comapnies speakers are great and image perfectly, then stereo sounds incredible (and can even mimic discrete 5.1, but for that you need to be dead center w/ a disc such as Roger Water's -Amused to Death recorded in Q-sound).

Line source main speakers are probably the best type for not having a center speaker so if 'what's his name?' is using speakers with 24 tweeter line arrays and can't get a sharp crystal clear center image, then his speakers are set up wrong or his amp is garbage (and it's hard to buy a garbage amp, so I'd guess the former).

I use Newform Research which have 45" ribbons and no center speaker. Even off center (people sitting on the end of the couch) the sound images perfectly from left to dead center to right, and is razor sharp anywhere in the soundstage.

I can get pretty close to the same even w/ my $220 Axiom M3ti's too.
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post #21 of 57 Old 07-26-2002, 04:04 PM
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There is more than one way to skin this cat. I did have a set way of thinking on this but I'm open to new ideas. Yes, even the Goldmund concept Azryan describes has it's happy practicioners.
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post #22 of 57 Old 07-26-2002, 04:42 PM
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What's the 'Goldmund concept'? I've heard of the company Goldmund, but I wasn't aware that they had anythingto do with inventing the idea of a phantom center? Or is it some famous old designer I haven't heard of? It'd have to I guess 'cuz stereo imaging's been around for many a decade.

For the record I used to have a center speaker (a couple of them). The mistakes I refer other people often making are mistakes I believe I have made myself when I didn't 'really' know how to set up speakers correctly. When I didn't even consider than a center speaker could possibly be worse than no speaker esp. when the whole world has turned 5.1.
I'm kinda young too so don't think I'm some old coot who can't accept multi channel systems. My pre/pro can do 7.1, and I've tried it, but I find 4.1 to create a full solid surround field.

Oh yeah... Down w/ di/bipoles too!

The dual center thing also related to how the center speakers are arranged. The best you could probably do it is if it was an MTM design and placed one on top of the other. Then you'd mostly just have a problem w/ the tweeters being too far apart.

A design like I mentioned where the tweeter sits on top of the cabinet would be really bad in a pair 'cuz the two tweeter's would probably end up ~10-12" apart.

Place any center speakers side by side in the center and you'll have the worst mess of all.
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post #23 of 57 Old 07-26-2002, 05:05 PM
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bigwally,

Checking out your room picture, I gotta say, I can't imagine you needing a center speaker in anyway whatsoever. You're dead center between those ring radiator Rockets. You should have a PERFECT phantom image.
Please try it out. I couldn't imagine a set up less needing a center speaker.

The only sonic benefit would be that you could goose (turn up) the center speaker if you couldn't make out the dialouge that well, but with Rockets, I really doubt that'd be the case.

I bet you could sell that center and blow that money on something else.

Hmm... Anyone know if current SACD or DVD-A players can output a phantom center? I'd think they would, but maybe we'd have to wait for the digital out universal players to do this?

Haven't jumped in to those formats yet. Most people haven't maxed out thier CD's output anyway. My system blows away all the SACD / DVD-A demos I've heard (not that those formats aren't better -I know they are), and I could still improve my CD output further.
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post #24 of 57 Old 07-26-2002, 10:13 PM
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Thanks Azryan, it's true that I don't "need" a CC speaker, but I do prefer to use one for multi-channel music and movies. For 2ch music you're quite right, those 750's image like a ba$tard. I've been buying, selling, trading, and otherwise playing with audio gear seriously or semi-seriously since the early 70's when I had my father's Dynaco tube/ EV rig as my first victim, so I have indeed tried more than just the configuration you see there. For a couple of years in my early HT days (before AC-3) I did in fact use a phantom center configuration. This is where I am now and I'm very satisfied. (By virtue of that last statement alone, I must not be a "true audiophile"!)
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post #25 of 57 Old 07-27-2002, 12:09 AM
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I have NHT VT-2 spks (front/rear) with Super Two towers for the sides in Lex's 7.1. My single centre (VS-2a) wasn't able to keep up with my VT-2's durning certain L to R, R to L pans. My GURU (who builds sound system for some of the best walk in theaters) told me to double up (after checking out the spk closely) my centre spk. The VS-2a is angled in the back for upright/downright position. The best thing these spks have is a tilt braquet for spk position. We stacked both spks on top of each other so the tweets were siting on top of each other right in the middle. Then we locked both spks together with the tilt braquet, and it looks like one hugh centre spk. My centre consists of two 1 inch soft dome tweets, and four 5.25 inch long throw woofers powered by a Nak PA5A II (150 watt) amp.

My room is 11 1/2 by 28, and I like my centre to come right at me. BTW, we took the form (voice) bar off of the VS-2a (under the tweet) and the spks opened up so much more. I did it to my VT-2's. The double centre is truly a plus with my system. There's nothing like great dialog!!

