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Topic: Loudspeaker cables - horses For courses? (Read 22434 times) previous topic - next topic
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Loudspeaker cables - horses For courses?

I recently bought a venerable Rotel RA-820BX4 for my PC-audio rig.

I needed a system which will 'work' at low volumes, that is at small scale. If I were to play music at 'realisitc' levels I'd get evicted from my flat.

So - a pair of JPW mini-monitor-golds (on DIY solid timber pillar stands) and the Rotel, which is 'class A/B' - it uses an array of output transistors (4 per channel) and delivers the few few watts in class-A. This is confirmed by the BIG heatsinks and the heat that comes off them even when the amp is idling.

Many (most, in fact) integrated amps don't really sing til the wick is turned up - I found this with an Arcam Alpha 3 I owned a few years back,  powering an identical pair of  JPW's (given to friend who's still using them).

HERE'S THE THING.

I didn't have any 'speaker-cable' to hand on setting up, so I cannablized an good 'OFC' interconnect. Very thin multi-strand.

Well, it works as I hoped it would - at  low volume levels I still get 'scale', detail and ambience from recordings. Result.

But today, when I knew my neighbours were out, I cranked it up. it got loud, for sure, the Rotel is rated at 30+30 RMS into 8ohms, and double that into 4 ohms  ....

BUT it got, to put it simply, 'congested' and not a simple scaling up of the delicious soundstage and detail I had been listening to at the diminutive levels I've got accustomed to in the last few weeks.

This was listening to Supertramp's 'Crime Of THe Century' and Stereolabs's 'Margerine Eclipse'.

I suspect that the cable I'm using, the chopped up interconnect,  has a bearing on this.

If I were to use 'proper' 15-amp-of-mains-current speaker cables, I think I'd improve the sound for party-level volume levels like I tried this afternoon, but I then likely lose the pleasing small-scale sound-stage and detail I hear (and need)  in day-to-day listening.

So - speaker cables - worth some thought when setting up your rig, and you're not intending on declaring sonic-war on your neighbours.

Rainer.

Edit - So what's my point?  That using thin, high resistance, (low capacitance?) wire (of good quality - hence interconnect cable)  for driving speakers, might serve many peoples' purposes where getting 'good' sound at low in-room levels is an issue.

Loudspeaker cables - horses For courses?

Reply #1 –
Using interconnect as speaker cable is very dangerous. Cheap interconnects often develop short circuits, and good ones can do if they are DYIed. And a short circuit can mean the death of the amplifier.

The two parameters that significantly affect the sound of a speaker cable are resistance and capacity. Both will tend to reduce treble.

A big cable is as capable of faithfully transmitting a very weak signal as a small one. If interconnect sounds softer to your ears, maybe you speakers have a treble response that is agressive. That can be the case if they are set on your side rather than in front of you.

Edit : being coaxial, an interconnect will usually have a higher capacity than a speaker cable.

Loudspeaker cables - horses For courses?

Reply #2 –
Quote
Using interconnect as speaker cable is very dangerous. Cheap interconnects often develop short circuits, and good ones can do if they are DYIed. And a short circuit can mean the death of the amplifier.

The two parameters that significantly affect the sound of a speaker cable are resistance and capacity. Both will tend to reduce treble.

A big cable is as capable of faithfully transmitting a very weak signal as a small one. If interconnect sounds softer to your ears, maybe you speakers have a treble response that is agressive. That can be the case if they are set on your side rather than in front of you.

Edit : being coaxial, an interconnect will usually have a higher capacity than a speaker cable.
[a href="index.php?act=findpost&pid=307622"][{POST_SNAPBACK}][/a]


I agree, care is needed, but i mentioned using good quality wire, and of course care will be required in the terminations..

But you're incorrect regarding capacitance, it blocks DC, and hence is used in crossover networks as a basic high-pass for tweeters. The simplest 2-way cross-over consists of nothing but a capacitor in series with the tweeter.

I'm suggesting (to repeat) that amp/speaker systems intended for low-volume in-room listening might benefit from the use of thin, high resistence, low capacitance wire , which good interconnects are, as speaker cables.

At high volumes, considerable current flows as the amp drives the speakers and, as I said, such wire will probably not work well. This seems actually to be  my experience so far,

Rainer.

edit - my prose is apalling.

edit 2 - I mean appalling. sigh.

