Naim BD NAP160 and HiCap. Replace capacitors?

[Jez1234]

I am one of the people involved primarily in "high end" audio repairs, design and the odd small run of amp builds etc and I'm afraid I find myself very often disagreeing with the forum stalwarts on this subject....
FWIW I'm actually banned from many hi fi forums for taking such a vociferously anti "foo" stance on things such as magic mains cables, enchanted £120 fuses which allegedly can transform the sound of your hi fi, special speaker cable @ £500 a metre and anti vibration platforms for solid state amps etc. I was even banned from one for refusing to concede to the site owner that yes indeed all phono sockets sound different from one another!! (for the entertainment of those unaware of this, there are even "grounding boxes" being sold, often for £500+, which consist of a wooden box full of soil and gravel and with a row of binding posts on the back!)

However.... I certainly do not agree with the prevailing attitude here that "all amplifiers of <0.5% THD and having a flat response from 20Hz - 20KHz sound the same".

I'm sure our "everything can be explained by the scope screen, FFT and maths" members* will not be happy to accept "there are more things in Heaven and Earth, Horatio, than are dreamt of in your philosophy" but after decades of working in this field I've kinda come to accept that that's just how it is and to stop questioning the fact that two amplifiers both measuring 0.01% THD or less, flat from 5Hz - 70KHz and with exemplary square wave response can indeed sound very different from one another.

* They are no doubt right of course in a perfect world where we knew of and possessed ALL the relevant information for analysis, even with vastly complex waveforms of music etc etc but unfortunately the current state of the art lies somewhat short of this or all amplifiers would be perfect...

To drift more towards on topic....

Both the quality of electrolytics fitted to amps and, often more importantly, the way they are used/misused in a given design can mean some amps do indeed benefit from blanket recapping whilst some other models will be fine even after 30 years. The largest "aggravating factor" in this is the silly practice of many audiophools of leaving their amps switched on 24/7/365!!
You try telling them that it is a very bad idea, after the manufacturer and dealer have told them otherwise, and see how far you get

I've had many amps in for repair which in spite of being only say 8 years old are full of leaking electrolytics and the ones which are not oozing electrolyte over the PCB mainly measure as very high ESR or even virtually open circuit and zero capacitance. Radial through hole caps eg 1000uF 35V seem to be the worst afflicted and often the much larger smoothing caps which see the ripple current are still hanging in there.

There are easily explained reasons for this of course and badly designed equipment with caps right next to voltage regulators, close to heatsinks, often right at their max V rating, in a warm at idle amplifier, combine with the effect of the owner leaving it on 24/7 to produce the inevitable results...

The same model used only a few hours per week and switched off the rest of the time may well last 20+ years of course.

OTOH I have a 1964 Scott valve integrated amp in at the moment which the owner thought needed recapping but I was somewhat surprised to find that all the electrolytics AND all the coupling caps ("American Radionic Co" 0.1uF 400V caps obviously much better than TCC!) are basically serviceable after all these years. A very small number of electrolytics will be replaced as they measure a little higher than I would like to see on ESR but they are certainly not at the point where they were about to cause a fault. Obviously it won't have been left on 24/7 and I wouldn't be surprised if it had seen periods of no use of 10 years or more at times during its life.

Naim unfortunately do recommend that their gear is left on 24/7.... and that it is returned to them or one of their approved dealers after ten years for a recap Try explaining that it is a bad idea and that they do not need to be switched on 24/7 and you'll get "I don't care if you are an engineer and have repaired thousands of amps, designed lots of amps, worked for leading UK audio companies etc. Naim say it has to be on 24/7 and so does my dealer and everyone on the hi fi forums so you obviously don't know what you are talking about pal!". Believe me, I know....

After 10 year of 24/7 use though it unfortunately is a good idea to do a blanket recapping and in the specific case of Naim power amps there is a well known issue of a couple of tantalums in the regulated supply which fail after around this time and cause oscillation....

[Jez1234]

Originally Posted by Valvepower

I’ve a pair of NAP135s and a NAC32 in the round tuit pile… these about 6 months to year away from getting put on the bench.

I’ve heard the stories of the tantalum capacitors and no doubt I’ll be replacing some of them, however it’ll be a process of testing the amplifiers checking the actual parts and some common sense.

Personally, the competent repair/restoration of this sort of amplifier can only be performed by using suitable test equipment.

There is a blurred line between blanket recapping and replacing just the faulty parts. For me there is sensible middle ground based on electronic testing and common sense.

