Amplifier porn

Discussion in 'Power Amps' started by 9suns, Jan 24, 2018.

  1. iFi audio

    iFi audio MOT iFi Audio

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    And that wooden box to make this monster just a wee bit innocent :p
     
  2. Ferrum

    Ferrum Acquaintance

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    I have a friend who makes amplifiers - Audion - and I was fortunate to be able to try them out for a while. My room was packed with goodies.

    [​IMG]

    [​IMG]

    Ferrum
     
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  3. fastfwd

    fastfwd Friend

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    Found this ancient thread while searching for something else. Really cool to see some of those photos.

    Here's a preamp I worked on 25 years ago. It's sort of the pinnacle of what appealed to Japanese high-end audio buyers at the time: Heavy faceplates and controls, wood accents, lots of text on the circuit boards, etc. I had nothing to do with the analog circuitry or ID; I only did the microprocessor-controlled features -- front panel, remote control, relay switching, etc.

    The remote-controlled quad (balanced stereo) volume control was interesting. We went through three completely different designs. First was a 128-step relay-based nightmare that clattered like mad whenever the volume or balance was changed. It sounded, said the English director of R&D, "like a skeleton having a wank in a coffee tin."

    The second design was crazy: A huge microprocessor-controlled stepper motor driving a wiper around 4 stacked circular attenuator boards, each populated with 100 precision resistors -- plus extra bits for balance control. The assembly cost more than some of the company's entire preamps. The aforementioned R&D director had done turntables at Roksan, so he knew something about moving parts in high-end audio equipment, but the company's broad expertise was really elsewhere, so there wasn't much confidence in the reliability of the thing and it was shelved.

    The final design was purely solid-state, using cheap digital potentiometer ICs. The ones we used actually sounded fine, indistinguishable from the pricey Vishay resistors in the stepped attenuator. There were a number of technical issues -- too few steps because only a portion of the devices' 64-step range was linear enough to use, channel imbalance because we had to use multiple 1- or 2-channel pots rather than one 4-channel, etc. We solved all of those, mostly with software, but a bigger problem was that buyers of equipment in this price range distrusted ICs and expected very expensive discrete components instead. There was a lot of internal debate, but this design measured great and sounded as good as any other, and it was reliable and inexpensive, so in the end it's what was used.

    Anyway, photos. None of these are mine, I found them all on the web:

    Front:
    [​IMG]

    Back:
    [​IMG]

    Inside. The mezzanine board in the foreground is the volume control:
    [​IMG]

    3x 6922 + 2x 6L6 + 2x 12AX7 per channel:
    [​IMG]

    Power supplies. 2x 5U4G each, 20kg each:
    [​IMG]

    Very custom remote control. There was talk of machining a mirrored case for left-handed customers; I don't know whether that ever happened:
    [​IMG]

    In situ:
    [​IMG]
     
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    Last edited: Jun 11, 2020
  4. fls.audio

    fls.audio Facebook Friend

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    ^ That's an amazingly well-designed amp! I love the invisible wiring.
    Do the 6L6s get hot though? Those caps right next the heatsink and tubes may have to endure a lot of heat, no?
     
  5. fastfwd

    fastfwd Friend

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    I don't remember that being a problem, although I didn't really get involved in the audio-circuitry design meetings where thermal issues might have been discussed.
     
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    Last edited: Jun 12, 2020
  6. iFi audio

    iFi audio MOT iFi Audio

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    Hey, thanks for sharing, great stuff. That pre looks stout!
     
  7. Forza AudioWorks

    Forza AudioWorks MOT: Forza AudioWorks

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    It's fair to ask how much such a preamp would cost today, if it had some well-known high end manufacturer's sticker on it.
     
  8. fastfwd

    fastfwd Friend

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    It was around $20,000 in the mid-90s. Random web inflation calculator says that's around $30,000 today. Which seems approximately right, since similarly top-of-the-line preamps -- from Audio Research, for example -- cost that much now.
     
    Last edited: Jun 18, 2020
  9. Forza AudioWorks

    Forza AudioWorks MOT: Forza AudioWorks

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    Yup, makes sense, thanks. In my head I guessed 30k.
     
  10. RobS

    RobS RobS? More like RobDiarrhea.

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    WARNING: Zip-tie porn ahead

    Look at this fucking piece of art:

    Jadis DA-88S Mk II
    [​IMG]


    JADISJA200
    [​IMG]

    Naim Nait 5
    [​IMG]

    Naim NAP 250
    [​IMG]

    [​IMG]

    Naim NAP 200

    [​IMG]
     
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  11. Thad E Ginathom

    Thad E Ginathom Friend

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    I am not an electronics guy at all. It took me several moments to realise that there is not one circuit board there. The whole thing is built on/with that grid of copper, perhaps better called bars than wire.

    If I had one of those, I would want to put it, bottomless, on a glass shelf with a mirror underneath it. It is certainly a fucking piece of art, and I would absolutely want to look at it!
     
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  12. dark_energy

    dark_energy Friend

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    Nice big phat transformers
     
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  13. fls.audio

    fls.audio Facebook Friend

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    You might like the tube amp I’m working on then...

    [​IMG]
     
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  14. Forza AudioWorks

    Forza AudioWorks MOT: Forza AudioWorks

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    This.
     
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  15. Zurvv

    Zurvv Rando

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    i'm living on a porn set! :)
    (well.. in fact, i was problem shooting as my unit sounded like ass. In the end it was a snake oil cable screwing it up. grrr.)

    [​IMG]
    [​IMG]
     
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  16. Priidik

    Priidik MOT: Estelon

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    Wiring OCD level 35.
     
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  17. Thad E Ginathom

    Thad E Ginathom Friend

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    Actually, even if it's only a plug, I've always thought that wiring that looks good is also likely to be good.
     

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