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  • Jca20H Mod thread and owners club.

    The Jca 20h Owners Club and Mod Thread

    Yes I do custom mods/parts lists/Mod other amps, pm me for more info/pricing.

    The purpose of this thread is going to be for discussing Mods to the jet city 20H, or any other topic pertaining to the JCA model 20H.

    The stock 20h

    The stock 20h is a 2 el84, 3 12ax7 amp featuring a soldano slo Treble, Middle, Bass tone stack with a Presence control in the Power Amp. Two 8 ohm output taps and one 16 ohm output tap. Excellent price for an amp with no unneeded frills.

    Sound Clips

    Guitar World

    http://www.youtube.com/watch?v=mdI7GuVOXCU

    A Real owner

    http://www.youtube.com/watch?v=zck6uFzZl8A

    Stock Schematic



    High Voltage Warning

    WARNING! - Please Read this Information Carefully:

    The projects described in these pages utilize POTENTIALLY FATAL HIGH VOLTAGES. If you are in any way unfamiliar with high voltage circuits or are uncomfortable working around high voltages, PLEASE DO NOT RISK YOUR LIFE BY BUILDING THEM. Seek help from a competent technician before building any unfamiliar electronics circuit. While efforts are made to ensure accuracy of these circuits, no guarantee is provided, of any kind!

    USE AT YOUR OWN RISK: THE WEBMASTER, PROJECT COORDINATOR, PROJECT CONTRIBUTORS AND WEB SPACE PROVIDER EXPRESSLY DISCLAIM ALL LIABILITY FOR INJURY OR PROPERTY DAMAGE RESULTING FROM THIS INFORMATION! ALL INFORMATION IS PROVIDED
    Jca 50h/ 100h/ 22h Mod thread and Owners Club
    Jca20H Mod thread and owners club
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  • #2
    Other Mods

    Dues'(or should I say vh4's now?) mods

    Pending permission from duese i think that i can post his schematic in this thread, for now I'll post a link to his thread. His mod were the bassis for my mods (minus the "voicing switch", thats mine).His mods are

    Choke,depth, Channel switch (with pot or switches to controll the gain), an effects loop(no he will not give away the schematic to it), a master for each channel, a "global master and various resistor and capacitor differences.

    Here is the link to his topic with the schematic to his mods on page 3

    http://acapella.harmony-central.com/...-for-299/page3

    This is dues's schematic



    All credit for this goes to dues (VH4 here on the forum)

    Here is a brief explanation and discussion of the depth pot.

    http://acapella.harmony-central.com/...uctions-please

    Sound Clips

    Les Paul

    http://www.youtube.com/watch?v=hchMfnL3BJo

    Strat

    http://www.youtube.com/watch?v=tdBn83FQYAE

    Dave Friedman's mods

    Dave friedman of Rack Systems Inc. is offering his "Brown eye" mod for the jca 20H. I seem to recall it costing about 300$ and an additional 50$ for a "saturation" switch (a Jose master volume).

    Sound Clips

    http://www.youtube.com/watch?v=6lTmRSI1n4Y

    Depth Mod

    This mod is depicted in dues' mod.







    Quote Originally Posted by ledvedder
    View Post

    I guess it doesn't matter where the wires go on the pot? VH4's instruction says to solder the 4n7 cap to the left and middle pins of the pot. You have the 4n7 cap to the left and right pins.




    Works both ways

    This is how I wire it



    how duese wires it



    an here's an extra little diagram to help those who are more visually inclined.



    I have no clue who some people are removing the nfb wire from the pcb and making more trouble for themselves.
    Jca 50h/ 100h/ 22h Mod thread and Owners Club
    Jca20H Mod thread and owners club
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    Comment


    • vintonalan
      vintonalan commented
      Editing a comment

      I did this mod with a 500K Bourns pot out of a cry baby volume pedal. Worked well! Gave some low end balls to the amp it was missing. And I agree with something I read along the way, just lift the yellow wire off the output txformer and go to one side of the pot with cap and take the other side back to the 16 ohm jack +.

