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Cobalt cable theory on bi-wiring. Fact or fiction?

The follow was taken from colbalt cables web site. I was just wondering what those with more knowledge and experience think of this theory? If the theory is sound, it will save alot of people some money for more component upgrades. "Bi-wiring is a technique becoming quite popular in speaker applications. However, in our opinion, there are only a few situations where bi-wiring makes sense and MANY situations where bi-wiring is just hype. Here is what we think the complete story is about bi-wiring, and why it really does not make any sense for most people's equipment. The simple explanation for why the advantages of bi-wiring are very slight or nonexistent is that most people only have speakers built for bi-wiring, while their amplification is not. By using the same amplifier channel for both sets of bi-wire cables (both sets are connected to the same binding posts on the amplifier or receiver), the same electrical path is being used for both sets of terminals on each speaker, thus negating the core advantages of bi-wiring.

For example, most bi-wireable (we invented a new word) speakers come with some sort of plate or bar that connects the two (+) and the two (-) terminals (one for high frequency and one for low frequency) to each other. By using these plates or bars, you are "bridging" the two sets of terminals together creating only one connection point, so that you only need to make one speaker connection to each speaker.

By using the same amplifier channel (and terminals) for each set of bi-wire terminals on your speakers, you would be bridging the two sets of terminals together with your amplifier (since they share the same connection point on the amplifier). From an electrical perspective, this is NO different than running one speaker cable to the speaker, and bridging the two sets of terminals together with the bar or plate.

But wait, there's more! If you act now... (just kidding).

The only advantage in most setups (only speakers built for bi-wiring) for bi-wiring would be using twice as much physical wire (two separate runs to each speaker, thus dropping three gauge) as a standard wiring configuration.
However, if you are already using a fairly low gauge speaker cable (like our 10 AWG Ultimate Speaker Cable), there is little to be gained by "doubling-up". Plus, the added expense of running twice as much speaker cable for a barely audible (at best) difference, probably does not make too much sense.

The funny thing is, bi-wiring is actually a sound theory (pun intended, HA!), but the advantages can really only be had when it is used in conjunction with bi-amping (running more than one amplifier channel per speaker). In order to bi-amp the "right way", an external crossover between the preamplifier and each amplifier channel will be needed (so that only the high-frequency or the low-frequency parts of the signal will be amplified), and the internal crossovers inside the speakers will need to be disconnected (so that each amplifier will go directly to the corresponding speaker driver, i.e. the woofer for low frequency and the tweeter for high-frequency). WHEW! We personally don't know of too many people who will go to these extremes to take advantage of the benefits of bi-wiring, so bi-wiring just ends up getting WAY more attention than it should. We think that you should know what some of these other companies are up to out there. Straight-up and at ya partner."




dbx
zoya
120 posts
 
I just had to put my 2c in. To understand the benefit of the biwiring you have to realize that speaker wires are not ideal conductors and low and high frequencies have different effects on the wire.
Low frequency signal carries most of the current, and high current means high magnetic fields around the wire.
High frequencies are more affected by the capacitance of the dielectric material.
So, by making low and high frequency signals travel separately from amp to the speaker terminals they have less interference on each other and each part of the speaker cable can be designed for the optimal performance in their frequency range.
I hope this answers some questions.
eldartford
4,262 posts
 
There is some theoretical effect (could be improvement or degradation) due to bi-wiring. It relates to the small signal that exists at the common (-) terminal of the speaker as a result of the impedance of the speaker wire. If you don't bi-wire, the tweeter signal is referenced to the voltage at the low end of the woofer, which may be slightly different from the voltage (ground) at the amp. Because the woofer is a complex load (not purely resistive) this error signal is not just an attenuated version of the music signal.

All this is just theory, but it is the only scientific reason that I have found to suggest that bi-wire has any effect at all. Note that it suggests that only the return wire (-) needs to be doubled up, and also that use of very heavy wire will eliminate the effect (resistance goes to zero). In fact, this effect may explain why heavy wire sounds better for a mono-wire connection.

If one were to experiment with bi-wire, I suggest that you use very small wire (say #30) so as to aggravate the effect (when mono-wired) enough to be clearly heard.

PS: My Maggies are bi-wired. It was an experiment, using #24 wire for the tweeter so as to replace the 1 ohm tweeter padding resistor with cable resistance. It's hard to say if there was an improvement, but certainly no degradation so I have left these wires in place.
zaikesman
3,017 posts
 
Zoya, it has always seemed to me that for your position (sorry to refer to it that way, I know it's not an original idea with you) to even stand a chance of making any 'sense', one must first buy into the proposition that in a biwire setup, the amp will somehow discriminate between which frequencies it sends through which cables - *and* that the so-called 'back-EMF' generated by the woofer will decline to find its way into the cable connected to the tweeter upon its arriving back at the amp's output terminals, even though at that point the two sets of cables are in intimate contact with each other.

I don't buy any of that, although I freely admit I'm not technically competent to scientifically evaluate all the arguments (much less Eldartford's post :-) It seems to me that even in a biwire setup, the tweeter and woofer sections will still 'see' each other - plus both runs of cable, whether or not the two runs are endowed with differing physical/electrical properties - within the overall amp/cable/speaker circuit.

Speaking of Eldartford, until recently I wouldn't have though twice about his passing comment on heavier-guage wire sounding better, all other things being equal (whether that was achieved through biwiring or simply employing a heavier single run). But that was before I brought in a set of Audience's Au24 SC for audition, wherein the wire for both legs of the connection plus all the dielectric and jacketing materials are bundled into a cable exactly 1/8" thick, or about the diameter of your average computer mouse cord. I think all the positive notice this product has been receiving is probably justified, and Audience's theory here, as I understand it, is that AC resistance, which they equate with inductance, is most important (along with capacitance) to minimize in an audio circuit - as opposed to DC resistance - providing that the wire guage is sufficient to handle the current-carrying demands made upon it.

I'm not qualified to speculate on Audience's theory of their product's operation, but though I'm still not finished in my testing, I can tell you that compared to my reference Satori SC (a fine cable - maybe even preferable for those seeking warmth - next to which the puny Au24 looks simply comical), bass response does not seem to have suffered (though its presentation is different), and top-to-bottom clarity and overall temporal integrity seem to have improved. (I should note, however, that my most positive impressions have been with the cable mated to my reference VTL tubed amps ; when I initially did this comparison using a McCormack SS amp and the same speakers, I thought I preferred the Satori overall, but I need to revisit this issue now that the cables are more fully broken-in.)
eldartford
4,262 posts
 
Zaikesman...True that Impedance (not just resistance) matters. However, low resistance is a big step in the right direction, and much easier and cheaper to do than Inductance minimization.

I still think that the best approach is to minimize everything with wires about one foot long! (Monoblock amps).
jetkitty
53 posts
 
I will not even attempt to participate in the technical analysis of the merits of bi-wiring. What I want to add is that I can definitely hear a difference, and - yes - I have participated in 'blind' listening experiments to confirm this.

Of course, one cannot argue with those individuals that state that they can't hear a difference. If bi-wiring doesn't improve your sound, then don't spend $$$ to do it!
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