Big Overkill Amp Rebuild

edited July 2012 in DIY

I have an 'spare' amp, bought on a whim that is currently residing with a friend, a very capable hifi loving friend who has a soldering iron and knows exactly which end gets hot. What is more he is more than capable of constructing and or modifying almost any amplifier, and a lot more besides, so a simple check-up has become a rather more elaborate affair.

When rebuilt, it / they will be monoblocks with two 1000va transformers, so pretty hefty. Each (big fat) transformer weighs 7kg!  So that's two 1000va transformers in each amp. >:)

This is patently ridiculous overkill, but I sold all my spare accumulated HiFi stuff to make this project self-funding - if I'm going to make that kind of sacrifice I want it to be fun!

On the recommendation of my executive amplification consultant ^:)^   I have also bought some pretty fancy (and hyper expensive) smoothing capacitors - a set for each traffo. And some really trick bridge rectifiers (it was very interesting - and something of a bonus - to learn what it is they do).

So the whole thing is pretty exciting, I'll post more later when they are closer to being built (apparently we are waiting on some parts).

In a general sense, does anyone know what sort of difference larger power supplies should make to an amplifier?

Comments

  • They make the amplifier heavier Alan. Considerably heavier.
  • Btw Alan, I'm impressed! I look forward to hearing how your project progresses. :-)
  • They should give you greater dynamics and grip.
  • Having gone up the NVA range of amps, using the same circuit each time (the only change being PS size), I felt the larger amps were capable of reacting faster. This, dynamics and grip are all good, but I'm hoping it won't simply be a bulldozer, an egg-cracking sledgehammer if you will.

    I enjoyed going to the TSS as it not only did the 'bigger' thing but was so much better at the 'soft' stuff, like texture and low level detail. What I am wondering is if all that was down to the power supplies.
  • PSUs and component quality, I'd say.
  • edited July 2012
    So here is a preliminary shot on the workbench, trying to work out how to lay out the components. There's nothing really to show scale unfortunately, but it's cool to see it all there for the first time.Photobucket



  • Was getting some prices on casework, trying to get some acrylic like before but just too dear. Probably going to get some hardwood front & sides made up.
  • Have you tried Paul? Didn't he start offering acrylic stuff recently?
  • I didn't TBH, I have an acquaintance who machines acrylic in a local supplier. The price I got wasn't quite 'mates rates' but was less than full RRP, and we were still looking at approx £70 + VAT per case...it's the thickness we need.

    I am going with some nice hardwood front & sides, not too dear by comparison and potentially much more attractive IMO. Also, there is the faintest chance of a further rebuild in the years to come...

    I am minded towards something like Zebrano. My first choice was American Black Walnut, but this can look really boring, and seeing as I'm not going to be able to hand pick my wood I'll take the stripes...

    image
  • Fairy nuff!

    Wood looks groovy.
  • mmm...gravy..

    Ordered the Zebrawood now, too late to have second thoughts. It wont be too dear to have a couple of perspex top plates made up (with hole for ventilation), it might be fun to be able to peek inside.
  • See dem 'tronics leapin' aroun'? :-)
  • Alan,

    Go to the tip. find duff flat screen TV monitors there in side each you find a nice big very flat clear acrylic sheet.
    That is what I did worked very well.

    Col
  • Nice! Thanks for the tip Col (see what I did there?)


  • Nice one Alan, 
    Really looking forward to what you find, 
  • Alan what value caps are they? and the 4 diodes what type please.
  • The caps are 22000 uf Kendeils. I don't know much about the bridges, but I believe they use TO220 Schottky diodes, 20amp. Not that I know what this means...
  • edited July 2012
    Nice one Alan, 
    Really looking forward to what you find, 
    Thanks mate, I'll keep you posted, as promised!
  • The caps are 22000 uf Kendeils. I don't know much about the bridges, but I believe they use TO220 Schottky diodes, 20amp. Not that I know what this means...
    Part number should be on them, what voltage is the transformers and do have any idea of the current or power you need?
  • I know not of what you ask, but then I am not doing the work (so the parts are not here). I did forward your last email and my amp man assures me the parts are up to the job.
  • edited July 2012
    I want to thank those of you that emailed me for your kind concern, and to say please don't worry about it. (the rest of you will have to read betwixt the lines!)

