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Jca20H Mod thread and owners club.

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  • Hi to all

    I am (or rather hoped) to be a new member of the community. I bought second hand a JC20H received yesterday. I have the 2x12 baffle on it's way too. I am a french guitar player and have a few clips there My soundcloud page


    Unfortunately, not exactly what I expected from the videos and sound clips here... The amp is making a loud buzz making it impossible to use clean, and it produces a weird clipping noise used solo with gain past 12 o' clock. My first take is I may have to change all tubes for a start, they may have been damaged in the delivery process (the amp was badly protected).

    I am very interested in all mods alound here.  Something lie the brown sound is appealing to me. AS well as a sort o two channel mod with  clean channel. And as well an effect loop. All these make quite a lot... I will have to choose I guess.... I have yet to finish reading all 64 pages of the topic...


    • Quick question regarding the clean channel mod on the first page for anyone who still follows this thread:

      -Where it says  "You then bypass the original 1m resistor r53 with a 250pf capacitor", is this simply putting a cap in parallel with R53 or "piggybacking" the cap on to it? Or should this resistor be removed entirely?  Thanks for any input.


      • Hello everyone, I'm new here.
        I have an Jca20h, a big amp, but he has a problem that I can not solve, I appreciate if someone can help me.
        Anyone know what may cause the burning of R3 resistor?



        ***Problem solved,  short on R7


        • Does anyone know what mods Hovercraft does to the  JCA20H to make it a Dwarvenaut 20?

          I'm looking at a gut shot and it seem like there i s some sort of double version of the depth mod and  then a voicing switch added to the input jack ..


          • jhadl
            jhadl commented
            Editing a comment

            Here is the stock gut shot


            and here is a modded one


            Attached Files

        • Damn I jump back on this thread because I want to try some new mods and all the schematics and pics are gone via broken links. I'm bummed


          • Originally posted by jessepage1989 View Post
            Damn I jump back on this thread because I want to try some new mods and all the schematics and pics are gone via broken links. I'm bummed
            Most of us moved on over to the new JCA thread on
            Come join us at the NEW Jet City Lounge on


            • Hi guys and gals. My story....

              Ok so I got a JCA 20h gave it to a amp guy to do this mod -

              Got it back and it sounded awful.

              Took it back. He checked it all out and he is confident that it's exactly as the mod says. It cost me £180gbp for the mod.

              He still has the amp but he's tearing his hair out trying figure out the problem.

              Any help advice welcome



              • i know this an old post but i have jetcity20 H that came with a bunch of stuff i got in a selling it its got J&J and Ruby tubes in it works fine..$100


                • It's too bad they don't make these with 6V6s. I'm not a fan of EL84s.
                  Originally posted by MrKnobs
                  God, that's beautiful man! And they say romance is dead!