ESS / Heil Air-Motion Transformers Available Again!

[toobwacky]

My eyes bugged out of my head when I got the new Parts Express sales flyer yesterday. New ESS AMTs are going to be available for sale on 7-3. Pricey at $350 each, but I'm getting a pair nonetheless.

What JBL woofer should I pair with these? It has to be around 92db and work in a 3 cubic foot or smaller box.

Thanks!

[speakerdave]

The 2214H, currently available both new and used, was used in the 4425 Monitor up to 1200 Hz, which would be about right:

http://www.jblpro.com/pub/recording/4425.pdf

[Horn Savant]

My eyes bugged out of my head when I got the new Parts Express sales flyer yesterday. New ESS AMTs !

I don't see them in online version, but wouldn't mind trying coupling some Bohlender Neo 8's to my JBL 2350 horns at rectangular flange after removing 2" driver adapter -- XO 250hz? http://www.parts-express.com/pe/show...number=264-713

[Mr. Widget]

It's there and damned tempting too.

http://www.parts-express.com/pe/show...number=264-600

Just what I need... another project.


Widget

[MikeBrewster77]

Order them direct from ESS Labs and get a color gift box

http://essspeakersusa.com/index.html

I had a pair of mid 80's ESS's (don't recall the model) but they were a 2-way with the AMT tweeter and an 8" woofer with a rear mounted 8" passive radiator. It's been about a decade since I owned them, but I recall them being quite impressive (especially the top end.) I still count them amongst the "shouldn't have let them go you dumbass" list of former gear I've owned.

[toobwacky]

Order them direct from ESS Labs and get a color gift box

http://essspeakersusa.com/index.html

Thanks for that link Mike. Their site indicates ESS woofers and crossovers are, or will be, available again too. Hopefully they'll make the passive radiators also.

Cool! Now we can resurrect a complete ESS speaker system.

[Horn Savant]

Speaker Builder magazine of 04/82 had a two-part project for a "Horn-loaded Heil" (home made horn & AMT !) with a crossover of 300 to 500 hz.
Claimed to have exceptional performance.
Article/project was by Kenneth Rauen of Detroit. Looks easier to buy one than to make them yourself.

[Ducatista47]

He had a patent for FET's twelve years before the bipolar (so well named ) transistor. His wife, whom he lost to Stalinist travel restrictions, was also brilliant. http://en.wikipedia.org/wiki/Oskar_Heil

Off topic, I found this paper in a link. It explains, for the technically minded, what is so great about JFET's like those used by Nelson Pass in his best amps. http://www.tkhifi.com/div/Erno_Borbe..._articel_1.pdf
"This description implies the primary difference between a bipolar transistor and a JFET: the pn junction in a JFET is reverse-biased, so the gate current is zero, whereas the base of a bipolar transistor is forward-biased, and the base conducts a base current. The JFET is therefore an inherently high-input impedance device, and the bipolar transistor is comparatively low-impedance."

Real word translation, the bipolar transistor is a current, not voltage, amplifier but serves better as a switch than as an amp. Amplifier use leads to thermal runaway, necessitating other circuits to prevent it or protect against the consequences.

Is this new Heil driver an update of the 1970's design or a reissue?

Clark

[speakerdave]

I was there at an electronics show in San Francisco when Dr. Heil presented his AMT woofer (double 8" cones connected with carbon rods, using a special amp). Not long after I heard rumors that the owners of the company, which had made a lot of money on speakers, blew it all on oil drilling rights or futures (this was the mid/late 70's). Anybody know the truth about this tale?

Always wondered what happened to that woofer.

[toobwacky]

speakerdave, I believe you are referring to the woofer technology used in the ESS Transar:

[Hoerninger]

Off topic, I found this paper in a link.

Erno Borbeley has his own page. He deserves a link, there is much more to read:
http://www.borbelyaudio.com/special_articles.asp
____________
Peter

[speakerdave]

speakerdave, I believe you are referring to the woofer technology used in the ESS Transar:

That's it. Do those speakers actually exist in any number or is that a one-off prototype?

[toobwacky]

Yes, they exist, but I doubt that many were made or sold. I think they required / came with a conventional outboard woofer, but don't quote me on that. I'm going by memory here and that's risky

[jcrobso]

He had a patent for FET's twelve years before the bipolar (so well named ) transistor. His wife, whom he lost to Stalinist travel restrictions, was also brilliant. http://en.wikipedia.org/wiki/Oskar_Heil

Off topic, I found this paper in a link. It explains, for the technically minded, what is so great about JFET's like those used by Nelson Pass in his best amps. http://www.tkhifi.com/div/Erno_Borbe..._articel_1.pdf
"This description implies the primary difference between a bipolar transistor and a JFET: the pn junction in a JFET is reverse-biased, so the gate current is zero, whereas the base of a bipolar transistor is forward-biased, and the base conducts a base current. The JFET is therefore an inherently high-input impedance device, and the bipolar transistor is comparatively low-impedance."

Real word translation, the bipolar transistor is a current, not voltage, amplifier but serves better as a switch than as an amp. Amplifier use leads to thermal runaway, necessitating other circuits to prevent it or protect against the consequences.

Is this new Heil driver an update of the 1970's design or a reissue?

Clark

Transistors are current operated and tubes are voltage operated in basic terms.

[Tom Brennan]

The Heil woofer was evidently driven more by a need to do it different than a need to do it better. I heard a set at Musicraft, no big deal. They didn't come with a conventional woofer.