    It's not an unusual thing to modify an amplifier, just look at DIYAudio forums or Pink Fish Media, or HiFiWigWam, or AudioSmile (formerly ZeroGain), or Art of Sound...the only factor at play here is the original manufacturer of this particular amplifier. To my knowledge, no comment has been passed by this person regarding the rebuilding of Naim amps by end users with Avondale parts, or ID Design amps being rebuilt/uprated, or similar (there are loads of examples).

    I am quite aware there will be no sympathy, far less support if the project goes wrong but I never expected, nor asked for any.

    At the end of the day, I am not "plagiarising" anyone's design, nor am I out to provoke any kind of response (any more than I'm interested in reading these responses). I am simply having my NVA amp rebuilt - as hundreds of people do with their own amp of choice - for fun. The design of the amp is not changing, the circuit will be untouched as I want an improved amp with same qualities I value in NVA. This is because I really rate NVA, not, as I am told has been suggested, because I want to "knock NVA".

    Why is it OK to do this with other amps, but not this one? Or for others to do this, but not me? Or on other forums, but not this one? So please dont be concerned, I'm not even going to read it, as I have no problem with it.
  • Don't be deterred Alan. I for one am looking forward to seeing this project progress. It's just a box of electronics at the end of the day, it's yours and you should do whatever you want with it.

    James/FAF*

    Fellow Amp Fiddler.
  • Don't be deterred Alan. I for one am looking forward to seeing this project progress. It's just a box of electronics at the end of the day, it's yours and you should do whatever you want with it.

    James/FAF*

    Fellow Amp Fiddler.
    I have no intention of being de-turd! :D Thanks James, I appreciate your kind words. I'm kind of worried about all that faffing though, can't be good for your eyesight?...
  • Go for it big Al'!
    We await your progress reports. :-)
  • Twin 1000va trannies???  :D

    That means now that you can drive seriously big loud speakers!  I'm thinking THX certified 140dB 12ft high monsters!

    Looking forward to the outcome Alan.  Ignore any dissent RE the amp.  It's your decision and yours alone and so glad to hear that you are not going down the route of being a de-turd as that wouldn't be very hygienic  :-& or photogenic b-(


  • Big trannies is good, we say! :-)
  • edited July 2012
    You say! So they say... :D
  • :-\" :-\"
    We ( I ) am waiting eagerly to know what the outcome is....
    I know the size the the A80 heatsinks and with that as a reference those tranies and caps are BLOODY MASSAIVE!!!
    I'm waiting for the amps to either blow up and make a staggering difference!  I hope it works out well for you.
  • They almost certainly won't blow up. That same circuit has four thumping great power supplies on the TDSs I have. None of the power supplies are as big as those Alan is using, but there were some NVA amps that were even bigger than the TDSs, back in the day.

    My betting is that Alan may be on to something.
  • 'I' am onto nothing, all credit has to go to the evil amp genius who came up with this hair-brained scheme...

    Before anything is made too permanent I am going to crack open my TSS amp and photograph the innards, just to make sure nothing much changes from the black box range to statement range (bar PS size/quality etc). The circuits I have in the rebuild are from a mid nineties A80, so there may have been recent changes. I'll pop them on photobucket or something so 'EAG' (Evil Amp Genius) can have decent look.

    I'll post one or two of the pics if anyone is interested in electronicy stuff? Otherwise I won't, as I don't know what I'm looking at.
  • edited August 2012
    Right-O chaps, here is a link to an album of 25 internal pictures of my TSS power amp. I took loads to try to show everything, they are in no particular order. It looks messy because it is a prototype amp.

    Here are a few shots:

    image

    image

    image
  • I'm no expert Alan, but those squiggly coloured things look like wires of some sort...

    Seriously, i'm getting nervous just looking at those pics - please put the base panel back on ASAP! :-0
  • It's back on already, I didn't want those 'tronics escaping into the garden!

    So, EAG has informed me that the first pair of power supplies has been made. He hooked up one of the circuits and has run it into his test speaker for a couple of hours with no drama as yet, and all the magic smoke has (as yet) stayed inside where it belongs! WooHooo!
  • Yep. I've been plugged into the live commentary feed from the EAG Stadium this afternoon :-)
  • Amp #1 was running for over three hours yesterday, much to my relief and pleasure. EAG is starting to think about shoe-horning it into a case of some kind now.

