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Bi-Wiring Configurations

205.139.187.21
Posted on July 12, 1999 at 11:50:02
Ken


 
I recently bought a new pair of Paradigm Monitor 9s and then decided to upgrade my cables, interconnects, etc. to get the most out of the speakers. My primary system consists of a Rotel RC-980BC preamp, Rotel RB-970BX amp, and Velodyne 1215X sub.

I bought 50 feet of Cu 8-strand single sheath cable for the high end and 50 ft of Ag coated Cu 16-strand double sheath cable (the 16 individual sheathed strand are encased in 1 overall sheath) for the low end (Apature 16). Each of dealers I have been working w/ have said that I should have one cable dedicated to the high end and one to the low end.

The Paradigm bi-wiring instructions recommended wiring one set of cable to the negative and one set to the positive terminals, thus splitting the cable between the high and low end. I noticed a tremendous difference in the imaging and clarity after bi-wiring (I had been using 12-gauge single wire monster cable).

The question is should I separate the cables and dedicate to the either the low or high frequencies or leave the configuration split as displayed by Paradigm in the users manual. Paradigm probably assumed that the same cable material would be used throughout.

My only concern about dedicating a line to each frequency range is that my 16-wire cable does not have a clear color coded scheme to seperate the pos and neg. They are all different colors, 7 w/ stripes, 5 solid. I have seperated them and am confident that I was consistent w/ my wire grouping but would rather not test it if I don't have to.

Any thought on this issue would be greatly appreciated. Thanks.

Ken


 

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Re: Bi-Wiring Configurations, posted on July 12, 1999 at 13:38:40
Rob Bertrando


 
One thing I always wonder about, is why so many bi-wired setups have the larger gauge wire for the bass, and the smaller for the highs. It should be exactly the reverse, I would think, since skin effect is more pronounced at higher frequencies, and that is the main rationale for larger gauge wire (I think).

 

Re: Bi-Wiring Configurations, posted on July 12, 1999 at 19:29:20
Ken


 
I think the larger wire recommendation is mainly because most people think that the low end requires more power to drive, thus a hardier cable. I have been told that that is not necessarily true and that high frequency peaks require a lot of extra power to produce a distortion free signal. Another consideration is that since I was using Ag coated Cu, it could make my speakers a little brighter sounding than I like. My amp is already a little on the bright side. Maybe I should switch and see how it sounds, especially since I have a good sub for everything below 80 hz.

Ken

 

Re: Bi-Wiring Configurations, posted on July 12, 1999 at 21:16:02
Jon Risch


 
[ The Paradigm bi-wiring instructions recommended wiring one set of cable to the negative and one set to the positive terminals, thus splitting the cable between the high and low end. ]

If by this you mean having one cable used for the HF section, and one for the LF section, then this is normal bi-wiring practice.

If however, you mean that one cable is used for the negatives, and one cable is used for the positives, this is not typical, and would cause a great increase in inductance, and would loose most of the benefits of biwiring. If this is how you have your speakers hooked-up, then read the bottom section of this post:
/audio/cables/messages/17.html
its a long one, so run the bar down to about the 1/3 point and then start scrolling slowly till you see "Biwiring 101".

Just in case it is still not clear, let me spell it out. On a bi-wire capable speaker, there should be two pairs of terminals, one HF pair (Pos & Neg), and one LF pair (Pos & Neg).. When the speaker is not bi-amped, there is a set of jumpers that run between the two Pos terminals, and a jumper betweeen the two Neg terminals. When you bi-wire, those jumpers are removed, and the LF and HF sections of the crossover are completely separated electrically. You now would hook up the cable chosen for the lows to the LF pair of terminals, and the cable chosen for the highs to the HF pair of terminals, and you would want to keep the two cables physically separated along the run back to the amp by at least 6-8 inches (all the while keeping both away from metal objects, but especially steel).

As for which cable to use for the lows and which for the highs, that is a matter of personal preference in many cases. In your case, theory suggests that you would be better served with the 16 wire cable on the woofer, using 8 wires for the Pos connection , and 8 for the Neg connection, preferably with the Pos and Neg interleaved. If the cable is a ribbon, and the wires are all in a row, interleaving would have them alternate polarity, just be sure to connect the same wires to the Pos and to the Neg at both ends, use an ohmmeter or what ever method you must to assure this.

If the cable is a circle of 16 wires, then again, having the polarites interleaved, first Pos, then Neg, then Pos, then Neg, will reduce inductance to a minimum, and mantain maximum control over the woofer.

The same goes for the 8 wire cable, interleave the wires for lowest inductance, and the best transient response.

Normally, you would want to use the lowest DCR cable for the woofer, and the lowest inductance cable for the highs. It is also typical for silver plated wires to sound a bit bright, so I would not recommend the 16 wire cable for the highs due to this.

Larger wires have more HF roll-off relative to their bass transmission than smaller wires, so the way you speak of using the cables sounds like the way to go.

Jon Risch

 

Re: Bi-Wiring Configurations, posted on July 12, 1999 at 21:19:48
PEB


 
(PEB): I think the first thing you've discovered is how much better inidividually-insulated solid core wire sounds than stranded wire of any gauge. IOW, I give more credit to the geometry/construction than the bi-wiring.

As far as gauge application is concerned, the larger wire is used for bass in order to carry more current to the woofer. The smaller equivalent gauge wire is fine for the tweeter.

As far as skin effect, this phenomenon is worse with larger wire. (Which is partially what the Monster 12 was doing.) Again, the smaller wire is better for the tweeter. If one had to actually deliver a lot of power at high frequencies, the cable would actually be a very large Cu coax construction with the inner conductor being a thin-walled tube!

 

Re: Bi-Wiring Configurations, posted on July 14, 1999 at 15:26:07
Thom


 
The opposite is true. In any conductor, the higher frequencies tend to propagate closer to the surface of the conductor (skin). In a single large gauge conductor of multiple frequencies, this allows for a diffence in propagation rate in time and phase for the high vs the low frequencies conducted in the same wire. Small wires have less diameter, so for a given skin depth, all frequencies now have less tendency to conduct at different rates. (Some will argue that skin effect is of no concern at audio frequencies, but my ears hear the difference. Psycho or not ... my .02 worth.) The ideal conductor would have a gauge radius exactly equal to the skin depth as required for the frequency conducted. Since a compromise must be made, ala KimberKable, often multiple conductors of increasing size are used to provide an "ideal" gauge for a group of frequencies. Tantamount to this concept is the fact that a smaller wire has a higher resistance per foot and less current capacity, so multiple conductors are utilized to satisfy the total gauge of conductor needed to supply the current requirements of the low frequency drivers.

Yes... the higher current requirements of bass reproduction require a larger conductor than higher frequencies. Large conductors = lower resistance per foot. High current times high series resistance = voltage drop along the conductor. We prefer all the voltage be available to the driver. Skin effect is of no concern and copper mass (read Romex) is the important parameter. This is why you often see high powered bi-polar SS amps in the 200-300 watt range driving subwoofers and 30-60 watt tube amps driving the midrange and treble in bi-amp (or tri-amped) systems. In a true bi or tri-amp situation, the subwoofer crossover region is way below the critical midrange and differing amplifying systems that would be interactive (and audible) at 1000 Hz are inaudible at 80 Hz and below. In a bi-wired system, with the crossover region typically much higher than 80-100 Hz, only one amp, or two identical amps, would be highly preferred.


Thom

 

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