Speaker designers, what would you do?

[Klipschguy]

I am currently building a pair of speakers that will use a dual tweeter design. The tweeters will be wired in parallel. Two of the vintage tweeters I have measure 13 ohms. The other two measure 16 ohms.

Question: Would you put the matching 13 ohm tweeters in one cabinet and the matching pair of 16 ohm in the other, or would you parallel one 13 ohm tweeter with a 16 ohm tweeter in each of the cabinets? In other words, should I keep matching tweeters together or split 'em up? Why?

Thanks guys,

Andy

[Islander]

I'm no speaker designer, but doesn't it make sense when building a pair of speakers that they should be identical twins? That means a 13 and a 16 in each, otherwise you'd have to design a different crossover for each speaker to try to make them sound alike and I don't know if even that would make the two speakers sound exactly alike.

[oldtimer]

Agreed, but again no concrete experience here.

[DrWho]

I would go with a single tweeter and NOT wire anything in parallel...

[mas]

Generally speaking...

There are few instances where multiple drivers offer an advantage if the job can be done with one.

In fact, it is just the opposite. Multiple drivers introduce many problems that you will not be able to remove or successfully mitigate.

And I sure wish that the notion of the MTM/ "D'Appollito' configuration being a superior center speaker config would disappear! - especially as it is commonly laid on its side! [*-)]

It's indeed common, but a significant trade off.

(How's that for kicking the proverbial hornet's nest?) []

[]

[Klipschguy]

Well, I guess I screwed up. The cabinets are complete (right down to the lovely yellow maple finish); the dual tweeter holes already drilled and are ready to go, so for better or worse these speakers will have two tweeters.

I went with dual tweeters for increased output, less distortion, higher power handling, and greater dynamic range. The tweeters are mounted are so close together they are actually touching (which I presume should minimize lobing and comb filtering??).

Some other companies have tried multi-tweeter designs. Here's a few.

1)McIntosh with their "Bessel Tweeer Array" http://www.mcintoshlabs.com/mcprod/..%5Cdata%5Cbrochures%5CXR27br.pdf

2) Dynaudio with their Evidence line: http://www.dynaudio.com/eng/systems/lines/evidence/master.php

3) Miller & Kriesel (now bankrupt) used to have multi-tweeter designs. I remember my friend had a pair of M&K satellites with three tweeters stacked.

Any thoughts or recommendations if I must use two tweeters?

Andy

[DrWho]

What kind of tweeters are they?

One thing you could do is run a taperred array crossover on the tweeters, or completely divide their bandwidth. So let's say that each tweeter can cover 3kHz to 20kHz. You could run one tweeter from 3kHz to 7kHz and then run the other tweeter from 7kHz to 20kHz. Or you might try letting one tweeter run from 3kHz to 7kHz and then let the other tweeter run from 3kHz to 20kHz. The advantage of the latter is that you might be able to control the vertical directivity a bit without introducing comb-filtering at the higher frequencies. You'll want to pick the middle frequency based on the 1/4 wavelength spacing of your drivers. However, you'll have more distortion from the taperred alignment versus dividing the operating bandwidth in half.

So obviously in both of these cases, you would want to run one 16ohm and one 13ohm tweeter in each cabinet (that way you have perfect stereo symmetry).

Another thing you could do is simply mount both tweeters in the cabinet, but only hook up one of them. []

[Klipschguy]

Back to the drawing board.

[dtel]

If the holes are that close, just make it a rectangle and get yourself a big horn tweeter. []

[oldtimer]

Now that makes perfect sense dtel!

[Klipschguy]

If the holes are that close, just make it a rectangle and get yourself a big horn tweeter.

Don't temp me.

Actually I got it figured out (thanks for the recommendations). I went ahead and went with one tweeter (vintage Bozak aluminum cone - very natural and smooth) operating from 3000Hz to 9000Hz and a mid 90's New England Audio Resource 1" inverted titanium dome tweeter operating from 9000Hz on up. I was just listening to them a minute ago and they sound surprisingly good (of course my smoldering solder buzz hasn't quite worn off yet!) After a little more tweaking of the crossovers and these babies will be ready for action. The midrange is sweet already.

[oldtimer]

It's not tempting, it's the right thing to do. Dtel is a genius.

[mas]

McIntosh with their "Bessel Tweeer Array" http://www.mcintoshlabs.com/mcprod/..%5Cdata%5Cbrochures%5CXR27br.pdf

A TWO driver Bessel Array??? The optimal combination is 5. With options at 7, 9, etc. - but none less than 5.

And it would have been even more effective if it had been oriented horizontally instead of vertically! Instead they ended up with wide vertical coverage reflecting off the floor and ceiling with a narrowed horizontal coverage! Think a line array laid on its side... [*-)]

And DynAudio - their arrangement is correct because of "symmetry"? Really? That's indeed news! Its not quite that simple.

