Speaker cables: asked 100 times and never fully answered

You've lost me here ! It seems like you are annoyed and irritated rather than perplexed and seeking clarity.

Don't use high-capacitance cables and be careful with electrostatic speakers. If in doubt, ask your dealer for advice.

Strange to say about electrostatic speakers, none is more horrible as a load than the ESL [original 57 type], and yet Naim amplification from the Naits One and Two, and certainly the 5i, as well as all the separate power amps up to the 250 [all series] are entirely happy driving the horrendous load than varies from between something like fifty ohms at about fifty Hz, to about two ohms at twenty-thousand Hz.

Of course the speakers were designed in a time when amplifiers were based on voltage gain devices called thermionic valves and the output was decoupled with a transformer that reduced voltage and increased amperage.

But Naim is one of the few makers of transistor output amplifiers that are stable enough to cope with the ESL.

Most transistor output amps will start to terminally smoke within a minute driving the original ESL, and unfortunately take the speaker with it!

However with Naim, with NACA 5 of the recommended length complete stability is established and the amps runs cool as a cucumber. Further more, even at good listening levels, the actual current drawn from the amplifier is extremely small. With one ESL on one side of the NAP 100 at half volume on the control, the amp draws only two more Watts across the [Smart] mains meter than when there is no signal to amply.

Naim amps are made of stern stuff!

As a matter of interest the ESL [57] is nominally a 16 ohm speaker ... It is Naim or a decent valve amp for ESLs ...

ATB from George

Hi George,

Good to see you still enjoy your ESLs.

In the dim and distant past, ISTR that JV was an ESL57 or 63 fan. So no doubt he wanted to make sure his beloved 250 power amp would drive them without disintegrating !!! But, IASTR, that he arranged for a small modification, just to be on the safe side. Some sort of resistor in the ESLs or possibly the amp?

Perhaps my memory is confusing this matter with others. Perhaps you or others could clarify ?

I fear Strat, that you could well be right.

Dear Don,

JV admired the 57 to the extent that the planned top-line Naim speaker - the FL 1 -  was based on it, though the FL 1 was to be capable of going much louder. Physics beat them unfortunately and the DBL was then created in stead. 

No doubt that JV wanted to make a better ESL, and personally I think that it is a shame that Physics really does limit the possible volume of sound that a given area of Electrostatic membrane can generate before arcing across the stators ruins the speaker because of over-voltage.

The modification on the old series 250 was - as I understand - a voltage limiter to prevent the over-voltage situation that could cause an ESL to self-combust in a fraction of a second. Nowadays there are ways of protecting the speaker from over-voltage in the speaker itself, but the real trick is not to over-drive them in the first place. 

ATB from George

Intelligent and interesting comments as usual Huge.

As to Don's statement, no, I'm not annoyed with Naim at all. It's all a bit of cheek to stir the pot and see if they will provide a clearer answer one way or the other.

Anyway, I got my response from Naim. Terse and to the point. They declined to make any comment at all on the topic of operational load ranges for the amps or qualify the definition of "high capacitance" or "similar specification". I do stand by original statement that those phrases have zero meaning.

As an example, in my question to Naim I did mention I was using 5m lengths of an unnamed cable with 74 pF/m and did not mention the inductance. They merely said such a cable "should be OK with your 250". And then they repeated the NACA5 specs.

I think we can safely say this type of question has now been asked 101 times with the same answer. To do so again expecting a different result would probably be the definition of madness. For me, my take away from this is that within reason you can use whatever you like.

• Naim do still make their NACA5/SL recommendation for a non-commercial reason based on sound technical reasoning.
• If you're concerned then then only option is to use Naim cable (you won't get guidelines other than have already been published).
• For the rest of us, even without better guidelines, you can pretty much use whatever cable you want as long as it is not at the extreme ends of the scale - litz merely being an example. But the scale is not defined. You're not going to know if your cable is near the boundary of tolerances unless you start getting problems or the amp needs servicing sooner than expected.

Which basically is (as you all expected) the same story that has been told for 30 years.

Did they say they will still honour a warranty in case the amp blow up due to unsuited speaker cables?

In the US, Spectral does not. 

MIT or bust. :/

I did not ask this and they did not comment.

But then again, their wording, as strongly worded as it sounds, does not mention warranty invalidation so there is no reason to assume this. Remember, Naim do actually give guidelines for non NACA5 users (just not great ones IMO).

