Craig B
Re:trophile
Perhaps most are simply using appropriate lengths of the recommended speaker cables, and/or those alternatives that measure similarly.
Speaker Cables, A Special Note (from ye olde Naim Audio)
- Thread starter Craig B
- Start date
Arkless Electronics
Trade: Amp design and repairs.
I'm sure they are and that's because they've been brainwashed by "Naim lore" that there is no alternative. I'm sure that Naim are very happy to sell people this magic cable at typically say £150 -200 ish a time rather than buy my boxes and then use whatever is to hand of any length. Similarly they ain't going to start fitting the inductors to their amps as it would both destroy cable sales and be an admission that they forgot the inductor when they first copied the RCA app note and have been selling unstable amps all these years.
Craig B
Re:trophile
I hear you, Jez.
Many years ago, Naim used to be happy to advise on alternative speaker cable choices. Regardless, I am happy to run the numbers through Excel for anyone wishing to know if what they have, or are considering, is close enough.
Or, they can order up a pair of Arkless 'Matchbox' and be done with it.
Many years ago, Naim used to be happy to advise on alternative speaker cable choices. Regardless, I am happy to run the numbers through Excel for anyone wishing to know if what they have, or are considering, is close enough.
Or, they can order up a pair of Arkless 'Matchbox' and be done with it.
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MJS
Technical Tinkerer
I've retrofitted inductors to Naim amps just once. Alas, the customer had biwired speakers with about 3m of speaker cable length and line of sight from a hill top to the Wrotham FM transmitter a handful of km away. There was a fair bit of RF getting back into that amp - a NAP250 that ran red hot.
I really don't get why it wasn't included, but let's say there has always been a lot of inertia at Naim with the way things have always been done.
I really don't get why it wasn't included, but let's say there has always been a lot of inertia at Naim with the way things have always been done.
Jim Audiomisc
pfm Member
I can only guess that on a bench test, squarewaves and the frequency response 'looked better' without an inductor. Or 'sounded better' with the speakers and cable they happened to use when listening. More than once in the far past I've seen a 'reviewer' comment about an amp being 'marginally unstable' because they saw an HF ring due to an output network and 8 Ohm load. Sign of lack of awareness.
And once an amp is in use by paying customers "Ooops!" might not have been felt to be the most comfortable response to what then happened. 8-]
And once an amp is in use by paying customers "Ooops!" might not have been felt to be the most comfortable response to what then happened. 8-]
Arkless Electronics
Trade: Amp design and repairs.
Indeed that is quite likely. When testing into capacitive loads especially the ringing from the "tuned circuit" can look bad... Pretty irrelevant under real world conditions though.
Craig B
Re:trophile
So, Jim, are you suggesting that Exposure, DNM, and a small number of other manufacturers all had 'Ooops' moments when designing their amplifiers, as well; or, were they intent upon extending the Thiele network out to the loudspeakers terminals, such that they had a measure of control over the load that their amplifiers saw in use?
Arkless Electronics
Trade: Amp design and repairs.
I'll say it... All the above are incompetently designed yes. Sales of speaker cable may well have come into it.
Craig B
Re:trophile
The hole in your sales of speaker cable theory, Jez, is that Naim didn't supply their own cable until quite some years later. Plus, both NACA4 and Exposure Cable were among the cheaper options when first they came along; even cheaper if one went down the B&Q and grabbed some BICC outdoor lighting wire off the reel.
Martyn Miles
pfm Member
I don’t know about Pure Henry, but there’s a programme on Radio 4 Extra called ‘After Henry.’
Probably no connection, though...
Arkless Electronics
Trade: Amp design and repairs.
They may well also be wanting to give the impression there is something so special and "thoroughbred" about the amps that only a specific cable can release the full "magic" etc etc...
Craig B
Re:trophile
What, as opposed to releasing the smoke?
Jim Audiomisc
pfm Member
Erm, I don't know if they did or not. Nor, indeed, do I know if their amps are unconditionally stable, or close enough to that to be regarded as such in practice. I've not measured or used them.
What I do know is sometimes people miss things.
Not sure how your second comment is meant to relate to your question. You can't "extend" the network to the speaker end unless *from first release* you make plain exactly what *specific* cable type/length has to be used with *every individual design of speaker* you then *allow* your users to use. Changing cable transforms the load the speaker *plus cable* presents to the amp. Changing the length also does this.
Hence to do it that way you end up having to say:
You can use speakers 'A' only with this specific type and length of cable. Speakers 'B' with this (other) specific type and lenght of cable, etc,. *And hence may NOT use any speakers not on our list.
Has anyone done that from first release of their amps?
The point of ensuring the amp is at least near-as-dammit unconditionally stable is to give users a choice without them having to worry about this.
Either way, if informed, the potential customers can make a choice.
djftw
Heterodox Member
Even though Naim have never OFFICIALLY admitted it, that their later amps are more stable with other cables and that even a lot of their official dealers will happily sell more expensive cables with them where they can is surely a tacit admission that needing the correct speaker cable to be stable was not a strong (and probably not a deliberate) design decision?
Arkless Electronics
Trade: Amp design and repairs.
More like they also saw low voltage DC lighting cable and thought they could sell it as speaker cable!!
I've told this one a few times but at Alchemist we were laughing about people paying loads of money for magic speaker wire when one of the partners, Warren, said "on a serious note though obviously if we can get some cable made with Alchemist written on it we'll sell it for a damn good profit and say it's the only type suitable for our amps, business is business lads..."
Most such units have a Zobel network. The missing inductor and resistor is sometimes called a Theile network and is there to add impedance at "ultrasonic" frequencies so that at say 50KHz+ where the problems are the amp cannot directly drive a capacitor but has to do so through the Theile network which will add maybe 3-6 Ohms ish in line at 50KHz.
Craig B
Re:trophile
Points taken, however, it would appear that, in Naim's case, they wished to ensure that cable inductance fell not much lower than 4uH (see Arkless' "3-6 Ohms ish in line at 50KHz", above), and parallel capacitance didn't much exceed 320pF. This based upon the published specifications, and minimum and maximum recommended lengths of the cables that they supplied/recommended; these in addition to the late MD's comments on the subject via his company forum and via occasional interviews.
Obviously, many thousands of Naim, Exposure and NVA customers have existed over the years, I doubt that many weren't made aware of the loudspeaker cable requirements at time of purchase. I've also never heard tell of a Naim amp that actually succumbed to incorrect cable choice, however, I've seen a few that were killed by errant shorting of outputs (in fact, I have one here). Perhaps we should all be naming and shaming those designs that aren't fully protected against dead shorts? Maybe @Arkless Electronics would like to cast the first stone here?
Regardless, my offer stands to run the specs of any alternative cables that Naim owners wish to consider. As @Gervais Cote found, the difference could be down to one's amp running circa 8ºC more than is typical. Those alternative cable users that prefer to run their's 24/7 should really consider having a closer look.
Arkless Electronics
Trade: Amp design and repairs.
Personally I don't expect amps to survive dead shorts as this is user abuse in almost all cases... if numptys will try and change speaker cables etc without switching the amp off then they deserve what they get! My big issue here is that said numpty will then try and get the amp repaired under guarantee after claiming "it just stopped working honest" and cost a manufacture a lot of money!
The running 8C hotter will be due to the amp actually going unstable and oscillating. Depending on the amp and the precise circumstances this can often be instantly fatal to the amp (and often speakers when the amp goes DC!) but with Naims is typically more gentle oscillation and will cause high distortion and hot running.
tuga
Legal Alien
Thanks, that was clear.