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Can you spare me some TPRs brother? (project summary - long)

Discussion in 'd.i.y.' started by yairf, Nov 15, 2004.

  1. yairf

    yairf Trade: Teddy Pardo Audio

    Hi all
    I have finally found the time to complete the installation of the TPR boards within my 32.5, and bring the 32/140 project to the final scene.

    As for the TRPs - yes I know, the ALWSRs are WAYYYYY better, however the TPRs are just so cheap, so small and easy to build that I just couldn't say no...

    Anyway, putting all the pieces together, I have finally given the beast a listen and the sound is just jaw-dropping - so powerful, dynamic, so authoritative!

    I just couldn't belive this is an old pair of 32/140 playing - it could drive my B&W M801 ("The Gentle Giants") as if they were cute little monitors!

    I am certainly not done with modding these old chaps, there is a remote-control board + pot waiting to go into the 32.5.

    However, this is a very important milestone for me - after about two months of after-hours work, these two just came alive, BIG TIME, and they sound SOOOO GOOOD, only proving that the hard work paid itself.

    Before I go on with descriptions, I wish to thank this TREMENDOUS forum for the inspiration and information.

    A huge word of thanks goes to LesW - I just couldn't (and probably wouldn't) make it without you. :D

    For those who are interested, the current configuration is:

    - Kendeil K1s installed, output voltages increased to 29v.
    - each circuit has its own ground signal going towards the preamp star-earth (common ground broken into two, per Mr Tibbs mod) - the two of them routed via a normal SNAIC cable, replacing the audio lines within it (this way the shield is only doing its job, and NOT carrying the ground signal).

    - Loads of board mods, most of them are based on LesW's advice, balance pot bypassed, buffer boards remain but their bandwidth increased.
    - one TPR board physically and electrically adhered to each one of the four boards: two buffers, two gains. The (short) TPR links are essentially replacing the 27R/47uF in each board.
    - Cardas wiring throughout, shielded cables for Phono + Aux inputs, as well as signal output, wired directly to the motherboard pins holding the gain boards, terminated with RCA plugs (look mom! no DINs!!:D )

    Power amp
    - loads of mods to the boards, removal of protection circuit, change of input filter per NCC-200 values.
    - Local feedback resistors added to the long-tailed-pair input stage, per NCC-200.
    - Cardas wiring throughout, including a new star-earth.
    - Binding posts, DIN plug & mic cables - trashed, replaced with RCAs, binding posts and shielded cables, all sourced from Cardas. Signal input wired going directly from RCA sockets to the NAPA boards signal input.
    - Main caps replaced with BC-58, 10,000uF/40V (low ESR) - the size of which fits exactly within the space available in the PS boards. All the four are bypassed with 0.1uF Wima caps.

  2. tomek

    tomek pfm Member

    Hi Yairf,
    It looks like you have done a lot of good work :)
    I have a question - what reg have you used on TPR - a normal lm317t, or something like lm317at, or lt317t or lt1086ct ?

    Cheers, Tomek

    PS Happy listening !
  3. yairf

    yairf Trade: Teddy Pardo Audio

    Thanks Tomek.
    Just a Plain-Vanila LM-317T, which I found at a local surplus store (ST made).
  4. daVros

    daVros Turn it up a bit!

    Does anyone know where to buy these LM317T's in the UK?

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