Red Knob Champ 12

Discussion in 'Shock Brother's DIY Amps' started by grzz51, Feb 14, 2020.

  1. grzz51

    grzz51 TDPRI Member

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    I have a Champ 12 Red Knob that had has finally bitten the dirt after many years of mods and tinkering. The speaker and cabinet are still in excellent shape. Does anyone know of a DIY kit that might be a "drop in" for this cabinet? A low watt kit is preferable.
     
  2. chas.wahl

    chas.wahl Tele-Meister

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    "Drop-in" not really.
    But if you don't mind a DIY project . . . 6 knobs: might repurpose the chassis by building a Blackface Princeton Reverb in it; same watts, I realize. The Champ 12 cabinet is more than 4 inches narrower than that of a BF PR, but with some planning . . . it's a fairly small cabinet, some would say, for a 12" speaker, but if you've been living with that for awhile, maybe that wouldn't bother you. Going to a smaller speaker, say 10" might be a path forward too.
     
  3. schmee

    schmee Doctor of Teleocity Silver Supporter

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    What's it doing? I just got one a while back and love it. It fills a niche between PR/Deluxe and 6 watt champ very well.
     
  4. grzz51

    grzz51 TDPRI Member

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    Chassis is shot....very loud hum, plastic input jacks are broken, reverb doesn't work, pots need replacing....you name it, it doesn't work. I'd like to do a point to point kit and put it in this cab.
     
  5. schmee

    schmee Doctor of Teleocity Silver Supporter

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    Princeton Reverb might fit. Or do a 2 x 6v6 Super Champ?
    Or make a 6L6 champ
    or...
    You'll be doing everything like that (pots, jacks, reverb pan...) in a ptp build too though... :>)
     
  6. Davecam48

    Davecam48 Friend of Leo's Ad Free Member

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    When you say the "Chassis is shot" how is it shot? Is the metal broken?
    Loud hum............Probably a $10 electrolytic filter capacitor in the power supply.
    Pots need replacing............a squirt of WD-40 would, or could restore them!
    Reverb doesn't work...............maybe an input/output transformer open circuit ...then again a pedal reverb probably better nowdays anyway than the old style spring reverb if that's what it is.
    Input sockets broken ...$1.00 each and 5 minutes with the soldering iron.

    You may find it could be an easy repair. Probably a lot easier than assembling a whole new amp chassis.

    DC
     
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  7. grzz51

    grzz51 TDPRI Member

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    I think I'm ready for a PTP kit, just tired of messing with the printed circuit board. Been thinking about it for a while and am ready to start looking for something that would fit the cab.
     
  8. radiocaster

    radiocaster Poster Extraordinaire

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    For a Princeton Reverb you'd have to punch two extra big holes, one for the second 6V6 and one for the rectifier. It might get tight in there too.
     
  9. Asmith

    Asmith Friend of Leo's

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    I would fix up the amp and then just build a princeton head, you can use the champ as a cab with a switched jack or just get a new cab (I scored a marshall 4x12 yesterday for £80). Anyway IMO its not worth gutting an entire chassis and starting with just the metal work.

    If you dont want to fix the amp I say put it to one side for now. Learn how an amp works either by tedious research from either a book, or websites such as valve wizard and robrobinette, or build a kit with good explanations about what each part of the amp does.

    Then go back to the champ, salvage the transformers, chassis, valve sockets, knobs, switches, power cord, etc then build another amp without a kit for cheap using the salvaged parts.
     
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  10. tubelectron

    tubelectron Tele-Afflicted

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    Maybe it is possible to find a Champ 12 compatible aluminium bare chassis at suppliers like MojoTone ? Re-using the original chassis is possible, but may need morr work to make it compatible with what you want to do... Well, you decide ! ;)

    There's enough room inside to built a Princeton Reverb and I would skip the rectifier tube by choosing the appropriate power transformer : you would spare useful room and heat.

    Here is one of my DIY amps. A mix between a PR and a 18W Marshall, with reverb, 2xEL84 in cathode bias and no rectifier tube nor tremolo. The chassis dimensions are 365x160x65mm, 2mm thick aluminium, which is not very large :

    [​IMG]

    [​IMG]

    I think that a PR board kit would probably enter in a Champ 12 chassis if you use a bracket-mounted power transformer and no rectifier tube. But check the board dimensions vs the Champ 12 chassis dimension, though...

    Good Luck ! :):cool:

    -tbln
     
  11. radiocaster

    radiocaster Poster Extraordinaire

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    You wouldn't have been able to do that without that cap can. Actually you probably would have, because you're very good at making amps, but it would have been very tight.

    The Champ 12 is laid out differently too (pics from net):
    [​IMG]
    [​IMG]
    You'd still need to punch some tube holes and it's probably not a good idea unless the builder is experienced.
     
    Last edited: Feb 15, 2020
  12. tubelectron

    tubelectron Tele-Afflicted

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    Yes true @radiocaster : the multicap (the same as used on a PR) is a very room-saving solution.

    Yes, I agree again. So I was simply wondering if such kind of chassis as below - of suitable dimensions -wouldn't be available via amp parts suppliers like MojoTone and the like :

    [​IMG]


    https://www.tube-town.net/ttstore/tt-chassis-alu-typ-041-aa764-generic-style.html

    -tbln
     
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  13. schmee

    schmee Doctor of Teleocity Silver Supporter

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    No doubt, but there should be plenty of room with the reverb tank and OT out of the inside of the chassis.

    Depends on what void in the arsenal the OP needs to fill though. With a 6L6 based Champ or Vibro Champ the OP could re-use both his transformers. Punch one hole for the rectifier, or even just go with a SS rectifier and punch no holes. Seems like an easy conversion.
    I like my Champ 12 because it fills a void that hardly any other amps fill ... 12 watts! A Princeton seems like a much different amp (I have both), a 6 watt Champ just doesn't work for me.
     
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  14. schmee

    schmee Doctor of Teleocity Silver Supporter

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    Wasn't converting Champs to 6L6 a thing for a while?
     
  15. schmee

    schmee Doctor of Teleocity Silver Supporter

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    I sent you a PM.
     
  16. grzz51

    grzz51 TDPRI Member

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    My Red Knob is a single 6L6 with 2 12ax7's in the preamp.
     
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