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Speaker cable technicalities and related stuff

Arkless Electronics said:
I can offer a small in-line box to add the required inductance and hence allow any length of any cable to be used with amps such as Naim and NVA for £60 delivered. Slightly larger than a matchbox, with a few inches long flying lead terminated in a 4mm plug and a 4mm socket on the other end.
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FWIW Townshend supplied a pair of inductors to use with their high-capacitance cable runs. Essentally just spirals of lacquer-coated stiff wire what a banana plug at one end and a socket at the other.

The world would be much simpler (1) if every speaker maker was obliged to ensure their speakers had an input impedance of 300 Ohms resistive from dc to 100 MHz. :)

(1) Ahem. Except, perhaps for the speaker designers. 8-] However I'd not extend them *too* much sympathy given the nightmares they keep giving amp designers.
 
Jim Audiomisc said:
The world would be much simpler (1) if every speaker maker was obliged to ensure their speakers had an input impedance of 300 Ohms resistive from dc to 100 MHz. :)
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A bit tricky when most are around 6 Ohms in the 20 Hz to 20 KHz band

But tending to 100 Ohm gradually above 20 KHz, reaching it by 1 MHz and then staying there to UHF would solve most RF stability cases
 
Ross was given advice. He was also offered various cable options from NVA. The cheapest being 20 quid for a 2m pair. Surely this would have been the safe choice. Then again he wouldn't have had the opportunity to shit stir.
 
chartz said:
Peter Walker, “The most important thing about loudspeaker cables is that they should be long enough to reach the loudspeakers”.

Quad once famously demoed ESL63’s with lawnmower orange cable at a show because that was all they could find shopping around. Everybody was amazed at that mystery cable.

Copper is copper. As Warhol once said about Coke, “A Coke is a Coke, and no amount of money will buy you a better Coke”.
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Sure copper is copper but when you manufacture a cable from it then the resulting structure has specific properties. Steel is steel but I can't cut bread with a hammer any more than I can drive a nail with a knife.

Quad amps are unconditionally stable so you can connect them to a speaker with a 6 inch nail if you want. Naim and nva need a series inductance between amplifier and speaker and minimal capacitance. If they don't get this they can oscillate and be damaged. Naim and nva cables, used at the recommended lengths, provide this. Some other cables do too, but some don't.

None of this is voodoo, it's just physics in action.
 
Chunk McDaniel said:
Ross was given advice. He was also offered various cable options from NVA. The cheapest being 20 quid for a 2m pair. Surely this would have been the safe choice. Then again he wouldn't have had the opportunity to shit stir.
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2m of “electric cable” ( as per the nva website) for £20..........?
Not having a simple question answered?
Having a statement of fact censored out because it revealed a lack of customer focus and reflected badly on the management?
People who can’t take criticism make it easy to shit stir.
 
The vast majority of amplifiers I have or have seen have this inductance built-in.
So why not do it? To sell specific cables?
That’s odd practice.
 
Jim Audiomisc said:
FWIW Townshend supplied a pair of inductors to use with their high-capacitance cable runs. Essentally just spirals of lacquer-coated stiff wire what a banana plug at one end and a socket at the other.

The world would be much simpler (1) if every speaker maker was obliged to ensure their speakers had an input impedance of 300 Ohms resistive from dc to 100 MHz. :)

(1) Ahem. Except, perhaps for the speaker designers. 8-] However I'd not extend them *too* much sympathy given the nightmares they keep giving amp designers.
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Barrymagrec said:
I seem to remember someone (Serge?) saying something like 5 turns of 16 SWG round a pencil would do the job.
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Aha... I didn't know anyone had done it already...

It would be a bit more inductance than the 5 turns on a pencil and in fact be wound on high power carbon resistors to provide damping.

Hand wound of course and with 16SWG wire, plus the enamelled copper wire is a bugger to work with due to having to remove the enamel for soldering. Add a pair of decent chassis mount 4mm sockets and banana plugs, some super flexible cable, and a suitable small box then the labour to terminate the plugs and sockets etc...

It would mean that Naimees and and owners of similarly tetchy amplifiers could use whatever type of speaker cable they fancy and at any length without worrying about oscillation.