    It's nice to know it works though. :)
  • One of those nice ones with wheels and an extendable handle would be good. You don't want to go carrying it, now do you? :-)
  • Hello Alan, I don't know what's the alternative, but for my experience the nva amps partnered with the right speakers are among the best amplifier i've heard so far.
    I've read on a italian magazine (about dyiy audio) about a quite well know amp technician in italy, his name's Nardi (a technician  for audionote) who didn't succeed in repairing a nva ap50 and he left only the shell , inside he built a gainclone...what a pity for the owner...

    ciao!
    s
  • Interesting project Alan - you are brave!

    Just one thing to consider with this circuit.
    It is clearly a heavily tuned circuit designed to operate under certain known conditions. This is to be expected with a very wideband design which eschews input and output filtering.  In such circuits, the layout of the amplifier can be critical to the correct operation - even the way it is wired within the case.

    I wouldn't choose to modify one for that reason, unless I'd designed it in the first instance as you are unlikely to improve it IMHO.

    Don't be tempted to push the output capability. The output transistors will carry a maximum rating, partly dependent on the device and partly the heat sinking provided. Don't be tempted to push the supply rails higher, especially if you are giving virtually unlimited current reserves from a massive PSU. There will be a thermal/stability limit for the design and no doubt NVA know those limits and stick to them.

    If you want to experiment with good amp circuits then the gainclone designs are good as are the Avondale cards. Both are filtered and current limited.

    Sorry I don't want to put a downer on things, I just don't want you blowing yourself up!

    regards,
  • edited August 2012
    Interesting project Alan - you are brave!

    Just one thing to consider with this circuit.
    It is clearly a heavily tuned circuit designed to operate under certain known conditions. This is to be expected with a very wideband design which eschews input and output filtering.  In such circuits, the layout of the amplifier can be critical to the correct operation - even the way it is wired within the case.

    I wouldn't choose to modify one for that reason, unless I'd designed it in the first instance as you are unlikely to improve it IMHO.

    Don't be tempted to push the output capability. The output transistors will carry a maximum rating, partly dependent on the device and partly the heat sinking provided. Don't be tempted to push the supply rails higher, especially if you are giving virtually unlimited current reserves from a massive PSU. There will be a thermal/stability limit for the design and no doubt NVA know those limits and stick to them.

    If you want to experiment with good amp circuits then the gainclone designs are good as are the Avondale cards. Both are filtered and current limited.

    Sorry I don't want to put a downer on things, I just don't want you blowing yourself up!

    regards,
    Thanks mate, for the kind words. Good to see you around again!

    I shall pass on your comments to Dr EAG (Evil Amp Genius), who is doing all the work here and deserves any credit should it actually work! The idea behind the bigger PS wasn't really 'more power' [/Clarkson], AFAIK.

    As regards thermal limits, we already added more heatsinking to be on the safe side, as it seemed a bit marginal before. TBH I don't honestly know exactly where we are just now as I haven't been along to see for myself for a while, and real life is gloriously intrusive in the summer!

    We did discuss an interesting alternative build a few weeks, but although I can see it might very well result in a better amplifier I don't think I can fund it right now. So this rebuild will continue at a leisurely and economical pace until EAG is satisfied with wot 'e 'as done. If that day doesn't arrive we might look at the alternative out of necessity.

    Thanks Rob! :)
  • You're welcome Alan - I pop in now and again and of course follow you on the Twitter thingy  :)

    Will the mysterious Dr EAG ever be revealed?
  • edited August 2012
    You're welcome Alan - I pop in now and again and of course follow you on the Twitter thingy  :)

    Will the mysterious Dr EAG ever be revealed?
    Dr EAG is far too sensible to 'come out' just yet - apparently RD is watching this thread and blindly sniping from a dark corner of the internet with nothing positive to say, and Dr EAG won't want to get dragged into all that. Anyway, he knows where Chews is should he want to join this silliness - I hope he will if RD doesn't put him off.

  • How's this progressing Alan.
  • I don't think it is to be truthful, not for the moment at least. Dr EAG has a life beyond doing me favours (the cheek!), and I don't want to hound him. I told him to take his time as he had other things coming up and that is what happened. Anyway, I have a stonking amp that keeps me happy in the meantime.

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