Just because someone does it (even a company with a big name), does not make the physics correct!

If you are going to copy a design, please be sure that the fundamentals are correct.

Oh, and for horizontal placement, turn the diagram on its side. Oh, the frequencies are normalized.

[Marvel]

I believe Klipsch also did five tweeters on one of the MCM systems. Mostly for power handling.

[Klipschguy]

McIntosh with their "Bessel Tweeer Array" http://www.mcintoshlabs.com/mcprod/..%5Cdata%5Cbrochures%5CXR27br.pdf

A TWO driver Bessel Array??? The optimal combination is 5. With options at 7, 9, etc. - but none less than 5.

And it would have been even more effective if it had been oriented horizontally instead of vertically! Instead they ended up with wide vertical coverage reflecting off the floor and ceiling with a narrowed horizontal coverage! Think a line array laid on its side...

And DynAudio - their arrangement is correct because of "symmetry"? Really? That's indeed news! Its not quite that simple.

Just because someone does it (even a company with a big name), does not make the physics correct!

If you are going to copy a design, please be sure that the fundamentals are correct.

Oh, and for horizontal placement, turn the diagram on its side. Oh, the frequencies are normalized.

Whoa there. I did not copy a design, or even claim to, I just said reputable maufacturers have used multiple tweeters in their own designs. They may be junk for all I know - probably are. My reasons for using two tweeters were higher power handing, increased spl, wider dynamic range and lower distortion. Whether my tweeters are horizontally or vertically oriented is a secret.

[dtel]

Marvel, I like the picture so much I have it as one of my desktop pic's on the computer. This is one of the others, thanks to Mark 1101, this one will be here one day !

[mas]

McIntosh with their "Bessel Tweeer Array" http://www.mcintoshlabs.com/mcprod/..%5Cdata%5Cbrochures%5CXR27br.pdf

A TWO driver Bessel Array??? The optimal combination is 5. With options at 7, 9, etc. - but none less than 5.

And it would have been even more effective if it had been oriented horizontally instead of vertically! Instead they ended up with wide vertical coverage reflecting off the floor and ceiling with a narrowed horizontal coverage! Think a line array laid on its side...

And DynAudio - their arrangement is correct because of "symmetry"? Really? That's indeed news! Its not quite that simple.

Just because someone does it (even a company with a big name), does not make the physics correct!

If you are going to copy a design, please be sure that the fundamentals are correct.

Oh, and for horizontal placement, turn the diagram on its side. Oh, the frequencies are normalized.

Whoa there. I did not copy a design, or even claim to, I just said reputable maufacturers have used multiple tweeters in their own designs. They may be junk for all I know - probably are. My reasons for using two tweeters were higher power handing, increased spl, wider dynamic range and lower distortion. Whether my tweeters are horizontally or vertically oriented is a secret.

You seem upset over the reference to "copying" a design.

You are missing the point. I don't care if you copy a design or not - there are few unique topologies in the speaker world.

But whatever you do, you are still subject to the 'laws' of physics. And your stated reasons are the same reasons that many have always added drivers. The problem is that while wanting to achieve the stated goals, you also introduce some destructive variables and response characterisitcs that cannot be overcome. And the negatives generally far outweigh the advantages you sought to achieve.

And MANY designs did EXACTLY what you suggest in the past before a
better understanding of the resulting interference patterns. What use assume will be achieved does not manifest itself as you imagine it will. In fact,
it is a fundamental reason that line arrays have largely replaced point
and shoot arrays for SR use! I am sorry if this is not what you hoped to hear..

Rather than try to convince you of this, I will simply refer you to one of many sources that document this problem. Sound System Engineering. 3rd ed. pp. 342-347.

You are better off going with a more efficient single HF driver IN ALL CASES than using multiple drivers (short of a line array or 5 unit Bessel array). But if you do opt for either of the latter designs, you also need to be cognizant of the substantial phase issues at the crossover characterisitc of the array configurations...

[Klipschguy]

Naw, I'm not upset; I actually appreciate your input...just wanted to let you know you misread my post leading to non sequitur assertions. Funny it is hard to read inflection in these posts. I was actually pretty cheery when I wrote that last post.

Anyhow, I knew about the high frequency lobing when I built the speakers, but I figured the good might outweigh the bad. They actually did sound quite good with the dual tweeters - very dynamic. It just kind of seemed like the sweet spot was a little narrow. So after bouncing some ideas off you guys, I decided to dig into my stash of project drivers and whip out a couple of titanium dome tweeters for the high treble. Now there will be a low and high treble tweeter. Will the design have compromises? Absolutely, which speaker doesn't. Will it sound good to me? I hope so.