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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 atmasphere

atmasphere's avatar
atmasphere
12,116 posts
 
Hi Ulf,- it remains a fact that not all amps will drive all speakers, in fact, you have to be very careful to make sure that the amp and speaker interface is doing what it should.

Speaker cables, the length of the cables, the use of negative feedback, input impedance (already covered), load reactivity, output section stability and literally a host of other issues define the arena of your question.

There are speakers that transistor amps cannot drive and there are speakers that tube amps cannot drive. As you have seen, the speakers that you might think would be OK for a given technology are not always what you might predict. Generally there are more speaker products on the market then any other type of high end audio product, and you simply cannot blame an amp manufacturer for not knowing how well their amp will interface with a speaker, especially if it is a little bit more obscure! There are just too many speakers out there for that. Of course the manufacturer is the one to ask first, but your experience is important too.
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