Dual Center Speaker- (1 Viewer)

[pink]

I just hooked up two center speakers, one on the bottom of screen and one on top, this is the most incredible improvement on my system, does any one else have dual centers and what do you think, smoking or what????

 

[Robert_J]

No one else does it because you want to have a single source of sound for each channel. It is probably a little louder. You could have accomplished the same thing with proper calibration.

-Robert

 

[Cees Alons]

Depends on the position of his volume dial.
He accomplished something else: the sound source will now be located better in the center of his TV screen, not above or below it.

Roger, did you use two identical speakers?


Cees

 

[chuckg]

I was not happy with the center sound coming from above my TV, and so I put two identical speakers wired in series to each side of the TV. My own impression is that the sound comes directly from the center of the screen, and it is a huge improvement - it is as good as when I set my audio to "phantom center" after getting disgusted with a poorly-matched center. I now have six identical speakers arranged around me, and though there are some very slight differences in sound from one to the next, the overall quality is vastly better than I had with different cabinets from the same "family"

Wiring the speakers in series means that the sound level is identical, or nearly so, as having one speaker.

It may be that there are some lobing effects, but I have not found any bad spots yet, and I sit on the centerline anyhow. There might be some comb filtering, but it is undetectable to me. And yes, I do know what it is like when these two effects are noticeable to me. blech.

Blanket statements often miss the mark...if it sounds better to you, though, then I say go for it!

 

[JohnRice]

I've never been bothered by the sound coming from just above the screen (or below if the screen is high) but it annoys some people. If you want to use dual centers, Roger's approach should be the better solution. Two speakers aligned vertically should have far less chance of causing pboblems, plus the sound stays centered if the viewer isn't centered.

 

[Robert_J]

I can see it working IF both are exactly the same distance from the listener. Otherwise there will be a phase issue.

-Robert

 

[JohnRice]

Well, there is a theory that the distance between your two ears factors in with horizontally placed dual centers. Someone can (and probably will) provide the math, but that distance can cause a phase cancellation in the upper midrange, which is also a critical area for dialog, which is why horizontally placed centers can be a problem. Plus, like I said, the viewer has to be perfectly centered for the dialog to stay centered, which seems like the entire point to begin with. So, above and below might work pretty well.

 

[Gregg Loewen]

generally speaking...this is a very bad idea.

 

[chuckg]

Aside from the possiblity of lobing or phase cancellations, why is this a very bad idea? In my situation, it sounds just great.

I remember the good old days, when we only had two speakers. Nobody ranted and raved about the "very bad idea" of putting the singer's voice equally in both channels to make them sound as if they are in the center...

Help me understand why I'm wrong, and I may be gracious enough to agree! (I'm easy, just stubborn)

 

[Cees Alons]

I've done a lot of testing with multiple speakers, in my time, and I can safely tell you: if they're below and above the TV (rather close together, much closer than the listening distance), there are hardly any ill effects. Partly, this is caused by the acoustic "filling" of the space between them, even by a reflective surface (your TV-set).
(And don't forget that most floor-standing speakers have multiple drivers below one another, often two of the same type among them.)

Multiple speakers in general aren't a very good idea, unless you're willing to perform a lot of measurements, tests, etc. and then it may be very problematic still.

But this specific situation can work very well, especially if you're one of those indeed who's bothered by a sound coming from beneath your screen or from above it.


Cees

 

[JohnRice]

Cees, did you mean having them below and above the TV?

 

[pink]

(QUOTE) did you use two identical speakers?

I am using the same speakers for top and bottom. These speakers also have a great design, they have a focused array tri tweeter assembly and an 11 deg. frontal incline which allows for optimun placement either above or below the screen. If you put them on the bottom you have that 11 deg. incline coming up at you and if you flip them the other way and you use the speaker for the top they fire 11 deg. down, so the sound is NOT coming straight out,it is going right to the listeners ears and using two of these it's the best improvement i made to my system for the dollar amount spend which just happens to be $1000.oo each. both centers are also bi-amped which to me is another whole dimension in sound.