Loudspeaker cables - horses For courses?

Reply #3 –
Of course, the AB I need to try is the wire I'm using against a big multi-strand cable such as mains cable, QED whatever.

This is easier said then done, as usually I listen to music when I want to listen to music, and for no other reason. I like to think I have a grasp of the basics/theory and can set the kit up right from the get-go.

I really don't enjoy the manic swapping of components in and out and then tryng to compose myself for 'the test'.

R.

Loudspeaker cables - horses For courses?

Reply #4 –
Heany gauge zip cord will do the trick.  If you think that expensive "sound pipe" and similar wire is any different, go for it.  Then try to ABX the difference between that and heavy gauge zip cord.  I have never seen any demonstration shown or quoted in 40+ years that can point to "better sound" from more expensive wires.   

If you want to be really scared, look inside the amps.  Skinny wire there. 
Nov schmoz kapop.

Loudspeaker cables - horses For courses?

Reply #5 –
Quote
Heany gauge zip cord will do the trick.  If you think that expensive "sound pipe" and similar wire is any different, go for it.  Then try to ABX the difference between that and heavy gauge zip cord.  I have never seen any demonstration shown or quoted in 40+ years that can point to "better sound" from more expensive wires.   

If you want to be really scared, look inside the amps.  Skinny wire there. 
[a href="index.php?act=findpost&pid=307650"][{POST_SNAPBACK}][/a]


what?

R.

Loudspeaker cables - horses For courses?

Reply #6 –
Quote
Quote

The two parameters that significantly affect the sound of a speaker cable are resistance and capacity. Both will tend to reduce treble.

   ...
Edit : being coaxial, an interconnect will usually have a higher capacity than a speaker cable.
[a href="index.php?act=findpost&pid=307622"][{POST_SNAPBACK}][/a]


But you're incorrect regarding capacitance, it blocks DC, and hence is used in crossover networks as a basic high-pass for tweeters. The simplest 2-way cross-over consists of nothing but a capacitor in series with the tweeter.

[a href="index.php?act=findpost&pid=307634"][{POST_SNAPBACK}][/a]


Someone has to say it.... Aughh!  Ever study AC circuits?

Yes, a capacitor blocks DC and passes high frequencies.  The capacitance in a speaker cable is between the 2 lines (red/black, +/-, whatever), not between the input and output.  So this *parallel* capacitance acts as a low pass filter by allowing some high frequency signal to go from + to - without going through the speaker..  How much effect it has depends on other things like the output impedance of the amp, resistance of the wire, and input impedance of the speaker.

Loudspeaker cables - horses For courses?

Reply #7 –
And to confuse you further, do not confuse resistance or capacitance with "characteristic impedance", in ohms, which is a parameter of transmission lines that results in a lowpass filter effect in the megahertz range that is generally not considered relevant to audibility.


.... and do not confuse "characteristic impedance" with "impedance", in ohms, a complex value formed by the resistance (real axis) and capacitance/inductance (imaginary axis), which can be used to simplify the calculation of circuit/filter solutions and is applicable at all frequencies.

Loudspeaker cables - horses For courses?

Reply #8 –
Quote
Quote
Quote

The two parameters that significantly affect the sound of a speaker cable are resistance and capacity. Both will tend to reduce treble.

   ...
Edit : being coaxial, an interconnect will usually have a higher capacity than a speaker cable.
[a href="index.php?act=findpost&pid=307622"][{POST_SNAPBACK}][/a]


But you're incorrect regarding capacitance, it blocks DC, and hence is used in crossover networks as a basic high-pass for tweeters. The simplest 2-way cross-over consists of nothing but a capacitor in series with the tweeter.

[a href="index.php?act=findpost&pid=307634"][{POST_SNAPBACK}][/a]


Someone has to say it.... Aughh!  Ever study AC circuits?

Yes, a capacitor blocks DC and passes high frequencies.  The capacitance in a speaker cable is between the 2 lines (red/black, +/-, whatever), not between the input and output.  So this *parallel* capacitance acts as a low pass filter by allowing some high frequency signal to go from + to - without going through the speaker..  How much effect it has depends on other things like the output impedance of the amp, resistance of the wire, and input impedance of the speaker.
[a href="index.php?act=findpost&pid=307660"][{POST_SNAPBACK}][/a]



So, what are your recommendations for speaker cable for a given application?

