Speaker Cables: An Observation

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Simon Hickie
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Speaker Cables: An Observation

Unread post by Simon Hickie »

At the outset of this post, for the purposes of those elsewhere who might be viewing this forum, I must point out that I do not have any NVA equipment so have no axe to grind or fanboydom to defend.

I’ve been making my own interconnects and speaker cables for some years and have read fairly widely on the underpinning theory and empirical evidence relating to speaker cable design. A comment I have seen repeatedly made regarding NVA amplifiers is that they need low capacitance speaker cables and specifically NVA’s own if the warranty is not to be voided and that this is viewed by some as totally unreasonable as they wish to use whatever cables they like. So is this objection a reasonable one or is it one based on prejudice and a misunderstanding of what speaker cables do?

Let’s cut to the key purpose of speaker cables straight away. They have one job to do: that is to communicate faithfully the output from an amplifier to the speakers without introducing distortion, filtering or artifacts. It sounds simple enough until you realize there’s a whole industry out there trying to persuade you that brand X is superior to brand Y because….. We also see people saying things like ‘my amp and speakers sound better with this brand than that brand, but in my second system a different brand sounds better’.

So why is this the case? The answer is in fact pretty simple. Different speaker cable conductors (materials and size), dielectrics and construction topologies do indeed have different sound characteristics and can sound different in different systems i.e. a cable that sounds good in one system can sound poor in another. But why? Simply put, the best speaker cable is no cable. The next best is the cable that has a minimal sonic signature of its own. In other words all cables exhibit degrees of distortion (by which I mean alterations to what’s coming out of the amplifier) and may or may not introduce additional artifacts stemming from their design.

Speaker cables then, are sound modifiers that alter the sound of the system depending on the level and type of distortions and artifacts being introduced. Speaker cables cannot ‘improve’ what’s coming out of an amplifier. All they can do is alter it to a greater or lesser degree. What they can to is to attempt to compensate for deficiencies either at the amp end or the speaker end or both by introducing such distortions or artifacts which mitigate against some particular undesirable characteristic or other.

So what of NVA amplifiers and speaker cables? Is the stipulation that low capacitance cables are a must and that the use of non-NVA speaker cables will void a warranty a reasonable one? Discussion of capacitance, inductance, dielectrics, conductor materials and design topologies is probably beyond the scope of this post. However, what I can say is that a system is just that – a system comprising separate but connected elements designed to achieve a particular objective.

Those who complain that they are forced to use a particular cable rather than their favourite brand may be forgetting that their brand works with their system because it complements the sonic characteristics of their existing amp and speakers (not to mention the listening room). My understanding is that people buy an NVA amplifier because its sound signature is essentially one of neutrality and transparency. Therefore, why would one want to use a speaker cable that has a particular set of distortion and artifact characteristics and complain about having to use cables which are a better electrical match for the amplifier you’ve chosen to buy because of its neutrality and transparency? It’s a bit like buying a car with an engine designed to run on super unleaded 98 RON petrol and then complaining that you cannot use the regular 95 RON stuff without performance suffering or bad things happening to the engine.

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Re: Speaker Cables: An Observation

Unread post by zebbo »

NVA equipment has always been designed to use the absolute minimum of components required to provide music. That includes any sort of protection on the speaker output so the use of any cables above the recommended capacitance will cause the amp to go unstable. The Doc never used to require people to use NVA cables, just cables that had a low capacitance. However, due to poor understanding and/or poor manufacturer information, people were still blowing up their amps. Hence the requirement to only use NVA cables. I can talk here from experience as, a good few years back I came across an NVA AP80 amp at a stupid price and bought it just because I liked the look of it! I'd never even heard of NVA and didn't have a clue about speaker cable capacitance so just hooked it up with the Goertz cables I was using at the time - the amp lasted about 30 seconds!! :lol: :oops: :oops:
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Re: Speaker Cables: An Observation

Unread post by CN211276 »

I do not have technical knowledge but can see the sense of synergy between amplifier and cable. Because of this I bought NVA cable before NVA amps. The cable improved the transparency of my then system to a large extent. With NVA amps another veil was lifted.
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Re: Speaker Cables: An Observation

Unread post by Geoff.R.G »

I would say that the designer of any piece of equipment has the right to require that appropriate peripheral equipment is used with it. If an amplifier needs a low capacitance cable then the designer/manufacturer is right to insist that it is used. There are many instances of manufacturers insisting that the correct parts are used and many instances where users have thought they knew better, some even live to tell the tale.

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Re: Speaker Cables: An Observation

Unread post by Dr Bunsen Honeydew »

The problem is people have been told a cable is a cable, they are not different and they believe them, so there is mental wall of bullshit to break through, and the only way is to experience it yourself, but lots just refuse to try, or have amps and systems at the moment that are incapable of showing differences.

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Re: Speaker Cables: An Observation

Unread post by Geoff.R.G »

Some years ago we had a 747 with a couple of phones that didn't work. All the usual checks had been carried out but no faults were found. A colleague, who should have known better, declared that the cable between two units wasn't the problem. The end result was that we hung a new cable between two of the boxes and it worked. The original cable had been bent at too small a radius and the impedance was then such that the RF signals were blocked. A cable isn't just a cable!