Personally, speaking some of the ‘urban folklore’ surrounding audio [electronics] is starting to become rather tiresome. I’ve been in the audio electronics industry from leaving school in the mid-70s and ducked and dived all sorts of tends, folklore and suchlike, however of late the madness is starting to get to a point where I’m thinking of escaping the foolishness.

Anyway, that's my two penn'orth...

Terry

Just seen your post Terry and I couldn't agree more strongly! Like you my career in electronics has been largely audio and hi fi based and I too have become so worn down and sickened by all the BS and folklore (much of it incompatible with the laws of physics) that if I could take my skills elsewhere to some other field I'd probably do so. Unfortunately analogue, linear and especially anything involving music production/reproduction have been the centre of my focus for the decades I've been at this and, in this day and age, almost all other areas of electronics outside of hi fi and guitar amps etc have become digital and/or based around "200 pad BGA SMD IC's" etc. Hence, whilst it was not actually my intention, I find I'm now basically a "specialist" in vintage audio! I feel for the guys who spent a lifetime as engineers on steam trains only to find that "progress" had rendered their talents "obsolete"

Unfortunately it's not just a few crank journalists for certain hi fi mags that now propagate all the "foo" but pretty much the entire industry, including the majority of manufacturers (i know who you work for and they, along with the likes of Quad are amongst the more sensible one's). The majority of manufacturers have taken the attitude that as almost all audiophools have been completely brainwashed into believing the foo, and almost all hi fi dealers, hifi mags, online advertisers etc are singing from the same hymn book, they may as well jump on the gravy train and tell the customers what they want to hear (or have been primed to expect to hear!) and rake in the extra profits it brings.... ie the customers all believe that special expensive speaker cables and IEC mains leads etc are required and to the extent that if a manufacturer tried to persuade them otherwise they would now doubt the integrity/sanity of said manufacturer.... hence many manufacturers think "let's give 'em what they want and rake the extra money in". (When working for Alchemist Products many years ago a group of us were bemoaning the foo situation one evening when along came one of the partners, who agreed entirely, but then added "of course if we can get a good deal on some chunky cable and get our logo on it we'll obviously flog it as the best sounding for use with our kit. We would be foolish from a business perspective not to")

I've conducted a one man war on all these aspects of the industry for years and whilst I've had a (very few) converts it's basically got me banned from all the hi fi forums... who are of course part of the foo conspiracy in often hosting advertising from companies selling £120 magic 13A fuses!

It's become so bad, so entrenched, that if you are in the business of audio these days you are basically required to agree with and propagate all the BS and foo or keep to the backroom and STFU

[Radio Wrangler]

I designed an amplifier for myself. Mostly for the fun of it, partially because my speakers weren't easy to drive. Just for the hell of it I set myself some tough specifications and worried about it clipping cleanly and recovering without hang-ups, that it could slew quickly without distortion of other signal components.

It came out to my satisfaction, and a small batch was made at HP. I certainly did not publish it anywhere. It could have made a bit of useful money, but it was around the time the hifi business had gone crazy. No way was I going to jump into that bear pit. Trying to argue a point with people who haven't got the basic knowledge, but still have strong opinions and an unassailable belief in them.... has to be one version of hell.

I reckon next year's big thing will be audiophile grade spiked shoes for musicians.

David

[wd40addict]

The rot set in during the 80s. Any technical articles slowly disappeared from Hi-Fi magazines to make way for 'superstar' reviewers' opinions. The internet has only made it worse, some Hi-Fi forum dwellers seem to think amplifiers are designed by wizards and unicorns rather than engineers.

[Jez1234]

Originally Posted by Radio Wrangler

I designed an amplifier for myself. Mostly for the fun of it, partially because my speakers weren't easy to drive. Just for the hell of it I set myself some tough specifications and worried about it clipping cleanly and recovering without hang-ups, that it could slew quickly without distortion of other signal components.

It came out to my satisfaction, and a small batch was made at HP. I certainly did not publish it anywhere. It could have made a bit of useful money, but it was around the time the hifi business had gone crazy. No way was I going to jump into that bear pit. Trying to argue a point with people who haven't got the basic knowledge, but still have strong opinions and an unassailable belief in them.... has to be one version of hell.

I reckon next year's big thing will be audiophile grade spiked shoes for musicians.

David

I can confirm it being one version of hell yes! The bit that really had me spitting feathers and near apoplexy was when the site owners or moderators then (repeatedly!) gave me public dressing downs along the lines of:

"it is merely your opinion that £120 mains fuses or solid silver IEC mains cables do not and cannot make a difference and the opinion of those who claim they make a night and day improvement is just as valid as yours even though you design amplifiers and they are a taxi driver/plumber/accountant. The so called laws of physics may yet prove to be wrong and I'll thank you not to upset the members of my forum by telling people that the claims they make for magic wire and fuses etc are actually impossible or you'll find yourself on a ban at this rate"

And that's genuinely as close to verbatim as matters... unbelievably!

