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Does using a point source driver in a horizontal center speaker resolve the MTM issues of other speakers?
 

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I'm embarrassed to say that after a half century in audio I don't know what point source driver is and I'm not familiar with issues relating to an MTM configuration. Perhaps if you told us a little about what you want to accomplish, we might be of help.
 

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Quote:
Originally Posted by tongr  /t/1524695/point-source-driver-in-center-channel#post_24540962


Does using a point source driver in a horizontal center speaker resolve the MTM issues of other speakers?
Yes, but they're rare, and the better ones are expensive.
 
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There are some KEF bookshelf models with a single concentric driver (tweeter/mid) that make good LCR speaker sets - Q100, Q300, R100, LS-50. (Because of the single Uni-Q, unlike most speakers, they can be laid on their side as a center without affecting the sound.)


After struggling with several LCR sets with horizontal center speakers (we have a wide seating area, and I'm sensitive to lobbing) I tried three KEF Q100's LCR and it solved the problem immediately. No more lobbing, clear dialog, very even/seamless front sound stage, etc.


Three identical speakers LCR across the front will typically sound better than any "horizontal" center speaker.
 

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I use a Kef Reference center. Although it's not a single driver ie Kef Q95c, it has two bass drivers on either side.


Brilliant center.
Quote:
Three identical speakers LCR across the front will typically sound better than any "horizontal" center speaker.

That would be interesting...blocking the TV LOL
 

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Discussion Starter · #6 ·
KEF, Tannoy, Thiel and Vandersteen are the only point source speaker manufacturers I know of and of those KEF is the only one that uses a point source driver in a horizontal arrangement with other bass drivers on either side. Are the above mentioned manufacturers what you were referring to as "better"? I do respect your opinion and was hoping you would see this question and respond. Thanks
Quote:
Originally Posted by Bill Fitzmaurice  /t/1524695/point-source-driver-in-center-channel#post_24541839


Yes, but they're rare, and the better ones are expensive.
 

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Quote:
Originally Posted by fatbottom  /t/1524695/point-source-driver-in-center-channel#post_24544856


I use a Kef Reference center. Although it's not a single driver ie Kef Q95c, it has two bass drivers on either side.


Brilliant center.

That would be interesting...blocking the TV LOL

Not so fast
In my post I listed four KEF bookshelf speakers with a single Uni-Q driver that can be laid on their side for use as a center (if space is an issue). The KEF Q100 on it's side is the exact same height as the KEF Q200c horizontal center, the Q300 on it's side the same height as the Q600c center, and the R100 on it's side the same height as the R200c. The LS-50 on it's side is the same height as either the Q600c or R600c center speakers.
 

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Some of the JTR speakers are point source also.


Per Bill F's comment ... the JTR's along with the Vandersteen's, Thiel's and Tannoy's are on the pricey side. KEF seems like the most reasonably priced point-source speakers (that are easily available here in the US).
 

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Quote:
Originally Posted by sdg4vfx  /t/1524695/point-source-driver-in-center-channel#post_24546939


Not so fast
In my post I listed four KEF bookshelf speakers with a single Uni-Q driver that can be laid on their side for use as a center (if space is an issue). The KEF Q100 on it's side is the exact same height as the KEF Q200c horizontal center, the Q300 on it's side the same height as the Q600c center, and the :mad:R100 on it's side the same height as the R200c. The LS-50 on it's side is the same height as either the Q600c or R600c center speakers.

My main speakers aren't standmounts.


Kef have a large center speaker, matched to the Reference mains

http://www.hifix.co.uk/graphics/pics/large/108172.jpg
 

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The danley soundlabs synergy horns basically function as a point source, correct?

The SM96 seems like a reasonable choice.

The issue that I am concerned about: would this thing have a problem if it were placed on the floor and angled up around 15 degrees? It is the only option I have for speaker location, so raising it up off the floor or behind the screen are not options. Mainly just wondering if this speaker design would be particularly bad as a center channel speaker on the floor.
 

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The danley soundlabs synergy horns basically function as a point source, correct?

The SM96 seems like a reasonable choice.

The issue that I am concerned about: would this thing have a problem if it were placed on the floor and angled up around 15 degrees? It is the only option I have for speaker location, so raising it up off the floor or behind the screen are not options. Mainly just wondering if this speaker design would be particularly bad as a center channel speaker on the floor.
It's the best possible choice of any speaker design out there for that particular situation, at least regarding the primary concern of floor bounce. You can essentially lay that speaker on the floor and have very little concern about floor reflections. Tilt it up a little and those concerns are non-existent.

