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idiots guide to amp building

Discussion in 'd.i.y.' started by say it as it is, Feb 26, 2021.

  1. say it as it is

    say it as it is pfm Member

    ok hands up I am pretty clueless but reading on here has pickled my head even more!

    have an old 260Z just about understanding it. just! plan was to get NCC200 (check) Cap6 (Minicap6 check) and a decent transformer ( might be sorted waiting on Les)

    then been asked am I going to regulate the front or back end?

    lost here only had non regulated amps 140/180 in past.

    so regulation how is this achieved and what it cost relative to performance as the ncc200 spec amps seem very good as they are?

    doing this on a shoestring so what components and costs are involved in going to regulation.

    I see the hackernap transformers for example have 4 sets of secondary outputs, so is a specialist transformer needed or an additional transformer.

    if still at the build stage wonder if I should take this into consideration or is the simple transformer - Minicap6 - NCC200 still acceptable?

    yes I know the NC220 is better but that would mean having to change both amps and costs spiral then.

    apologies if this been covered to death just getting into the idea of using something outwith the big manufacturers offerings.
     
  2. JimmyB

    JimmyB pfm Member

    You originally started as a straight NCc200 build to match your current one. Probably the easiest route is just to build it with a single 2 X 35-0-35 transformer and minicap. This gives you an amp that would compare to one costing a LOT to buy from a dealer.

    All the rest including front end separate P/S and regulation can be added at leisure later as funds and time allows.

    Rule of thumb is KISS or else you end up never finishing the build!!!
     
  3. divedeepdog

    divedeepdog pfm Member

    Regulated front end will almost double build costs, regulator boards, additional minicap6, transformers, so on that shoestring stick to basic 260z recipe.

    The one concession I’d make is the cases, if you can make them mono blocks now it’d make the step to Voyager easier
     
  4. JimmyB

    JimmyB pfm Member

    And there's the question big do I go the VBE route or full on HCR200 for front end regulation.

    TBH, although satisfying, sometimes having a DIY break and buying more music is a better way to go*

    *not that I've ever followed my own thinking.
     
  5. say it as it is

    say it as it is pfm Member

    ok points taken I have bought a case from a fellow fishie just tight to fit it all in with just a plain NCC200. The idea of the Hackernap transformer with 4 secondaries might be a future proof option then. Anyone run one of these are they as quiet as the AST that Les uses?

    I have seen the HCR200 boards on Avondale website not the VBE what is the difference?
     
  6. JimmyB

    JimmyB pfm Member

    They'll be quiet but hell of a price and if you never use the extra secondaries...
    Also, would it not be better to have entirely separate transformers for front end duties for the cleanest possible supply*

    Ask Les about VBE to HCR but why fret until you're ready.

    *Errr no
     
  7. Jo Sharp

    Jo Sharp Pulls on doors marked push

    VBE is a filter circuit and best used only for regulating the front end of the NCC200s/220s. The HCR is an improved version of the Naim regulator boards used in the 250 and 135 amps, designed to power the whole of the amp board, not just the front end.
    Many people have found that using either circuit for just the front ends of the 200s/220s, and running the output transistors from the PSU caps directly gives very good results.
     
    JimmyB likes this.
  8. muchtoofast

    muchtoofast pfm Member

    This may also be of some help, Alan's recommendations here:

    Im going down the same path, but with the NCC220s, as I'm sure many have before. Should be some kind of right of passage lol.
     
  9. muchtoofast

    muchtoofast pfm Member

    Ref the previous comment below from say it as it is:

    Quote:
    damn I wish i had done my research my case is way too small

    I was only looking to clone my existing amp now i see there is a whole other avenue with regulation!

    so do the latest NCC300 incorporate regulation then?

    I am kind of lost now the plan was to make 2 matching amps but now I know there can be further improvements grrrr.

    think short term will be 2 ncc200 amps maybe swap the transformer in the original amp for a quieter better grade.

    for future upgrades a pair of minicap6, a transformer looking at the specs only needs to be a modest output? looking at the pics I have seen not a toriod? and either a VBE or HCR200 or change the whole boards for NCC300?

    /endQuote:

    --------------------------------------------------

    Are you looking to build two ncc200 monoblocks? Im not clear on where your are currently with your power amp configuration and what you are trying to do? Bear in mind, I've just started this journey myself and I'm not even denting the surface of the fun of it, but I'll try to help where I can. I've read some stuff and happy to share :)

    Ive also seen just the transformers in another enclosure for emf isolaton purposes, so your smaller enclosure may be still be useable way further down the line - £30 on a second hand enclosure cant be too bad to experiment with. Besides, you can always sell it on :)
     
