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In Reply to: Two questions: MP3 gain, and bi-amping posted by Manuel on July 2, 2002 at 12:44:31:
Manuel,Use the search function to see specific previous posts concerning bi-amping.
I use a hybrid bi-amp system to run my Magnepan MG-20s: MA-1s for the midrange elements and tweeters, and a Bryston 4B solid-state amp for the bass wires. The MG-20 outboard crossover box is used only to block highs from the bass wires. The 6 dB/octave mid/tweeter crossover is accomplished with a small Teflon cap in front of each MA-1.
In my opinion, all capacitors are evil. The bigger they are, the more damage they do to the sound. One big benefit I see from my setup is that the large speaker-level cap in the crossover is replaced in function by the smallest, nicest cap I could find at line-level.
Other benefits include minimizing the MA-1's back-EMF exposure to the bass. Please see the article by Lynn Olson in Vacuum Tube Valley 18, "The Amplifier-Speaker Interface." While I don't agree with everything he says, and he tends to over-burden his discussion with incomplete hints about interactions, he does bring out a basic fact of life: the speaker (and room, as coupled to the speaker drivers) is a resonant electro-mechanical system that stores energy and returns it to the amplifier after significant time delay. Amplifier topology (single-ended, push-pull, complementary bipolar solid-state, FET, Circlotron) determines the scope of the back-EMF interactions within the amplifier, and design details determine the magnitude of the audible results. Thus, most of the tweaks discussed here have to do with minimizing the nonlinearity of circuit segments as they interact with back-EMF.
This tells me there is likely to be much bigger benefit from bi-amping than from crossover component upgrades or selection of a larger amplifier in almost any situation. Of course, the amplifiers selected have to be compatible with the speaker segments: you would not want to use M-60s for low impedance woofers, for example, at least without Paul Speltz' Zeros.
There is also the cost of additional speaker cables. Scrimping on cables nullifies the kind of benefits we expect from this level of tweak. This includes using long leads on Zeros in place of proper cables. However, if we were limited in cable cost, we should not be contemplating a second pair of M-60s.
These are opinions and not based on extensive experimentation. Please take with the usual large single-crystal of NaCl.
-Al
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Follow Ups
- Re: bi-amping - Al Sekela 11:34:34 07/08/02 (1)
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