New(to me)Amp Day - Jet City JCA20H head

Discussion in 'Amp Input - Normal or Bright' started by joe_cpwe, Sep 4, 2021.

  1. joe_cpwe

    joe_cpwe Senior Stratmaster

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    I've been low key looking for the right deal on a used Jet City for a few years. They rarely pop up, and are usually a bit of a drive ...and usually a combo.

    I don't really need another amp, and really, honestly, don't need a combo. But in my routine CL search for 'Marshall' this JCA popped up just 20 minutes away.

    -20 watt,
    - 2x EL84 (probably the stock, they are Chinese)
    - 3x Svetlana 12AX7 (not stock)
    - A goofy grill replacement in that wood piece
    - A very goofy power light replacement thing
    He gave it to me for $200, so I'm pretty happy with that.
    Through my Marshall 1965a cab it sounds better than the vintage 30 1x12 cab at the guy's shop. It has a Marshall-ish clean, and a bit hairier than Marshall dirt. The little I've played it so far, I like it.

    I am on the way to selling the Marshall Artist, 3203 (small box head) its sitting on top of for a variety of reasons. The JCA should sub for it just fine...I think.

    Would like to make a few mods to it. Looks to be a few ideas for that online.
    Any experience with these, input is welcome.

    20210904_141833.jpg
     
    Last edited: Sep 4, 2021
  2. Stonetone

    Stonetone Most Honored Senior Member

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    Very nice HNAD :thumb:
     
  3. Dadocaster

    Dadocaster Dr. Stratster

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    Was interested in Jet City heads but the plague rolled in and they got very scarce. Hope you enjoy it.
     
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  4. Robins

    Robins Dr. von Loudster

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    Friedman BE mod, job done.
    This will turn it into a little tone monster.
    Trust me.

    All the best,
    Robin
     
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  5. joe_cpwe

    joe_cpwe Senior Stratmaster

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    I have read about the BE mod, not finding details. I guess the guy behind much of the mod kits and work on Jet City has gone MIA so I'm looking around for info.

    I'd like to get more low end out it, more clean headroom/volume, and being able to switch into higher gain stage would be cool too.
    Looks like there's a simple mod for depth/resonance, which I assume will give some low end.

    Next time the house is empty I've got some 12AX7s I want to try in there. I also have two different sets of EL84s, see which I prefer over the Chinese tubes in there now.
     
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  6. Robins

    Robins Dr. von Loudster

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    The BE mod is a bit tricky to do but not that complicated.
    The depth mod is just a pot and a cap to solder in and install in the back panel.
    There are 12AX7s in there already and the chinese ones have the most gain but more "fizz" in the high end than JJs for example.
    The JJ EL84s are great for the amp but it would need a rebias (anyway).

    Taken from a blog
    https://toboy-diy.blogspot.com/2013/10/jet-city-jca22h-depth-mod.html
    Slightly different amp but you get the idea. Simple.

    Play it loud,
    Robin
     
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  7. joe_cpwe

    joe_cpwe Senior Stratmaster

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    Thanks :thumb:
     
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  8. Miotch

    Miotch Senior Stratmaster

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    I have a JCA22H and really like it. Will never give a crystal clean, but what is does give is great.
     
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  9. joe_cpwe

    joe_cpwe Senior Stratmaster

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    Now that I'm learning more about these amps, I can see that a 22H would be great. Have done any mods on yours?

    My JCA wasn't hanging with my Marshall 3203 at all. It was pretty thin sounding. So, I got out my Mini Mass attenuator, got the EL84s cranked up and with everything set at 6 it sounds quite a bit better.

    20210906_130044.jpg
     
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  10. Miotch

    Miotch Senior Stratmaster

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    No mods at all. Run it through a 2x12 with 8 ohm WGS speakers wired in series.
     
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