Did you ask your dealer? 

Or if you are not in UK, the best one to contact might be a distributor. ( who does a lot of warranty work )

I am surprised you didn't ask cuz, don't you wanna know if you are using non Naim cables? ( I would )

I think you are correct if it is indeed possible to offer these values, I say this as an electrical engineers toenail. I have however e-mailed a few cable manufacturers and asked them if X, Y, or Z cable is compatible with my Naim because I was interested. In each case, I received a response from all which contained their cable spec's and which one's would be suitable. That way I had assurances from each well known company and I felt at ease. By the way, as I bi-amp with a 200 & 250.2, each amp has it's own unique spec so they all took that into account and advised accordingly. I suffer PTSD and anxiety from war, and my shrink has taught me to look at the big picture and not sweat the small stuff because I used to fire up when I felt I was being taken for a ride. Pick my battles, as it were, and since Naim and other makers are willing to assist so our amps don't get damaged, it's a hassle, but not a major SNAFU. I mean no disrespect Zen, I hear you, but I personally think that since there is a solution, it's not worth a stroke. God knows I wish we lived in a perfect world.

Re. warranty.  If damage is caused by not following the instructions in the manual correctly (in this case, not using Naim speaker cable on a Classic Naim amp) then this could be considered "abuse".  It could well be argued that such a case falls outside of any warranty provision.

Of course every case is unique in its circumstances and Naim try to bend over backwards to help out its customers, so...

...the instructions, recommendations and warnings are made clear in the manual but I reckon that Naim prefer to stop short of declaring any definite sanctions until an individual case is properly examined.

Classic "By the book"answer..

Now back to reality. First of all, if there's a dispute, Naim has to prove that it actually IS the fault of the cable. Seems hard enough, if not impossible. 

Second, if it's not 100% clear, the customer will not be happy. In this digital world, that unhappiness is easy ventilated. Image damage will be much larger than repairing a single amp.

I'm not saying that everybody should ignore the manufacturers recommendation, far from it in fact.

However, such a comment raises the hairs in my neck. Unnecessary fear injection, (sorry, don't know the correct English phrase, but I guess everybody knows what I mean). Especially as someone asked a formal statement from Naim and apparently warranty is not mentioned when asked to use another cable. 

Streamz, I'm not sure what you mean "by the book" regarding my answer. Or how my answer may be considered in some way "unrealistic".

I don't speak for Naim here - I'm just giving my opinion, as someone who used to work within the company, on the possible position of Naim re. any possible warranty claim made for damage possibly caused by operating the equipment contrary to instructions and warnings in the handbook.  

I'm not sure how my opinion causes you angst here but if I am guilty of scaring you unnecessarily then I apologise.

Kuma, My dealer said it was fine. They carry the full Naim range short of Statement but they ditched A5 a decade ago because they don't like it. Naim have no problem with them not selling A5.

Sorry Streamz but I don't think the burden of proof if something goes wrong is on Naim. Handling support issues for years I can assure you that if something goes wrong and it is even in the remote area of the manual that was not read, then support is usually withheld.

I've seen banks nearly come to a standstill because their trade systems went totally offline during a trading day and even at that level, you can safely RTFM a client who decided they knew best and starts suffering consequences. In fact you need to for contractual reasons because as soon as you start pushing the manual aside you can be considered to have accepted responsibility for the problem.

Saying that, Naim don't take that approach. They do look at your gear and decide whether you were obviously pushing your luck or not.

On the other hand, let's not forget some basic truths.

• You have to be pretty unlucky to pick a cable that screws up your amp.
• The nice people at Naim are not out to screw you. They are reasonable people. If you want an example of how reasonable, I live in a country that runs 100v (actually you get 104v from the wall) and Naim do not do power supply for that. Before buying all my kit I asked whether it would work and would they honour the warranty. They said the tolerance on a 115v PS was +/- 10% so it should work. If it works they will honour the warranty, if it doesn't from the outset they wont. Bought a UQ2 to test. It worked, so Naim said OK and now I have the rest of my gear and it functions fine. They pulled out of this country over the power supply issue but still gave me a green light.

To me that says that, despite not agreeing with how they handle the cable issue, they go to some lengths to be as reasonable as possible.

