center channel DIY?

[markw]

One good turn deserves another.

My mains are MTMs and they perform very well off axis. With three speakers up front, properly positioned, off axis is really not much of an issue unless you have weird seating.

Now it's my turn to warn you about with whom you're arguing.

 

[fuzz092888]

That is a very false statement. We are talking about center channels here, not the front speakers in general. Of course MTMs as the front left and right sound good and measure good off-axis. That's because they are positioned vertically. An MTM center speaker, which is positioned horizontally is where the problems start. Of course it will sound good if you're sitting in the center, but that shouldn't be an excuse for a poorly designed center channel.

There you go again, grossly overstating the problem. Yes the off axis response of horizontal MTM's aren't as good as a vertically aligned speaker, but for most "normal" seating arrangments it's not a big deal. I doubt you'll find a well designed MTM that can't perform at minimum 15 degrees off axis and probably still be pretty good up to 30 degrees off axis. At a pretty typical listening distance of 9 feet, that yields almost 5 feet of coverage for 15 degrees a little over 10 feet for 30 degrees. That's a pretty wide seating area.

For a typical living room that should be more than enough coverage, and many well designed MTM's will go even wider than that. As I type this I'm sitting probably somewhere between 50-60 degrees off axis. I'm not critically listening to music, but I watch TV and an occasional movie from way over here occasionally and I don't feel as though I lose as much as you would claim I do from being directly on axis. I definitely notice a bit of a difference, but nothing anywhere near as dramatic as you would have everyone believe.

 

[j_garcia]

There you go again, grossly overstating the problem. Yes the off axis response of horizontal MTM's aren't as good as a vertically aligned speaker, but for most "normal" seating arrangments it's not a big deal. I doubt you'll find a well designed MTM that can't perform at minimum 15 degrees off axis and probably still be pretty good up to 30 degrees off axis. At a pretty typical listening distance of 9 feet, that yields almost 5 feet of coverage for 15 degrees a little over 10 feet for 30 degrees. That's a pretty wide seating area.

For a typical living room that should be more than enough coverage, and many well designed MTM's will go even wider than that. As I type this I'm sitting probably somewhere between 50-60 degrees off axis. I'm not critically listening to music, but I watch TV and an occasional movie from way over here occasionally and I don't feel as though I lose as much as you would claim I do from being directly on axis. I definitely notice a bit of a difference, but nothing anywhere near as dramatic as you would have everyone believe.

Beat me to it. YES, combing can be an issue for an MTM, however with a properly designed speaker, you can get pretty far off axis before it actually becomes an issue. A speaker doesn't just radiate in ONE direction, the dispersion spherical, not just one or two axes. Laying an MTM on its side doesn't mean it radiates in one flat pattern and that automatically applies to every speaker ever built. GR actually provides response curves for my speakers at 30 degrees off axis for both horizontal and vertical and the performance is still quite good.

It isn't that it is a gross overstatement, it is a lack of understanding.

 

[lsiberian]

That is a very false statement. We are talking about center channels here, not the front speakers in general. Of course MTMs as the front left and right sound good and measure good off-axis. That's because they are positioned vertically. An MTM center speaker, which is positioned horizontally is where the problems start. Of course it will sound good if you're sitting in the center, but that shouldn't be an excuse for a poorly designed center channel.

Horizontally oriented MTMs are not a problem when the first order refection angle is below 30 degrees with the wall. If you get above that you will probably have issues, but most speakers have issues above that. If they were such a poor design experts wouldn't use them. The MTM does fit around a TV, allow for larger enclosures, and look aesthetically pleasing. For example the Primus 350 center channel is not a poorly designed center channel and it uses an MTM like arrangement.

 

[ridikas]

Horizontally oriented MTMs are not a problem when the first order refection angle is below 30 degrees with the wall. If you get above that you will probably have issues, but most speakers have issues above that. If they were such a poor design experts wouldn't use them. The MTM does fit around a TV, allow for larger enclosures, and look aesthetically pleasing. For example the Primus 350 center channel is not a poorly designed center channel and it uses an MTM like arrangement.

An MTM "like" is not an MTM. The Primus 350 is not an MTM center channel.

 

[ridikas]

There you go again, grossly overstating the problem. Yes the off axis response of horizontal MTM's aren't as good as a vertically aligned speaker, but for most "normal" seating arrangments it's not a big deal. I doubt you'll find a well designed MTM that can't perform at minimum 15 degrees off axis and probably still be pretty good up to 30 degrees off axis. At a pretty typical listening distance of 9 feet, that yields almost 5 feet of coverage for 15 degrees a little over 10 feet for 30 degrees. That's a pretty wide seating area.

For a typical living room that should be more than enough coverage, and many well designed MTM's will go even wider than that. As I type this I'm sitting probably somewhere between 50-60 degrees off axis. I'm not critically listening to music, but I watch TV and an occasional movie from way over here occasionally and I don't feel as though I lose as much as you would claim I do from being directly on axis. I definitely notice a bit of a difference, but nothing anywhere near as dramatic as you would have everyone believe.

Well, you are correct in what you state... But good enough does not make it for a well engineered speaker. Sure, at 15 degrees off horizontal axis it might still sound and measure good. But aren't most of us at Audioholics want the ultimate in performance? An MTM center channel is far from that goal.

 

[fuzz092888]

Well, you are correct in what you state... But good enough does not make it for a well engineered speaker. Sure, at 15 degrees off horizontal axis it might still sound and measure good. But aren't most of us at Audioholics want the ultimate in performance within out respective budgets, that meet our respective aesthetic needs, and/or that timbre match the rest of our system/front L/R? An MTM center channel could perfectly satisfy those conditions

If an MTM center channel measures +-1db on axis and +- 3db off axis up to 30 degrees then I would say that it is a well designed speaker/crossover.

