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The Littlest Heil

wualta

wualta

permanently nonplussed cat
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There may be a smaller one somewhere, but I doubt it. This diaphragm is about three-fourths the height of the one in the mini-Heil in my Fortura 12s (UPDATE: well, not quite-- the foam is hiding the true size. see below). It's called a "corona field" tweeter (after the magnet structure), and it's from a 1975 Lafayette Criterion 2005, and it was used as a dipole-- and I think the Lafayette and the Forturas were the only dipole mini-Heils. One of the prettiest Heil magnet structures evar (more photos to follow).
Lafayette Criterion 2005 tweeter closeup.jpg
You can see the woofer-style ceramic ring magnet peeking out from under the pole piece.

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quite different

I have never seen one with the depression in the center like that. Similar to mine (Lafayette rebrand) but fewer slits. I will grab mine tomorrow and post a comparison. What's the vertical height of the diaphragm? did you put the foam in there or is that OEM?
 
mypasswordis said:
It is indeed quite pretty. How's the treble, and is the crossover point pretty high up?
Click to expand...
These just arrived today, so I haven't had the chance to install them in anything yet.

In fact, I just unwrapped the other tweeter of the pair and I see that the foam has deteriorated enough to get a proper measurement. Though this is indeed the littlest Heil, there were others just as small. Measured from the top gathered edge (sealed with black lacquer) to the bottom is about 48mm or 1 7/8". The diaphragms in my ESS LE-20s are about the same size.

The size of the cutout in the intact foam in the photo above is only 1.5", which I would take to be the effective size of this tweeter.
P1000514a.jpg

You can see that the diaphragm is glued to a circular piece of cardboard which was intended to be held in place by the foam.

I suspect that the diaphragm discs were installed before the tweeter was assembled, since there's no installation slot. If you blow the diaphragm on this tweeter, you throw the whole thing away or get a big hammer and try knocking the pole pieces off, something I wouldn't want to try without steel-toed shoes.

I would imagine the crossover on the Lafayette 2005 is nominally 1500 Hz, as it is on the Forturas and other small-Heil ESS speakers. But there was also a Criterion 2004 (bookshelf), which is what I hope Spikedart has. Come in, Spikedart!
Spikedart said:
I have never seen one with the depression in the center like that. Similar to mine (Lafayette rebrand) but fewer slits. I will grab mine tomorrow and post a comparison.
Click to expand...
Very much looking forward to that! I don't have any shall we say stock photos of the earlier Lafayette/ESS speaker.

PS: If anyone gets a pair of these, be very careful to keep them away from anything magnetic, like valuable old tapes or credit cards. The flux leakage from these things is horrendous.

Here's a rear shot of the Heil installed in the Criterion 2005 cabinet.
pix%20146a.jpg
The sides are solid but they made a big aperture to let the Heil's backwave out. The photo is lousy but it appears that the factory damped the Heil with strips of something, maybe fiberglass, possibly cotton.

By the way, High Fidelity tested the 2005 back in October 1976. Download the pdf here.
 
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I used my ESS amt-4 Mk1 as a test bed for the Lafayette Heils.

I should explain that the amt-4, one of the first-generation Heil-equipped speakers from ESS, came in two flavors. The first used what at first looks like a Great Heil:
image-2a.jpg
When you realize that's a 10" woofer (in one of the very few ESS sealed cabinets I know of), you become aware that something's out of scale. It turns out that the amt-4 was the only ESS speaker to use what I call the Munchkin Heil. It's built just like the first-gen Great Heil but it's only half the size.

Here's what the later (and more common) amt-4s looked like:
amt-4-2.jpg

As you might expect, the way these two magnet structures shape the sound that comes out of them is markedly different. The Munchkin is, like its first-gen big brother, very directional vertically. You don't want to listen to this speaker from any vertical position but directly on axis or all the treble disappears. The socalled Mk2's tweeter doesn't get in the way of wide treble dispersion, especially the vertical, nearly so much. This same "dual-plate" tweeter was used in many other ESS speakers, including the monster amt-6. To my ears, it's the best single-driver compromise between the severe directionality of the Great Heil and the wide dispersion of the mini-Heils.

