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Jca50H / 100h/ 22h mod thread and owners club

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  •   Haven't read the entire thread but Im interested in taming the OD channel-making warmer like the crunch channel actually. I think the crunch chanel is great for what I do but switching to the OD for leads is thinner sounding. Anybody actually mellow out the OD channel more in line with the crunch channel? TIA Bob


    • käsebrot
      käsebrot commented
      Editing a comment

      @ Bryan:

      Yes, it's that red wire. Do the depth mod there.


      @ Rockon:


      Firstly, I would try another tube on V2 (2. and 3. Gainstage OD). If that doesn't work for you, try 0,68uF at C8 and 10nF at C9.

    • rockon1000
      rockon1000 commented
      Editing a comment
      Thanks! got plenty (hundreds) of 12AX7's so I'll try that first. Bob

  • Excuse my ignorance but after reading all 40 pages of this thread which has probably added to the confusion..hahaha.  I'm still not quite sure what the SLO mod actually does, yes I understand it turns the od channel into the SLO,  but tonely what does it do. I ask cause I'm preparing to mod my JCA22H and what I'm looking to do is take some of the fiZz away from the distortion. I've already started with a pear of JJ EL84's, tun sol, an GE 12ax7's, which in all honesty really didn't do much. I'm fully aware that there is a ton of other options out there.Just in case its im told to turn it up for the fiZZ to go away, I use the jca22 for small live use so the ouput is turned up fairly high, gain no more then 9-10 oclock, honestly for the most part I really like the way the jca22 sounds an the simplicity of it. I'd just like to get that Fizz to go away. So any help or direction on this would be Greatly appreciated.

     Thanks guys.   


    • Hi Guys
      i love the crunch channel of my JCA100 but i find the lead almost unusable (boomy, fizzy and too much gain)
      I would like to "duplicate" the sound of the crunch channel (with the gain maxed) on the lead, with added gain on top (but not the fizz)
      do you think it is possible ? where to start ?
      Last edited by kaoslord; 06-04-2014, 03:06 PM.


      • Hi all
        I would like to share my experience with modding my JC100H

        Depth mod - Gre


        • Hi all

          I would like to share my (little) experience with modding my JCA100H

          Depth mod - Great addition to this amp and very easy to do. However, I find myself playing with the depth always at 0 as turning the knob add too much bass to the sound, maybe the pot/cap values should be adjusted ?

          SLO100 lead preamp mod - This mod is the swap of a resistor, 2 caps and the gain pot (1M to 500K). I did and... to me there is no change to the sound of the lead channel... It is louder than before with still tons of muddy bass frequencies.. not worth it in my opinion.

          Swap of coupling cap after V2a (0.02 --> 0.002 uF) + swap of R36 (1M to 470K) : this is a nice one! Gain pot is more usable and the lead channel is less bassy/muddy. I recommend this one !

          Swap of slope resistor into tonestack: i have added a DPDT switch to choose between 33K and 68K.
          33K is too loud and bassy. very huge sound...
          68K is very nice, kind of modern sounding scooped style.
          ​also it makes the whole amp quieter, allowing to push the master a little more, which is a good thing.

          Have fun modding!


          • Hi All,

            another great mod that I have found:
            remove the bypass cap C19 on the cathode follower. this will help to "clear up" both channels: the clean will stay clean up to 4-5 on gain (depending on pickups) and the lead gain will be more usable, less fizzy/boomy with extreme settings (> 8). i was planning to make it switchable but it sound so good that will leave it unbypassed.