Vintage Asylum

Posted by mhardy6647 (A) on March 25, 2016 at 12:08:20

In Reply to: RE: the Duplex's HF unit was (is) a compression driver posted by J. Phelan on March 25, 2016 at 07:53:59

Not sure we're on the same wavelength (pun partially intended).

The Duplex is a true two-way speaker, although most versions lack considerable HF extension due to the horn and the XO design. That's just one of those things. The diaphragm on the treble driver in a Duplex is fairly big; again, I think it's similar to (although not identical to) the famed, venerable (and EXPENSIVE) Altec 288 compression driver.

A dome MR per se would be far less sensitive than the woofer or HF driver used in the Duplex. The Duplex's HF driver and horn might be best thought of as a MR horn, but as you can tell from the XO frequencies (in the subject line, and from memory, so I may not be dead on the range used by all Duplex versions ever made/sold) much of the MR was handled by that big, 515-like 15" driver and its paper cone and pleated (accordion) surround.

I like to say that the Altec 604 series Duplexes are the best midrange drivers ever made :-)

Now, back to that crossover: Time alignment of the original Altec XO was, arguably, the big "opportunity for improvement" of the Duplexes of yore. Doug Sax "MasteringLabs" sold one that was widely used (and, IMO, quite effective) in studios.

Jeff Markwart has also designed improved XOs for some of the Duplex drivers. See link below.
all the best,
mrh

• http://home.earthlink.net/~jmarkwart/   (Open in New Window)