[James Tanner]

Hi Folks,

I am going to be experimenting with something that Magnepan calls a "TRI-CENTER" setup

This involves using 3 speakers for the center channel instead of just one. Sounds complicated I know and I will post some pictures to make things clearer going forward.

The last couple of demos Magnepan has done at shows has shown different versions of this basic idea - for instance the CES demo in January used a single dedicated speaker/channel in a 3-channel stereo (fronts)/surround setup. The advantage of this setup was a huge sweet spot where you could move around the room and the images stayed locked in position.

The new Tri-Center idea takes this one step further and produces a much more holographic soundfield. The surround setup is using the standard 5.1 setup but a Tri-Center arrangement instead of the normal single Center channel. Magnepan is so enthused with the results they are threatening to demo it at CES 2012.

More to come

james

[mg3720]

Hi

I recently created a tri-center channel setup using two MMC2s and a CCR in my theater.  It took a bit to get it all together, but as a hobbyist, that is what makes the hobby fun. 

Well worth the effort.  It solved some of the problems with having a large screen.  The MMC2 and CCR combination integrates extremely well with my 3.7s as the front left/right.

MG

[James Tanner]

Hi

I recently created a tri-center channel setup using two MMC2s and a CCR in my theater.  It took a bit to get it all together, but as a hobbyist, that is what makes the hobby fun. 

Well worth the effort.  It solved some of the problems with having a large screen.  The MMC2 and CCR combination integrates extremely well with my 3.7s as the front left/right.

MG

Hi MG

Well I envy you. You're already where I want to be. Any setup tips?

James

[BrysTony]

Since I did not have a clue what this was about I looked around for some information.  Here is a good article providing an explanation:
http://www.theaudiobeat.com/blog/magnepan_tricenter.htm

Tony

[JohnR]

If all three speakers are sent the same signal, won't there be all kinds of lobing off the horizontal center position? (Just asking from a technical PoV mostly.)

[James Tanner]

If all three speakers are sent the same signal, won't there be all kinds of lobing off the horizontal center position? (Just asking from a technical PoV mostly.)

Hi John,

It is really based more on the empirical evidence we seem to be gathering.


James

To keep the action centered on the screen for listeners far off-axis, the movie recording industry has no choice.

What happens to all the phase information when multiple sources are reproduced from one speaker? The ear/brain evolved to detect whether it was a saber toothed tiger or a squirrel-- and where it was located. I don't hear those cues from the center channel.

The former owner and president of Theta Digital, Neil Sinclair, discussed the problem of the center channel with me. Even if we put a 3.6 or 20.1 in the middle as a center channel speaker, the results were the same. A solution had to be found because the industry will not change because of the problem of the off-axis listener.

One can raise technical objections why the Tri-Center should not work. We did blindfold tests with some of the best Golden Ears in the Twin Cities and non-audiophiles. They all chose the Tri-Center. So, we are trying to find a technical explanation for why it DOES work.

Wendell

[mg3720]

If all three speakers are sent the same signal, won't there be all kinds of lobing off the horizontal center position? (Just asking from a technical PoV mostly.)

Hi John,

I have a general understand of lobing, but I am by no means a technical expert.  I tested with pink noise through the tri-centers only.  When walking across the room parallel to the speakers, the sound is very smooth with little variation in frequency or volume.  Very interesting.  I wish I knew more about the phenomenon.  I agree with Wendell’s comment in that it works, but cannot technically explain why.

MG

[mg3720]

Hi MG

Well I envy you. You're already where I want to be. Any setup tips?

James


Hi James,
The hardest thing for me was fishing the speaker and control wires through the wall so if doing a permanent install, know where the studs are and where you want to make your connections.

Instructions that come with the MMC2s and the controller are very good in stepping you through the install process.  Use the provided template or you will never get it right.  Although the drive mechanisms are forgiving, try to get the upper and lower brackets as close to level and plumb as possible.  There is some vertical fine tuning you can do to the drive rollers once they are up if you are off a little.  Make sure the brackets are snug to the wall, especially the top one that houses the drive mechanism.  I found if there is too much give, the wheels will not engage at the same time between the two speakers.

