Theoretical multicell Q

**bfish** · May 29th, 2009, 09:36 PM

Just wondering if you scaled down a multicell for a cutoff suitable to pick up where a large format driver begins to fall, how high could you go before cell beaming...

**Panomaniac** · May 30th, 2009, 09:16 AM

Do you mean a tweeter multicell, or something else?

**bfish** · May 30th, 2009, 11:15 AM

Exactly. A tweeter multicell for use above the range where a large format driver rolls off.

Having access to a nice sheet metal shop with a plasma cutting table with nesting software makes a guy wonder about such things.

**Panomaniac** · May 30th, 2009, 12:13 PM

IIRC, the early Altec coax drivers used a true multicell tweeter. I was said to sound much better than the later faux multicell and other horns.

Someone here will know for sure.

It's going to be small and tricky to build, right?

**martyh45** · May 30th, 2009, 03:24 PM

I made a cast of one of the larger 604 horn cells. Flattened out, the length of a side is 3-5/128ths of an inch, small end is 9/16? and the large side is two inches. The flair sides are a 1?1? radius connecting the two points. A guy could probably do a better job of transitioning from the throat if you didn?t have to make it fit inside of another speaker. A 10 or 15 cell horn based on these little sections sure would look cool but I can?t say where you would start to experience comb filtering. Perhaps someone can use the dimensions I provided to calculate that for you.

If anyone has a beat up 808 they can take a casting from I would love to have one. I always wanted to build a 1508 type multicell for tangerine driver use.

**bfish** · May 30th, 2009, 03:51 PM

Well, the old 604 MCs were kinda what I had in mind, but while they're closer to a true MC, there's still a lot of compromising going on to make it work in a duplex.

I was thinking more along Wente's patent design. For ~5k-20k, or a 2 octave BW, my weak brain thinks it should be possible, I just can't do the math.

http://www.google.com/patents?id=KOB...J&dq=1,992,268

Then there's the requisite for a plane-wave at the throat. Is that even possible with today's available drivers, or was that already compromised out by the time Altec built MCs for 288s?

Thanks for the dims Marty, that's exactly the kind of info I'd need to work from (cut dims instead of flare rates).

**Audio_by_Goodwill** · May 30th, 2009, 04:09 PM

I've got a pair of little Pioneer super tweeters that look like little Altec multicells...... I have no idea if they actually function by the same principles, Though. I got them from a pair of trashed CS-88A's

**martyh45** · May 30th, 2009, 05:30 PM

Originally Posted by bfish

I was thinking more along Wente's patent design. For ~5k-20k, or a 2 octave BW, my weak brain thinks it should be possible, I just can't do the math.

ACOUSTIC DEVICE - Google Patents

Then there's the requisite for a plane-wave at the throat. Is that even possible with today's available drivers, or was that already compromised out by the time Altec built MCs for 288s?

I don?t know that that would be superior to allowing the inlets to form a roughly spherical plane. I believe the early western electric multicells had bent cells at the exterior but they switched to a more spherical layout on the inlet and outlet sides. IIIRC, the drivers already include a small section of 800Hz conical expansion as part the body so I?m thinking that would preclude a perfectly planar wave at the inlet of the cells anyway. But I?m speculating rather than calculating so take that last with a grain of salt.