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Re: Speaker Cables: An Observation

Unread post by kimangelis »

For non-IT people out there...

Unscreened Twisted Pair (UTP) network Cat6 cable (as opposed to cat5 or cat5e) requires a given bend radius. Cat6 is designed to carry 1Gb/sec transmission speeds above a given distance. Reducing that radius has a significant affect upon the transmission speed to a 70% affect. Both cat5e and cat6 are high purity OFCu. It's the impedence caused by the bend radius that inhibits transmission speed.
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Re: Speaker Cables: An Observation

Unread post by Simon Hickie »

In DIY land in particular, CAT 5 or 6 cable has given rise to a lot of cables with very high capacitance indeed. Some of the braided creations look like the proverbial bird's nest and all in the name of minimising cable inductance and adding 'shielding'. The irony is that the individual strands, as Kim says, are actually pretty decent with good quality copper, a good cross sectional area and decent dielectric (usually PE in the solid core versions). If you have the patience to remove the outer sheath and then unravel each of the twisted pairs before then putting together several cores in parallel for each conductor, you can put together a reasonably low capacitance cable. An electric drill with a reverse gear and variable speed may work, but I haven't tried it. 14 x CAT 5 strands per conductor will give you about 2.8mm2 per conductor, whilst 12 x CAT 6 strands will give you a similar CSA.

Kimber 8TC has a pretty high capacitance at 100pf/ft. Russ Conway/Abbott/Andrews also peddles the myth in the description that "large strands favour lower frequencies and smaller strands favour higher frequencies." This isn't the case. Audioquest in their 2006 paper say that "A common misunderstanding of skin-effect results in the claim that “the bass goes down the fat strands and the highs go down the little strands.” The surface of a fat strand is just as good a path as the surface of a thin strand, only the fat strands also have a core which conducts differently. In cables with fat
strands which are straight and little strands which take a longer route, the path of least resistance at higher frequencies is actually the surface of the fat strands. Since the lower frequencies are less subject to skin effect, they travel everywhere in all the strands."

Without knowing the precise topology of the NVA LS series or the materials used, but surmising based on their descriptions, I would expect them to be as neutral as one could achieve at their respective price points. Once my house move happens, I'll be putting together some DIY speaker cables based on 7 runs of 0.8mm silver plated copper with PTFE dielectic per conductor giving a CSA of about 3.5mm2. My trial using 8 stands of CAT 5 donor wire per conductor (so only a CSA of 1.6mm2 but over a shortish run) shows great promise compared with using conventional stranded wire or larger gauge solid core (1.5mm2 per wire). Bass is tighter and better defined in particular. The interesting thing pointed out in the Audioquest paper is as follows:

"If a single strand is too large, skin-effect will cause each frequency component of an audio signal to behave differently. Each frequency component will exhibit a unique current density profile. The result is that some of the delicate high frequency information, the upper harmonics, will be smeared. We hear sound that is dull, short on detail and has a flat sound stage. The energy is there, the amplitude (frequency) response has not been changed, however the information content of the signal has been changed in a way that makes it sound as though the midrange notes have lost their upper harmonics."

So the cables might measure the same in terms of amplitude response, but actually sound different for the reasons given above. I'd say that's a vote for subjective, empirical evaluation, but backed up with some reasonable looking science.

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Re: Speaker Cables: An Observation

Unread post by Geoff.R.G »

Geoff.R.G wrote: Fri Sep 15, 2017 4:33 pm Some years ago we had a 747 with a couple of phones that didn't work. All the usual checks had been carried out but no faults were found. A colleague, who should have known better, declared that the cable between two units wasn't the problem. The end result was that we hung a new cable between two of the boxes and it worked. The original cable had been bent at too small a radius and the impedance was then such that the RF signals were blocked. A cable isn't just a cable!
I should probably point out that I am NOT talking about Cat5 or Cat6 cable here and the cable assembly carried a number of different wires as well as a 50Ω coaxial RF cable the point being that cables need to be matched to the job and treated appropriately.

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Re: Speaker Cables: An Observation

Unread post by Simon Hickie »

Understood Geoff! This https://www.venhaus1.com/diycatfivecables.html is the sort of thing I had in mind. Note the following caution and especially the last sentence - somewhat judgemental as to what constitutes a 'properly designed amplifier' and no doubt helps to fuel anti-NVA (or similar) sentiment.

"Caution: Although this cable has a low inductance design, its capacitance is relatively high (falls between other highish capacitance cables such as Kimber 8TC and Goertz). While the high capacitance is virtually a non-factor as far as sonics go, it MAY be a problem for unstable amplifiers and cause them to oscillate. This can be mitigated by NOT using very long lengths of cable (>8 ft.), and making sure your amp isn't one of the few that are unstable into highly capacitance loads. Most modern properly designed amplifiers should not have a problem."

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