Upscale MTM?

[KEW]

So does this 'offsetting' of the tweeters create a definite left and right and as far as placement?

I noticed that the pictures at Salk had the tweeters on the inside. If my theory above is correct, assuming there is no great toe-in, having them on the inside would allow you to stand with less reduction in dispersion.

 

[zieglj01]

I noticed that the pictures at Salk had the tweeters on the inside. If my theory above is correct, assuming there is no great toe-in, having them on the inside would allow you to stand with less reduction in dispersion.

From my experience with off-set tweeters (now do not tell anybody ) I do
prefer them placed on the inside.

However all in all - a well designed and engineered speaker regardless of
the tweeter off-set or not, will get the job done. It still comes down to
the overall design as a whole.

 

[zieglj01]

I noticed that the pictures at Salk had the tweeters on the inside. If my theory above is correct, assuming there is no great toe-in, having them on the inside would allow you to stand with less reduction in dispersion.

Here is some interesting reading
http://techtalk.parts-express.com/showthread.php?208226-TM-Tweeters-Centered-vs-Offset

 

[Swerd]

So does this 'offsetting' of the tweeters create a definite left and right and as far as placement?

When I first got my speakers, I put them with the tweeters off set towards the center. The speakers are fairly widely spaced, about 10-12' apart, because of other furniture. I've never bothered to switch them to see if it made a difference. Call it laziness, but I doubt if it makes much of a difference.

I noticed that the pictures at Salk had the tweeters on the inside. If my theory above is correct, assuming there is no great toe-in, having them on the inside would allow you to stand with less reduction in dispersion.

It all depends on the off-axis behavior of the mid woofers, the tweeter, the crossover frequency and how steep it's slopes are. Don't forget location of the listener and the speakers. This can vary widely with different speakers and different owners. Of course, all this changes drastically if you bi-wire with teflon coated silver wires .

I really think the main issue is the off axis performance of the mid woofers in the octave below the crossover frequency (roughly 1200 to 2500 Hz in my speakers) where they might begin to beam, and much less what the tweeter does in the 5 to 10 kHz range, where it's beaming might begin to be noticeable.

Here is some interesting reading
http://techtalk.parts-express.com/showthread.php?208226-TM-Tweeters-Centered-vs-Offset

I think that discussion illustrated how widely opinions differ on this subject. Another way of looking at it is that it is really a minor issue, and different approaches, that look like they might be major differences, really aren't.

 

[Dennis Murphy]

Alex got real close.

High frequency sound coming from tweeters will interact with cabinet edges, causing small peaks and valleys in the frequency range of about 4 to 8 kHz. The exact frequencies are determined by the distance from the tweeter to the cabinet edge. This is called diffraction, and in effect, it creates new points of origin for sound in addition to the tweeter.

If the tweeter is centered in a tall narrow cabinet such as in many MTMs, there will be two identical tweeter-to-edge distances, with identical diffraction peaks and valleys that add up. If the tweeter is slightly off center there will be two slightly different tweeter-to-edge distances. They may generate more peaks and valleys than with a centered tweeter, but because they are at differing frequencies and won't add up, they will each be smaller in amplitude.

Dennis Murphy always prefers off-set tweeters in his designs because he can easily see the difference in his measurements. He is not certain that this makes an easily audible difference, but off-set tweeters are easy to make at no extra cost during construction, so why not do it.

The exceptions are speakers like the Philharmonic 3 or the Salk HT1 & HT3 where the tweeters are centered, but the cabinets are not rectangular, and the front baffles don't have parallel edges.

So, off set tweeters can make a measurable difference in a single speaker in mono. What happens in stereo? Are off-set tweeters better toward the outside or the inside? People wonder and argue which is better. I doubt if it makes any difference. Take your pick.

Edit: This explanation is, of course, an oversimplification. A longer discussion of cabinet edge diffraction can be read here http://www.salksound.com/wp/?p=160#more-160.

That's pretty much it. With one wrinkle. All of this relates to the response directly on axis. Unless you toe your speakers in so that the tweeter is firing directly at you, the fist arrival you will hear will be off axis, and many of the diffraction dips and peaks you see from a centered tweeter are greatly reduced even a little off axis. So I don't think the tweeter location is a big deal. Also, I got some push back when I sent out pics of a new monitor I'm introducing that had the tweeter and midrange offset. People really didn't like the look, and the latest version I'm building now has everything centered. I'll have to see whether there's any real sonic cost to that. I doubt it.

 

[Swerd]

That's pretty much it. With one wrinkle. All of this relates to the response directly on axis. Unless you toe your speakers in so that the tweeter is firing directly at you, the fist arrival you will hear will be off axis, and many of the diffraction dips and peaks you see from a centered tweeter are greatly reduced even a little off axis. So I don't think the tweeter location is a big deal.