Anyhow I'm super cynical about the whole hi fi shebang these days... doesn't matter how good an idea it is, that no one else is now offering them, that they are too straightforward to be in any way risky, that they will do "what it say's on the tin".... Unless half a dozen people who don't know a resistor from a risotto recommend it, it's reviewed in a glossy mag etc etc... there will no doubt be precisely zero demand!
For those of more sensible outlook who want to try "non Naim compatible" cable, it's available. Just PM me.

Jim. You wouldn't be thinking of a certain RF feeder there with that impedance figure by any chance?
I'd go for a rather lower figure myself... let's say 50R...
Philips once made 800R (IIRC) speakers to go with OTL valve amps they made but I believe it was for economics/profits reasons... lose the output transformer and that's a fair saving on the BOM! I believe it was for radiogram type applications...
 
I did rig an inductor a few years ago by cutting a notch out of a length of NACA5 and soldering in the inductor and resistor. Coated with heatshrink it was a bit Heath Robinson but it proved a point and stopped a very hot 250 from misbehaving. I've yet to turn it into a product because we have absolutely no idea if it'd sell or not. I don't think you could guarantee that it would enable the owner to use any type of cable and maintain stability. Maybe it could be sold as an RF choke to limit interference, as I've successfully used this cure here too.
 
MJS said:
I've yet to turn it into a product because we have absolutely no idea if it'd sell or not.
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Sell cables instead, it's much more lucrative. ;)

But come on, why on earth would any serious amp manufacturer not include that network inside their boxes? Most do.
 
My understanding is it's left out for audio quality purposes. Again, my understanding is it is included for a lot of the reasons discussed here; it makes things simpler for the end user.
 
Okay, so half marketing ploy, half science then. Still, silly practice when any old cable would have worked fine.
Was it exposure that did the same?
 
Of course he wasn't. But his amps could prove unstable, which is unacceptable.
Plus he had to sell stuff, and cables are profitable. Zobel networks are invisible and don't sell amplifiers.
Look at what they charge nowadays for their spaghetti.
 
chartz said:
Of course he wasn't. But his amps could prove unstable, which is unacceptable.
Plus he had to sell stuff, and cables are profitable. Zobel networks are invisible and don't sell amplifiers.
Look at what they charge nowadays for their spaghetti.
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As I understand it Naim made and sold amps like that before they sold cables, but sold through dealers that advised and supplied suitable cable, so in a system context nothing was unstable.
However what if somebody does not buy that way? Or buys second hand, does not understand, uses the wrong cable? Or indeed perhaps Naim spotted a few extra £ and made their own. Why not? However the Naim cables were reasonably priced back then. A small percentage of a system budget, don't think they were Naim's focus at all, no Naim focused on shifting boxes, adding PSUs, active cross overs, more amplifiers. They used to actively deride the idea that it was value for money to spend larger sums on cables, they advocated more boxes always brought more to the table.

It is only relatively recently, post JV era, that Naim and fancy mains leads, internconnects, speaker cables etc become big ticket items.

To look back 50 years and suggest Naim designed their amps before they sold relatively modest speaker cables to sell the big ticket cables they do now seems extremely long sighted of them and somewhat unlikely to me? No the change in direction came with the loss of JV, and the merger with Focal, that much seems clear.

EDIT: Besides, this thread is not really about Naim amps so all this is OT, OP has NVA as I understand it, happy to be corrected.
 
stevec67 said:
Sure copper is copper but when you manufacture a cable from it then the resulting structure has specific properties. Steel is steel but I can't cut bread with a hammer any more than I can drive a nail with a knife.

Quad amps are unconditionally stable so you can connect them to a speaker with a 6 inch nail if you want. Naim and nva need a series inductance between amplifier and speaker and minimal capacitance. If they don't get this they can oscillate and be damaged. Naim and nva cables, used at the recommended lengths, provide this. Some other cables do too, but some don't.

None of this is voodoo, it's just physics in action.
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True when presented as above. But dubious when presented in terms of 'sounds better'. Hence the need for clarity wrt safety and reliability and that any cable that meets the *electronic* requirement, and why.
 
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