Just acquired, unusual 'Alternative Acoustics' Dave Herren made speakers

[Scopeman]

I just acquired this pair of Alternative Acoustics speakers. These were made in Portland Oregon c. 1980's by Dave Herren, locally known in the day as Stereo Dave. He was the longtime owner of a local stereo shop.
This design consists of two sealed enclosures, one for the woofer, the second for the midrange, with an odd "plumbing" between them with a valve, whereby one can adjust the coupling between these two enclosures.
Has anyone seen anything like this before? Operating the valve doesn't seem to do much sonically, at least by my ear.
These work ,and sound pretty good in my small space, but the high frequency tweeter at the top of the stack on both appear dead. I haven't been able to identify the driver, and they have no marking yet found.. They are being driven, but I don't hear anything from either one. Both measure open with an ohmmeter. Could they be capacitive drivers?

Some background here: http://www.stereodaves.com/dave.php

 

[doctorolds]

Wow, crazy design on those. No help from me other then suggesting that you contact theses folks. An old timer there may possibly be able to help you out?

http://www.stereodaves.com/

 

[A400]

Mad scientist stuff, cool. Some nice drivers in there. Would like to know more about what the link is supposed to achieve.

The top driver looks like it might be a piezo and likely playing only very high frequencies which may not be easy to hear.

 

[GordonW]

That's a KSN-1005 piezo tweeter with the horn cut off.

Why someone would want to couple a sealed woofer enclosure with a sealed midrange enclosure, is a mystery to me. The concept of a Nestorovic enclosure with two dissimilar woofers in the same enclosure can sometimes have a valid acoustic benefit- but I can't see where coupling the enclosures of two dissimilar speakers, operating in different frequency ranges, would help whatsoever. Only thing that would probably occur, is an increase in intermodulation between the drivers... not usually a good thing.

Regards,
Gordon.

 

[Scopeman]

Thanks for the comments!
The link shows a period picture of these, or similar, speakers in production, in what looks like a garage!

 

[doug76712]

I'd still be looking for the pilot light somewhere around that gas valve.