 

[pink]

Volume is not the issue, since i have both speakers bi-amped with 425 watt cinepro amps. to me dual centers just add a whole new window to my HT. maybe it's not a good idea, but it sure sounds great.

 

[drobbins]

In my last house I used two centers in my theater. I couldn't notice any issues with the setup and no one else complained either. So worst case it didn't sound bad at all, best case I enjoyed movies a lot more because I wasn't looking at the bottom speaker for the actors.

My new current theater, I wired for 2 centers. I first had one under the screen. This did not work out for my back row of seating because the sound was blocked by the first row. I now have the center mounted above the screen. I had to set it into the drop ceiling at angel so it would not be in the picture. This is a improvement, except my back right seat does not get any sound from it. The way it is mounted does not point at that seat. Next I plan on trying phantom mode with out a center. If that doesn't work out, I will go back to 2 centers, but the top one will be angeled differently. I hooked mine up in parallel.

Here are other threads on this topic:
http://www.hometheaterforum.com/htf/...-speakers.html
http://www.hometheaterforum.com/htf/...on-screen.html
http://www.hometheaterforum.com/htf/...t-up-help.html

Dave

 

[Cees Alons]

Sorry, yes that was what I meant to write.
I edited it now. Thanks, John!


Cees

 

[pink]

No other feedback on Dual centers???

 

[Martino]

I was wondering - since you said "screen", it seems like you have a system with a projector - would it be possible to get a sound transparent screen and mount 1 center speaker directly in the center, behind the screen? If the sound above and below is an issue, why not have the source in the center itself? You could then use the same speaker as on the sides, directly in the center, and it would help with your immaging and panning as well...

 

[DeeF]

I've just received a new plasma, Pioneer 151HD, complete with speakers. It sits on its stand on top of a long bureau. In my new apartment, I haven't gotten around to installing the speakers, so I'm not using my center speaker, a JM Lab high-quality unit. Instead, I've hooked up the plasma's speaker set as my center channel, and use my JM Lab speakers for the main speakers, and surround. The center speaker goes unused.

I'm vaguely dissatisfied with the sound, but that may because I'm inferring that the Pioneer's speakers are inferior to my JM Lab center speaker.

Should I disconnect them, and reconnect the old one? And then, what about placement? It can't go below the plasma, so it will have to be installed above, which is a big task I'm not ready for.

 

[pink]

Why dont you wall mount your tv, then you can set the center on top of the bureau. As you know you're center is the most important speaker in an HT setup and the speakers you have are very good.

 

[csalcedo]

Hi there, my name is Cedric, long time listener, first time caller. Sorry Pink, I know your inquiry is already a month old but here’s my two cents if your interested. As a professional loudspeaker designer, I’d like to offer a some thoughts regarding center channel loudspeakers. First, your typical MTM (D’Appolito) typology WILL have lobbing effects off (horizontal) axis, due to the difference in distance of the two woofers reproducing identical freq. range to the listener. This is not a secret. The listeners sitting off-axis will notice a considerable deterioration of sound around the cross over frequency. Unfortunately the off-axis listeners are, in my opinion the main reason for existence of the center channel to begin with, and this region is also, being the higher part of the vocal range, is the most crucial part of the center channel reproduction. Similar to this negative interaction between the two woofers of a typical MTM arrangement, two center channels placed vertically on both sides of the display will have the same effect on the horizontal plane, only now a we have the vertical arrangement of the two woofers to contend with. Same can be said when placing the two cabinets above and below the display. Having said that, I agree with Chuckq’s comment, “Blanket statements often miss the mark...if it sounds better to you, though, then I say go for it!” At the end of the day it’s you who forked out the coins for the system and it’s you who would need to enjoy it and be satisfied with it. BTW, though I mentioned some inherent known acoustical challenges for the MTM typology, Dr. D’Appolito is, and will always be a smarter man than I am. All the center channel loudspeakers that I’ve ever designed uses the MTM driver arrangement and with careful driver selection, appropriate x-over design, and yes luck, we lab-rats grapple with the totalitarian rule of physics.