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In the Forum: Audio Discussions
In the Thread: The loudspeakers for a powerful SET
Post Subject: Working with parallel woofersPosted by Paul S on: 4/15/2008
Greg, do you have any experience with the Eminence drivers?

When the Audax PR380M2 I use (8 Ohm) became unavailable, Dick Osher specified the 15" Eminence driver as a drop-in substitute for the BZ series.

I happen to use a single 15 " Audax  in a BR enclosure per side, to keep real world efficiency up (97 dB); but impedance still drops to 4 Ohms at one sharp drop point, right below a 40 Ohm spike.  FYI, the FR ML2 is not at its best with this.  Where would impedance go with 2 or 4 drivers, and how much real world power would this require?  The "ripol" link re-linked into a home/advertisement page when I checked it, and as this is written I still don't know what "ripol" means.  I did buy my Audaphon JP2 naked ribbons from those guys, however, and it is a nice stock unit, when that time comes.

So, has anyone following actually tried the 15" Eminence or similar in parallel?  How big would such a cabinet have to be to get 20 Hz?  This seems important when we figure total cabinet/baffle size for the whole thing.  This is the part that always got me chewing my pencil.

As I said up the thread, my experience with "pro" type drivers has been that they are power sinks.  By this I mean to say that even if they are rated 98 dB or even higher, if they also allow 600 watts input, then they are likely to wind up actually demanding lots of power, which is to say more than SET could provide.

There are a couple of Gm70 SET amps out there that have 50 watts.  Of those, I am guessing that the Wavac and the Lamm might make enough USEFUL power.  Kron may also have something out there that might work.  I don't know about how any of these sound, but the crux is likely to be iron rather than the tube, and I assume that if the amp is not outright terrible then it might be massaged to sound better.

Best regards,
Paul S

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