Acoustat Answer Man is here

[bolserst]

Originally Posted by bear

Now, here's a question - there was an outfit in Florida that was making replacement transformers, do you know if they or someone else is still around??

See bottom of products page for prices on replacement Medallion transformers from Russ Knotts.
products


Excerpt >>>

All New Acoustat Medallion Bass step-up transformers each built by us to Acoustat Medallion specs $225.00

All New Acoustat Medallion Midrange step-up transformers each built by us to Acoustat Medallion specs $125.00

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[speedracer5]

Hello Andy!
Great to see you here!
Could you maybe offer some insights as to what high current amps from new era or say less than 10 years old you would select to run Acoustats. I have been running just one 9" panel per side with bone stock Mk121A interfaces from a pair of Model 3's. I did not move the bass tap either. The single panel per side has limits of course but sound just right IMHO and the beaming is much less. They actually make rather astounding amount of deep bass. A difficult load though it would seem. Just one panel by itself is supposed to be tougher than multiple panels on one interface. Using a mid 90's Harman Kardon PA2400 and it runs the dickens out of the Model 3's as well as one single panel per side. Tried running the single 9" panel with a mint condition Krell KSA200s and the auto bias ramped up lit the front panel up like a christmas tree and she went immediately into protection. The Krell basically said "fuggedaboudit". The HK with 170wpc however runs them just fine. Sounds delicious.

Anyway I'm considering the Frank Van Alstine offerings since he is known for fixing and modifying Hafler high current designs and has several of his own designs rated into 2 or 1 ohm loads. avahifi - Power Amplifiers Comparison Grid
Any other recommendations for a more recently manufactured "high current" design that won't break the bank? I had thought about Pass Labs also but I would be pretty disappointed and suffer having to sell the thing if it did not work. Expensive decisions.

[Atom66]

Hey Andy
I presently have Spectra 22s. I have been able to acquire the parts (extra panels and Spectra 44 /66 transformers) to build a Spectra 44 .Only problem I have is that the room that they have to go in does not have the height necessary to stack the panels as in the 44 and 66. What I was thinking of doing is placing the 4 panels side by side .Is this something you have tried? Should I be moving to a new house?
Thanks
Andrew
PS here is a link to some construction pictures of Acoustat panels in heavily reinforced steel /wood frames.

Canuck Audio Mart &bull; View topic - The making of modified steel Acoustat's

[AcoustatAnswerMan]

Originally Posted by hella356

Andy, any info on how Acoustat tested regarding the angles of the panels, particularly the 4 wide speakers? Also, how important it is to mix 8" & 9" panels vs just going with 9 inchers in a Model 8 / 4+4 type? I'm planning to build such a speaker with all the extra panels I've got. Thanks!

The angle-between-panels varied over the years, with some of the later models (i.e. 2+2) having less angle than an earlier Model 4. I believe the final angle was about 9 degrees between panels. Of course the Spectra Series had no angle between panels, since the panels were electrically curved (convex when viewed from either side!)

The combination of 8" and 9" panels was an effort to 'spread-out' the low frequency resonant point, the 8" being a slightly higher frequency. If all you have are 9" panels, I would not let that stop you from building a Model 8-like design. Note that the 8" panels were used only in 3-panel and 4-panel wide systems, like the Model 3, 4, 6 and 8. The 2+2 and all of the larger Spectra's (even the mighty 66/6600) did not use the 8" panel.

[bear]

Atom, The spectra panels are intended to spread the HF from the center out... so assuming that the center panel has enough HF dispersion then in theory anyhow only one panel should be run as full range... the others not... otherwise the whole idea is somewhat out the window.

Otoh, 4 side by side is an Acoustat IV which is quite good, and has the deepest bass of the side by side versions.

In practice it might make no diff if you run them as spectra, or tie the stator wires together. The replacement cells I got were spectra cells, and I just tied the stators together in my IVs and IIIs...

_-_-bear

[bear]

Speedracer - the hands down best amp I ever ran with my Acoustats was a highpower tube amp with a pair of 811a in the output running @~1100vdc B+... for whatever reason it made all the solid state things ever tried, even my 128lb Symphony No.1 sound thin and anemic by comparision.

Also, consider a Strickland designed TNT 200 amp?? It can use some upgrades and mods, but more or less it is designed to work with the Acoustat amps...

_-_-bear

[Atom66]

Bear
Was that an Altec 1570B tube amplifier?
Andrew

[AcoustatAnswerMan]

Originally Posted by bear

Atom, The spectra panels are intended to spread the HF from the center out... so assuming that the center panel has enough HF dispersion then in theory anyhow only one panel should be run as full range... the others not... otherwise the whole idea is somewhat out the window.

Otoh, 4 side by side is an Acoustat IV which is quite good, and has the deepest bass of the side by side versions.

In practice it might make no diff if you run them as spectra, or tie the stator wires together. The replacement cells I got were spectra cells, and I just tied the stators together in my IVs and IIIs...

_-_-bear

Only 1/2 of one panel width is run at full range in any Spectra model, the rest of the panel area is mid/lows or lows only. Spectra panels can be used in non-Spectra applications, and I consider it optional to tie the ends of the split stators together. Connecting both wire leads together (white-to-white and blue-to-blue) will make the stator all the same circuit.

[AcoustatAnswerMan]

Originally Posted by speedracer5

Hello Andy!
Great to see you here!
Could you maybe offer some insights as to what high current amps from new era or say less than 10 years old you would select to run Acoustats. I have been running just one 9" panel per side with bone stock Mk121A interfaces from a pair of Model 3's. I did not move the bass tap either. The single panel per side has limits of course but sound just right IMHO and the beaming is much less. They actually make rather astounding amount of deep bass. A difficult load though it would seem. Just one panel by itself is supposed to be tougher than multiple panels on one interface. Using a mid 90's Harman Kardon PA2400 and it runs the dickens out of the Model 3's as well as one single panel per side. Tried running the single 9" panel with a mint condition Krell KSA200s and the auto bias ramped up lit the front panel up like a christmas tree and she went immediately into protection. The Krell basically said "fuggedaboudit". The HK with 170wpc however runs them just fine. Sounds delicious.

Anyway I'm considering the Frank Van Alstine offerings since he is known for fixing and modifying Hafler high current designs and has several of his own designs rated into 2 or 1 ohm loads. avahifi - Power Amplifiers Comparison Grid
Any other recommendations for a more recently manufactured "high current" design that won't break the bank? I had thought about Pass Labs also but I would be pretty disappointed and suffer having to sell the thing if it did not work. Expensive decisions.

I'm using a Hafler 9500 with my Spectra 4400's, and find the combination very satisfying. Any of the later Hafler's, such as the 9500 or 9505 (w/balanced imputs) will work well, although they do not qualify in your quest to find something 'less than 10 years old'. BTW, Jim Strickland designed the Hafler 9500, and it is a further refinement of the original Acoustat TNT-200. I have used the TNT-200 as well, and I consider the 9500 a significant improvement.

[speedracer5]

Thanks Andy!
What I need to do now is find two identical examples. That is to do what I'm planning.