Here it from the people who mixed/mastered it...LEXICON
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post #26 of 57 Old 07-27-2002, 08:46 AM
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MRWILLL, you said -"My single centre (VS-2a) wasn't able to keep up with my VT-2's durning certain L to R, R to L pans.

How didn't it "keep up"? Not sure what you really mean.

I looked at NHT's web site and it looks like that center uses the same exact dual 5 1/4" drivers and 1" tweeter as your mains.
Quote from NHT's site -"It <the VS-2a> is precisely matched to the upper-range drivers of the VT-2 A/V tower."

I could see it "not keeping up" in the area of bass -maybe. But set to a typical 80Hz x-over to a sub and this shouldn't be a problem. That center should be able to hit a solid 80Hz, but maybe not?

The phrase "Keep up" implies 'speed' to me -if anything- and using the same drivers as your mains means just the one center speaker'll be just as fast as the mains. And two won't be any faster.

I assume you use the same amps too? A slower amp can greatly effect the 'speed' of the drivers. You mentioned the center speaker amp. Is it diff. from the mains?

Since the tweeter in that center speak is mounted near the top of the cabinet, having another flipped on top of it shouldn't be as bad as it would be it the tweeter was mounted in the center of the cabinet (like most center speakers are), but the size of the sound waves a tweeter is asked to create gets VERY tiny, and you're not actually gaining fidelity at all by doing this. It looks like your tweeters are about 2" or so apart from eachother. Not the end of the world, but this is not good, or 'better' than a single tweeter.

No actual production speaker would ever be designed like that.

Like has been said before, you're gaining effi. though, which would gain you fidelity over one center speaker on the midrange drivers (which seem at least decently close to eachother) if you used to hit the limits of the single center speaker's maximum output volume before.

I kinda doubt that you have though. That's pretty screamin' loud.

You also said, -"BTW, we took the form (voice) bar off of the VS-2a (under the tweet) and the spks opened up so much more."

Voice bar?? Did you mean 'foam bar" maybe? -as in the strip of foam that NHT placed there to absorb baffle reflection, and getting rid of it you find the tweeter 'opened up'.
Sorry, but that's also screwing up your treble response.
They put it there for a reason.

For example, when I listen to stereo, I drop a nice thick blanket over the plastic screen of my RPTV. This eliminates the treble reflection (boost) from off the screen.
Clarity, depth of soundstage, and freq. improves by doing this. Even moreso if I got rid of the TV all together, but I only have the one HT/Stereo room, so that compromise has to be made.
The treble sounds louder if I take it off though, but it's not 'better', or 'more correct'.

You could mount a peice of glass above your center speaker and that thing would really 'light up' your center speaker. Wouldn't sound better though.

You said -"There's nothing like great dialog!!"

Very true, but seriously, could you explain how you think dual over a single center speaker improved your movies dialog? You could have just raised the level of the center speaker on your Lex if you just wanted your center louder than your mains.

Does your GURU post here? What's a 'walk in theater' by the way? You said the GURU designs them?
Do you mean hi-fi shop theaters? Or home theaters?

If you mean a 'typical movie theater', then you should know movie theaters are very far from hi-fidelity sound. They're not designed to be.
A modest HT almost always sounds better. Just not often as loud.
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post #27 of 57 Old 07-27-2002, 05:31 PM
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azryan...

When I said "keep up", I meant the sound not changing within the front three as far as pans. With my double centre being crossed over at 120hz (Lexicon's L7), and my fronts at 40hz, I need all the help I can get for the smooth sounding pans.

I bi-amp in a passive mode with 225 watts to the highs/mids, and 250 watts to the lows. My amps are the same for the Centre/front/rears, with mono blocks for the sides.

The foam was put there for a reason. My reason was to take it off, and my spks opened up more. If I didn't like the sound, it was no problem to order more and put tem on. My girlfriend has the VT-2.4's (my spks are soft dome...hers are aluminum), and her spks do not have the foam bar. On another forum I opened this up to folks using the VT-2 spks, and they loved the idea. Small tweak!!

You said: "Very true, but seriosly, could you explain how you think dual over a single center spk improved your movies dialog"??

With a single centre, the sound was not like how I like it. I like my centre dialog to hit me right in the face, and that's what it does. Without two spks, it doesn't do it. If you know anything about HT, just raising the centre doesn't cut it.

My GURU use to post (through me) over at DTF. Some of the guys (just as you have) wanted him to post directly. He's been through the forum wars. So we stoped.

He builds sound systems for walk-in theaters. I agree that a modest HT can sound better than a walk-in theater.

Alln-all, it's all about the sound. If you could sit in my room and listen to HT blindfolded, IMHO (Out-of-all-do-respect), I don't think you could have come up with the same questions/answers. I've seen Industry people go at it pretty good.

Here it from the people who mixed/mastered it...LEXICON
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post #28 of 57 Old 07-28-2002, 09:29 AM
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You said the matching NHT center -identical to your mains (redundant just to make the point) doesn't match the mains?
I can't imagine how two of the same center speaker now sounds the same as the mains -or even 'closer to the same'.