Because it seems to me that, unlike any other part of the signal path, speaker cables are expected to carry audio signals at a huge range of currents, and I don't think a single wire can 'do it all'.

In setting a system up it seems obvious to me that you have to decide whether you want those conductors to work at fractions of an amp (to deliver a believable soundscape in your little flat at sound pressure levels that won't get you evicted) , or many amps for palpitating bass at party levels

Which is to be? I want a system that will work at fractions of an amp - that is a couple of watts at the most. I think I should use an approriate wire, and that isn't going to be  a cable that looks like it's designed to power an arc-welder.

It's a kinda intuitive thing, but if you think a cable as thick as your wrist is 'all things to all men', go for it.

R.

Loudspeaker cables - horses For courses?

Reply #9 –
The argument that larger cables don't work as well for small currents is sort of specious. Maybe if you thought of the cable as a tank of electrons, and the amp has to work really hard to add/remove electrons for the tank, would that make sense.

Let me go all fundie electromagnetism on you for a second. The amp is short for ampere, which is a unit of electric current defined as coulombs per second. What a current is, in some sense, is electrons moving along a wire so that a certain amount of charge passes through a cross section of wire at a given speed. charge divided by time equals current.

Pay close attention to the word "cross-section". It does not factor into the current calculation. That implies a certain surface area, which is related to the thickness of the conductor. If you double the thickness of the conductor, the surface area of the cross section doubles, but the current does not change. The amplifier only cares about the voltage and current it needs to drive; both of those quantities do not change as the cross section changes. As long as the cable doesn't overheat from being too thin to handle the current, it does not matter how thick it is. It could be as thick as your wrist and your amp could drive it!

Loudspeaker cables - horses For courses?

Reply #10 –
Using a big cable for low signals is a bit like using a truck to carry one tomato. But the tomato is delivered in time and at the right location all the same.

Loudspeaker cables - horses For courses?

Reply #11 –
In fact, the cable size is determined according to safety. For a given current, the cable must not overheat, which could start a fire. For high currents, a minimal size is given, but there is no maximum size.

However, for speaker cables, there is another consideration : sound. If the cable is too thin, or too capacitive, or too long, it will act as a filter. Resistance will interact with the speaker impedance and change the frequency response. Capacity will act as a lowpass filter because it is in parallel with the speaker (it would be a high pass filter if it was in serial). This does not depend on the amount of current. It occurs at high levels as well as low levels.
Thus it leads to a maximum resistance and maximum capacity for the whole cable, for the sound to be unaltered. That's why thin cables are not a good choice for speaker cable. This is not a problem for interconnect cables, because the impedance of the termination is much higher (47000 Ohm versus 8 Ohm for speakers), which turns the cable impedance (resistance and capacity) neglectible in comparison.

Loudspeaker cables - horses For courses?

Reply #12 –
Quote
In setting a system up it seems obvious to me that you have to decide whether you want those conductors to work at fractions of an amp (to deliver a believable soundscape in your little flat at sound pressure levels that won't get you evicted) , or many amps for palpitating bass at party levels

Which is to be? I want a system that will work at fractions of an amp - that is a couple of watts at the most. I think I should use an approriate wire, and that isn't going to be  a cable that looks like it's designed to power an arc-welder.
[a href="index.php?act=findpost&pid=307691"][{POST_SNAPBACK}][/a]


Hmmm... it was also obvious to you that a cable with lots of capacitance would act as a high pass filter when in fact it is more the opposite.. Don't always go for the obvious.

14 or 16 guage zip cord actually does a pretty good job of getting a signal to the speakers for reasonable (home applicaton) lengths and power.

Reasonable changes (that is, with good cause) from that baseline could be things like:

1) flatter cable to run under carpet

3) smaller for space constraints

4) some adaptation to make it pull easier through conduit

5) more flexible.

6) esthetic considerations like color, or you just think round cables look better.

Loudspeaker cables - horses For courses?

