Help with Cables "which ones best for my set-up?"

While I have no reason to doubt Johnnyb53's sonic observations, the explanation is not quite right.

Slowed or degraded risetime is NOT the result of time-alignment issues, or of some frequencies arriving at different times than other frequencies. Electrical signals propagate through wires at roughly 60% to 90% of the speed of light in a vacuum (that speed being approximately 186,000 miles per second), so the time difference between departure and arrival across the length of a typical speaker cable is utterly infinitesimal, for ALL frequencies.

Slowed risetime is the direct result of ATTENUATION (reduction in amplitude), not delay, of high frequency spectral components, which results in turn from bandwidth limitations.

This Wikipedia article on Litz wire presents some background that is relevant to the type of construction Johnny is advocating.

Best regards,
-- Al

08-07-10: Almarg
While I have no reason to doubt Johnnyb53's sonic observations, the explanation is not quite right.

Slowed or degraded risetime is NOT the result of time-alignment issues, or of some frequencies arriving at different times than other frequencies.

I never said they did. Maybe I didn't explain well enough but I was trying to say that rise time tracks with HF bandwidth. "Fast" cables have HF response well into the MHz or even GHz range. Components with a rolled off treble also show a corresponding slowness and greater curve to the corners in their square wave response.

...
Slowed risetime is the direct result of ATTENUATION (reduction in amplitude), not delay, of high frequency spectral components, which results in turn from bandwidth limitations.

That's what I was trying to say, especially when it comes to detail and clarity. Limited HF response slows rise time, which by definition smears the onset of the signal. In other words, HF response also affects the time domain by determining rise time.

The other part about arrival times was speculative on my part. However, when there is a poor impedance mismatch, can't that result in signal bounce between the terminals, setting up some time smear that could be audible?

All I really know is 1) the Zu cables are wicked fast (1 GHz interconnect; even their iPod cable is 100 MHz) and 2) they transmit tight, focused, and extended bass. 3) They also transmit a lush, detailed presentation with extended and delinated soundstage. I *think* the bandwith/fast rise time has something to do with all this.

Rise time tracks with HF bandwidth.... Components with a rolled off treble also show a corresponding slowness and greater curve to the corners in their square wave response.... Limited HF response slows rise time, which by definition smears the onset of the signal. In other words, HF response also affects the time domain by determining rise time.

Agreed 100%.

When there is a poor impedance mismatch, can't that result in signal bounce between the terminals, setting up some time smear that could be audible?

That claim is made in the marketing literature of a few specific speaker cables, which are designed to have unusually low "characteristic impedance", in the area of 4 to 8 ohms, such that it approximately matches the impedances that speakers have at audio frequencies.

At radio frequencies, hundreds of kiloHertz and higher, a mismatch between cable characteristic impedance and source or load impedance results in the reflection and time smear effects you alluded to. Those are known as vswr (voltage standing wave ratio) effects. However, those effects do not become "significant" until cable length becomes a "significant" fraction of a wavelength. The wavelength of a 20kHz electrical signal propagating in a wire is in the rough vicinity of 6 miles. The wavelength of a 20Hz electrical signal propagating in a wire is in the rough vicinity of 6000 miles. Even allowing for the fact that in audio very small effects can be audible, the length of a typical speaker cable would certainly seem to be insignificant in relation to those numbers.

Also, at ultrasonic or radio frequencies at which reflection effects may begin to become important, speaker impedance will typically be MUCH different than the 4 or 8 ohm kinds of impedances speakers have at audio frequencies. In the case of dynamic speakers, the impedance will be MUCH higher, due to tweeter voice-coil inductance. Data I recall seeing for a typical dynamic speaker indicated that at frequencies of a few hundred kHz the impedance was around 50 ohms, which actually is a much better impedance match to a conventionally designed cable than to one having very low characteristic impedance.

IMO the reason for the sonic signatures of speaker cables that have very low characteristic impedance is simply that they have extremely low inductance and extremely high capacitance (those being the factors that result in their very low characteristic impedance). For a speaker cable, inductance is normally the more important of those two parameters, and low inductance works in the direction of increasing bandwidth and high frequency extension.