    Last edited: Feb 27, 2021
  10. say it as it is

    say it as it is pfm Member

    Hi no trying to keep them stereo amps. When I picked up an old set of SBLs most agreed the biggest benefits to them was to go active ( whole other story i was going to use a miniDSP 2x4 but been told that not a good idea). So choice was get a multichannel amp or one to match my existing A260z or NCC200. Only when I started to look into it I see the voyager set up. Then I found the transformer in my existing amp may benefit from an update. So has kind of snow balled now. But yes your point is valid I suppose a seperate box with the power eg transformers and caps to feed 2 amps could be a bespoke situation in the future.
    For now think it's going to be a plain NCC 200 stereo amp.
    But now I have seen what potentially is out there who knows in the future!
    Just need a crash course in electronics to do this one haha
     
  11. muchtoofast

    muchtoofast pfm Member

    Yes, I wish I'd paid more attention to my analogue electronics part of my education lol. As far as I can tell these amps are relatively easy to bodge together. Tranformer with two 35-0-35 outputs (more outputs required if you intend to upgrade further) -> cap 6 on each channel -> NCC200 or NCC220 on each channel (quiescent current needs setting on the NCC200 and a DC check on the speaker output terminals need to take place) ...as for adding soft start and speaker protection, I havent worked out if that's necessary. Needless to say, if lights go out and the cones of my Allaes end up on the floor, then I should have invested in both :):D Laverne has some videos on youtube regarding the quiescent current settings on the NCC220, I gather the NCC200 is the same procedure but with 20mA and not the 120mA for the NCC220.
     
  12. say it as it is

    say it as it is pfm Member

    yes am the same I went into mechanical engineering so only dealt with larger scale electrics. the exposure to PLCs well on the cranes I used to work with well they were clunky and outdated when built haha.
    so far have got a case, a bit on the small side and think I will see about getting a slab of aluminium to act as a heatsink, Pair of minicap6 (Les reckons these be fine against Cap6), pair of NCC200. Still waiting on a transformer but with my high mains voltage (249/250V) I have checked a 33-0-33 230v that gives 51V after Minicap6. Once that arrives will start thinking about placement as depending on size of the transformer that limits things a bit. Waiting on soft start as well not looked at speaker protection the 260z does not have this either.
    when in get stuck I will come on here.
    just now the only thing confusing me is the switch and board that came with the case and how that with the soft start, looking at the 260z it takes connection from the cap6 into the switch as well as from the soft start module.
     
  13. muchtoofast

    muchtoofast pfm Member

    Don't have a clue about the soft start configuration in the 260z, maybe someone more knowledgeable can fill you in on that one. I always thought it was simply switch and inlet into one board with the output going onwards from said same board.

    You've got me thinking about my mains now, so I went and measured it. My cheap multimeter fluctuates between 242 and 250VAC. Ill get hold of a fluke tomorrow and have another go. Thanks for pointing out this pitfall. :eek:
     
  14. 337alant

    337alant Negatively Biased

    The Bias current on the NCC200 is 34-38mA as stated on the schematic

    As for soft start I prefer a speaker protection module that also has a switch on delay
    A soft start does not stop switch on thump in my experience
    Alan
     
  15. JimmyB

    JimmyB pfm Member

    Deffo add speaker protection, sods law says if you don't......

    Be careful sticking a cheap DMM into the mains, friend fried his by doing this but he was lucky that it was all that was stone dead at the end.
     
    Last edited: Mar 1, 2021
  16. muchtoofast

    muchtoofast pfm Member

    Yeah, ouch... lucky mine took it then, i normally use the positive probe to push down the plug socket earh to reavel pos and neutral holes, then ram the nagative in then remove and insert the positive in to other AC hole. Stand at arms length and switch on the plug socket without getting anywhere near the DMM. Probably a good idea to pop the DMM in an oven baking tray to stop the caprpet catching fire should the worst happen I guess.

    Worst I ever had was stripping the wire in between the christmas tree lights and neglecting to unplug prior. My fillings almost all jumped out of my mouth. I now know all my dental nerve endings intimately. I expect theres a thread somewhere on stupid stuff with mains. To be taken seriously!
     
  17. say it as it is

    say it as it is pfm Member

    must confess i have tested the effectiveness of my breakers in the house in the past accidentally, mostly by meter probes touching where they should not haha
     
  18. bugbear

    bugbear pfm Member

    That's what my Sugden has.

    It dims the room lights when I turn it on!

    BugBear
     
  19. a.palfreyman

    a.palfreyman pfm Member

    Was monitoring the mains a few weeks ago. On the Sunday it was all over the place, anywhere between about 240 and 227 which was getting very close to the newly-built front-end positive regulators in my NCC200 dropping out. Normally runs around 237.
    On the subject of stupidity with the mains, was working on a washing machine many years ago (at a friends house) with a sticking interlock solenoid. All of a sudden, my upper arm muscle was pulsing very rapidly. Thankfully had heavy boots on which I have no doubt helped so the current leaked through the pullover sleeve! Managed to fix it but can't remember what I did now, but that incident sticks in my memory!
     
  20. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I can tell roughly what the mains voltage is from day to day here by the temperature my class A amps run at!
     

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