And so it was when I plugged the Lafayette tweeters into my amt-4: with the speakers on the floor I could stand up and move around the room and still hear treble and the speaker sounded pretty good. When I squatted down to listen on axis, the beaming mids from the woofer overwhelmed the little Heil. This is why Neil Davis recommended building a mini-Heil to go with your DIY Great Heil way back in 1977.

Owners of 2-way Great Heil ESS speakers, take note, especially if you don't have your speakers raised up to ear level. You might want to see if a disgruntled Fortura owner wants to part out their dipole mini-Heils.

Final note: This Lafayette Heil is the only Heil tweeter I've seen, including the European ones, where all the surfaces that an emerging sound wave sees are rounded. From that I conclude that the chances of this tweeter actually sounding better in real-world use (because of reduced diffraction effects) are pretty good.
 
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wednesday nite

I'll post my lafayette monopoles. turns out they are at my brother's with most of my pieces and parts. Mine have a plastic enclosure to seal off the driver from the blast of the woofer. I have burned one or two diaphragms and still have a spare. I have to cut the backs off to replace them or re-solder a wire. I have to mount them with mirror tabs on 4 sides since the plastic back used to reach to the front as a mounting plate and I cut the ugly thing off.
 
Lafayette Criterion 2004 speakers.jpg
Aha, so in the 2004 they used monopole Heils. Flush mounted, as I recall, and I have a picture in my head of them being uncovered, ie, no grille cloth. Am I close?
 
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Found them! Had to dig deep.

I will also post some scanned pix this weekend with them being used in a project from 20 years ago. The speakers I ripped them out of did have brown grills. 2 way, ported, 10" driver. I had a friend with the tower series from Lafayette. His monopole amt's were a bit taller than mine, in an oblong shape. 12" woofer and passive radiator. We threw in a 5" Oaktron midrange (identical to the cheap JBL's of the era) and modded the crossover to make it 3 way. Sounded better without it.
 
Heil project started in 1997

But never finished. Obviously.
We are looking at monopoles in which one needs a lead resoldered and tufflex replaced, fronts cleaned up and repainted. The 5.25 inch woofers are Altec-Lansing carbon fiber originally made for auto use. Crossovers are adjustable. I can not find any specs on this stuff so will have to test myself. The passive radiators are home made, the discs in the center are tops from nut cans. Completely covered in black silicone rubber and at present, untuned. These came off some unknown cheap-o system I popped the magnets off of. The enclosures are approximately 2-2 1/2 cubic ft and still in my ex's garage in california. The AMT's have been used in numerous projects, I can find a cool 4-way passive radiator project from 1990 that I will post scans in the next post. I wish I had tracked the progress of more of my dozens of home-made systems.
 

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Altec crossovers

If anyone has specs on the Altec woofers, model ALS525 and the associated XO contour, I would be most appreciative. Here are the XO's, with a hi and mid contour.
 

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Excellent! Neato project, if those carbon wooferlets behaved themselves.

That Heil looks like some other small-Heil monopole tweeters of the time. Some had plastic cups filled with fiberglass covering the rear of the diaphragm, as yours did.

By the way, you can compare the private label Fortura line's dipole mini-Heil to the Lafayette 2005 dipole. Same size diaphragm, slightly crippled dispersion pattern due to differences in mounting, with the squared-off edges causing lots of diffraction.

Fortura 8a.jpg
FORTURA 8
 
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wualta said:
These just arrived today, so I haven't had the chance to install them in anything yet.

In fact, I just unwrapped the other tweeter of the pair and I see that the foam has deteriorated enough to get a proper measurement. Though this is indeed the littlest Heil, there were others just as small. Measured from the top gathered edge (sealed with black lacquer) to the bottom is about 48mm or 1 7/8". The diaphragms in my ESS LE-20s are about the same size.

The size of the cutout in the intact foam in the photo above is only 1.5", which I would take to be the effective size of this tweeter.

LafayetteCriterion2005tweetercrumbl.jpg


You can see that the diaphragm is glued to a circular piece of cardboard which was intended to be held in place by the foam.

