From: DPierce@world.std.com (Richard D Pierce)
Subject: Re: Wanted to know bi-amp speakers advantages
Organization: The World Public Access UNIX, Brookline, MA
Date: Mon, 11 Jan 1993 11:21:40 GMT

In article <TONYB.93Jan6155705@ursula.juliet.ll.mit.edu> ( Tony Berke ) writes:
>
>OK, so the poor guy flubbed up pretty seriously.  But then you go on
>to leave out most of the main advantages of multi-way amping yourself.
>I'm sure you're aware of them, but left them out in the heat of the
>moment.

As I stated in my reply, there are many reasons, but that I was bnot going
to point them out. The purpose of the reply was to debunk the reasons stated.

>First of all, the poster's assertion about biamping's reduction of
>"phase distortion" might have been bogus, but biamping can certainly
>reduce IM distortion in the amplifiers, for obvious reasons.

"for obvious reasons?" First, you'd better be prepared to support the
assertion that IM distortion is a problem to begin with using the
amplifiers that are typical for bi-amped systems. This is not a
particularily tough problem to solve simply by doing the amplifier right.

Tony goes on to mention two advantages of multi-amping, both of which
suggest an increased level of safety, which I, in general agree with.
However, again, I was not out to exhaustively treat the advantages of
multi-amping

>I'd also be interested in seeing the numbers for the insertion loss,
>distortion, and cost, of a really steep, really high-power, really
>low-frequency crossover, say 60Hz, for those who want a subwoofer set
>up that way.  I imagine that the inductors will either cost a lot,
>saturate easily, be huge, or have high losses (most likely, a fair
>portion of each).

I provided one particular example where an inexpensive network had
broadband losses of about .5 dB.

>Perhaps this is just a leftover from my PA roots, but in the sound
>reinforcement world, midranges and tweeters are often MUCH more
>sensitive than woofers, and a passive crossover might have to pad the
>mids and tweeters a good 10dB to get things to match up.  Granted, the
>bulk of the energy is in the bass, and typical direct radiator mids
>and tweeters aren't all that sensitive, but the flame-ee did gave a
>(potentially) valid point there.

The vast majority of drivers suited to home loudspeaker use are matched
sensitivity-wise to within far smaller ranges than 10 dB. Typically
they're within 3 dB. Part of the job of a successful engineer in this
business (which the checks I receive regularily each month suggest that I
am) is to select drivers that are closely matched, sensitivity being one
of the most important criteria. Adding a 3 dB pad to a tweeter crossed
over at 4 kHz still does not constitute "high power dissipation", as the
spectral weighting of music is such that you can get away with an L-pad
designed with 5 watt resistors and never have to worry about it again.

Also, Tony relates a lot of his experience as being associated with PA,
where I will readily conced that the rules are quite different!
-- 
|                Dick Pierce                |
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