B-wire - four cables or jumpers?


I have a pair of speakers for which the crossovers are specifically optimised for bi-wiring/bi-amping (Von Schweikert VR5s). As the singal current reaching the speakers comes from an identiscl source, namely the amp teminals, what is the difference between running a second set of cables from the amp, as opposed to using jumpers between the input terminals on the speakers? It seems to my uneducated electronic mind that the only differnce is in the length of the second set, as the signal is merely taken from the speaker terminals, rather than the amp terminals.

If that is so, then what is the sonic (realtime audible) advantage in spending twice the amount of money to run two sets of cables from the amp?

This really puzzels me!
brianjh

Showing 2 responses by brianjh

Yes Rockvergo, I agree all the current passes down the cable. but the high and low frequencies are split at the crossover, not at the amp or the speaker binding posts. I know some say a low frequency signal will follow the line of least resistance, and that this is an arguement for mixing stranded and solid core conductors in the same cable. Hence it would, if this is really true, make sense that the second pair of a bi-wired set (the woofer pair)should be of a larger cross-sectional area (and therefore have greater current carrying capacity?) than the pair going to the mid/treble section. However, many very high quality cables do not do this, eg Nordost for one. And in any case, this could also be applied to the jumper leads.

So my basic puzzlement remains: if the current arriving at the speaker binding post is the same as that leaving the amp - which it is - then apart from the length, aren't the jumper leads simply acting as a second pair of cables in a bi-wired system?

I will check out the sites suggested by Bomarc and Audio_Buff, to see if these articles throw any light on this.
Hmm... it's a long long time since I did any physics, but I seem to recall being told that current is like water and finds its own level. The signal is "carried" by the current I suppose as a modualated sine wave and when it reaches the loadspeaker voice coil is converted back into mechaical energy which vibrates the diaphram and appears as sound waves. I guess the current per se keeps on flowing round the circuit provided the circiut is closed, ie the mains is switched on, and there's an input signal being created.

That sounds a bit crude, and I don't think it's quite right either. But, nevertheless, the signal arriving at the speaker binding post continues through the binding post down the internal wiring to the crossover. As I understand it, the low, mid, and high, frequencies are filtered and processed by the crossover and proceed to the respective drivers. So what's the point of having another long set of cables from the amp to the second set of binding posts on the speakers, when ostensibly just joining the two sets of posts by jumpers is serving the same function. In other words the signal starts at the amp, is carried to the upper binding posts on the speaker, and via the jumper to the lower binding posts. As far as I recall, because of the hydrostatic nature of electricity, there will be no diminution of current or signal at either set of binding posts. In each case the signal continues through the binding post via the internal wiring to the (in the case of the VR5s) two separate crossover boards, where its filtered (at 3khz and 300khz). I suppose what I am saying is that it seems to me that what happens at the amp end if two sets of cables per speaker are used, is the same as what happens at the speaker end, if jumpers are used: it just takes place at the end of the cable run instead of the beginning.

I've looked at the two suggested sites, but they don't, as far as my maths allows me to determine, address this question. Dielectric parameters etc should be virtually the same using jumpers because of their very short length and the fact they are in essance a continuation of the main cable.

If I had sets of identical cables and jumpers, I would experiement with great vigour! Unfortunately I don't, and here in the UK it's difficult enoough to find dealers willing to let you demo cables without a committment to buy one or another, let alone borrow them for this sort of thing.