No speaker is perfect, no setup is perfect, and people need to get the best that they can within their respective budgets and setups. MTM's are a perfectly viable way of creating a truly excellent center channel. Are there better ways? Yes, both horizontally and vertically, there are better ways. Can an MTM fulfill the criteria that I added to your post? Most definitely.

If an MTM can measure +- 1/2 db on axis and +- 3db up to 30-45 degrees off axis and that covers your entire seating area, then with RC further improving performance, why would you need anything more than that? Why pay hundreds or thousands more, adjust your entire setup for something you don't need or that would get you improvements that may or may not be audible?

Also, you admit that an MTM can sound and measure well off axis. So it sounds to me you're arguing about the the design, and your distaste for it, rather than what it can actually do.

 

[ridikas]

If an MTM center channel measures +-1db on axis and +- 3db off axis up to 30 degrees then I would say that it is a well designed speaker/crossover.

No speaker is perfect, no setup is perfect, and people need to get the best that they can within their respective budgets and setups. MTM's are a perfectly viable way of creating a truly excellent center channel. Are there better ways? Yes, both horizontally and vertically, there are better ways. Can an MTM fulfill the criteria that I added to your post? Most definitely.

If an MTM can measure +- 1/2 db on axis and +- 3db up to 30-45 degrees off axis and that covers your entire seating area, then with RC further improving performance, why would you need anything more than that? Why pay hundreds or thousands more, adjust your entire setup for something you don't need or that would get you improvements that may or may not be audible?

Also, you admit that an MTM can sound and measure well off axis. So it sounds to me you're arguing about the the design, and your distaste for it, rather than what it can actually do.

Problem is, there are no MTM center channels that can do +/-3dB at 30 degrees horizontal off-axis.

 

[fuzz092888]

Problem is, there are no MTM center channels that can do +/-3dB at 30 degrees horizontal off-axis.

Says the guy who's obviously tested every MTM that exists

 

[ridikas]

Says the guy who's obviously tested every MTM that exists

Typical...

 

[Send Margaritas]

Typical...

Well, it's your opinion vs Dr. Joseph D'Appolito, and you've stated some strong, controversial, opinions, several times before. Surprised?

 

[jostenmeat]

If an MTM center channel measures +-1db on axis and +- 3db off axis up to 30 degrees then I would say that it is a well designed speaker/crossover.

No speaker is perfect, no setup is perfect, and people need to get the best that they can within their respective budgets and setups. MTM's are a perfectly viable way of creating a truly excellent center channel. Are there better ways? Yes, both horizontally and vertically, there are better ways. Can an MTM fulfill the criteria that I added to your post? Most definitely.

If an MTM can measure +- 1/2 db on axis and +- 3db up to 30-45 degrees off axis and that covers your entire seating area, then with RC further improving performance, why would you need anything more than that? Why pay hundreds or thousands more, adjust your entire setup for something you don't need or that would get you improvements that may or may not be audible?

Also, you admit that an MTM can sound and measure well off axis. So it sounds to me you're arguing about the the design, and your distaste for it, rather than what it can actually do.

I have to admit that excellent off axis response up to 30 degrees is a higher number than I have ever come into. If you meant 15 degrees each way, for a total of 30 in that sense, okay then. I'm not saying you aren't correct! It's just higher than I've yet read about. I usually see something on the order of trying to remain under 20 degrees. When last using a horiz MTM, I was told by someone when considering its xover point and driver spacing, that the mids were 180 out of phase at about 20 degrees.

That said, I think 20 degrees really is quite a bit more than people might expect it to be; I think a great majority of setups have viewers within 20 degrees, or at the very least, definitely for at least the first few or several viewers (before you start bringing in seats from other rooms or something).

As I understand it, a better off axis performing one would have a lower xover point, with closer spaced mids. I suppose as the drivers got closer and closer, the tweeter would be forced to be nestled in the little space above, but then the problem becomes a taller speaker, which undoubtedly would make it either a tight or impossible fit for many cases, which would kill sales.

I would love to see some of the resident speaker experts try to create the "awesomest horiz MTM" (even if one or two of them would have an issue with the word awesome combined with horiz MTM) with two limits: certain budget, and certain height. We'll just give them great liberty for depth and width (even though that could pose an issue for a fewer amount of people).

Hm, did the OP mention a budget limit, or height limit?

Well, it's your opinion vs Dr. Joseph D'Appolito, and you've stated some strong, controversial, opinions, several times before. Surprised?

Hm, but wasn't the intention of the design to be specifically vertical in this case? Besides horiz dispersion goals, having them vertically oriented reduces floor/ceiling bounce. However good they are at eliminating bounce, well I imagine that must also mean how bad they are at horiz dispersion when oriented horizontally? Just a dumb guess though.

Joseph D'Appolito - Wikipedia, the free encyclopedia

 

[ridikas]

Well, it's your opinion vs Dr. Joseph D'Appolito, and you've stated some strong, controversial, opinions, several times before. Surprised?

It has nothing to do with D'Appolito. His MTM designs were meant to be listened to vertically, not horizontally.

 

[fuzz092888]

Typical...

Many say the same thing about you

Funny how easy it is to call out everyone else as being typical. Glass house and all, but then I guess it isn't really glass when the person living in it doesn't really care.

If nothing else you sure do make me laugh

 

[Send Margaritas]

...Hm, but wasn't the intention of the design to be specifically vertical in this case? Besides horiz dispersion goals, having them vertically oriented reduces floor/ceiling bounce. However good they are at eliminating bounce, well I imagine that must also mean how bad they are at horiz dispersion when oriented horizontally? Just a dumb guess though.

Joseph D'Appolito - Wikipedia, the free encyclopedia

Valid point, my bad.