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Bi-wiring 101


Soundthought

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I've been doing my homework on bi-wiring and I thought I might pass along my findings for all to see.

Bi-Wiring

First, let me say that bi-wiring is really only affective if the loudspeaker has bi-wiring capability.

Some speakers have bi-wiring capability and are easily identified by four binding posts on the speakers' input cup.

Bi-wiring effectively isolates undesirable electrical feedback known as Back EMF, and channels it safely away from the speaker.

Bi-wiring is recommended for cleaner, more refined mid and high frequency performance as well as improved dynamic range.

In speakers with bi-wire capability, the crossover networks electrically isolate their low and high frequency sections, connecting them only at the input cup on the back of the speaker.

When bi-wiring, Back EMF from the woofer is prevented from interaction with the midrange and/or tweeter, and is instead channeled back to the output terminals of the amp or reciever.

There, it can be eliminated by the inherently superior grounding and damping capability of the amplifier output section.

To bi-wire, you need 4 pairs of speaker wires.

2 pairs running from each amp output to each speaker. One set for LF, one for HF.

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  • 7 months later...

minn male, they sell "bi wire" cables, which is just a normal looking cable that splits into the 4 that you need. when you buy them like this sometimes the HF cables are optimized to work with high frequency tones, and the LF cables for the lows. this is one of the advantages- that you can have optimized cables for each frequency band.

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ok...

i don't want to spend some big bucks for an experiment....how are these cables configured? what are the gauges?..solid or stranded?

i work at an electronics distributor...we have over a million feet of cable in our building...i plan to make this cable myself...

anyone have some experience with this??

russ

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Russ- It's just differing designs based on specific engineering goals/theories.

The concept really relates to the idea that HF is naturally going to gravitate to the thinner gauge cable, be it solid or stranded, in a multi cable run.

The reason I use solid is because of certain properties of cable theory suggest that a smooth surface solid conductor works best for this application. (smooth suface theory)

Plus, my own experience with bi-wiring has lead me to believe that solid core cable yields the best results.

John

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The theory behind wire types is simply this:

Stranded = more flexible and less resistant to breaking if moved a fair bit BUT.... not good for in wall use as it can be damaged by moist conditions more easily than solid conductor wire ect...

Solid = less flexible and less resistant to movement breakage but is more commonly used in walls/behind vapor barriers as it handles moisture better (does not tarnish as much ie: greenish color)

Oh, and another thing, have a look at your copper pipes in your basement, are they somewhat greenish/bluish in color in some spots? That is a sign of radon gasses in your basement.... just FYI :)

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Thanks for a reasonable explanation of bi-wiring.

If I purchase the specialized cables for lo-freq and hi-freq and wire the things backwards, will I get a frequency response of 100hz-1Khz?

Are we SURE this isn't snake oil to sell more $$$ cables??

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I took the chance when I ordered MIT Terminator2 Bi-Wire cables from Audio Advisor a little over a year ago. They exceeded my expectations nicely in the "sound improvement" catagory. They are just about as big around as a garden hose from the amp as they use VERY STIFF solid core from the "magic boxes" to the speaker's binding terminals.

Audio Advisor has them for about 1/2 off MSRP.

FWIW- I remember reading somewhere on the net that the greater the resistance between the LF and HF drivers the more the improvement can be heard.

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Actually, it IS radon gas... if you do some hunting on the subject this is one of the possible trouble signs. Copper does turn color from oxygen yes... but it also does this from radon gasses collecting in the basement... Trust me.. I did some research....

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Yeah, he told me that the HF electrons will move faster down the thinner wire than the LF electrons going down the thicker wire. Said to make it about a foot longer to compensate for the difference in time it takes...9.gif

Eh... I dunno, thats what he said anyway. He could be wrong for all I know. It seemed logical to me.

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Huh...I could see it.

The foot thing is probably relative to the specific length of the cable run your making.

The longer the run the longer the gap between the HF cable and the LF should be.

I wonder if there is a formula for that.

Although, I would imagine that if someone designs a bi-wirable crossover network, they would take in consideration specific frequency arrival times.

I don't know.

I've read countless articles about having the terminations the exact same length.

My guess is that most if not all engineered crossover networks are designed in conjunction with a loudspeakers'driver alignment to compensate for those time differences in an evenly terminated cable.

Be it bi-wired or not.

FWIW. Bi-wiring doesn't nesessarily separate the HF from the LF.

It does aid in natural separation by allowing two different size pathways/surfaces for a signal to flow.

I believe the principle behind a small gauge for HF relates to natural resistance the LF is going to have when choosing a path way from the amp outputs to the speaker.

It seems to me, the bulk of the LF range will choose the path of least resistance, that being the larger cable.

The HF at its highest freqencies rides on the surface of the conductors, so the thinner cable would be able to accomodate more HF harmonics and less LF energy by nature.

That in turn lessens the load on the crossovers' networks.

This is where bi-wiring becomes most efffective. (better damping properties aside)

Bi-wiring halves the load on the crossover allowing each section of a two way loudspeaker to focus on rolling off a frequency range one way or the other.

The easier you can make it for the crossovers to do their job, the better the end result will be.

In the near future, there will amplifiers with HF-LF speaker outputs.

Frankly, i'm surprized there isn't already.

Heh Heh...

Maybe there is and i'm just out of the loop.9.gif

Regards,

John.

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