I suspect that the diaphragm discs were installed before the tweeter was assembled, since there's no installation slot. If you blow the diaphragm on this tweeter, you throw the whole thing away or get a big hammer and try knocking the pole pieces off, something I wouldn't want to try without steel-toed shoes.

I would imagine the crossover on the Lafayette 2005 is 1500 Hz, as it is on the Forturas and other small-Heil ESS speakers. But there was also a Criterion 2001, which is what I hope Spikedart has. Come in, Spikedart!




Very much looking forward to that! I don't have any shall we say stock photos of the earlier Lafayette/ESS speaker.

PS: If anyone gets a pair of these, be very careful to keep them away from anything magnetic, like valuable old tapes or credit cards. The flux leakage from these things is horrendous.

LafayetteCriterion2005tweeterchambe.jpg


Here's a rear shot of the Heil installed in the Criterion 2005 cabinet. The sides are solid but they made a big aperture to let the Heil's backwave out. The photo is lousy but it appears that the factory damped the Heil with strips of something, maybe fiberglass, possibly cotton.

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Click to expand...

That backdoor photo looks very familiar:D My brother in law loves his "inherited" Criterions.
 
Aha! Can you fill us in on whether or not the Heil from the Criterion 2005 had fiber damping?

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From last December? Probably is the same photo.

In dipole form, this is an excellent tweeter, but as I pointed out, the dispersion pattern is nothing like the one from the Great Heil, which can be a very good thing, depending on your room.
 
Lafayette fiber question

The monopoles had a plastic cup that held the magnet assembly and also was packed with small rectangles of tufflex. Here is a picture of the "oblong" AMT's I mentioned earlier which my friend owned. These are not his, but are the same ones. I believe they are from the "PS" series, as were my 5 1/4" round ones. His was a tower system nearly 40" tall and was 2-way with a 12" bass driver and PR. He threw in a cone midrange which I felt degraded the sound somewhat.

If anyone is interested I will throw in 20 year old pix scans of one of my more ambitious projects using the little AMT. Tiny <2 cu. ft box, passive radiator, direct-reflecting midrange pair, true 47Hz response.
 

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I think a separate thread with your speakers in it would be very popular. Meanwhile, do you know who made Tufflex and whether it can still be got?

P.S.: I use a tweeter like the ones pictured above in my Ohm Walsh 3 that blew its tweet.
 
excellent use of an AMT

wualta said:
I think a separate thread with your speakers in it would be very popular. Meanwhile, do you know who made Tufflex and whether it can still be got?

P.S.: I use a tweeter like the ones pictured above in my Ohm Walsh 3 that blew its tweet.
Click to expand...

You must have the driver assembly exposed since the baskets would never cover such a tall form factor. Got a pic?

Several years back the factory that made Tufflex brand sound deadening material burned down and they stopped making it, according to John Strohbeen. I offered to give him a large box of the stuff that I received from a laboratory in New Hampshire, but they recycle theirs from the upgrade trade-ins. Unfortunately, it has been in my brothers' basement and much of it is useless since it got wet and moldy this summer. I still have a few good strips but not enough to stuff a cabinet any more. If you really need a piece, I could send you a strip approximately 4" x 18" long if that would help.

On the other hand, you can get newer materials from B-quiet, and the stuff is really affordable and has been spec'd. Here is the web site : http://www.b-quiet.com/compare.html
 
Spikedart said:
You must have the driver assembly exposed since the baskets would never cover such a tall form factor. Got a pic?
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You bet. And I believe the cans fit back on nicely.

Spikedart said:
Several years back the factory that made Tufflex brand sound deadening material burned down and they stopped making it, according to John Strohbeen.
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Ah, thanks for that bit of info. I'd tracked the Tufflex trade name through several identical spellings that are now applied to several different products. Apparently it was first a product of a long-gone company called Wood Conversion. Then it was Conwed and then the company was sold... and I didn't know it was now completely kaput, but I'll take Strohbeen's word.

Spikedart said:
On the other hand, you can get newer materials from B-quiet, and the stuff is really affordable and has been spec'd. Here is the web site : http://www.b-quiet.com/compare.html
Click to expand...
Ah, thanks! this looks like the stuff, if you'll pardon the expression..
 
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