BI WIRE EXPERIENCE DARK SIDE

FWIW, I would disagree with the statement in the Audioquest paper that was referenced by Tony (Tls49). That statement being:

When BiWiring, the two (bass and treble) cables must either be identical, or have essentially identical geometries. If the cables have different geometries they will have different capacitance and inductance. Capacitance and inductance are the values used to create a loudspeaker’s low-pass and high-pass filter networks, together making a crossover. Having different values in the two cables effectively redesigns the crossover...not a good thing! The integrity and coherence of the speaker will be compromised.

As is often the case in cable marketing literature, effects are claimed as being audibly significant without being put into quantitative perspective.

The value of the capacitors in speaker crossovers are typically in the area of several microfarads (uf) or more, and generally have tolerances (sample-to-sample variations) in the area of +/- 3% to 5% or even more. The capacitance of most speaker cables of reasonable length will be in the rough vicinity of 0.01% of several uf. Which is not only a miniscule fraction of the value of the crossover capacitors, but is even a miniscule fraction of the variations in capacitance between supposedly identical capacitors.

In the case of a few speaker cables having extremely high capacitance, such as Goertz, the 0.01% figure may increase to the point of being a significant fraction of 1%, but it will still be much lower than variations among supposedly identical capacitors.

Likewise for inductance. Although the inductance of different speaker cables can differ considerably, as a rough order of magnitude it can be assumed that the inductance of a 10 foot length of speaker cable will often fall in the rough vicinity of 1 to 3 microHenries (uH) or thereabouts, and in some cases will be much less than that. That is a negligible fraction of the inductance of nearly all crossover inductors.

Which is not to say that cable inductance is necessarily insignificant. If speaker impedance is low at high frequencies, as it especially tends to be with electrostatic speakers for example, the impedance presented by the inductance of some cables at those high frequencies may be audibly significant (as the impedance presented by an inductance increases in proportion to frequency). However, that would have nothing to do with whether the low frequency cable has the same inductance or a different inductance than the high frequency cable.

The bottom line: **If** in fact it is preferable to use identical high frequency and low frequency cables when biwiring, it is not because of the reason stated in the Audioquest paper.

IMO. Regards,
-- Al

04-05-15: Springbok10
Almarg, do you believe that is harmful, for instance to use a copper cable such as Cardas Golden Cross on high frequencies and Clear Day, silver, on low frequencies?

Not necessarily, Denis. Consider, for example, that some highly regarded manufacturers of amplifiers and speakers suggest that in situations where tube amps are being used it may sometimes be desirable to use different amplifier taps for the highs and the lows. That certainly figures to have more of an effect on differences between the highs and the lows than the type of metal that is used in the speaker cables. Different amplifier taps have significantly different signal voltages on them.

That said, if the impedance of the low frequency section of the speaker is low, and/or if the length of the cable is long, personally I'd be hesitant to use a silver cable such as Clear Day for that connection, at least in anything less than the double shotgun version. The relatively narrow gauge of the lesser versions, and of some of the silver speaker cables from other manufacturers, IMO can result in a high enough resistance to be a concern under those circumstances. The opinions of others about that may differ in some cases, but given that the resistance of copper is only about 6 to 8% higher than the resistance of silver, for equal gauge and length, if those other opinions are correct there would seem to be no need for the very heavy gauges of the copper cables many audiophiles use. (Increasing the diameter of a conductor by just one gauge size reduces its resistance by about 20%).

Best regards,
-- Al

DB, the only way I can envision that causing any damage, especially given that you will be keeping the volume low, would be if the amp happened to be on the verge of failing anyway, and doing that would put it over the edge.

I wouldn't totally rule out the possibility, though, that the amp's short circuit protection mechanisms, as mentioned in the manual, might interpret the combined loads as being a short, and shut down the amp. I say that in particular because the impedance curve of the LS50, as shown here, dips to 4 ohms around 200 Hz. So the combined impedances would be seen by the amp as about 2 ohms around that frequency. The fact that you would be connecting to the MF/HF terminals of the mains doesn't change that.

My guess, though, is that there would be no problem at all.

Regards,
-- Al