[Jez1234]

...and while I'm on the soap box.... The majority of the members on these hi fi forums believe that beyond the fascia of an amplifier "here be dragons" and that anything about slew rate, frequency compensation, loop gain, PSRR etc etc may as well be ancient Egyptian, don't matter anyway, and "we don't need experts", whilst espousing that basically the performance of any given amplifier is entirely dependent on which foo accessories are used with it. ("It sounds bass light? What you need is a Russ Andrews mega mains cable. It will add at least 20Hz extension to the bottom end and it's only £470")

Oddly enough said accessories can always be fitted in seconds by someone who cannot wire a mains plug and without lifting the lid...

[Radio Wrangler]

If all transistors were fitted in standard-sized sockets, they'd be as full of foo as valves...

David

[Cathovisor]

Originally Posted by Jez1234

...and while I'm on the soap box.... The majority of the members on these hi fi forums believe that beyond the fascia of an amplifier "here be dragons" and that anything about slew rate, frequency compensation, loop gain, PSRR etc etc may as well be ancient Egyptian, don't matter anyway, and "we don't need experts", whilst espousing that basically the performance of any given amplifier is entirely dependent on which foo accessories are used with it. ("It sounds bass light? What you need is a Russ Andrews mega mains cable. It will add at least 20Hz extension to the bottom end and it's only £470")

Oddly enough said accessories can always be fitted in seconds by someone who cannot wire a mains plug and without lifting the lid...

I got involved with building music studios decades ago. Sure, they had Neumann U87s and U89s, AKG C414s... but the wiring was very run of the mill indeed at the time. Plain old "star quad" for microphones, solid core wire to break-out panels for multitracks. Nothing magical involved, no fairy dust.

When subjectivism usurped objectivism is when I stopped reading hi-fi magazines. These days I listen to the music, not the system: I don't panic about the stray neutrinos bombarding my amplifier.

As for "the so-called laws of physics"... give me strength (or more beer)

[Cathovisor]

Originally Posted by Radio Wrangler

If all transistors were fitted in standard-sized sockets, they'd be as full of foo as valves...

David

This is something we've discussed before, ISTR... "wine-tasting", you called it

[Jez1234]

For the amusement of any who didn't know this... in the very early days of transistors many items, especially for radio hams so RF pre amps, converters etc, were indeed built precisely as a valved counterpart would have been even down to all the transistors being in sockets on top of the chassis.

One can only imagine the chaos with audiophools if things were still thus! "NPN, PNP, Ft, gain what's all that nonsense about, sounds like a load of BS to me and it's got the same pin out just like an ECC81 and ECC83 and I'm gonna try it...."

[bikerhifinut]

We're drifting off topic a bit maybe?
But I'm enjoying the discussion so perhaps mods might split the non relevant threads off?
As to "semiconductor rolling" as opposed to "Toob rolling", this is a thing.
I'm thinking about opamps in 8 pin DIL packages and in stuff like Quad 405 amps to give an example, and one where I have a limited experience.
I bought a heavily "breathed on" 405 at an audiojumble chock full of "Special" Black Gate electrolytics and of these a liberal amount were Non polarised jobs in locations where Mr Walker never designed them in. Underneath the PCB it looks like theres a liberal sprinklin of film capacitors as bypasses I assume. And a fancy opamp in the socket where originally a TL071 resided, along with a feedback tweak to reduce the sensitivity to around a Volt I reckon. It came with a sheaf of paper extolling the virtues of these mods.
Well........ I can't say that it has any magic sonic virtues over an above the 405-2 boards a certain mr valvepower of this parish repaired for me. In fact I'd go so far as to say the repaired boards are possibly "nicer" in sound but thats subjective and all I know for sure is that Terry measured after the rebuild and the amp boards measured exactly as per specification. No capacitors were replaced apart from the cream crackered 10uF non polarised jobs on the on board clamp circuit, it was this that probably caused the boards to blow their output silicon I am led to believe.
We had a discussion about that and Terry made a very effective replacement involving a couple of 4.7uF film caps in parallel thus taking away the fear of a non polarised elco drying out . Terry may wish to throw his opinion in here........
I have a real weakness for the 405 and 405-2, I think when working as designed they are still very hard to beat for real world listening and as i use a pair of ESL989 they are well suited to that task.
I hear all the critique of the 405 and 405-2 and agree the clamp circuit isnt their best moment, but the thing for me is they are extremely serviceable units, as robust as any other commercial offering and once the couple of underspecced parts have been replaced etc then they're good for another "lifetime" of pleasure. That a 40 year old power amp can still perform as well as the day it left Huntingdon with a minimal amount of servicing says it all for me.
Back to the op amp comparisons, I do wonder what all this swapping of various flavour of the season devices achieves, the TL071 that ended up in later models is, to me, perfectly adequate and suited to the design, even the critique of it being in an inverting circuit seems a bit nit picky, I can't hear the noise floor etc. But people will shove all sorts of op amps in a socket and I wonder if they think about possible adverse stability effects etc.
Andy