The Danley design has the best pattern control I have ever personally experienced and likely the the best pattern control available in the industry - residential or commercial.
 

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It's the best possible choice of any speaker design out there for that particular situation, at least regarding the primary concern of floor bounce. You can essentially lay that speaker on the floor and have very little concern about floor reflections. Tilt it up a little and those concerns are non-existent.

The Danley design has the best pattern control I have ever personally experienced and likely the the best pattern control available in the industry - residential or commercial.
ok great, I think I will put an order in for one of these soon!
 

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Unless I'm mistaken, the problem with Horizontal MTM occurs at a frequency associated with the distance between the bass drivers. For example, if the distance between the two bass drivers is 18" (1.5ft), then the associated frequency is 750hz.

If the bass drivers crossover at 1000hz, then this becomes a problem with lobing and comb filtering. If the bass drivers crossover at 500hz, then it is not a problem because those driver are not reproducing 750hz.

Note this also occurs in vertical MTM, but the lobs are near the ceiling and the floor, and it doesn't matter that much.

You can solve the problem in a number of ways.

Make the Center a 3-way or perhaps a 2.5-way. So both bass drivers are not playing at the critical frequency.

Simple cross the bass drivers below the frequency associated with the distance between the drivers.

Make the speaker an MMT, instead of an MTM. In a horizontal Center, MTM, in my opinion, is simply for visual summitry, it has nothing to do with the sound, it just look cool.

Just a few thoughts.

Steve/bluewizard
 

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Well, there are multiple issues that have been discussed.
1) Lobing, due to a horizontal array. Not a problem with a vertical array, coax, or Danley point source. As you said, lower crossovers can reduce this for horizontal arrays.
2) Floor bounce, due to being close to the ground. Not a problem with a big horn.
3) Timbre and phase matching. Not a problem if the LCRs have the same drivers and crossovers.
 

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Bose Jewel too. Better, cos they're smaller. And they're BOSE!:D Never heard of Reaction Audio.
They're a newer ID company, really nice speakers using very high quality Radian coax drivers. Definitely worth checking out, they were actually at a very recent east cost GTG this past weekend and did very going up against some nice JTR speakers and JBL M2's. I don't think anyone thought they were outright better but definitely held their own and at less then half the cost.
 

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I think for a true single point source speaker, the necessary size of the driver is too big for most Center Applications. Generally 6.5" is about as big as you can go on a Center in a typical room.

Though you really don't need that much bass for a Center speakers, especially if you want clear sound in the vocal range.

If we look at this example of a KEF Q200C Center, best guess on the problem frequency would be about 765hz. The speakers crossover Bass-to-concentric Mid-Bass/Tweeter at 500hz, well below the problem frequency.

http://kef.com/html/us/showroom/hi-...ets/Centre_Dipole_Subwoofers/Q600c/index.html

Dayton Audio does have a new series of Point-Source full range (more or less) drivers for those interested in building their own speakers.

http://www.parts-express.com/Search.aspx?keyword=Dayton%20Audio%20PS&sitesearch=true

The Dayton Audio PS 6.5" driver at about $100 each, has a rated frequency response of 48hz to 25khz with a Vas of 1.43 cubic feet. By today's standards, 1.43ft³ is a pretty big speaker.

http://www.parts-express.com/dayton-audio-ps180-8-6-1-2-point-source-full-range-neo-driver--295-344

Here is a spec sheet on that driver. Notice the Treble is not all that well behaved, and some action would have to be taken to soften the output above 3khz.

http://www.parts-express.com/pedocs/specs/295-344-dayton-audio-ps180-8-specifications.pdf

As others have pointed out, we would need a lot more information about your setup and how the speakers are placed to make a more precise comment. But the fact remains that for average users, Point Source are very rare.

Far better to get a 2.5-way or 3-way Center speaker that will overcome any inherent problem with the MTM Horizontal Center Design.

Or, if your circumstance are workable, get a vertical center speaker of some type.

I think the Reaction Audio speakers are about 40" high, that clearly works for FatBottom, but that's definitely not going to work for everyone.

Again, to make precise recommendations we simply do not have sufficient information about your room, your circumstances, and your needs to make more productive comments.

Steve/bluewizard
 
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