Quite. Remember the early Naim kit was around in the time when there were some particularly 'interesting' cables around with some horrible LC characteristics - remember Litz cables. If you want to go off piste with other cables to tune the sound a bit then just don't stray too far from the NAC-A5 specs and you'll be fine. 

But the product page for the NAP250, for example, states 'The NAP 250 is stable into any load...'

Several Naim owners have switched over to Tellurium Q Black as an alternative to NAC A5.  Are there any incidents of overheated amplifiers after using Tellurium Q at lengths over 3.5 metres?

Why would there be - it has similar characteristics to NAC-A5. 

James (Ex TQ Black owner)

I'm not sure I see the connection here, unless we're arguing semantics. I think use of the amp as per the instructions is assumed here - i.e. Naim speaker cable.  Remember that by providing the required inductance, the cables effectively form part of the amp.  While a very low impedance below 2 ohms will likely trip the amp protection circuit, no load presented by the speakers should make the amp go unstable.  Even highly reactive loads from some electrostatics like the Quad ESLs that can cause so many transistor amps problems, should be no issue, although the high current from the NAP250 may risk pushing the ESL beyond its limits

dsc,

Quoting just one part of the statement from the manual isn't helpful.  To take it out of context and  truncate the statement in the way you have, also makes it patently untrue.  No-one in their right mind would expect a NAP 250 to be stable into a dead short.

You also omitted a different part of the manual...

"Only Naim Audio speaker cable should be used to connect a loudspeaker to the output of the NAP 250. Custom Naim Audio loudspeaker connectors are supplied to make the connection and in order to comply with current European safety regulations these should always be used. DAMAGE TO THE AMPLIFIER MAY RESULT IF “HIGH DEFINITION” CABLE OR ANY OTHER SPECIAL CABLE IS USED TO CONNECT THE LOUDSPEAKER''

... when using recommended cables" 

I have a very large spanner I use to test discharged car batteries, I call it a low impedance 'load' to avoid obfuscation. I assume this is a suitable load for the NAP 250 from the product page, or do I?

Edit: Beaten by 2 seconds by Huge!

Incidentally, in the 90s when I worked at a Naim dealer, I saw the odd slip of the hand round the back of the speaker terminals shorting a 250 for a second or so. The amp has balls. It survived every single one. One of those cack handed incidents was even caused by a hungover me.

By the same token a split second contact on of the cables with a Linn amp and there was instantaneous smoke and fireworks. Customers bring in shorted amps was not that rare.

Thank you Richard, Huge, hafler3o and feeling_zen for your replies to my post.

My quotation was from under the heading 'Technology & Craft' on the NAP250 product page on the Naim website, not the manual. I truncated the sentence in the interests of brevity but here it is in its entirety: 'The NAP 250 is stable into any load and able to drive a 2-Ohm load for long periods of time.'

https://www.naimaudio.com/product/nap-250

I did not interpret this to mean that the NAP250 could drive a load with an impedance of less than 2 Ohms or, in the extreme case, a short-circuit. The issue is more one of how it behaves into a reactive load. By definition, the load applied to an amplifier is what appears at its output terminals, not at the end of some length of cable. I speak as a practising electronics engineer with 40+ years experience, including the design of high-power linear amplifiers operating in the audio frequency range. Therefore, I naturally took Naim's statement about being stable into any load at face value. Call me pedantic if you like, but if Naim do not really mean what is written on their website, then the above statement is misleading and should be removed. My expectation is that an audio amplifier should be unconditionally stable.

Unfortunately what is written on the website (and in the manuals for that matter) has to be targeted at 'The Man on the Top Deck of the Clapham Omnibus' rather than at knowledgeable electronics engineers; and 'The Man on the Top Deck of the Clapham Omnibus' will regard the speakers as the load on the amp, not the cables and the speakers combined.  He may be wrong (actually he is!), but the fact remains that that is how he'll view it.

The other part of this is to do with slew rates, current rise times and response to transient conditions.  To make an audio power amp unconditionally stable means internal compensation and compromising these parameters to some degree.  Unfortunately it's been discovered that these are some of the factors that correlate to  maintenance of psychological interest in the music being reproduced.  Power amps that are absolutely unconditionally stable tend to sound somewhat 'duller' than designs that are designed for stability into practical loads within certain limitations.  It's part of the engineering compromise.