Something doesn't seem right about this...

If these wires are next to each other, the incoming signal (+) will be affected by the outgoing (-) won't it?

Yes, it will. The result of that will be a reduction in inductance, which is generally a good thing.

As described in this Wikipedia writeup, "a changing electric current through a circuit that contains inductance induces a proportional voltage, which opposes the change in current (self-inductance). The varying field in this circuit may also induce an e.m.f. in neighbouring circuits (mutual inductance)."

So the voltage induced by the current flowing in one conductor, which would tend to oppose rapid changes in current flow (i.e., which would tend to attenuate high frequencies), will be partially cancelled by the equal and opposite voltage induced by the current flowing in the other direction in the other conductor. Which amounts to a reduction in inductance, and therefore a reduction in the degree to which rapid changes in current flow will be opposed, compared to the situation where the two conductors are separated.

Regards,
-- Al

Here is a link to a good primer on cable design, and what is going on electrically. It's on a cable manufacture's website, but it is not pseudo science.

http://www.absolutefidelity.com/thedesign.html

Two wires, positive and negative, together reduce electromagnetic and capacitive noise pickup. They also reduce noise radiated from these wires. It is because noise is being picked-up (or radiated) by both wires that are at opposite polarities thus cancelling. Twisting wires greatly helps because both wires are exposed more evenly to external fields. Speaker output is also (in most cases) an input to amplifier and wire acts as antenna for noise.

Twisting wires reduces inductance, as Al stated, but also increases capacitance. In case of the speaker wire capacitance does not play as much role as inductance. In interconnects it is just the opposite but twisting is still used to reduce noise pickup.

Are you guys suggesting that it can be a good thing to have the + and - speaker cables together and/or twisted? I have a pair of Tara speaker cables that separates them. They give you 4 separate runs of cable.

Hi ZD,

I agree completely with all of the comments Kijanki provided, as I usually do. (My response was narrowly focused on interaction between the signal currents flowing in the two conductors, which appeared to be what the OP was asking about). And, yes, we are saying that it CAN be a good thing for the two conductors to be twisted together.

I have no particular familiarity with the Tara speaker cables, but presumably if some of their models keep the + and - conductors separate their designs are either giving priority to factors other than those that have been mentioned, or are controlling those factors in ways other than by twisting.

Best regards, and happy holidays!

-- Al