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In Reply to: Biamping tube amps a No No? posted by shpickering@yahoo.ca on February 21, 2007 at 13:58:07:
The only reason bi-amping would cause a problem with ANY type of amplifier is if the amp in question is not stable without a load. When bi-amping with passive crossovers the amp will be essentially unloaded in the reject band (low frequencies if driving a tweeter). Some amps will oscillate without a load.I used to have an bi-amped system using active crossovers, two modified Dyna Stereo 70 amps and Altec Voice of The Theater horn speakers. It worked very well.
Follow Ups:
PeteThat's because of global feedback.
Without GFB amps are stable into no load.
Of course I don't use GFB in mine.
If you bi-amp there is no need for the
increased dampening factor for the bass
it isn't doing so I say remove it.
If you NEED GFB for your amp to be linear,
then sell it and buy a good one IMO.
DanL,It is not feedback per se, but the incorrect use of feedback, that causes problems. As for damping requirements, the speaker needs dictate the damping requirements. In the case of the Altecs I mentioned, they were over damped to begin with so a low damping factor was desirable. Modern small box speakers tend to need (and are designed assuming) high damping from the amplifier.
Ok. I'll fill in the details. The tube amp is a McIntosh MC275 V and will be running the mids and tweeters using the speakers internal crossovers. The crossover for the mids is 350HZ. The speakers are B&W 804S units. The MC275 has a input level control. For bass I was planning to use the SS Rotel RB 1070 amp I already have. Preamp may be a McIntosh C220.
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