mrfeedback said:
How much do you need? Why is so much copper required to feed a loudspeaker that's using wire not much thicker than a hair?
se
Generally we treat a driver like a black box. For a given voltage v and frequency f we get some acoustic output A. Ideally A is constant across some domain f and is proportional to the square of v.
Now we introduce speaker cable. If the impedance > 0, we get nonlinearities. We have to. The lower the impedance, the lower the nonlinearity.
It doesn't matter that the black box has impedance >> the impedance of the cable. The cable's job is to deliver the voltage as accurately as possible to the black box. Run the numbers and see for yourself.
Now we introduce speaker cable. If the impedance > 0, we get nonlinearities. We have to. The lower the impedance, the lower the nonlinearity.
It doesn't matter that the black box has impedance >> the impedance of the cable. The cable's job is to deliver the voltage as accurately as possible to the black box. Run the numbers and see for yourself.
Steve, we cannot avoid power losses due to the resistance of the voice coils, due to size constraints. There is plenty of space for large speaker cables.
Tim.
Tim.
LS CABLE.
Hi,
Teflon?
Who cares?
We're talking low impedance and audiofrequencies here.
A good speaker cable doesn't have to be fat with lots of metal, an enamelled solid core copper wire pair is often far better than all this multistrand + fancy insulator rubbish.
Cheers,😉
Hi,
Teflon?
Who cares?
We're talking low impedance and audiofrequencies here.
A good speaker cable doesn't have to be fat with lots of metal, an enamelled solid core copper wire pair is often far better than all this multistrand + fancy insulator rubbish.
Cheers,😉
tiroth said:
Er, we get nonlinearities? What nonlinearities?
I have. So now where is the nonlinearity you speak of?
se
trwh said:
So what's the big deal about a little power loss? Hell, your typical amplifier's not running at anything greater than 50% efficiency to begin with. What's the difference if your amp's able to deliver 100 watts to the load versus 99.95 watts?
se
20 pair Works Fine For Me.
Hi Steve,
I have not done the measurements, but I believe that 20 pair approaches 8 ohm characteristic impedence.
20-pair also exhibits very low series inductance, and in my understanding this is the most important parameter.
In my experience this cable works very well for short or long runs, is readily available and cheap, and especially so from scrap metal merchants.
The other day I heard some 'Monster cable' that retailed for AUS$28.00/meter, and imo/ime cheap 20 pair kills it hands down.
Also the voice coil wire is not the only arbiter, unless of course full range drivers are used.
Eric / - Can't be bothered with other wires.
Steve Eddy said:
Hi Steve,
I have not done the measurements, but I believe that 20 pair approaches 8 ohm characteristic impedence.
20-pair also exhibits very low series inductance, and in my understanding this is the most important parameter.
In my experience this cable works very well for short or long runs, is readily available and cheap, and especially so from scrap metal merchants.
The other day I heard some 'Monster cable' that retailed for AUS$28.00/meter, and imo/ime cheap 20 pair kills it hands down.
Also the voice coil wire is not the only arbiter, unless of course full range drivers are used.
Eric / - Can't be bothered with other wires.
Steve Eddy said:
OK, fair point.
Steve Eddy said:
I maintain it is acoustcially beneficial to use heavy guage speaker cable. Here is a quote from a Crown user manual:
"It is important to use loudspeaker cables with sufficient
gauge (thickness) for the length being used. The resistance
introduced by inadequate cables reduces both
the output power and the motion control of the loudspeakers.
The latter occurs because the damping factor
decreases as the cable resistance increases. This
is very important because the amplifier’s excellent
damping factor can easily be negated by insufficient
loudspeaker cables."
Crown supply a nomograph for calculating the recommended wire gauge for specific applications. For instance, in my setup I have a pair of 4 ohm speakers on the end of a ~ 6m run of cable. In order to achieve a minimum damping factor of 50, I would need to use 14 AWG cable. The cable I use has a 2.5mm^2 conductor area, although I don't know how this relates to its AWG value.
Tim.
Characteristic impedance is irrelevant unless the run is a good fraction of a wavelength at, say, 20kHz. For normal runs in a house, the length are ridiculously shorter than that.
Resistance (impedance, really) IS a bigger issue than Steve makes out. The problem is that speakers have nonuniform impedance curves with frequency, some varying by a decade or more over the audible band. If the cables have a significant resistance, the voltage divider formed driving the speaker will cause changes in the frequency response. In EVERY case where I've been able to verify changes in sound due to cable swapping (that didn't involve amps going unstable, a rare event these days), it was precisely due to this effect.
No one has yet demonstrated that people can hear things like exotic insulations or magic oils or the effects of plated versus unplated copper, but it's well-established and without controversy that people CAN hear small changes in frequency response.
Resistance (impedance, really) IS a bigger issue than Steve makes out. The problem is that speakers have nonuniform impedance curves with frequency, some varying by a decade or more over the audible band. If the cables have a significant resistance, the voltage divider formed driving the speaker will cause changes in the frequency response. In EVERY case where I've been able to verify changes in sound due to cable swapping (that didn't involve amps going unstable, a rare event these days), it was precisely due to this effect.
No one has yet demonstrated that people can hear things like exotic insulations or magic oils or the effects of plated versus unplated copper, but it's well-established and without controversy that people CAN hear small changes in frequency response.