[Craig Sawyers]

Tektronix throughout the 7000 series scopes and plugins used socketed semiconductors. It makes fault finding easier for sure - it is dead easy to pull a transistor and test it.

Back to leaving amps on 24/7 - why? Any semiconductor amplifier, whether preamp or power amp that take more than 10 minutes to settle down is a poor design. Valved designs might take 30 minutes or so after switch-on to settle down.

Even Russ Andrews, a died-in-the-wool 24/7 guy now advocates switching off at the mains when not listening, and finds that after a short time after turning on, it sounds precisely the same.

Craig

[Radio Wrangler]

Wandering back towards the original topic. If Naim were daft enough to say users should leave their amps on 24/7 and their customers were daft enough to follow it, then in a warm-running amplifier, all the wet capacitors have had an accelerated life test and we're getting into the territory where a complete replacement of all electrolytics might not be so daft.

It would still be interesting to run round them all with an ESR meter. Facts are always better than assumptions. And it's comforting to have justification for your choices.

But why was that 24/7 edict issued? It could have been to counter failures due to thermal cycling. It also could have been to counter an issue with turn-on surges and overshoots. Or it could have been un 'omage to Tommy Flowers and Colossus. Whatever reason, it was made in an era where energy prices were nothing like today's.

David

[Radio Wrangler]

24/7 with mains connected, even if the gear is not switched on, racks up the hours on those lovely, golden Rifa smoke bombs in the mains filters.

David

[Jez1234]

Originally Posted by bikerhifinut

We're drifting off topic a bit maybe?
But I'm enjoying the discussion so perhaps mods might split the non relevant threads off?
As to "semiconductor rolling" as opposed to "Toob rolling", this is a thing.
I'm thinking about opamps in 8 pin DIL packages and in stuff like Quad 405 amps to give an example, and one where I have a limited experience.
I bought a heavily "breathed on" 405 at an audiojumble chock full of "Special" Black Gate electrolytics and of these a liberal amount were Non polarised jobs in locations where Mr Walker never designed them in. Underneath the PCB it looks like theres a liberal sprinklin of film capacitors as bypasses I assume. And a fancy opamp in the socket where originally a TL071 resided, along with a feedback tweak to reduce the sensitivity to around a Volt I reckon. It came with a sheaf of paper extolling the virtues of these mods.
Well........ I can't say that it has any magic sonic virtues over an above the 405-2 boards a certain mr valvepower of this parish repaired for me. In fact I'd go so far as to say the repaired boards are possibly "nicer" in sound but thats subjective and all I know for sure is that Terry measured after the rebuild and the amp boards measured exactly as per specification. No capacitors were replaced apart from the cream crackered 10uF non polarised jobs on the on board clamp circuit, it was this that probably caused the boards to blow their output silicon I am led to believe.
We had a discussion about that and Terry made a very effective replacement involving a couple of 4.7uF film caps in parallel thus taking away the fear of a non polarised elco drying out . Terry may wish to throw his opinion in here........
I have a real weakness for the 405 and 405-2, I think when working as designed they are still very hard to beat for real world listening and as i use a pair of ESL989 they are well suited to that task.
I hear all the critique of the 405 and 405-2 and agree the clamp circuit isnt their best moment, but the thing for me is they are extremely serviceable units, as robust as any other commercial offering and once the couple of underspecced parts have been replaced etc then they're good for another "lifetime" of pleasure. That a 40 year old power amp can still perform as well as the day it left Huntingdon with a minimal amount of servicing says it all for me.
Back to the op amp comparisons, I do wonder what all this swapping of various flavour of the season devices achieves, the TL071 that ended up in later models is, to me, perfectly adequate and suited to the design, even the critique of it being in an inverting circuit seems a bit nit picky, I can't hear the noise floor etc. But people will shove all sorts of op amps in a socket and I wonder if they think about possible adverse stability effects etc.
Andy

Complains about people going off topic and then the remaining 95% of the post is about the Quad 405 and the merits/demerits of modifying them!