You just repeated yourself about that 'foam bar' thing.
You didn't clarify at all how you think it's 'opening up' that dual center channel, or refuting how I explained what it is doing -which is just louder, more reflected treble w/ a more ragged freq. response.

Then again, you don't notice that effect from those dual tweeter that are at least 2" apart from eachother, so what's more tweeter damage 'eh?

You said -"On another forum I opened this up to folks using the VT-2 spks, and they loved the idea."
I don't get it. Do you mean you told people to remove this foam baffle reflection strip to 'tweak' other people's NHT's?

I asked you how dual centers improve dialog -but you only wrote -"With a single centre, the sound was not like how I like it. I like my centre dialog to hit me right in the face, and that's what it does. Without two spks, it doesn't do it. If you know anything about HT, just raising the centre doesn't cut it."

Hmmm. I actually do know something about HT, so I guess I should be able to make sense of this statement, but just can't seem too.

Maybe you could clarify "hit me in the face" dialog and explain how it only happens by the use of two center speakers and doesn't with only one.
I see you think that it has nothing to do with the center being any louder than before though.

You said -"My GURU use to post (through me) over at DTF. Some of the guys (just as you have) wanted him to post directly. He's been through the forum wars. So we stoped."

Ok. He can do as he pleases, but you mentioned the guy, and said this dual center was his idea, so I'd rather hear from him directly than from you who, sorry to say, doesn't really seem to know technically what he thinks he did.

Sorry, but "hit me in the face" dialog isn't very technical.

You said -"He builds sound systems for walk-in theaters. I agree that a modest HT can sound better than a walk-in theater."

Again, you just repeat yourself. I asked you what a 'walk-in theater" is. I assumed it meant 'typical movie theater', but I didn't want to guess. I guess I can eliminate "home theater" though, and I'll just assume you mean "typical movie theater" and not hi-fi shop theaters or anything else.

As long as you're repeating yourself, let me say again -"Typical movie theaters have horrible sound, and are designed in a totally diff. way than a HT should be."

Find me any speaker ever made that has two dome tweeters 2" or more apart from eachother like your 'dual center' your GURU made for you.
You should have just built a big horn in front of the single center speaker. That'd 'hit you in the face' with dialog like crazy.
I'm suprised your GURU who probably deals w/ hornloaded P.A. speakers in movie theaters didn't suggest this. Woulda been cheaper than buying a second center speaker.

You said -"If you could sit in my room and listen to HT blindfolded, IMHO (Out-of-all-do-respect), I don't think you could have come up with the same questions/answers. I've seen Industry people go at it pretty good."

I don't get the 'Industry people going at it' line at all? Honestly, all I could think of is a crude punchline. -heh

I wouldn't need a blindfold to hear your system. You're thinking of a comparrison test between two diff. things -the blindfold worn so I won't know which I'm hearing.

You don't imply a comparrison at all. You just say "If you could hear my system". That doesn't take a blinfold.

I've heard NHTs before. Not bad, but I've never been a big fan. Also, I've never heard them called world class by anyone ever, so if you imply I'd love your system if I only could hear it. I'm pretty sure I wouldn't.

I wanted to stay away from that issue though and just stick with the technical details of your dual center's effect on soundwaves. I don't wanna get personal. Sorry.

If you could hear my system with no center at all, you'd hear how open, transparent, and solid a 2 chan. front end soundfield can be. IMO, better than any center I've ever heard - and I've heard B&W, Linn, Revel, TAG, etc...

I suggest you check the set up of your mains to get them to image correctly, and test a 'phantom center' just to hear the diff.

Like I've said before, this is inherently a 'perfect match' to your mains. Something you said yourself you can't get with NHT's own 'matching center'.
And something I'm sure you're still not getting from 'even less matching' dual centers.

BTW, does that dual center really need to be x'ed over at 120Hz? That's too high to blend w/ non directional bass.

I'm guessing the 'hit you in the face' effect you speak of is from the brighter, harsher treble you now have, and the disconnected low end bass. I could very much imagine that would make dialog easier to hear, and would be very diff. than (as you said) just turning up the center level.

Wouldn't sound smoother, more natural, or more realisitic though. That GURU's steering you wrong.
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post #29 of 57 Old 07-28-2002, 01:28 PM
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Azryan, your take on the phantom center mirrors what John Meyer states. It's true, if there is not a center channel speaker available that seamlessly pans with your mains this is the ideal approach and as you are a Newform owner, I can understand your position. FYI, many VMPS advocates were in the same camp with you and Meyer until Cheney came along with first the 626R, and now the Large Ribbon Center.
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post #30 of 57 Old 07-28-2002, 06:30 PM
 
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That the only dual (front) center ch speaker configuration that works. Recommended only in a big screen/front projector set up. It works very well.
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