      2 wire mod + one hole drilling. I happened to mount mine on the back panel just to the left of the speaker outs.

       


    • Graunke
      Graunke commented
      Editing a comment

      I'd like to do the 'depth' mod to my 22H, is the schematic similar, or does someone have one they can share? I tried to skim through all 65 pages, but did not see it. Only the one for the 20H


  • #3
    I haven't done any mods myself to mine, but I just got mine back from Dave Friedman today with the brown eye mod and a saturation switch. It sounds killer. Depending on the difficulty, I am interested in possibly adding an FX loop to mine down the road, but I don't know how do-able that would be for a noob like myself
    VHT/Fryette DEATH SQUAD

    Great deals here and on Rig-talk with: Boatshoes/smucarolina, goldwing68nv, tkozuch, chakosh, Norton666

    Current whoredom: VHT Pitbull 50/CL

    Past whordom: Peavey 5150 II | ENGL Steve Morse 100 | Jet City JCA20H | Mesa Boogie Mark V | Sunn 200s | Orange Thunderverb 50 | Peavey 5150 | Laney GH100L







    Originally Posted by MarkBastable


    You don't crap in the bidet, you colonial peasant.

    Comment


    • #4






      Quote Originally Posted by spawnofthesith
      View Post

      I haven't done any mods myself to mine, but I just got mine back from Dave Friedman today with the brown eye mod and a saturation switch. It sounds killer. Depending on the difficulty, I am interested in possibly adding an FX loop to mine down the road, but I don't know how do-able that would be for a noob like myself




      Thats a very asked for mod, All thought it doesnt appeal to me personaly, I am willing to investigate. With a schem and soldering iron (and some soldering know how) it should be very doable. Hey you dont mind if I put your friedman modded video on here as a sound clip right?
      Jca 50h/ 100h/ 22h Mod thread and Owners Club
      Jca20H Mod thread and owners club
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      Comment


      • #5
        Yeah sure, go ahead
        VHT/Fryette DEATH SQUAD

        Great deals here and on Rig-talk with: Boatshoes/smucarolina, goldwing68nv, tkozuch, chakosh, Norton666

        Current whoredom: VHT Pitbull 50/CL

        Past whordom: Peavey 5150 II | ENGL Steve Morse 100 | Jet City JCA20H | Mesa Boogie Mark V | Sunn 200s | Orange Thunderverb 50 | Peavey 5150 | Laney GH100L







        Originally Posted by MarkBastable


        You don't crap in the bidet, you colonial peasant.

        Comment


        • #6






          Quote Originally Posted by spawnofthesith
          View Post

          Yeah sure, go ahead




          thanks man.
          Jca 50h/ 100h/ 22h Mod thread and Owners Club
          Jca20H Mod thread and owners club
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          Comment


          • #7
            Damn I really want one of these now.



            But I have something already that's so similar.
            My Rig
            Youtube

            Comment


            • #8
              Oh ya let the games begin. I originally got a JCA50H and it was a lemon and the guys at JCA were great and getting to taken care of. In the mean while I bought a JCA20H from Music123 new for $209.00 Killer. It gets here Tuesday the 6th. My tubes have already arrived.

              2-JJEL84

              2-JJ12ax7 standard

              1-JJ12AX7 balanced

              1-JJ12AT7 standard

              1-JJ12AX7 HighGain

              1-TungSol 12AX7

              1-EH 12AX7



              Going to mess with that for a minute and soon as I can find a Series Loop mod I am modd'ing



              Thanks for starting the thread I hope that this takes off so an arm and a leg is not spent for mods and you can learn something. I love DIY. Amp to this point are really the only thing that I have yet to touch.....I can't wait..



              Did you post on the JCA FB page?



              theDogger
              - Ibanez MTM2(EMG-18Voltz) -
              - Ibanez RG2610E -
              - ESP/LTD KH-602 -
              - ESP/LTD EC-400 -
              - Mesa Boogie Single Rec -
              - Bugera 6262 -
              - JCA20H -
              - Custom 4x12 Build DIY -
              - JCA20H Mod Thread and Owners Club -

              Comment


              • #9






                Quote Originally Posted by theDogger
                View Post

                Oh ya let the games begin. I originally got a JCA50H and it was a lemon and the guys at JCA were great and getting to taken care of. In the mean while I bought a JCA20H from Music123 new for $209.00 Killer. It gets here Tuesday the 6th. My tubes have already arrived.

