Does this Mcintosh speaker have a flat, convex or concave front baffle?

Must be an older model?  Their current lineup only shows just one bookshelf speaker (XR50) with one tweeter and two tiny midranges in a vertical array (TMT).

Their larger home theater speakers have multiple tweeters.

The XRT2K 110 driver floor standing speakers has 40 tweeters flanked by 64 midranges (32 on each side) in a vertical line array with 6 - 12"woofers directly behind the midrange/tweeter array and looks like it has a flat baffle. (7 ft. tall, 450 lb. monster in sealed aluminum cabinet)

The XCS2K 55 driver center channel speaker has 20 tweeters flanked by 32 midranges (16 top, 16 bottom) in a horizontal array with 3 - 12" woofers directly behind the midrange/tweeter array and this one has a curved convex baffle (McIntosh's "exclusive" Arc Array).

Steve

 

Destroy your hearing?

I think a great question is, what does the crossover look like? Perhaps they do a lot of fill in a more narrow band?

Danny talked about tweeters on opposite sides of a speaker, and the problems with that. But what happens when there's no gap?

Well, I'm curious now as well. Is it a compromise?

On the cover of Stereophle....
8+ years ago was a well reviewed Speaker
((Weeg?)) which had 5 tweeters in a semi-circular arc with Midranges contained
within this arc of tweeters. 
If I recall the reviewer & JA both found them to sound good & measure well.

Of Course M&K have had two or Three vertical tweeters for years.

Hmmmm. Were those things designed by Dalek? 

"Exterminated!"

(Your bank account, that is: $100K for the mains, $35K for the center)

Steve

For decades McIntosh speakers have had multiple tweeters/midranges/woofers, why?  Can't they get loud enough with one of each (like most manufacturers)?  I know distortion goes down and power output goes up with more drivers, and I'm not smart enough to quite understand how a Bessel array works, but as Carl quoted the phasing issues must be an absolute mess.  Frankly I've never been able to hear coherent imaging from an array (except a curved array, but then only from far field).

Not surprisingly even as a former McIntosh owner I've never been impressed with the sound of their speakers (or the sound of their big blue meters). 

The only time I've heard Mcintosh speakers sounding good is in very large rooms (25' x 40' +) where I'm well back from them. If I'm at a show with my wife and their speakers are in a small room, she won't even go in the room.  All I can get from her is that she doesn't like them and they sound "wrong".

Danny,
 Hey young man , Mcintosh has a stand mount speaker with 5 tweeters running horizontal. What does that do? Does it give a larger sweetspot? Please explain this.

 I could ask Mcintosh but I'd rather have it come from you.
Thanks you

Let me explain how this whole multiple tweeter deal works. And this isn't just what Danny thinks, or the opinion of one guy. This IS what happens.

Anytime you have multiple drivers or output from multiple sources you will get some coupling and cancellation effects. In low ranges the wavelengths are long and couple easily. In the upper frequency range where wavelengths are short then they cancel each other out easily.

Anytime one driver is delayed in time by half of a wavelength then it is out of phase from the other. The effect is cancellation. Check this wavelength chart to get an idea on the distances: http://www.soundoctor.com/freq.htm

With planar magnetic drivers the whole driver is the voice coil. So it is a little different animal, but with standard drivers we can take the center of the driver as the acoustic center. Center to center spacing on standard tweeters need to be within a wavelength of the upper range they cover to avoid driver to driver cancellation patterns. So a dome tweeter needs to be within an inch or so of one another center to center to avoid cancellation up to 20kHz.

And anytime ANY driver plays a frequency range where the wavelength is shorter than the diameter of the diaphragm then it is in what we call its beaming range. In other words its off axis response falls off dramatically. The same holes true for multiple drivers. If you create a line of small woofers 4 feet long then what you really have is a driver that is as wide as the width of one woofer by as long as the length of the line. So it's off axis response will be very limited vertically if it is a vertical line. The same is true for a tweeter line. In a line source like the LS-6 or LS-9 the high frequency output changes before you even reach the end of the line. And outside the length of the line the highs fall off so fast they are practically gone. You have to stay within the length of the line.

So if you make a small line of tweeters the off axis effect is the same as a single tweeter that is the length and height of the group, and that is if there are no driver to driver cancellation patterns from over spacing.  So a 6" ribbon or a 6" line of 1/2" dome tweeters will have the same off axis response as a 6" woofer. The highs will fall off quickly outside the width of the driver.

So speaker like this will have a very limited horizontal coverage in the upper ranges.



Just move off axis and the highs will be gone.

The theory I hold to is that arrays cannot image in the direction they're oriented in.  So vertical arrays cannot image vertically (and unless they extend very nearly floor to ceiling will not load the room in a cylindrical versus spherical pattern for improved efficiency).

Waiting now for the flames...

You are close. Just replace the word image with off axis response.

Imaging refers more to layering and separating the sound stage. Line sources can do that quite well.

But the have no real off axis response in the direction they are oriented. That is why line sources need to be near ceiling to floor to cover the whole room well.

Hi Danny,

Very interesting information you have provided.  I was not really aware of what was happening when designers used multiple tweeters but your comments helped me understand.  What about designs like the one on the link below.  It uses two tweeters placed side by side.  Is this done to limit dispersion? 

http://www.daedalusaudio.com/Argos.html

Thanks again.  You are a real asset to AC and I hope you continue in some form if your company is purchased.  This is not as good a place without you.

Jack

Those will have considerable cancellation in the vertical off axis and leave holes in the response down to about 2kHz. This will also show up in the room response with a very uneven reflection pattern in the room.

If you want to see a little meat on the whole coupling and cancellation effects that is easy to understand then here it is.

I took these measurements several years ago when some guys were asking about stacking speakers on top of each other.

So I took a pair of A/V-1's and stacked them on top of one other tweeter to tweeter. The acoustic centers of the tweeters were 6.5" away from each other.

A/V-1:

I then put the microphone 1 meter away and just off of dead center between the two boxes. So almost inline with the top of the box. I'd say it was about 1" off dead center.

I then measured one speaker only and saved it in red. Then I measured both speakers playing together and saved it in purple.

Next I moved the mic up 2". Yes just 2" up vertically at 1 meter.

I played the single speaker only and saved it in orange. I then measured them both playing together and saved it in blue.

Then I moved the mic up two more inches and measured again. With the single speaker playing I saved it in yellow and with both speakers playing I saved it in green.

One last time up another 2". I measured the single speaker and saved it in grey and the two playing together and saved it in light blue.

Here are the measurements of the signal speaker moving up 2" per measurement:



Here are the measurements of them both playing together with the mic in the same places moving up 2" per measurement.



As you can see it doesn't take much vertical movement to put the tweeters out of phase. And the further off axis you go the longer the time delay gets and the effect reaches lower as the wavelengths get longer.

Here is an overlay of all of the curves so you can see where they couple (more output) and where they cancel (less output than a single driver).



Pretty clear huh.