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From: strong@tc.fluke.COM (Norm Strong)
Newsgroups: rec.audio.high-end
Subject: Re: bi-amping
Message-ID: <9058@uwm.edu>
Date: 21 Jan 91 14:20:22 GMT
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Approved: tjk@csd4.csd.uwm.edu
Originator: tjk@csd4.csd.uwm.edu

In article <8754@uwm.edu> hull%janus.Berkeley.EDU@ucbvax.Berkeley.EDU (Christopher Hull) writes:
}In article <8661@uwm.edu> you write:
}>
}>      I am interested in bi-amping by B&W 801s (currently bi-wired with
}>Tara Return).  I have a lot of questions:
}>
}>1.  How much power is required for the tops (mid-range and tweeter) where
}>the cross-over is, I believe, around 300 Hz?  I'd like to use a low to medium
}>power tube amp (less than 100 watts per side).  How much is necessary?
}>
}>2.  Is an active cross-over required or can I simply feed the passive crossover
}>already used for bi-wiring?  I have a dealer who says I need an active
}>crossover if the top and bottom amps are not identical.  Could someone give me
}>a technical explanation in more detail.
}>
}
}
}You can use a passive crossover, however that will negate most of the
}advantages of bi-amping since both amps will have to deal with the whole
}spectrum.  In that case both amps will need to be high powerd, especially
}the one for >300hz, since its distortion will be most audible.
}
}If you use a low level crossover (either electronic or passive, but before
}the amps!) than each amp can be about 1/2 of the power you would normally
}require.  If you are going to equalize your subwoffer than you would need
}more on the bass amp.  I recommend that the high pass part of the crossover
. . .

I must disagree with the statement that each amp can be 1/2 the power you
would ordinarily need.  Unless you spend your time listening to white
noise, both amps will have to be full power--especially the bass one.
This arises because you don't know what note is going to tax the amp to
the limit.   In my experience, it's usually in the bass end.  

-- 

Norm Strong  (strong@tc.fluke.com)
2528 31st S.   Seattle WA 98144