Reply #13 –
Quote
Quote

In setting a system up it seems obvious to me that you have to decide whether you want those conductors to work at fractions of an amp (to deliver a believable soundscape in your little flat at sound pressure levels that won't get you evicted) , or many amps for palpitating bass at party levels

Which is to be? I want a system that will work at fractions of an amp - that is a couple of watts at the most. I think I should use an approriate wire, and that isn't going to be  a cable that looks like it's designed to power an arc-welder.
[a href="index.php?act=findpost&pid=307691"][{POST_SNAPBACK}][/a]


Hmmm... it was also obvious to you that a cable with lots of capacitance would act as a high pass filter when in fact it is more the opposite.. Don't always go for the obvious.

14 or 16 guage zip cord actually does a pretty good job of getting a signal to the speakers for reasonable (home applicaton) lengths and power.

Reasonable changes (that is, with good cause) from that baseline could be things like:

1) flatter cable to run under carpet

3) smaller for space constraints

4) some adaptation to make it pull easier through conduit

5) more flexible.

6) esthetic considerations like color, or you just think round cables look better.
[a href="index.php?act=findpost&pid=307800"][{POST_SNAPBACK}][/a]



I must admit I had the nature of capacitance, how it's generated in a audio conductor wrong, and I thank you for the correction. But the fact is that it tends to increase in audio/AC conductors with the guage and number of strands. (although Pio might be right and the close proximity of the hot and earth conductors in coaxial wire might in itself actually create some).

For example, DNM Reson cables are single core with the conductors kept apart by the 'ribbon' cross-section of the insulator, and they are known to be about as low-capacitance as you can get.

Whatever, to repeat, I've found  that my ad-hoc use of  a reasonable quality signal wire as speaker wire does seem to work at  low volumes (plenty of  low-level detail that I wouldn't normally expect to hear) (edit - that includes 'timbre' and 'ambience'), but conversely (and not unexpectedly) the sound with the volume cranked up (but certainly not anywhere near the Rotels rated/continous) isn't good at all - rather flat sounding.

I owned exactly the same speakers (gave them ot friend who still uses them) with an Arcam Alpha 3 back in the early 90's, so I'm pretty familiar with their sound, and I also remember that combination didn't  really 'work' unless the 40+40w Arcam was turned up - so I otherwise used it's tone controls to help compensate.

As I said, I bought the Rotel (which has no tone or 'loudness' controls)  because I had a hunch it's design would lend itself better to low volume listening than some amps (including the otherwise pretty good Arcam) and happily it does indeed.

I know I have a couple of lengths of half-decent multistrand that a friend got with Bose system and didn't need, so the answer is to swap the cable and confirm (or not) what I think I hear, although I'm quite content with the sound as is.

Rainer.

Loudspeaker cables - horses For courses?

Reply #14 –
I'm afraid multiple strands of cable have no effect at all over capacity, because all strands from each conductor are together and touching, and because capacity happens between positive and negative conductors, not inside each conductor. Coaxial or twisted pair cable does have higher capacitance. Multi-stranded has not. Also, capacitance, or it's effects, don't vary with the amount of output power, because cables are linear devices.

Loudspeaker cables - horses For courses?

Reply #15 –
Quote
I'm afraid multiple strands of cable have no effect at all over capacity, because all strands from each conductor are together and touching, and because capacity happens between positive and negative conductors, not inside each conductor. Coaxial or twisted pair cable does have higher capacitance. Multi-stranded has not. Also, capacitance, or it's effects, don't vary with the amount of output power, because cables are linear devices.
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The strands might well be in contact, but the surface of the individual strands forms a slight 'dialectric' or insulator between them. Whether this has any bearing on the measured capactitance of a given cable, I don't know, but generally speaking, single core conductors are measurably less capacitive.

In choosing a wire for a tonearm, and the external run from it's base, it's well known that if high-capacitance stuff is used it can profoundly affect the tonal balance of a cartridge, producing as it is a signal measured in millivolts.

R.

Loudspeaker cables - horses For courses?

Reply #16 –
Quote
The strands might well be in contact, but the surface of the individual strands forms a slight 'dialectric' or insulator between them.


