Bi-wiring

[Ian Mackenzie]

In audio we call that the dampening factor. The higher the number, supposedly the better equipped
is the amp to deal with counter EMF. Its the whole mass in motion thing, the woofer becoming a generator as its phisical motion goes out of phase with the output waveform.

Woofers can and do receive, and generate large amounts of current.

The bi-wire sceme wishes to let the amp deal with the counter EMF, as the shortest path to ground state, leaving the HF cables out of the picture, and the signal less effected,,, even though it is still connected to the same amp.

For the same reason, phones and computers have their own tap off the step-down transformers, somewhat isolating them from all the high current antics caused by the machinery on the shop floor.

1audiohack.

I think your closer to a plausible theory than perhaps some of the other responses.

Its important to realise even a speaker cable has finite impediance.

If you have a bunch of filters daisy chained in parrellel along that length of cable with their loads producing a back e.m.f then the farthest point on the cable with a filter is most likely to be a point that is modulated by the previous load along that length of cable.

By offering each load its own dedicated cable back the reference voltage source (zero ohms) then in theory there is less possibility of modulation of the other loads. Of course the whole idea falls over if the amp reacts to the back emf.

I should point out solid most amps with large amounts negative feedback have a low output impediance at low frequencies. They can however be influenced by load characteristics because of stability or what might be call transient response damping to reactive loads as a result of large negative feedabck ratios.

I am less convinced of the idea of seperate cables for corresponding frequencies unless you have the crossover filter at the amp end of the cable.

In reality I confess to using Zilch's cat 5 twisted ends cable to biwire my JBLs when I am too lazy to biamp.

Ian

[jblnut]

I think the largest gains to be made here come from being able to use different amps for the highs and lows.
I'm not alone in using a large transistor amp for the lows and a smaller (two mono amps in my case) tube amp for the highs. It's great that many of the larger, newer JBLs allow for this type of configuration. I've not swapped out my speaker wire or tried anything different on the high end. I'm not a huge "cable guy" and I feel the money is better spent elsewhere.

jblnut

[Harkness]

it's a bit of a strange article, as it seems to suggest some of the benefits of bi-amping will occur with bi-wiring.

personally i think bi-wiring only makes sense in a single (stereo) amp situation. otherwise you are better off splitting the signal before it gets to the amps to avoid wasting amp power on frequencies that will be filtered out at the crossover.

no point in using a sweet little tube amp(s) for mids and highs and then sending a full-range signal through it. the bass range will eat up a lot of the amp headroom unnecessarily.

[jblnut]

Is this really the case ? My knowledge of such things is admittedly limited, but I believe that tube amp will not be called upon to deliver bass frequencies because the crossover network that the mids and tweeter are attached to will filter out anything that low. I can tell you that in practice the setup works extremely well. The tube amps are able to keep up with the transistor amp driving the low end, even though they only have 1/4 of its rated power. When I drive the system full range with only the tube amps, the output is far lower becuase they are now acutally powering the woofer.


jblnut

it's a bit of a strange article, as it seems to suggest some of the benefits of bi-amping will occur with bi-wiring.

personally i think bi-wiring only makes sense in a single (stereo) amp situation. otherwise you are better off splitting the signal before it gets to the amps to avoid wasting amp power on frequencies that will be filtered out at the crossover.

no point in using a sweet little tube amp(s) for mids and highs and then sending a full-range signal through it. the bass range will eat up a lot of the amp headroom unnecessarily.