Braiding vs side by side?

Sorry to butt in here but I can't help myself....As usual, Al, you are a wonderful person to have around. Your advice is always pertinent and detailed. I always learn something from your posts, including this one. Thanks.

I think leaving them separate would let them act as a radio antenna, and may pickup signal interference also.

Thanks for the responses.

Hifihvn, good point. So far the braided seems best but they are still pretty new.

Elizabeth, not sure how good my braiding was. I'll check for uniformity tomorrow and make it so if not.

Al, Cables are 8' in length, speakers are Magnepan 3.6's. I'm using 2 different amps, a pair of Pass XA100.5 monos and (hope you're sitting down) a pair of Cary 805 AE monos. The insulation is very thin teflon. I can try and measure it tomorrow, for now I'd guess 1/32" or less.

I've used this wire on my hi-eff/2 way 8 ohm speakers for years and really like it. It has just one wire per spade and have tried it that way on the Maggies but my friend had a little left over so I had him make up a set using 2 wires per spade wondering if the Maggies would like the extra current. These are so skinny to begin with, looks like it could be 16 ga, maybe even 18 ga. Don't know how much the silver factor fits in.

The Pass and Maggies are a nice match but the Cary has an output impedance of about 1.5 ohms giving it a damping factor of only 3 or 4 into the Maggies. There is a feedback control which if I switch in could reduce the impedance to around .5 but I'd rather not use it. Was wondering if the thicker wire would help the Cary out in the damping dept?

Thanks.

Here is a graph from Stereophiles measurements.
(Can't get the graph to appear but here are their comments)

The speaker's impedance (fig.1) approximates a resistive load of around 4 ohms over much of the audioband. However, there is a slight magnitude peak centered at 1.6kHz, due to the crossover between the ribbon and the midrange diaphragm. The minimum value is 3.3 ohms at 10kHz, which is not going to be problem for any good amplifier to drive, while the increasingly positive electrical phase angle at the top of the audioband is, I assume, due to the residual inductance of the ribbon driver. There is a small wrinkle in the trace between 50Hz and 60Hz, which is probably due to the tuning of the woofer diaphragm.



Fig.1 Magnepan MG3.6/R, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

This can be seen to the left of fig.2, as the big peak in the mid-bass. This is a nearfield measurement, which will exaggerate the behavior of the bass panel.

Tgrisham, thanks very much for the nice words.

Here is a link to the Stereophile measurements on the Maggie that Onemug referred to.

Data for 16 gauge wire can be obtained from this wire gauge table. Plugging the 1.29 mm conductor diameter that it indicates into this calculator yields an inductance of 5.95 uH (microHenries) for the 16 foot round-trip that the signal has to make, based on the worst case assumption that the two conductors are widely spaced.

Based on the formula for inductive reactance (the inductive form of impedance), 2 x pi x f x L, where f is frequency in Hertz and L is inductance in Henries, 5.95 uH corresponds to an inductive reactance of 0.75 ohms at the worst case frequency (20kHz). That verges on being negligible in relation to 4 ohms, taking into account that the phase angles of that reactance and the speaker's impedance differ considerably. (If the angles were identical, the resulting loss at 20kHz would correspond to 4/(4 + 0.75) = -1.5db).

Alternatively, this calculator, which was called to my attention by Shadorne in a thread a while back, can be used. For wide spacing of the conductors, it indicates a loss of about 0.1db at 20kHz into an 8 ohm resistive load (and less than that in relation to the slight loss that occurs at low frequencies, due to resistance). That would approximately double into 4 ohms, and increase a little more due to the somewhat inductive impedance characteristic of the speaker at high frequencies.

As that calculator makes clear, the loss numbers would diminish to complete insignificance if the wires were twisted, especially given that the thin insulation makes it possible for the conductors to be in close proximity.

So the bottom line for the 8 foot run length and the particular speakers appears to be, to the extent that cable effects are explainable by generally recognized science, that it probably won't make much difference either way, but twisting can't hurt (assuming you have confidence in the integrity of the insulation, so that shorts won't occur) and may help slightly. That may also be true for the reason Hifihvn cited, if either of the amplifiers are sensitive to rfi that may be presented to their output terminals.

Was wondering if the thicker wire would help the Cary out in the damping dept?

I doubt it. The 16 foot round-trip length of 16 gauge wire corresponds to a resistance of 0.064 ohms, based on the wire gauge table I linked to above. Paralleling two conductors for each leg would halve that to 0.032 ohms. Adding either number to the 1.5 ohm amplifier output impedance would not change the damping factor significantly.

Best regards,
-- Al