First time I have notion of such weird phenomena. If there's no actual dielectric between them (they are conductive cables with conductive surfaces and really touching), then there's no dielectric and no possible capacitive effect, even more when, again, capacitive effect happens exclusively between + and - conductors, not inside each conductor. See, even if there was an actual dielectric insulating each strand, there would be no capacitive effect, given that the + and - conductors were far enough from each other. Please check your electric theory.

Quote
Whether this has any bearing on the measured capactitance of a given cable
, I din't know, but generally speaking, single core conductors are measurably less capacitive.
[a href="index.php?act=findpost&pid=307961"][{POST_SNAPBACK}][/a]


Any actual proof of that (in form of measurements)?

Edit: more explanations and examples.

Loudspeaker cables - horses For courses?

Reply #17 –
Quote
Quote
The strands might well be in contact, but the surface of the individual strands forms a slight 'dialectric' or insulator between them.


First time I have notion of such weird phenomena. If there's no actual dielectric between them (they are conductive cables with conductive surfaces and really touching), then there's no dielectric and no possible capacitive effect, even more when, again, capacitive effect happens exclusively between + and - conductors, not inside each conductor. See, even if there was an actual dielectric insulating each strand, there would be no capacitive effect, given that the + and - conductors were far enough from each other. Please check your electric theory.


Edit: more explanations and examples.
[a href="index.php?act=findpost&pid=307964"][{POST_SNAPBACK}][/a]


It's not weird at all, each strand has a slightly work-hardened and oxidised surface created as they are drawn thru dies in manufacture, and which is not perfectly conductive (no material is, apart from 'room-temperature' superconductors which are the holy grail of researchers) , before being brought together as a cable.

It's the reason it's  a good idea to 'tin' the ends of multi-strand wire (such as bare speaker cables) with solder to make sure all of them are equally coupled to the terminations at both ends of the run.

R.

Loudspeaker cables - horses For courses?

Reply #18 –
Quote
It's not weird at all, each strand has a slightly work-hardened and oxidised surface created as they are drawn thru dies in manufacture, and which is not perfectly conductive (no material is, apart from 'room-temperature' superconductors which are the holy grail of researchers) , before being brought together as a cable.
[a href="index.php?act=findpost&pid=307974"][{POST_SNAPBACK}][/a]


That has nothing to do with the existance of a dielectric between strands. Despite they not being perfectly conductive (currently no known material is at regular temperatures), every strand is at same potential, so there's no possible capacitive effect.

Loudspeaker cables - horses For courses?

Reply #19 –
The biggest immediate effect is that stranded wire has less area of copper for the same guage due to the gaps between close-packed circular cross sections... so more resistance per foot.  So for the same resistance the stranded would be larger and create more capacitance.. but the percentage difference is pretty small.  Other effects are that it is more flexable and gets less work hardening than solid for the same amount of flexing.  Work hardening will lead to cracks which sort of defeats the purpose.


If you want to check for capacitive effects try Litz wire which actually has insulation between the strands.

If there were a problem with bad contact between strands on the same wire you will have a lot more audible effect with diodes being formed than capacitors. 

Quote
For example, DNM Reson cables are single core with the conductors kept apart by the 'ribbon' cross-section of the insulator, and they are known to be about as low-capacitance as you can get.


Can I direct you to a couple of books about this stuff?  I mean it would really help the conversation if you knew what capacitance is and what affects it.  It irks me a bit because for over 10 years my job was mostly about analyzing small scale parasitic (unintentional) capacitance.  Even with that it all starts with the basics, not ad copy or a review in some high end audio magazine.

The main reasons those cables are low capacitance are a) the conductors are relatively far apart, and b) the dielectric is mostly air.

Loudspeaker cables - horses For courses?

Reply #20 –
Plus copper (I) oxide (CuO) is a semiconducter and thus not a very good dielectric material. So even if there was a potential in different strands there would not be any signifigant capactience.

Terminal ends of the wires are tinned mostly for strength, secondly for oxidation.

Loudspeaker cables - horses For courses?

Reply #21 –
Quote
In choosing a wire for a tonearm, and the external run from it's base, it's well known that if high-capacitance stuff is used it can profoundly affect the tonal balance of a cartridge, producing as it is a signal measured in millivolts.[a href="index.php?act=findpost&pid=307961"][{POST_SNAPBACK}][/a]


That's right. Because of its impedance, the cartridge is sensitive to the capacity of its load.
However, if it outputted several volts, but with the same output impedance, it will still be as sensitive. It depends on the output equivalent impedance, and on the load impedance, but not on the voltage output.

