2. amps-preamps
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Why dosome high pwr amps fail to drive some spkrs?

I have Audio Artistry Beethoven speakers. They are dipoles with main panel, active xover and separate unpowered subs. In the main panel ther are 2 10´ woofers covers the range 100-200 Hz. This speaker A A Beethoven was Speaker of the year by Stereophile 1998. According to S. test the speaker has a sharp drope in impedance in than region 100-200 hz to about 3 ohm. The problem is that some amps fail to move this 2 10´woofers. A Rowland 8TiHC (high current) of 400 w and lots of current fails to drive the woofers resulting in a lack of midbass (otherwise the Rowland was very good). Also "the worlds best amp (Stereophile cover)" Halcro DM 68 at mega bucks also fails to drive the woofers. Halcro says that this amps has no problems down to 2 ohms. BUT a 10 year old Classe 300 (300W) at budget price drove the woofers with no problem.I finaly settle with big Krell monos and they have absolute no problems in this area.
I was told by a well know audiophile on Audio Asylum that he had the same problem with the even bigger Rowland model 9 that fails to deliver midbass to Big Avalon speakers.
Can someone explain this to me or has anyone similare experince?
I can also say that the speakers are truly world class now with the Krells!! I use a Krell KSA 300 to power the dipole subs with exellent result and 20Hz wall shattering bass.
ulf

Showing 1 response by gregm

gregm
3,413 posts
 
Ulf -- you've got OUTSTANDING speakers, you lucky .....:)!
As to the drive issue: it's strange as these aren't insensitive speakers...
Could be related to the phase angle @ ~90-100Hz where (I think) the woofs kick in. In conjunction, the sound (or lack of it) could be related to the amps output impedance. Krell has tried (or its marketing has) to minimise effects of impedance/ energy transfer in the spkr-amp interface.

However, I would think an active biamp approach would serve best. Finally, why not try contacting Linkwitz himself -- he designed these spkrs and I'm sure he'd be interested! Cheers
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