Yes, Resistance Does Matter.
Hello ?,
Consider that due to cdp RF output and downstage THD and IMD, fundamentals and harmonics will be transmitted that go out to well past 20kHz, and this can well affect a NFB amplifier connected to a reactive (non resistive) load, and here a defined cable HF characteristic impedence becomes of more importance.
I agree that the relatively small frequency response aberrations caused by non-uniform load impedence and resistive cable are audible, and can be very noticeably so.
In past experimenting with a homebrew interconnect cable using 4 strands of 0.7mm silver plated 'six nines' copper per channel (star-quad configuration), there was a most definate and clearly audible sonic difference according to whether the individulal strands were naked or insulated by a thin sleeve of teflon.
I found the thin teflon sleeves to cause an objectionable sonic hardness that disappeared upon removal of the teflon sleeves.
I have found teflon insulated Cat-5 to exhibit this same 'flavour' sonic hardness in later experiments, so I conclude that this is not a frequency response issue 'per se', and more so a spectral characteristic.
Eric.
SY said:
Hello ?,
Consider that due to cdp RF output and downstage THD and IMD, fundamentals and harmonics will be transmitted that go out to well past 20kHz, and this can well affect a NFB amplifier connected to a reactive (non resistive) load, and here a defined cable HF characteristic impedence becomes of more importance.
I agree that the relatively small frequency response aberrations caused by non-uniform load impedence and resistive cable are audible, and can be very noticeably so.
In past experimenting with a homebrew interconnect cable using 4 strands of 0.7mm silver plated 'six nines' copper per channel (star-quad configuration), there was a most definate and clearly audible sonic difference according to whether the individulal strands were naked or insulated by a thin sleeve of teflon.
I found the thin teflon sleeves to cause an objectionable sonic hardness that disappeared upon removal of the teflon sleeves.
I have found teflon insulated Cat-5 to exhibit this same 'flavour' sonic hardness in later experiments, so I conclude that this is not a frequency response issue 'per se', and more so a spectral characteristic.
Eric.
This is simply not an issue with any competently designed amplifier, i.e., 99% of modern amps. It might be an issue with some of the fashion amps which are not designed with the idea of the output accurately replicating the input, but that's a pretty small niche. And cable reflections are the least of the inaccuracies there.
What's a cdp? Chateauneuf-du-Pape?
Re: LS CABLE.
Yup. I'm getting along just fine with 30 gauge magnet wire in a simple quad braid.
<center>
<img src="http://www.q-audio.com/images/magnetwire2.jpg">
</center>
se
fdegrove said:
Yup. I'm getting along just fine with 30 gauge magnet wire in a simple quad braid.
<center>
<img src="http://www.q-audio.com/images/magnetwire2.jpg">
</center>
se
WISHFUL THINKING.
Hi,
Unfortunately not...
A CDP is one of those awkward pieces of RF emitters AKA a CD-Player.
Cheers,😉
Hi,
Unfortunately not...
A CDP is one of those awkward pieces of RF emitters AKA a CD-Player.
Cheers,😉
Re: 20 pair Works Fine For Me.
Great. So what has any of that to do with the amount of copper used? You recommended against Cat5 because it didn't have enough copper. I'm still wondering what the amount of copper has to do with it.
I didn't say the voice coil was the only arbiter. I was just wondering why you were so concerned about the amount of copper in the cable when the copper in the voice coil's as fine as hair.
se
mrfeedback said:
Great. So what has any of that to do with the amount of copper used? You recommended against Cat5 because it didn't have enough copper. I'm still wondering what the amount of copper has to do with it.
I didn't say the voice coil was the only arbiter. I was just wondering why you were so concerned about the amount of copper in the cable when the copper in the voice coil's as fine as hair.
se
Hash Brown Notes.
Frank and SY,
Yup, that is precisely what I meant - a big reason that vinyl can sound 'nicer' than compact disc.
Eric.
fdegrove said:Hi,Unfortunately not...
A CDP is one of those awkward pieces of RF emitters AKA a CD-Player.
Cheers,😉
Frank and SY,
Yup, that is precisely what I meant - a big reason that vinyl can sound 'nicer' than compact disc.
Eric.
trwh said:
Damping factor is perhaps one of the most worthless amplifier specs to come down the road save for PMPO (Peak Music Power Output or somesuch) power ratings which allow manufactuerers to get away with claiming 200 watts for a $30 pair of powered multimedia speakers. And like PMPO, it's little more than a marketing ploy foisted on the public by amplifier manufacturers.
The motion control of the loudspeaker (i.e. damping of its fundamental resonance) is dominated almost exclusively by the DC resistance of the loudspeaker's voicecoil.
Amplifier source impedance (including the resistance of the cable) doesn't play much of a role at all in terms of damping until it begins to approach the DC resistance of the voicecoil.
se
SY said:
Sure. You can take cable resistance to an extreme just as with anything else.
But this goes back to Eric's recommending against Cat5 because it doesn't have enough copper.
Cat5 has four pairs of 24 gauge conductors for a total equivalent gauge of 18. Any reasonable length of which would only result in a small fraction of a dB difference in frequency response.
Show me a loudspeaker whose frequency response doesn't vary by considerably more than that. Hell, show me two otherwise identical drivers whose frequency response doesn't vary by more than that.
se
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