MTM center channel speakers suck!!!! - AVS Forum
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post #1 of 10 Old 12-18-2002, 06:39 PM - Thread Starter
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Why do manufacturers still make them?

If you do not know yet, MTM (midrange - tweeter - midrange) configuration for center channel has the worst vertical dispersion of any speaker design. There are also dips in the crossover region as deep as 15 dB!! No wonder, all of the center channel speakers which uses the MTM design never matches the main left and right speakers.

If you own an MTM center channel speaker and non MTM front left and right speaker, just compare the pink noise of the front speakers. You will see how different the center channel sounds.


Do people notice this or is it just me?

James
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post #2 of 10 Old 12-18-2002, 06:42 PM
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I have read that MTM designs are not the best. Look at the B&W Nautilus line centers - not MTM.

The 15db thing - mine is +-3db and it is MTM. I don't think you can't claim that as a rule across the board.

Kevin
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post #3 of 10 Old 12-18-2002, 06:49 PM - Thread Starter
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Yes, on the specs it does usually say + - 3 dB, but when they are measured, like in Stereophile, you will see that the off axis response, you will see dips as deep as 15 dB in the crossover region. Most of the time, our ears are off axis of the speaker, So this is what we will most likely hear.

James
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post #4 of 10 Old 12-18-2002, 07:29 PM
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I wonder why more manufacturers don't build center speakers like the Canton Ergo CM51, which I have used for 2 years?

At first glance it looks like a typical MTM speaker, except if you look closely there is a 4" midrange and 1" tweeter in a coaxial configuration in the center. The dual 7" woofers are crossed over at a somewhat low 600 Hz (instead of the usual 1800-3000 Hz for dual mid-bass drivers). It could be stated that the CM51 is not an MTM speaker, but a W(T-M)W speaker.

Over the two years I have used a horizontal and a vertical orientation for the speaker. Either way the speaker sounds great. In fact I have heard this speaker in a 5.1 system where all five speakers were CM51s.

Michael
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post #5 of 10 Old 12-18-2002, 09:18 PM
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To get good off-axis response, you would have to have the voice coils time aligned, and 4th order L-R crossover. This ensures when you are not directly centered, the wave reconstruction from the 2 adjacent drivers would sum up uniformly.
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post #6 of 10 Old 12-19-2002, 12:25 PM
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I am listening on B&W LCR6 S2 which is an MTM speaker for L&R, vertical orientation. They sound great to me. Any comments on this particular speaker's crossover arrangement? I auditioned everything I could afford in B&W's line at the time I bought these and they sounded the best to me.

-Mike

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post #7 of 10 Old 12-19-2002, 02:11 PM
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Try standing it up on end so that the tweeter points at the listening position and the two midbass drivers are above or below the tweeter. It doesn't look as pretty, is why the marketing departments always show them on their sides, but they sound a lot better oriented vertically and were designed to be used that way.

You see a lot of full-range (not center channel) speakers that are MTM and sound fine, but they're all in a vertical configuration.

Best of luck,

John
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post #8 of 10 Old 12-19-2002, 03:04 PM
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I just popped into this thread because I was unaware that Mary Tyler Moore was making speakers, and that they suck.:)
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post #9 of 10 Old 12-19-2002, 04:27 PM
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jhnmdahl. The 600 series B&W center is a 2.5 way, not a 2way. So it won't suffer from the off axis lobing your typical horizontal mtm 2way center will.

The coaxial three way is great. So are the many other 3 way centers that keep the tweeter and mid in vertical allignment and then have flanking woofers crossed over much lower than a 2way mtm.

There are some decent 2way mtm centers though. None commercially available I know of though. The GR-Research AV1+ is supposed to work just fine in a horizontal allignment. But it gets the flanking woofs as close together as possible.

Also the response problem on the mtm center is only evident off axis. If you are on axis you won't notice anything wrong.
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post #10 of 10 Old 12-20-2002, 06:44 AM
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ACI has been saying for years that the center should be vertical if possible. Their new centers the Veritas and Essence are perfect examples:

http://www.audioc.com/speakers/Essence/intro.htm

Two-Channel Forever! Anthem Amp 2 and Pre 2, Modulus 3A and Belles 150A Hotrod, SF CD-1, DH Labs Silver Sonic throughout, Tube traps in corners, ACI Jaguars with ACI Titan II subs. Family room: NAD L40 with ACI Emeralds and Force sub.
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