Make sure there is enough horizontal room to accommodate the front speakers and the new inboard MMC2s.  A problem I had to deal with because I have a very wide screen.  I had to push the front speakers out to avoid the MMC2s from being inline with them. 

I am sure more will come to mind (like spllitting the center channel signal, balancing the output, etc.).
MG

[James Tanner]

Interesting input on this concept:

http://www.ampzilla2000.com/trinaural.html

http://www.stereophile.com/musicintheround/904music/index1.html

james

[James Tanner]

http://www.theaudiobeat.com/visits/monday_at_magnepan.htm

james

[James Tanner]

June 23, 2011

Is it Cold Fusion?

What in the world could induce me to fly to Minneapolis in 103‐degree weather?

The chance to probe into a question vexing Wendell Diller at Magnepan: Wendell joked that maybe they had stumbled upon the formula for cold fusion. His questions made me curious. What is behind the sonic results from a particular combination of speakers and electronics—what is it that makes stereo sound better than, well, stereo? Being that Pro Logic II decoding was somehow involved, a technology to which I played midwife at Dolby, my curiosity got the better of me.

On the surface, the system is pretty straightforward: a pair of full size panels for L/R (3.7s in this case) with smaller speakers used for the center channel, all driven from a 3‐channel signal processor. No surrounds? So which is it – stereo or surround? It’s a fusion of the two. Take the best of full range stereo playback via Magneplanar dipoles and supplement it with a dose of center channel anchoring from a Pro Logic II decoder running in 3‐channel mode. No extracted ambience through surround speakers.

What Wendell discovered was that a particular configuration of center speakers they call Tri‐Center, a sense of spatial depth was revealed that had previously eluded not only 2‐speaker playback, but also conventional surround playback. There was no denying the effect – the problem was in rationalizing why it existed when common wisdom said, like cold fusion, it ought not be possible. On one level, the advantages of using a center speaker have been known since Bell Labs’ demonstrations in the 1930s. Few of us remember those demos! More recently, adding a center speaker is a standard feature for movie playback in theaters and homes, where it helps lock dialog to the on‐screen actors no matter from what angle you view the screen. During the heyday of 5.1 music production, mixing engineers noted the benefits in timbral accuracy that a matched center speaker could deliver compared with the comb‐filtered sound resulting from phantom center imaging. Still others, chief among them David Greisinger of Lexicon fame, taught that when a direct sound—a vocalist—is reproduced from a direct speaker, and that singer’s room reverberation is delivered from other speakers with diffuse spatial properties, the brain perceives a more realistic sense of space and depth than if all the sound is delivered by a pair of stereo speakers.

And so it was at Magnepan. Playing a variety of stereo recordings, particularly with vocals, switching between stereo and 3‐channel mode was a night and day difference in depth. But not just to the usual degree I’ve experienced before. No, there is indeed something special going on here that is not a result of merely adding a center speaker to an otherwise superb stereo system. In fact, when we tried using a smaller “conventional size” dipole center speaker alone, the effect collapsed. Whereas listening in stereo portrayed a wide and tall soundfield between the speakers, using the small center created a kind of bow‐tie effect, making the center image shorter between the tall L/R sounds. If there was any new sense of depth present, it was overshadowed by the discontinuity in spatial image height across the front.

Tri‐Center
Take that same center speaker and add a pair of smaller Magneplanar MMC 2 panels, mounted almost as high as the main L/R panels, all driven from exactly the same center signal, and it’s a whole new ball game. The center image is now as tall as the L/R, but there is also an obvious sense of depth to the vocals that was remarkable; much deeper than I hear from conventional speakers driven from the same PLII processing. My theory is that the Magnepan L/R dipoles naturally create a larger proportion of reflected energy in the room than box speakers, and when coupled with direct sound from the center speakers, this creates a stronger contrast between the direct and diffuse sounds, thus further enhancing the sense of depth.

