[cyanbomb]

Okay, I'm a n00b at these physics/electrical things, but I need to ask! I like to go down to the local cable shop to custom build my cables, but I'm not sure what cables are suitable for which application.

Can I use a so-called speaker cable as an interconnect, and vice versa? What are the real differences?

 

[NiceCans]

I believe the difference lies in the Interconnects being shielded or braided in such a way as to eliminate noise and interference as well as crosstalk since any noise would be amplified down the line increasing it's negative effects.

 

[cyanbomb]

Quote:

Originally Posted by NiceCans /img/forum/go_quote.gif I believe the difference lies in the Interconnects being shielded or braided in such a way as to eliminate noise and interference as well as crosstalk since any noise would be amplified down the line increasing it's negative effects.

Hmm, that makes sense. But then, if speaker cables have less/inferior shielding, wouldn't they act like antennas since they're usually much longer than interconnects, also degrading the audio signal?

 

[xnothingpoetic]

Quote:

Originally Posted by Blue Jeans Speaker cable is a bit different from a lot of the interconnect cables we handle, in several respects. Because speakers are driven at low impedance (typically 4 or 8 ohms) and high current, speaker cables are, for all practical purposes, immune from interference from EMI or RFI, so shielding isn't required. The low impedance of the circuit also tips the balance of concern from capacitance, which is important in interconnect use, to inductance, which, while a concern, can be controlled only to a limited degree. The biggest issue in speaker cables, from the point of view of sound quality, is simply conductivity; the lower the resistance of the cable, the lower the contribution of the speaker cable's resistance to the damping factor, and the flatter the frequency response will be. While one can spend thousands of dollars on exotic speaker cable, in the end analysis, it's the sheer conductivity of the cable, and (barring a really odd design, which may introduce various undesirable effects) little else that matters. The answer to keeping conductivity high is simple: the larger the wire, the lower the resistance, and the higher the conductivity. We offer a few alternatives in large-gauge speaker cable, either raw or terminated, as follows:

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[Jon L]

Low capacitance is the main thing you want in interconnects.

Low inductance is very important in speaker cables. Resistance comes into play more and more as your speakers become more power-hungry and less sensitive, requiring more current throughput. Guys with 100+dB horn speakers often do great with 18 AWG magnet wire.

 

[bigshot]

Quote:

Originally Posted by cyanbomb /img/forum/go_quote.gif Hmm, that makes sense. But then, if speaker cables have less/inferior shielding, wouldn't they act like antennas since they're usually much longer than interconnects, also degrading the audio signal?

It's perfectly possible. But RF interference doesn't degrade the signal. It interrupts it. If you've ever heard CB chatter from passing trucks through your stereo, or have a ham radio operator next door, you need to deal with extensive shielding. If not, normal shielding will do. A little more shielding won't make the sound a little bit better. Either it's an issue or it isn't.

See ya
Steve

 

[Uncle Erik]

Quote:

Originally Posted by cyanbomb /img/forum/go_quote.gif Hmm, that makes sense. But then, if speaker cables have less/inferior shielding, wouldn't they act like antennas since they're usually much longer than interconnects, also degrading the audio signal?

Yes. Any wire can act as an antenna and pick up stray RF. Not just radio, but AC motors, switching power supplies, fluorescent lights, and many other househod products create RF noise.

 

[sejarzo]

The predominant reason that speaker cables don't act as effective antennas is that they are connected to a low impedance load, a speaker.....and there is not sufficient energy in most RF interference to create a significant voltage against that load to come close to audibility.

The main difference between interconnects and speaker cables is the current carried. A peak of 2.83V (the absolute peak from a typical single-ended CD player or DAC spec'd for 2.0 Vrms max output) feeding a 22.1 kohm load (typical of preamp or power amp inputs) represents a peak current of only (2.8/22,100) amps....that's 0.000127 amps, because voltage = current times impedance.

That same peak coming out of a 100 watt rms power amp at clipping into an 8 ohm speaker requires 40.0 volts--14 times the voltage coming out of the unattentuated source--but that requires (40.0/8) amps.....5 amps.

The analogy with running water is that voltage is like pressure and amperage is like the flow rate. The speaker requires (5/0.000127) or 39,400 times as much current to flow through the speaker cable on that peak as flows through the interconnect. The current flow increase is nearly 3000 times the increase in voltage!

One must be careful not to compare liquid flow and electricity too closely, but here's the question: Do you think that the single 3/4" pipe that supplies your home or apartment with plenty enough water could do a similarly fine job supplying all the water to a town of 40,000 residents?