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Stacked LSTs + 4 AR-1W Woofer Only Boxes

Pete B

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We should start a new thread:


I've already worked out Bi-wiring the LSTs, taking the

autotransformer out of the woofer path. Never had a pair

come my way to test it, so I never offered it here. This

isn't absolutely needed with the series connection.

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>We should start a new thread:




>I've already worked out Bi-wiring the LSTs, taking the

>autotransformer out of the woofer path. Never had a pair

>come my way to test it, so I never offered it here. This

>isn't absolutely needed with the series connection.

What circitry is that?


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You ask what circuitry, you mean that I've drawn, or to put

them in series?

I've always wanted to measure the electrical response of the

crossover in the LST, however AR makes this difficult because

they put the XO in the ground path. I was talking to a few

people with LSTs some time ago and thought I might measure

them so I redrew the schematic for a common ground. Functionally

exactly the same, but the common ground provides for simple

test equipment hookup.

Then I drew another version to allow bi-amping and to remove

the auto-transformer from the woofer path. Also gets rid of

the big cap. I would not push this on anyone, but it might

be interesting to try on a pair of not so mint LSTs. I have

these schematics around here somewhere.

What do you think of the stack idea, 3a-LST-LST-3a?

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Pete B. sounds overwhelmingly great! The logistics are my concern here in terms of elevation from the floor and actual needed space and appearance. As it is most who dare to enter my living room feel I’m a 1970’s ‘throw-back’ stereo ‘head-case’ even if the music sounds great. There are components and speakers all over the place, very unsightly. If there was a woman here with me, I’d be asked to collect all this stuff and play with my toys down in the basement. Being divorced does have its privileges though.

Each LST is approximately 90+ pounds each and the 3a’s 53lbs.+ each. That’s about three hundred pounds per stereo side, I don’t have a speaker stand that can take that weight, it alone would have to be huge and heavy itself, like those granite stands by Mark Levinson offered for his Amati’s in the 1990’s. Although beyond those parameters the idea does sound attractive to my better sense of craziness as we used to do similar stacking things in bands that I played in many years ago.

I saw some of your involvement and ability electronically speaking, I’m impressed to say the least, in that sense you’re far beyond my knowledge. Although I did have a major 1973 Buick Riviera collection through out the mid ‘80s, the neighbors hated me-they still do. My loud listening sessions are with all windows closed in my house during the summer, if I didn’t the police would be here every night. Driving four AR-LSTs with two PL400s with the volume up high generates a lot of sound as you may know.

Me, I’m mostly a DIY’er and have limited experience technically speaking. Would I have to tear the LST’s X-O apart to a point rendering them ‘not-original’ afterwards? Mine are in pretty decent condition on the exterior, although I’ve read and can for-see perhaps some components inside the cross-over needing replacement after all these years such as ‘caps’,etc. By the way my cabinets have the wood screwed on panel in back on which the cross-over is mounted which may make things easier to work on. Perhaps you can give me some ‘ball-park’ estimate in terms of changes to be made and then I could decide about the whole issue.

In any event I’d like to see the plans if you could show me, especially the ‘bi-amp’ configuration and some idea of cost and the actual changes made. Any information is appreciated.



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Hi Frank,

I'm here getting a good laugh at your comments about the living room and basement because I'm in exactly the same boat, well I try to keep things as neat as possible. I certainly understand.

About the stack, wondering, are your LSTs away from the wall? Enough so that the 3a's could go behind them in their own stack?

By the way, I think one half of this idea is a good way to add a

second woofer to a single pair of LSTs.

Oh nice of you to ask, there'd be no charge as I like big systems

and would probaby enjoy the work and hearing it. You providing the

equipment is enough, we can talk about it offline. If you wanted

me to do some large task that I wasn't planning then we could talk.

The series connection does not require a lot of extra work, as you

could leave your crossovers as is. On the other hand, it'd be a

shame for one of those caps to fail and loose a bank of midranges

or tweeters. What an AR nightmare!

About the logistics, cinder blocks come to mind and somehow bolting

the whole thing together to avoid an accident. I was thinking that

it would just be an experiment, if you want to keep it then

think about making it look better. A large screen with black grille

cloth comes to mind.

The Stereophile guys might want to come for a visit, that'd be

quite a vintage system you'd have there. AR woofer bliss!

Let me find those schematics.

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