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Amplifier Transformer Group Buy

Discussion in 'd.i.y.' started by 337alant, May 15, 2021.

  1. 337alant

    337alant Negatively Biased

    I was pricing up a Transformer from Tiger Toroid's for a stereo amplifier build to the following spec:-

    Continuous power rating: 818VA
    Primary: 0-240V @ 50Hz or (0-230/240/250v primary tapping option +£5)
    Electrostatic screen
    Secondary 1: 35-0-35V @ 5A rms - 350VA
    Secondary 2: 35-0-35V @ 5A rms- 350VA
    Secondary 3: 42-0-42V @ 0.7A rms- 58.8VA
    Secondary 4: 42-0-42V @ 0.7A rms - 58.8VA
    GOSS band
    Dimensions: approx 175x75mm
    Mounting: M8x30mm bush
    In a potted centre,
    Heavy gauge lead outs 300mm long

    This Transformer would suit any of the Avondale NCC builds and is the same spec as I used on my Hackernap build

    If any one is interested in a group buy I got an answer from Stephen Foster quoting the following:-
    1 off these will be £140
    10 off these will be £95 each (£100 with the Primary tapping option)
    So If anyone is interested and we can get 10 names then we could get them for £95 (£100) each
    Not sure what postage would be but I will find out
    337alant = 1
    John Luckins = 2
    Lanser = 1
    Christn = 1
    JimmyB = 1
    S-Man = 1
    Martin Clark =1
    Eddie = 1
    Say it as it is = 1
    Bugbear = 1
    RonR = 1
    Total = 12
    Last edited by a moderator: May 24, 2021
  2. say it as it is

    say it as it is pfm Member

    Stephen is a good guy I have just decided to go monos so ordered 2 smaller ones
  3. john.luckins

    john.luckins pfm Member

    I'd take a couple at £95 plus postage.

  4. 337alant

    337alant Negatively Biased

    Ok thanks John
    I have added you to the list
    I think £95 is a good price TBH
  5. bugbear

    bugbear pfm Member

    Re: recent threads on 110, 120, 220, 230, 240 V, how much extra would it be to add the primary splits and taps that the Rotel 850 traffos had?

    (image shows 2 traffos, each with 2 120V primaries, each primary with a 10V centre tap)

    [​IMG]850_tran by plybench, on Flickr

  6. 337alant

    337alant Negatively Biased

    Bugbear, is your response in the correct thread?.
  7. say it as it is

    say it as it is pfm Member

    Maybe not relevant but mine were made with extra windings for different primary eg 240/250
  8. bugbear

    bugbear pfm Member

    Yes - I'm suggesting (if they don't send the cost nuts) that the extra splits and taps on the primaries might make the proposed group buy traffo more useful to more people, widening your potential pool of buyers.

  9. 337alant

    337alant Negatively Biased

    OK I understand
    As this is a transformer meant for UK use there in no need for any 2x 120v tapping's as we already have a 240v
    So I can ask if there is a possibility for a 230v 240v 250v tapping's on the primary
    my mains used to be 253v and some 230v transformers used to buzz, so I ordered 2 off 240v transformers from Canterbury windings to this exact same spec and they were silent on 253v
    about 5 years ago the NEEB completely replaced the local transformer to our street and now its around 240v
    bugbear likes this.
  10. bugbear

    bugbear pfm Member

    Yes - I guess mainland Europeans and Americans are unlikely to be buying from Tiger Toroids. The postage would be truly awful, let alone various "international" complications.

    (I just thought the Rotel primaries were so neatly thought out and maximally versatile for use all over the world)

  11. 337alant

    337alant Negatively Biased

    OK I asked Stephen how much to add the 0-230/240/250v primary tapping option
    He said it would be £5 extra so doesn't break the bank
    Ill add that as an option if the majority want it
    bugbear likes this.
  12. say it as it is

    say it as it is pfm Member

    I think it would make it extremely flexible then and suit everyone. I need to clear things out and swmo have a fit if I got another piece of kit lol
  13. 337alant

    337alant Negatively Biased

    Stephen assured me his transformers will no hum at either of the voltages it will just allow you to get the secodarys closer to the actual figure desired.
  14. lancer

    lancer Well-Known Member

    I'll take 1.
  15. chrisn

    chrisn pfm Member

    I'll take one too for £95-100 plus post. I may need help if we end up with multiple primaries
  16. bugbear

    bugbear pfm Member

    Alan has (quite correctly) not accepted my suggestion of split primaries, so it's just multiple input taps. Very easy.

    Hmm. If you're going to add 2 taps, you can do it this way, and get 220V "for free", (assuming all taps have the same cost).

    [​IMG]drawing by plybench, on Flickr

  17. 337alant

    337alant Negatively Biased

    OK Lancer thanks, added you to the list
  18. 337alant

    337alant Negatively Biased

    hi Chrisn, OK thanks, I have added you to the list
  19. S-Man

    S-Man Kinkless Tetrode Admirer

    I'm very tempted Alan.
    I don't really need one but want one!
    I guess you will close this offer once you get to 10 pcs?

    I would prefer to see a couple of 0-12V 100mA secondaries for powering protection circuits... but most certainly do no change it for just me!

    240V only on the primary is all I need. If it's properly designed (which it seems it will be) there's not need for the other voltages IMHO.

  20. JimmyB

    JimmyB pfm Member

    Yes, I'm waivering too as I was going to tidy up my builds but as mono's and the 12V thing would be nice too but you're heavily into scope creep already!

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