                2-JJEL84

                2-JJ12ax7 standard

                1-JJ12AX7 balanced

                1-JJ12AT7 standard

                1-JJ12AX7 HighGain

                1-TungSol 12AX7

                1-EH 12AX7



                Going to mess with that for a minute and soon as I can find a Series Loops mod I am modd'ing



                Thanks for starting the thread I hope that this takes off so an arm and a leg is not spent for mods and you can learn something. I love DIY. Amp to this point are really the only thing that I have yet to touch.....I can't wait..



                Did you post on the JCA FB page?



                theDogger




                I should post on their face book.

                What im running in mine that I thought sounds best is a jj long plate in v1 a sovtek russian tube in v2 and the chinese sino in v3.

                Edit:I just posted it on their facebook......only to realize that some one beat me to the punch.......
                Jca 50h/ 100h/ 22h Mod thread and Owners Club
                Jca20H Mod thread and owners club
                Like me on facebook
                Follow me on twitter

                Comment


                • #10
                  Good morning! I will try to check here occassionally and offer assistance when I can...
                  www.jetcityamplification.com

                  new company launching 9.7.10:
                  www.whiteboxeng.com

                  Comment


                  • #11






                    Quote Originally Posted by jet city amps
                    View Post

                    Good morning! I will try to check here occassionally and offer assistance when I can...




                    lol Hey Doug is it alright if I post the official schematic on this here?

                    Thanks for supporting man.
                    Jca 50h/ 100h/ 22h Mod thread and Owners Club
                    Jca20H Mod thread and owners club
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                    Comment


                    • #12
                      So in! I want to know how different tubes affect the JCA20H.
                      Originally Posted by buddhapaugh


                      Rocking the spandex AND the depends!

                      Comment


                      • #13
                        I prefer to give the schematic to customers who buy the amp. that seems fair to me, but, what did you have in mind?
                        www.jetcityamplification.com

                        new company launching 9.7.10:
                        www.whiteboxeng.com

                        Comment


                        • #14
                          OK guys considering making a section dedicated to cosmetic mods (baffles + other things that people have done, like leds).







                          Quote Originally Posted by Yarbicus
                          View Post

                          So in! I want to know how different tubes affect the JCA20H.




                          I'll try to add a tubes tasting section if i can get more people to give some feed back on what tubes they have tried and where. Dogger give us a full report after you get yours.









                          Quote Originally Posted by jet city amps
                          View Post

                          I prefer to give the schematic to customers who buy the amp. that seems fair to me, but, what did you have in mind?




                          Ok, Doug, I'll respect your decision and not post the schematic on here, all though I think it would be a resource to have in this thread. Can you fill me in on the baffles situation (what is offered)? Also need info on the "jet packs" if you guys are even considering doing those any more.
                          Jca 50h/ 100h/ 22h Mod thread and Owners Club
                          Jca20H Mod thread and owners club
                          Like me on facebook
                          Follow me on twitter

                          Comment


                          • #15
                            I made a few low volume recorded clips just now of mine showcasing 3 fairly different sounds http://www.netmusicians.org/index.ph...0City%20JCA20H
                            VHT/Fryette DEATH SQUAD

                            Great deals here and on Rig-talk with: Boatshoes/smucarolina, goldwing68nv, tkozuch, chakosh, Norton666

                            Current whoredom: VHT Pitbull 50/CL

                            Past whordom: Peavey 5150 II | ENGL Steve Morse 100 | Jet City JCA20H | Mesa Boogie Mark V | Sunn 200s | Orange Thunderverb 50 | Peavey 5150 | Laney GH100L







                            Originally Posted by MarkBastable


                            You don't crap in the bidet, you colonial peasant.

                            Comment



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