The Hub: Acoustat X: 'stats with tubes!


While some companies ease their way into the public eye, others leap out with a big, bold statement product. Think of the Wilson WAMM, the Avantgarde Trio. In their less extroverted way, the Acoustat X (seen here) was no less audacious. The level of technological density rivals a late-model S-class Benz, only less prone to failure.

Last time out, I mentioned a visit to Frank Van Alstine's basement showroom, 'way back in 1978. Along with the Connoisseur turntable directly connected to earth ("earth", as in DIRT: the 'table was on a column Frank had constructed, anchored right through the floor to the cold, cold Minnesota soil), there were Acoustat Xs. I think Frank had tweaked the amps, just as he had tweaked everything else. I don't recall any details other than Frank's comment, "they (the Acoustats) make everything else sound like they're broken."

And so they did. Even at that point in my young life I was no stranger to 'stats, having heard QUADs, KLH 9s, the boxy, almost-forgotten Koss, hybrids from Infinity, ESS, JansZen and RTR, and an oldie which resembles our subject, even in name: the Acoustech X. As the audio village is a very small one indeed, it's not surprising how much inbreeding there was in that group: the KLH 9, Acoustech X and the Koss Model One were the work of Arthur Janszen, and the RTR elements were a descendant of the Janszen add-ons. More detailed history of the ESL can be read here, courtesy of MartinLogan.

But I digress, as always. Those Acoustats in Frank's basement were punchier and less-fragile-sounding than any of those other 'stats I'd heard. Their drive and dynamism were reminiscent of big Altecs or JBLs, with greater resolution and less coloration. How'd they DO that?

Electrostatic speakers are by nature high-impedance devices. There are basically two ways to drive them: either have a step-down transformer so that conventional amplifiers can drive them (assuming said amps can handle a capacitive load of widely-varying impedance), or directly-drive the elements with a high-voltage amp. QUADs, KLH 9s, the Koss, and most modern electrostats follow the former path, while both the Acoustech and the Acoustat followed the latter (as did Harold Beveridge's speakers, with amps designed by Roger Modjeski).

Jim Strickland, President of Acoustat, worked for "Jeep" Harned, the founder of MCI, the well-known producer of recording and mixing consoles and pro tape transports. Strickland handled the design of the tape-tension and logic systems, developed the first autolocator system for pro consoles, and wrote a few papers on tape-transport issues, which were published by the AES. Strickland and Harned developed an electrostatic speaker (named after Harned), which was reviewed in the Summer, 1966, Stereophile. Oddly, the speaker was a two-way which included a built-in amp for the treble panels, but had a matching transformer for the bass, so separate amps had to be used.

The Harned electrostat foreshadowed the ski-slope design of the Acoustat X, but the X refined the earlier design and improved it in every parameter. In the Stereophile review of the Harned, JGH had noted a phasey, unreal quality to the sound, and a rolled-off high end. Neither criticism was ever made of the Acoustat X.

Strickland brought elements of his tape-handling experience to the X, and subsequent Acoustats: the diaphragm was formed of a special Mylar utilized by Ampex in the production of recording tape, and the method used for applying conductive graphite was derived from methods of oxide-application. Each electrostatic-element panel was constructed of a plastic grid (which looked suspiciously like the diffuser element of a commercial fluorescent light fixture), rather than the perforated metal commonly used; this, coupled with a glued-wire element, produced a panel claimed to be indestructible. You can see the production process at this link.

The X used three full-range panels arrayed in an arc to minimize the beaming characteristic of most 'stats. The panels were driven by a hybrid solid-state/tube amps, designated "Servo-Charge", and if the 300 or 400 volts commonly found in tube amps makes you nervous, you probably don't want to hear about the 5000 volts found in sections of the X's amps.

A few minutes spent Googling the X (sounds like a SoCal NoWave band from 1987, no?) will show that a cottage industry has been built around maintaining, restoring and tweaking them. You can find ex-Acoustat guys who can do pretty much whatever you want with Acoustat Xs; the panels do indeed tend to be indestructible, but the amps will probably require maintenance, as any 30-year-old amp probably will. Ironically, later transformer-coupled models of Acoustats can be fried: not the panels, but the transformers!

Acoustat went on to build a wide range of 'stats, and some excellent and innovative amps. As most know, the company was bought by Hafler, and merged into the Hafler/Rockford-Fosgate family. In the US the brand disappeared in the early '90's, and was moved to Italy. More recently the brand reappeared in China, complete with vintage logo, and still appears to build electrostatic speakers. We may not have seen the end of this brand yet.
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Showing 1 response by klinerm

I've never heard the servo-charge amps, but I have Spectra 66s driven by CAT JL-3 monoblocks, and they SING!