Sorry couldn't resist the cognitive dissonance there

The 405 current dumper is a clever and interesting design and the production engineering of the unit is exemplary. I got one in with a 33 preamp the other day which the customer said he's had for 40 years. Good going!

They can be beaten on sound quality though. They're certainly much better than some of the things we've all read for decades about them being "slow, muddy, boring and can't drive any real world speaker" though, which is frankly BS. I wonder if in fact the real world VFM, reliability, 100WPC of power, good (and original) styling and pretty decent sound was a threat to the sales of much more expensive amps and so the rumours were started....

[Jez1234]

Originally Posted by Radio Wrangler

Wandering back towards the original topic. If Naim were daft enough to say users should leave their amps on 24/7 and their customers were daft enough to follow it, then in a warm-running amplifier, all the wet capacitors have had an accelerated life test and we're getting into the territory where a complete replacement of all electrolytics might not be so daft.

It would still be interesting to run round them all with an ESR meter. Facts are always better than assumptions. And it's comforting to have justification for your choices.

But why was that 24/7 edict issued? It could have been to counter failures due to thermal cycling. It also could have been to counter an issue with turn-on surges and overshoots. Or it could have been un 'omage to Tommy Flowers and Colossus. Whatever reason, it was made in an era where energy prices were nothing like today's.

David

My theory is that it is to give the image of them being so special, esoteric, thoroughbred and "finely tuned" that switching them off and allowing them to get completely cold etc would be akin to leaving a priceless Stradivarius out of its temperature and humidity controlled storage... Oh if it gets a touch too humid or cool the tone could be a touch off for tonight's concert!. I've seen claims by Naim devotees that after switching off for a week it didn't sound right again until 3 months on for 24/7 had passed!

[bikerhifinut]

Originally Posted by Jez1234

Complains about people going off topic and then the remaining 95% of the post is about the Quad 405 and the merits/demerits of modifying them!

Sorry couldn't resist the cognitive dissonance there

The 405 current dumper is a clever and interesting design and the production engineering of the unit is exemplary. I got one in with a 33 preamp the other day which the customer said he's had for 40 years. Good going!

They can be beaten on sound quality though. They're certainly much better than some of the things we've all read for decades about them being "slow, muddy, boring and can't drive any real world speaker" though, which is frankly BS. I wonder if in fact the real world VFM, reliability, 100WPC of power, good (and original) styling and pretty decent sound was a threat to the sales of much more expensive amps and so the rumours were started....

Guilty as charged m'lud.
But I did feel we were getting into a general discussion about tweakery and the like.
I'll get my coat.................

A

[Jez1234]

I tend to drift myself... and yeah enjoying the discussion also

[Analogue man]

Originally Posted by Jez1234

I am one of the people involved primarily in "high end" audio repairs, design and the odd small run of amp builds etc and I'm afraid I find myself very often disagreeing with the forum stalwarts on this subject....
FWIW I'm actually banned from many hi fi forums for taking such a vociferously anti "foo" stance on things such as magic mains cables, enchanted £120 fuses which allegedly can transform the sound of your hi fi, special speaker cable @ £500 a metre and anti vibration platforms for solid state amps etc. I was even banned from one for refusing to concede to the site owner that yes indeed all phono sockets sound different from one another!! (for the entertainment of those unaware of this, there are even "grounding boxes" being sold, often for £500+, which consist of a wooden box full of soil and gravel and with a row of binding posts on the back!)

I've been saying this for years but I'm luckier than most, I only have a small audience and for the most part they accept what I say and keep their hard earned cash in there pockets.

[Valvepower]

Hello,

To answer David’s question...

Yeah, I’m happy with the sound of the pedals and effect gadgets – alright I admit to some ‘fun’ germanium tweakery, I even get a big grin on my face when I find bag of 'tropical' fish capacitors lurking at the bottom of a box at a Sawpmeet, but I’m OK being like that.

After yesterday, I feel I need to take some time out of the forum for a short while as the line between being an engineer and someone who actively works in the world of audio (hi-fi and musical in instrument amplification) has got rather blurred... Anyway, I feel it would be beneficial to put some time into the wireless, electronic and audio pursuits/projects and suchlike in the workshop.

I’ll lurk keeping an eye on the wanted posts just in case I can pass on some of my unused stuff (wife says junk!), also If a thread really takes my eye, I could well chime in.

Caroline is just playing Simon and Garfunkel, Bridge over Troubled water… and to ‘lift’ the lyrics... hi-fi, audio and musical in instrument amplification seems to cause troubled waters

Terry.

Originally Posted by Radio Wrangler

Terry,

Are your fuzz pedals effective and produce a sound you seek?

David