By Jack Sharkey, October 17, 2018
Hopefully this article will clear up some misconceptions about bi-wiring and help you make your best decision when setting up your system.
In a bi-wired system the single output of the amplifier is connected separately to the MF/HF crossover and the LF crossover using separate terminals for each on the back of the loudspeaker.
Electrical current will pick the path of least resistance (or in this case least impedance).
The cable connecting the MF/HF signals presents a higher impedance to the amplifier during low frequency passages.
The cable connecting the LF signal presents a higher impedance to the amplifier during high- and mid-frequency passages.
Because of this electrical reactance, the separation induced by the cables creates a de facto high- or low-pass filter, depending on which frequency we are talking about. Therefore, high frequencies will naturally tend to travel through the cable connected to the MF/HF crossover and low frequencies will travel through the cable connected to the LF crossover.
Many knowledgeable people swear by bi-wiring and they back it up with science: namely the Hall Effect.
Hall Effect is the magnetic field developed across a conductor that is transverse (perpendicular) to the voltage on that conductor blah blah blah and is defined as the ratio of the induced electric field to the blah blah magnetic field and something to do with electrons, holes and ions and other stuff Edwin Hall discovered in 1879 but nobody cared about until it totally messed up early semiconductors seventy-five years later.
Basically, electrical conductors (in this case cables) become magnetically charged because of the electrical energy running through them. That’s why you're never supposed to run cables parallel and perpendicular to each other – it’s actually better for your cables to be a giant disorderly mess than an aesthetically pleasing array of neatness.
Proponents of bi-wiring claim the MF and HF benefit the most because the low current MF and HF signals do not have to travel on the same wire as the high-current LF energy. This leaves the HF and MF free from the disruption caused by the high-current LF field fluctuations and CEMF (Counter Electro-Motive Force).
Proponents of bi-wiring also claim you can choose cables specifically designed for specific frequencies, further enhancing your sonic reproduction. Personally, I totally disagree with this which I’ll detail later in this article.
Others claim you can hear enhanced airiness and a more well-defined soundstage with bi-wiring. I have experienced this, but in some setups every song I listened to – regardless of the production and mix – started to sound identically airy so I'm not sure if I was listening to an improvement or some effect caused by components or cables in the system.
People who scoff at bi-wiring maintain that there is no electrical difference between a run of standard gauge cable from your amp to the two terminals on a speaker cabinet and a single run of cable from the amp to one terminal that then splits the signals before sending them to their respective crossovers. Meaning that if bi-wiring was a thing your speaker's terminal plate would perform the same function as two separate cable runs.
CEMF from the bass driver is not an issue because it will be at such a small current (and at the same frequency the woofer just produced) that any current washing back into the crossover circuit will be either inconsequential or filtered out by the MF/HF crossover (like it was designed to do).
Due to skin effect on the cable, higher frequencies tend to travel on the outside of the cable and lower frequencies on the inside. Take this argument with a grain of salt because skin effect doesn’t really kick in as a nuisance until much, much higher frequencies than those in the audio range.
And anyway, that's why you need a crossover in the first place: To separate all of those busy little signals from each other into frequencies each specific driver can reproduce.
Is Bi-Wiring Better Or Not?
Yes. And No. Probably. Maybe. It depends on who you talk to. Half the people you talk to will swear by it, half the people you talk to will ridicule you for even thinking about it, and the rest will offer no opinion whatsoever.
Higher-end loudspeakers generally come with two sets of terminals and two distinct signal paths to the crossovers because the end-user deserves the opportunity to figure out what sounds better for themselves.
At the electron level there is merit to the argument that the signals created by a cymbal will find their own path on a cable separate from the signal created by a kick drum.
I have experienced a difference with bi-wiring compared to mono-wiring that was pure and definable, but I have also heard bi-wired systems I found distracting and somewhat unpleasant.
This all brings us back to the constant struggle in the audio world: separating the subjective data our brains think our ears are hearing from the actual physics of what we hear.
Because of the physics involved I am a proponent of bi-wiring. Regardless of your setup you will derive some level of benefit from bi-wiring – the catch is will you actually hear the improvement? There are so many factors involved when we are talking about these subtle kinds of changes that unless you’re really tuned in to what you are listening to, you may not experience what you hear the same way someone else does.
Bi-Wire Or Not, Here Are Some Best Practices To Help You Get the Best Sound Possible
Regardless of whether you bi-wire or mono-wire your system, your speaker cables should be the same length. Cable runs of differing lengths can present phasing issues and imaging deficiencies.
To reduce noise along the way, the shorter your speaker cables the better. If necessary for aesthetics it's better for your line-level cables and interconnects to be longer so you can make your speaker runs as short as possible.
Use the same type cable for all runs, whether you are going bi-wire or mono-wire. Different cables may have different physical characteristics and those differences may result in sonic inconsistencies. In the frequency ranges we're talking about, a cable that transmits 80Hz well will very likely transmit 10,500Hz equally well, but a cable that has more of one type of metal in it may wind up sounding completely different when compared to a cable with a different physical makeup.
Use the best quality cable you can afford, not less and not more, and never use smaller than 14AWG cable (higher number - 16AWG is smaller than 14AWG) for a standard loudspeaker setup. Smaller gauges can be used for rear channels in small systems or for certain custom installation configurations like sub-6" speakers in low-power systems.
It's not a big technical challenge to experiment with bi-wiring and all you'll be risking financially is another set of cable runs. Have some fun, try it out (do your A to B comparisons with the same music). Maybe you'll love it, maybe you'll hate it, or maybe you won't hear any difference.
I really can't tell you anything more than that. I bi-wire when possible, but there have been many times when I was unable to discern a difference between the two wiring methods.
KEF offers bi-wire/bi-amplification terminals on most of its passive product to give our customers the options they may want, so have at it. Maybe you'll hear something you like.