Best Center...

[Hi Ho]

I am planning on building a set of Ascendant Audio Arbiter TM speakers. They also have an MTM set. I have heard conflicting information about which is the best format for a center speaker.

Some say the MTM arangement of center speakers gives better dispersion while others say that five absolutely identical speakers is the best configuration.

Should I build five identical Arbiter TM speakers or make one MTM for the center?

 

[j_garcia]

Me personally, I'd build 3 MTMs for the front and smaller ones for surrounds I can't say that it is 100%, without question, necessary to have the front three identical. It IS important to have a good timbre match if you are after a seamless front stage, and the best way to do that is obviously to go with identical speakers. It sort of depends on what you are after and how picky you are...(and how much you want to spend).

 

[Josuah]

Identical speakers is the best arrangement, but it's often hard to stick a speaker in front of your TV or screen at the same height as the left and right speakers (so the tweeter is at ear level).

MTM is common for centers, I think, because it provides good horizontal dispersion when laid horizontally. Basically, for the people who aren't sitting in the middle where you are. A better arrangement, according to some people's design opinion, is to have an B(T/M)B which is two bass drivers with a tweeter above a mid-bass driver in the middle.

 

[Leprkon]

A better arrangement, according to some people's design opinion, is to have an B(T/M)B which is two bass drivers with a tweeter above a mid-bass driver in the middle.

I have also seen a number of articles and posts that claim the tweeter should be off the main axis. no clue as to the validity, but that is what is claimed.

 

[j_garcia]

I heard this when Paradigm did this with their CC370. I wasn't impressed with the v2 version, but the v3 had the tweeter offset from the axis of the midbasses - this made a noticable improvement in this speaker over the previous version. This changes the way the speaker images, though I can't exactly tell you why, I thought the result was definitely beneficial.

The Onyx Rocket center ("bigfoot") uses the config mentioned by Josuah and it is an excellent speaker. The downside is, it is a very large speaker.

 

[Hi Ho]

The design of the Arbiters calls for offset tweeters. I guess there is good reason for this?

I don't have the cash for three MTM's but I could do one for the center if it would be better than an MT sitting upright or on it's side.

 

[JennAir]

Off set tweeters help lessen the effect of diffraction at the baffle edges. In some cases it allows the woofers to be placed closer together which can help avoid comb filtering. Another potential benefit is you can place the tweeter on the top or bottom for your center and inside or outside for the mains.
This guy did it right.
http://www.us.alegriaaudio.com/RosaLCR.htm

 

[Buckeyefan 1]

Off set tweeters help lessen the effect of diffraction at the baffle edges. In some cases it allows the woofers to be placed closer together which can help avoid comb filtering. Another potential benefit is you can place the tweeter on the top or bottom for your center and inside or outside for the mains.
This guy did it right.
http://www.us.alegriaaudio.com/RosaLCR.htm

Swan does something similar with it's center channels:

http://www.swanspeaker.com/product/htm/view.asp?id=196
http://www.swanspeaker.com/product/htm/view.asp?id=158

B&W really goes out of their way here:
http://www.bwspeakers.com/index.cfm/fuseaction/products.models/Label/Model HTM1D

 

[tomd51]

Another vote for B(T/M)B...

One of Boston Acoustics most heralded center channel speakers, the VR12, is similar to the configuration Josuah noted. After having a couple solid centers (Infinity IL36, Boston Acoustics VR920), I have to admit this thing is killer. Great separation, strong midrange, midbass, precise highs and solid lows, this center has it all. Actually, I think the IL36C also has this config, too. I've also found the deeper the center cabinet, the better the FR seems to be, which I suppose makes sense.

I'd have to say the B(T/M)B center configuration just might be one of the best I've heard... -TD

 

[JennAir]

I could do one for the center if it would be better than an MT sitting upright or on it's side.

The only reason center channel speakers are configured with a shorter height than length is aethetics. Very few center channel speakers would be sold if they had the same vertical configuration as standard speakers. This is why the typical CC is WTW or MTM. The horizontal dispersion gets all screwed up when you lay a standard speaker on it's side. The extra mid or woof helps restore that.

 

[Timn8ter]

W/TM/W Center Channel

Designers are faced with particular challenges with center channels. The typical customer doesn't want to put a standard vertical speaker on top of their rectangular television. If we take a pair of woofers and put a tweeter in the middle and lay it on it's side it looks better. This is fine as long as you can cross the tweeter over low enough to keep the two woofers from cancelling each other out at frequencies above 1/4 wavelength of the distance between the two woofers. If you raise the tweeter up to get the woofers closer together you've made the box taller. One choice would be to sacrifice bass response by using smaller mid/woofs that can play higher without distorting and drop a standard tweeter right in the middle. Or, truncate the frames so you can get all three drivers close together, or, go with a 3-way design allowing you to spread the woofers apart and stack the tweeter and mid on top of each other. Trouble there is the cost goes up significantly, the cabinet is large(r), and you have to design a 3-way crossover.

 

[Hi Ho]

So what is the general concensus here?

I would like to spend as little as possible. Obviously, that would be the MT arangement. I have no problem setting the speaker upright above the TV. If I went with an MT arrangement, should I still offset the tweeter or should it be in the center?

The MTM design already incorporates an offset tweeter and Ascendant says it is voice matched with all of the other designs they offer.

Thank you for all the responses. I think I will give Ascendant a call as well and see what they say.