Acoustat Answer Man is here

[AcoustatAnswerMan]

Hello Audio Enthusiasts! Some of you may know my work on www.audiocircuit.com, where for many years I have been helping to advise Acoustat owners. I was an engineer and manager with Acoustat, starting when the David Hafler Co bought Acoustat out of bankruptcy, right up to the very end of US production under Rockford Corp ownership (sad day that was!). So I thought I'd lend a hand here, too, because I LOVE Acoustats and want to help as many owners as possible to keep their Acoustats running for many years to come. I don't sell parts or do repairs, but my advice is FREE! So let me know how I can help YOU with your ACOUSTAT's! (And this being a DYI crowd, I don't mind discussing modifications to the speakers.)

Andy Szabo

[Cal Weldon]

Hello Andy. Welcome aboard and thank you for the offer of assistance.

[planet10]

Good to see you here Andy. I used to sell Acoustats (pre Hafler) and owned a set of 2s (converted to biamped 1+1s for a long time), Sent them off to SY a long while back.

dave

[SY]

Hi, Andy! I've got some panels in my garage waiting for me to get time to do a rebuild (diaphragms went bad due to curious 6 year old and the wires are all starting to come loose). Any rebuild suggestions will be appreciated. I have some thin films of several different types of materials, capability to produce more, a corona treater, and can formulate conductive paint, but redoing the wires looks to be a loooooong project....

[bolserst]

Originally Posted by AcoustatAnswerMan

I was an engineer and manager with Acoustat, starting when the David Hafler Co bought Acoustat out of bankruptcy, right up to the very end of US production under Rockford Corp ownership (sad day that was!)....

Andy Szabo

Hello AcoustatAnswerMan,

Do you happen to know the details of what exactly was changed when the transformers were updated to "Medallion"?

1) Turns ratio? wire size? winding geometry? core size / core material? what exactly was updated.
2) What problems/deficiencies was the Medallion update trying to correct?

Thanks in advance for any info you can share.

[chinsettawong]

Hi Andy,

Welcome abroad! I'm sure that a lot of people here will enjoy your company here.

Wachara C.

[hella356]

Thanks, Andy. I learned a lot about my various Acoustats from your site. Did you ever experiment with a tube front end on the Servo amps?

[AcoustatAnswerMan]

Originally Posted by SY

Hi, Andy! I've got some panels in my garage waiting for me to get time to do a rebuild (diaphragms went bad due to curious 6 year old and the wires are all starting to come loose). Any rebuild suggestions will be appreciated. I have some thin films of several different types of materials, capability to produce more, a corona treater, and can formulate conductive paint, but redoing the wires looks to be a loooooong project....

As a factory guy, my standard answer would be that Acoustat panels are not repairable. No attempt was made at the factory to repair damaged wires or mylar, since the panel is 'permanently' glued together. Bad panels were replaced with new.

That said, the panels may or may not be seperated by prying apart the two halves, and if the panel is already bad, there is no harm in trying. The wires can be re-glued with epoxy, if you can get them to sit down flat against the grid. When originally glued, the panels were bent in a convex arc (when viewed from the wire side), so any loose wires may want to bend upwards away from a flat panel.

The original diaphragm was Dupont HS65, which may or may not be available, and if so, only in huge rolls. Attachment to the spacers was with a contact adhesive, and then tensioned with an industrial heat gun.

The conductive coating was a proprietary mix of carbon black, plastic compounds and solvents for bonding to the diaphragm. It was applied with a brush. Good luck in your attempts at Acoustat panel repair - if successful, please share your results.

[SY]

Thanks, Andy- I had them apart once before (replaced diaphragms), but that was a very labor-intensive process; that time, the wires were intact. This time, they're not... sounds like I may want to just do a scratch build of new ones. Any particular wire recommendations?

[AcoustatAnswerMan]

Originally Posted by bolserst

Hello AcoustatAnswerMan,

Do you happen to know the details of what exactly was changed when the transformers were updated to "Medallion"?

1) Turns ratio? wire size? winding geometry? core size / core material? what exactly was updated.
2) What problems/deficiencies was the Medallion update trying to correct?

Thanks in advance for any info you can share.

I can't answer all your questions. The Medallion versions used interleaved windings and considerably better Nomex insulation. The improved insulation made the transformer less sensitive to arc-over, although they were still by no means indestructible. I don't believe there were any changes to turns ratio, wire sizes or core size, and don't recall if the lamination material was any differerent.

The Medallions were developed before I joined the company, although due to the bankruptcy, they were not put into production until after the Hafler acquisition, which is when I joined the company to restart the operation. So I am not certain of the motivations to develop new transformers, but I suspect the improved sonics was an accidental discovery as a result of making the transformer more electrically robust. But don't quote me on that one!

The 'C-Mod', introduced after the initial use of Medallions, was actually suggested by David Hafler (quite the expert in transformers himself). It involved changing the input crossover network to the hi-freq transformer, resulting in a smoother freq transition and less liklihood of core saturation.