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Amplifier Transformer Group Buy

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

  1. bugbear

    bugbear pfm Member

    I've never traced it out, but my Sugden runs the speaker protection circuits off the (plenty of power available) 50V output transistor supply.

    (It happens to have a transformer very much like the one Alan is proposing, 2 high power secondaries, 2 high voltage lower current secondaries)

    BugBear
     
  2. Mike Hanson

    Mike Hanson Lovely!

    It depends on the protection solution you're using. I've gone three routes myself:
    • UPC1237, which typically requires 12-18VAC
    • XRKAudio, which accepts a wide DC voltage range (I drive mine with the 53V rail)
    • Avondale SPM1 (also supports fan control). I believe it needs 12VAC, although I'm not certain of that. (My NCC300 build is still waiting in the wings.)
     
  3. say it as it is

    say it as it is pfm Member

    The UPC1237 attached to speaker terminals looks a pain free option just need the 12vac supply.
    I must confess I don't have it on my amps, yet.
    I have always fitted soft start on stereo amps due to size of the transformer.
    Is this still required or does it replace the need for it?
    Do these have any effect sound quality?
     
  4. bugbear

    bugbear pfm Member

    The Sugden protection is built around the Hitachi ha12002; datasheet says power input range is 25 - 60V.

    EDIT; whilst googling, I found that NTE1635 is a replacement part for the ha12002

    BugBear
     
  5. Mike Hanson

    Mike Hanson Lovely!

    Generally speaking an SSM prevents a blown fuse due to the sudden current onrush at power-on. Another solution to this is to use a slow-blow fuse. Note that none of the older Naim amps had one, and many of them had pretty big transformers and PS caps. (I know nothing of the current range.)

    The SSM also prevents that initial speaker thump at power-on. If you have a Speaker Protection Module, this will not occur. An SPM also prevents blown speakers if your amps go DC.

    That's why an SPM is probably higher priority than an SSM.

    One final benefit of an SSM is that puts less stress on your power switch, which gives you more flexibility with switch choices.
     
  6. 337alant

    337alant Negatively Biased

    Back on track please gents as this is supposed to be a Transformer group buy not a discussion about speaker protection?.
    David thats a good suggestion and more useful that the additional primary tappings IMO and I agree 240VAC is fine for the UK and on custom made transformers like this it will not hum or buzz. 220V is completely pointless in the UK
    So I am going to make an options list so when/if we get to 10 transformers we can vote which one suits all our needs best ?
    Or possibly Stephen may make them to suit the individual options??,

    1, 240V primary only with all of the standard secondarys stated in the first thread
    2, 240v Primary only with all of the standard secondarys stated in the first thread + a 12v - 12VA additional secondary
    3, 230, 240, 250v Primarys with all of the standard secondarys stated in the first thread
    4, 230, 240, 250v Primarys with all of the standard secondarys stated in the first thread + a 12v - 12VA additional secondary
    Alan
     
  7. JimmyB

    JimmyB pfm Member

    Thanks for this Alan, all growing arms and legs there.

    With 248V on my mains just now I reckon you can put me down for one please.
     
  8. 337alant

    337alant Negatively Biased

    Jim
    OK thanks I will add you to the list
    Alan
     
  9. S-Man

    S-Man Kinkless Tetrode Admirer

    OK I will commit to 1 transformer if you get to 10, but preferably:
    2a: 240v Primary only with all of the standard secondarys stated in the first thread + two independant 0-12v @ a few VA additional secondaries

    (reason: I prefer to have a separate prot cct per channel)

    If 2a is not viable then I would go for #1 please.
     
  10. 337alant

    337alant Negatively Biased

    OK David thanks
    I will add you to the list
    Alan
     
  11. 337alant

    337alant Negatively Biased

    Come on guy only 3 more to go :D
    I'm surprised that some of the prolific amplifier posters have not seen this is a bargain opportunity:cool:
    A good quality transformer is one of the primary building blocks of a stable, effortless, reliable, quiet amplifier;)


    Alan
     
  12. martin clark

    martin clark pinko bodger

    damn you ;)

    Alan - I've no need in mind, but I'll take one please - as original description in post 1

    I'd also be entirely happy to take the cheap 'extra-over' cost option for an increased primary voltage tap too, if that matches group will/helps secure the buy.

    Thanks!
    Martin
     
  13. Mike Hanson

    Mike Hanson Lovely!

    I would get one, except that I'm in Canada and I currently have enough transformers for all my planned projects.
     
  14. martin clark

    martin clark pinko bodger

    Mike- yeah,and Plitron up your way make & offer some excellent kit! ATB.
     
    337alant likes this.
  15. 337alant

    337alant Negatively Biased

    LOL thanks Martin I will add you to the list
    Alan
     
  16. 337alant

    337alant Negatively Biased

    Understand, the postage would be more than the transformer :eek:
    Alan
     
    Mike Hanson likes this.
  17. muchtoofast

    muchtoofast pfm Member

    I've just bought one previously from CW of course, still tempted, but I think my wife would hit me! Darned good value for money I must admit, as mine was nearly twice this price.
     
  18. eddie pugh

    eddie pugh pfm Member

    Alan
    I'll take one. Not too fussed about final detailed specification as long as it has the basics as per your first spec. I have a couple of spare NCC200's kicking around here somewhere and a pair of Hackernap boards that I may one day get round to building
    so I guess I will need some power

    eddie
     
  19. 337alant

    337alant Negatively Biased

    Eddie thats great thank you
    I will add you to the list in the first post, I am going to put myself down for 2 so that means we have 10 now ;)
    Alan
     
  20. 337alant

    337alant Negatively Biased

    We will collectively have to decide on the final spec

    Option 1
    Continuous power rating: 818VA
    Primary: 0-240V @ 50Hz
    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
    Secondary 5: 0-12 @ 1Arms 12VA

    Option 2
    Continuous power rating: 818VA
    Primary: 0-230/240/250v @ 50Hz
    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
    Secondary 5: 0-12 @ 1Arms 12VA

    All will have
    Electrostatic screen
    GOSS band
    Dimensions: approx 175x75mm
    Mounting: M8x30mm bush
    In a potted centre,
    Heavy gauge lead outs 300mm long

    My own preference is Option 1 but I am happy to go with the majority

    Alan
     

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