It's a fine point, of minor importance compared to getting the crossover right for the drivers.

Also, I got some push back when I sent out pics of a new monitor I'm introducing that had the tweeter and midrange offset. People really didn't like the look, and the latest version I'm building now has everything centered. I'll have to see whether there's any real sonic cost to that. I doubt it.

It's always interesting how people seem to dislike things that look asymmetrical to them.

Tell these people they must use the grills, and that the fabric is made from special acoustic grade teflon-coated polyester that was made available only because a top secret Navy project was canceled.

 

[zieglj01]

I think that discussion illustrated how widely opinions differ on this subject. Another way of looking at it is that it is really a minor issue, and different approaches, that look like they might be major differences, really aren't.

I eat the fish and spit out the bones - all I care about is
that the speakers sound good.

A lot of times the eye and brain can hinder a good sound
experience - such is human nature.

 

[KEW]

Also, Parts Express has one
https://www.parts-express.com/dayton-audio-rs722cml-speaker-curved-maple-left--301-977l

https://www.parts-express.com/dayton-audio-rs722cmr-speaker-curved-maple-right--301-977r

There doesn't really seem to be a convention. The above products are designated left and right and have the tweeters offset towards the outside edge.

 

[zieglj01]

There doesn't really seem to be a convention. The above products are designated left and right and have the tweeters offset towards the outside edge.

You still have an option if you desire - switch the left to the right,
and the right to the left, and the tweeters will be inside. For some
if the speakers are near the side walls, they can still mount them
with the tweeters inside, if they feel reflections will be a problem.

Since they are sold each - it can help to keep you from buying 2
rights or 2 left speakers by mistake.

 

[psbfan9]

Did you test different placements with your Definitive Studio Monitor speakers?
They do have off-setting tweeters.

No experimenting. At least for the purposes of this conversation.
I had the tweeters to the outside, because when I toed them in it seemed to my acorn sized brain the tweeters to the inside would have created too narrow of a wave to the listening position.
I don't think I explained that very well.

 

[3db]

PSB has a sudo MTM design in their new Imagine series center channel; C3

 

[Alex2507]

I can't remember which way I oriented my tweeters but it's right whatever it is by virtue of the fact I ain't movin' it period. Those days are over.

 

[Rickster71]

Do you know why it works better?
I was thinking horizontal dispersion might be slightly improved since it is not quite as "trapped" between the mid-woofers.

This is a good article that may help a bit:
http://forum.blu-ray.com/showthread.php?t=89614

 

[darien87]

The Bamberg 6 is a gorgeous speaker.

Bamberg 6

I guess we have different definitions of "gorgeous". That thing is fugly to me.

 

[Cos]

GE Speakers are MTM

 

[Seize]

I've heard good things about the Clearwave Aperture S52's. They utilize Scan-Speak and SB Acoustics drivers in their MTM design. Would definitely like to audition a pair.

http://www.clearwavespeakers.com/webapps/p/98515/300200/1211493

 

[monkish54]

That's pretty much it. With one wrinkle. All of this relates to the response directly on axis. Unless you toe your speakers in so that the tweeter is firing directly at you, the fist arrival you will hear will be off axis, and many of the diffraction dips and peaks you see from a centered tweeter are greatly reduced even a little off axis. So I don't think the tweeter location is a big deal. Also, I got some push back when I sent out pics of a new monitor I'm introducing that had the tweeter and midrange offset. People really didn't like the look, and the latest version I'm building now has everything centered. I'll have to see whether there's any real sonic cost to that. I doubt it.

I have always hated the way offset tweeters look. Sometimes they are needed, but for the most part, I'd rather deal with diffraction in nearly any other way than offset tweeters. Even felt can look better and/or be hidden, and it works better for diffraction control than anything I have seen...

 

[GIEGAR]

The Appolito (sp) mtm design is supposed to offer significant benefits.
Certainly the most familiar example around here is the Ascend 340.
However I can not think of other (bookshelf speakers) examples among more upscale offerings. Ascend abandons mtm for all of it's Sierra line.
Is the "too tall" aesthetic of the mtm design to blame?

Hi Kurt, I must have missed your thread previously.

JTR Speaker's current lineup is dominated by W(T/M)W designs that could be described as "upscale".

Here's a selection: http://jtrspeakers.websitetoolbox.com/post/2015-is-a-year-of-big-changes-7176801.

 

[padgman1]

What about the XTZ Divine 100.33 speakers ? This speaker has been reviewed on this site and others, most recently on Home Theater Shack.....

 

[fuzz092888]

I just bought the Testarossa kit which uses dual Satori woofers with the RAAL 70-20 tweeter in a TMM configuration. However, there is also a version of this speaker that is MTM. With those drivers, I would call that a pretty upscale MTM.