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help with cloning

Discussion in 'd.i.y.' started by philiphifi, Sep 12, 2019.

  1. philiphifi

    philiphifi pfm Member

    Dear all,

    i am thinking of cloning a kondo neiro amp. There are circuit diagrams etc but i need some help with it + details with people who can manufacture a decent chassis.

    Please let me know if you are able to help

    thank you

    Philip
     
  2. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Unless you can get the proper output transformers it's a non starter!
     
  3. philiphifi

    philiphifi pfm Member

    i can source a decent output transformer. (hopefully anyway)
     
  4. thebiglebowski

    thebiglebowski pfm Member

    Tango, Tamura or Hashimoto are all good alternatives.
     
  5. Vinny

    Vinny pfm Member

    Curiosity, having just checked online and found that one sold second-hand for around £9K, 2 years ago, what sort of money would you expect to spend to make a respectable clone?
     
  6. stevec67

    stevec67 pfm Member

    What's so special about the OP transformers? There's a bit of talk on the web about "special windings", is this the case?
     
  7. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I'm not au fait with the specific ones used here but the output transformers are the most crucial part of any valve amplifier and have a massive effect on everything basically..
    IMO you cannot build a clone of a valve amp unless you can get the original output transformers... anything else would be "in the style of" but not the real thing and would not sound the same... maybe better, or worse or different but not the same!
     
  8. stevec67

    stevec67 pfm Member

    OK, thanks. So the anecdotes I have heard of people reusing mains trafos as OP trafos for audio are either fairy tales or going to sound pretty dismal, are they?
     
  9. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    It can be done but they would not be of hi fi quality and probably only good enough for a public address system, a "Tannoy" in a railway station or similar!

    High quality OPT's are made with special grain oriented silicon steel lamination's and with multi section interleaved windings. Without this they would have high distortion and no treble beyond maybe 8KHz! The high phase shifts would mean that little or no negative feedback could be applied without the amp going unstable.

    The design of really high quality OPT's for valve amps is often regarded as somewhat of a "black art"...
     
    davidsrsb likes this.
  10. Barrymagrec

    Barrymagrec pfm Member

    The improved magnetic materials developed during the war were much of the secret behind the various genuine hi fi amplifiers developed just afterwards. Williamson, Quad, Leak and so on.
     
  11. Dowser

    Dowser Learning to bodge again..

    The OP transformers in my DIY valve hybrid SEs cost over AU$1000 a pair...over 20 years ago! This was easily over half the cost to build them. At the time there was one recommended guy in Australia to get them from.
     
  12. davidsrsb

    davidsrsb pfm Member

    That proportion is about right, spend the money on a good transformer, not the front panel
     
  13. Dowser

    Dowser Learning to bodge again..

    Haha - you haven’t seen my mono blocs - money did not go on cosmetics :)
     
  14. coltrane

    coltrane electrobaroCKjazzer

    without going too deep into the matter, yes, the real secret of the Kondo/AN O/P transformers is that, the winding, which is quite intricate, not just reeling the wire on a metal laminate. this is mainly the reason why the circuit diagrams of the AN amps are readily available, and why PQ decided not to keep them secret (knowing clones would inevitably appear anyway)
     

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