Pro Logic II
And that takes us to the last element in the chain, the PLII processor. We experimented with a number of settings. It was easy to get it wrong and the benefits were lost. Wendell said that Bryston was considering offering a "recycled" SP2 processor that would remove any guesswork—push one button for movies, and push the "Tri‐Center" button for 2‐channel source material. (Yes, it also works if you want to play vinyl records.) Magnepan will have a webpage with instructions for proper system setup. If you love the putsy work of adjusting a 2‐channel system, you will love setting up this system.

Conclusion
It is addictive to hear stereo music portrayed this way, retaining all the best of normal stereo in so many respects, with the big Magnepan scale, ease and clarity, but with an added sense of depth and improved localization stability for center vocals that one can best describe as simply being more realistic. It’s a happy fusion of art and science.

Roger Dressler

[globalkiwi]

James, any update on your tri-center experiment?  Inquiring minds are curious.  Likewise, is there any word on when/if Magnepan will have a instruction page up for this setup?  I'm interested but am not sure how to wire a tri-center configuration...

[James Tanner]

James, any update on your tri-center experiment?  Inquiring minds are curious.  Likewise, is there any word on when/if Magnepan will have a instruction page up for this setup?  I'm interested but am not sure how to wire a tri-center configuration...

Hi

The latest issue (July/August) of Widescreen Review Magazine has about a 12 page article on the Magnepan/Bryston tri-center system.

james

[globalkiwi]

Thanks, I read that - & found it interesting (yet more enthusiasm for the tri-center set-up!) - but it doesn't say much about the wiring/configuration employed.

[James Tanner]

Thanks, I read that - & found it interesting (yet more enthusiasm for the tri-center set-up!) - but it doesn't say much about the wiring/configuration employed.

HI,

The tri-center gets the same feed for all three speakers from the center channel off the SP2 Surround processor.

james

[globalkiwi]

I won't be using an SP2 Surround processor - likely I will be driving the 3 centers (CC3 & MC-1s) with a single monoblock (though 3 separate channels are possible too) so wondered whether the center speakers should be wired in parallel, series or some combo ...?

[James Tanner]

I won't be using an SP2 Surround processor - likely I will be driving the 3 centers (CC3 & MC-1s) with a single monoblock (though 3 separate channels are possible too) so wondered whether the center speakers should be wired in parallel, series or some combo ...?

Hi,

We used a single 4B amp channel for the large center and a 4B channel in parallel for the 2 center flanking speakers.

james

[James Tanner]

I won't be using an SP2 Surround processor - likely I will be driving the 3 centers (CC3 & MC-1s) with a single monoblock (though 3 separate channels are possible too) so wondered whether the center speakers should be wired in parallel, series or some combo ...?

Hi

I spoke with Wendell at Magnepan and just a heads up ... he has tried a number of processors and none seem to have the 'magic' of the SP -2 with the tri-center setup. So maybe check with him regarding the processor you are using.

James

[klao]

Hi James & Wendell,

So, Tri-Center setup for two-channel music playback is not possbile with an ordinary stereo preamp (with two sets of outputs)?  How about for movie/concert playback, can any AVR or processor (other than the esteemed SP2 & upcoming SP3) be used?

Also, would the new Maggie Mini (whose user manual has been recently posted in Magnapan website) be good substitutes for the MC1 and MMC2 in Tri-Center setup?

Thanks,
Klao

[James Tanner]

Hi James & Wendell,

So, Tri-Center setup for two-channel music playback is not possbile with an ordinary stereo preamp (with two sets of outputs)?  How about for movie/concert playback, can any AVR or processor (other than the esteemed SP2 & upcoming SP3) be used?

Also, would the new Maggie Mini (whose user manual has been recently posted in Magnapan website) be good substitutes for the MC1 and MMC2 in Tri-Center setup?

Thanks,
Klao

Hi Klao,

From Wendell:

1. Yes, but, mileage may vary.

2. No, because it lacks the power response. The MIni Maggie System should only be used as a desktop or small room woofer/satellite system.