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Head amp interest check

Discussion in 'trade discussion' started by Arkless Electronics, Jun 20, 2022.

  1. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Latest names added. Nice to see so much interest! There must have been some huge ground swell in demand/market for head amps as about 5 years ago no one was interested!
     
    ChrisS likes this.
  2. Vinny

    Vinny pfm Member

    There are at least just a few people here now who sing their praises, having heard one or two.

    You were close to a lone voice in the wilderness 5 years ago?
     
    Arkless Electronics likes this.
  3. early

    early pfm Member

    I'm glad this is on track , I'm looking forward to trying it .

    I think there is a market for headamps but they need to high quality and adjustable for gain and loading , the kind of thing you buy once and it suits all (within reason) of you future cartridge choices .
    Having done the SUT merrygoround , it's a minefield that doesn't lend itself easily to choping and changing carts . Get it right and I'm sure there's a market out there , maybe it's a small one but it's there .
     
    Darren L and Arkless Electronics like this.
  4. Barrymagrec

    Barrymagrec pfm Member

    It has just occurred to me that that the simple common base design using a single OC81 (taken from an early sixties Mullard publication) that I used back around 1967 to match a low impedance tape head into the input of an EMI TR50 (normally a high impedance head straight to the first EF40) was in fact a head amp, not a term I was familiar with at the time.

    I expect your new design will be a little more sophisticated....
     
    Arkless Electronics likes this.
  5. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    As mentioned up thread, this is a transimpedance amplifier so everything is different compared to a conventional one. There is no "loading" as such with this type of amplifier. The cart see's a "virtual short circuit" and the head amp is "current input". Gain is not fixed with this type of unit and is in fact set by the internal resistance of the cart... the lower the resistance the higher the gain. Two gain ranges will be provided by a toggle switch on the back and should be enough to encompass >90% of carts.
     
  6. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    This is of course mainly for the benefit of those with less knowledge of hi fi history than yourself Barry:) but back in the 50's and 60's a phono cartridge was often known as a pick-up head, also many pre amps had an input for direct connection to a tape head and so there could be quite some confusion as to what exactly a head amp was.
    In fact MC carts were much rarer than today and suitably low noise amplification was largely absent and so for the few MC carts around (Leak, Ortofon, IIRC Voigt, early Denon 103 from '63 etc) an SUT was pretty much the only solution around and certainly in the 50's most would understand head amp as meaning an amp for a tape head.
    As MC carts are so low in output and were called "pick up heads", and as tape heads had a low output, "head amp" gained some usage for anything where a very low signal level had to be pre amplified in order to be used with a "normal" pre amp, in fact the term "pre-pre-amplifier" was sometimes also used.
     
    Perart1 and Vinny like this.
  7. Vinny

    Vinny pfm Member

    To some extent, still used in the US, often to explain, but usually confusingly, what "head amp" generally means today.
     
  8. mand

    mand pfm Member

    Any idea of what the gain will be?
     
  9. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    As mentioned twice above it is set by the cart. The lower the internal resistance of the cart the higher the gain.
    There will be a toggle switch on the back to select two gain ranges.
     
    nmtjb likes this.
  10. kneecap

    kneecap pfm Member

    Will this head amp project put back the availability of a Gti phono stage for audition?
     
  11. kneecap

    kneecap pfm Member

    put back as in delay...
     
  12. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I have many things taking priority over the phono stages at the moment and even I haven't a clue when I'll be making more. It is VERY unlikely to be this year though.
     
    Tarzan likes this.
  13. kneecap

    kneecap pfm Member

    Righty ho...
     
  14. Tarzan

    Tarzan pfm Member


    Boo!

    As they are rather good.1
     
    Arkless Electronics likes this.
  15. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I will definitely be making more though... Already bought in mucho components at great cost to do so:)
     
  16. kneecap

    kneecap pfm Member

    Okay
    I'll hang onto the 651p a while longer.....
     
  17. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    I will only be offering the Turbo versions when I start on them again BTW.
     
  18. kneecap

    kneecap pfm Member

    I wouldn't want to try anything less! :)
     
    Arkless Electronics likes this.
  19. Ali T

    Ali T pfm Member

    Hi Jez, could I be added to the list please?
     
  20. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Hi Ali, Hope you're well:)

    Added to list.
     

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