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bi-amping and effect on cross over

I am trying to understand the effect bi-amping a speaker will have on the designed specs of how a cross over should work. Dynaudio, for instance, does not offer up dual(or triple) binding posts because they feel bi-amping would negatively effect the way their cross over is designed to work.

with my simple knowledge of the way a speaker crossover works, it sort of makes sense to me that the speaker should "see" one amp connection and then shift highs and lows to tweeter/mid and woofer as needed. I am sure i am missing an understanding of how a crossover can compensate for bi-amping (and give the same designed crossover slope/effect but with more current to each driver). Would love some clarity. thanks.
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eldartford
4,262 posts
 
If you just use separate power amps for input to the high and low sections of the internal crossover (do not use a line level crossover) the two amps will output identical signals, so the crossover won't know the difference from using one amp.

True biamping involves use of a line level crossover feeding different signals, high and low, to two power amps. Dynaudio probably has elements in its passive crossover which the typical line level crossover won't duplicate, hence their discouragement of biamping.
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dangelod OP
40 posts
 
thanks. very helpful.
bombaywalla's avatar
bombaywalla
1,958 posts
 
From limited experience I have noticed that x-overs use both large C & L values. In those manuf that do not believe in biamping &/or biwiring, these manuf have used the combination of the large L & C value to effectively resonante each other out so that, at the input to the speaker, the amplifier sees a (mostly) resistive load.
Now, if you split the low & high x-over ckts, the large L no longer sees the large C & the large C no longer sees the large L. Thus, in the bass region the amp has to drive a large L & in the highs the amp has to drive a large C. Both of these conditions could render the amp unstable & the speaker manuf would rather avoid this situation.
shadorne's avatar
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shadorne
7,477 posts
 
They might be using a series crossover design. This woudl explain why they don't allow biamping.
eldartford
4,262 posts
 
Bombaywalla...An interesting observation. Of course the inductor and capacitor values are determined by the desired crossover frequency, not any consideration of overall inductance. This can't be a real-world problem because so many people are using this setup, which I call pseudo-biamping. (Real biamping uses a line level crossover).

Shadorne is also correct, although very few speakers use series configuration crossovers.
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