Who designed the AR LST/2?

[HepcatWilly]

Hi all,

Legend has it that Roy Allison designed the original LST, then left to start Allison Acoustics.

Does anyone know who designed the LST/2? Any background info on the speaker?

I just acquired a pair for restoration, and would appreciate any insight you might have on these.

Thanks!

Bill

[Steve F]

John J. Bubbers was AR’s Director of Engineering in 1973, so it is likely that he headed the design effort for the LST-2, which was introduced in March 1974.

Like many products in many industries, the LST-2 was primarily a Marketing effort intended to capitalize on an earlier sales success. The original LST was a sales and PR triumph beyond all reasonable expectations, so it was natural for AR to attempt to further the success of that product family.

From a purely engineering standpoint, much of the ‘heavy lifting’ had already been done with earlier AR products. The drivers were existing AR-5 units. The crossover (auto-transformer-type) had been done on the LST, and the -2’s was simpler with only 3 switch positions (although some early LST-2 literature erroneously shows 6 positions). The multi-angled cabinet manufacturing process and packaging for same had already been perfected on the LST.

Insiders often call this “parts bin engineering,” because the product is essentially a combination of existing and slightly-modified parts, culled together quickly, and brought to market in an effort to fill a perceived vacant niche.

There’s nothing inherently wrong with this; the LST-2 was a fine speaker and a worthy product. I owned a pair for over 10 years and enjoyed their sound tremendously. It’s just that when you asked “who designed it,” it probably wasn’t the result of some company-wide Manhattan-Project effort, like the 3, 3a, LST and 9 likely were. It was more a product of convenience, albeit a very fine one.

A few interesting details: the crossover specs for the LST-2 were always listed as being the same as the later 3a’s: 525 and 5000 Hz. Interesting, because the later 5’s—upon which the LST-2 is based—had x-o specs of 550 and 5000 Hz. Not a big deal, actually, because the stacked tolerances of crossover components would lead to at least that much variance in the x-o and add to that the real-world unit-to-unit driver variances and the acoustic crossover (as opposed to the electrical x-o voltage curves) would also vary a bit. 25 Hz is a somewhat too fine margin to spec a crossover. My very strong suspicion is that some mid- or lower-level office person simply copied the 3a’s x-o specs into the LST-2 brochure and they never got corrected.

Steve F.

[HepcatWilly]

I'm interested because I have both LST2 and Allison Twos. The Allisons are more musical at the moment (LST2s need to be restored), but the LST2 has sound floating all through our rambling house in ways that even the Allisons can't beat.

Both are great speakers, it is interesting how they both perform.