Loudspeaker cables - horses For courses?

Reply #22 –
Quote
In choosing a wire for a tonearm, and the external run from it's base, it's well known that if high-capacitance stuff is used it can profoundly affect the tonal balance of a cartridge, producing as it is a signal measured in millivolts.
R.
[a href="index.php?act=findpost&pid=307961"][{POST_SNAPBACK}][/a]


Yes that is so much a different kettle of fish that it's not funny. The tone arm circuit is relatively high impedance and very much load dependant, the load circuit of the tone arm is actually required to tune the circuit!.  The amplifier speaker interconnect is not in the least bit similar to this. Yours is a classic case of having just enough snippets of knowlegde in this area to be able to misue it.

Cable capacitance is determined by a combination of geometric factors and the dielectric constant of the insulator material used. Gerenerally both of these factors contribute to a higher capacitance in coaxial cable as compaired to ribbon or parallel pair type cable.

The formula for capacatance (per meter) of the two different types is:

Coax : C = 2 Pi * 8.85* k / ln(d2/d1))    : pF/m
where ln(.) is natural logarithm, d1 and d2 are the inner and outer conductor diameters respectively and k is the relative dielectric constant.

Parallel Pair : C = Pi * 8.85 * k / ln(d/r)  : pF/m
where d is the pair seperation and r is the radius of each conductor. Strictly this eqaution is accurate for the case for relatively widely spaced conducters in free air where the rel-dielectric constant is unity. For a typical insulated cable the effective dielectric constant will be somewhere in between unity and that of the actual insulator used. This is becasue while some of the electric fux is confined to the insulator dialectric a good deal of it is not and so passes outside the insulator and through free air. With coax on the otherhand all of the electric flux is confined to the dielectric. For this reason the parallel pair generally has a lower effective dielectric constant and hence a lower capacitance. In addition the geometric factor ln(d/r) versus ln(d2/d1) general has a higher ratio for a parallel pair again contributing to lower capacitance.

BTW. The primary reason why coax cables generally have lower characteristic impedance (not to be confused with DC resistance) than parallel pairs is due to the higher capacitance of the coax!

So now I've explained that now let me make it perfectly clear that it is totally irrelevent for a speaker interconnect anyway!!!!!!!!!!!!!!!!!!!!!!!!!!!

The typical capacitance per meter for coax is in the range of 100pF to 250pF per meter while typical values for paraller pairs is about 30 to 60 pF/meter.

So no matter what you use it's likely to contribute less than 1nF (and likely much less than this if you use a parallel pair). Now the output resistance of you amplifier is probably something like 0.1 or 0.2 ohms so the pole frequence of the 1nF would be something like 1/(2*Pi*0.1*1e-9) which is about a Giga-Hertz. So are you sure that your hearing and the rest of you system are up to handleing this frequency range Rockfan? No, just what I thought.

Of course the cable capacitance will be very small compared to the self capacticance of the speaker coil in any case, making all of the above even more futile. Pull a speaker voice coil apart some time Rockfan and take a good look at the wire from which it's wound. Meters and meters of wire, all thiner than your precious interconnects and all very closley spaced with only very thin enamel coating to seperate adjacent turns leading to a fair amount of self capacitance.

Loudspeaker cables - horses For courses?

Reply #23 –
Thanks for the enlightenment.

I recall reading somewhere cable impedance is insignificant so long as the cable length does not become significant relative to the wave length of the signal, which means you need a mighty long speaker cable to notice. Is this correct?
Veni Vidi Vorbis.

Loudspeaker cables - horses For courses?

Reply #24 –
Quote
Thanks for the enlightenment.

I recall reading somewhere cable impedance is insignificant so long as the cable length does not become significant relative to the wave length of the signal, which means you need a mighty long speaker cable to notice. Is this correct?
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Cable impedence only starts to matter when you find yourself with substantially different voltage at the ends of the cable, and those different voltages are due to time propagation.


For audio cables, this is quite some distance, only the telcos really get into this at audio frequencies under most conditions.
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J. D. (jj) Johnston