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  • #16
    Just got my JCA20H today and thought I'd post some pics...little worried about the amp as it looks as if MUSIC123 sent me a used amp by the looks of the box and old shipping label..













































    theDogger
    - Ibanez MTM2(EMG-18Voltz) -
    - Mesa Boogie Single Rec -
    - Egnator Vengeance -
    - TC Electronics G-Major
    - Custom 4x12 Build DIY -
    - https://www.facebook.com/bfgcabs/

    Comment


    • #17
      Here are some pics of the tube replacement. I love Hi-Res pics. I think that is the best way for thread like this not the photo camera's..that you can't see anything....The stock tube were biased cold 16.6ma. I swapped them out with some JJ's from www.EuroTubes.com They are great! I got the following tubes and will try and do a run down as soon as I can figure out how to get a decent recording..

      2-JJ-EL84

      2-JJ-12AX7 Standard (V1 & V2)

      1-JJ-12AX7 Balanced (V3)

      1-JJ-12AX7 HighGain (V1)

      1-JJ-12AT7 Low Gain (V2)

      1-Tungsol 12AX7 Standard (V1 & V2)



      I measured the Voltage at pin#7. It read 362. So I biased it @70%.

      11.5/362*.70=.021875 so I set the bias @ 21ma



      So I set it at 21ma. The JJ's quieted the noise a little, made it darker but in a good way. With the master set at 3 and the pre at 1 it was sounding like it wanted to break up so I swapped the V2 with the 12AT7 and tried it again and it was clean up to about 3 now before it sounded like it wanted to breakup.



      So fo now I have settled for the all standard JJ until I get use to the amp and can mess w/it more.



















      theDogger
      - Ibanez MTM2(EMG-18Voltz) -
      - Mesa Boogie Single Rec -
      - Egnator Vengeance -
      - TC Electronics G-Major
      - Custom 4x12 Build DIY -
      - https://www.facebook.com/bfgcabs/

      Comment


      • #18






        Quote Originally Posted by theDogger
        View Post

        Here are some pics of the tube replacement. I love Hi-Res pics. I think that is the best way for thread like this not the photo camera's..that you can't see anything....The stock tube were biased cold 16.6ma. I swapped them out with some JJ's from www.EuroTubes.com They are great! I got the following tubes and will try and do a run down as soon as I can figure out how to get a decent recording..

        2-JJ-EL84

        2-JJ-12AX7 Standard (V1 & V2)

        1-JJ-12AX7 Balanced (V3)

        1-JJ-12AX7 HighGain (V1)

        1-JJ-12AT7 Low Gain (V2)

        1-Tungsol 12AX7 Standard (V1 & V2)



        I measured the Voltage at pin#7. It read 362. So I biased it @70%.

        11.5/362*.70=.021875 so I set the bias @ 21ma



        So I set it at 21ma. The JJ's quieted the noise a little, made it darker but in a good way. With the master set at 3 and the pre at 1 it was sounding like it wanted to break up so I swapped the V2 with the 12AT7 and tried it again and it was clean up to about 3 now before it sounded like it wanted to breakup.



        So fo now I have settled for the all standard JJ until I get use to the amp and can mess w/it more.



















        theDogger




        Can't wait to hear since we're using a similar tube compliment.
        Jca 50h/ 100h/ 22h Mod thread and Owners Club
        Jca20H Mod thread and owners club
        Like me on facebook
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        Comment


        • #19






          Quote Originally Posted by theDogger
          View Post



          I measured the Voltage at pin#7. It read 362. So I biased it @70%.

          11.5/362*.70=.021875 so I set the bias @ 21ma




          I have the same tube replacement from eurotubes, but I am ordering my bias probe today so I haven't biased it yet. It just took me a couple weeks before I felt comfortable biasing my own amp. The way you figured out the bias, and the way I did are a little different. I use 12 watts dissipation, instead of 11.5. So... my amp is running at 360 plate voltage. I would do 12/360=.033 *.7= .023 milliamps. I double checked this with the weber bias calculator on their website and the numbers come out right. The link for the weber bias calculator is:



          http://www.webervst.com/tubes1/calcbias.htm



          I'm not trying to tell you you're wrong, it's just a sincere question and pursuit of tone.



          I will post some pics... but there is a pretty big mar on one of the big traces on the pcb. I don't think it is changing the sound of the amp.... it just doesn't look as pretty inside. I'm hoping I can get a second opinion.



          Even without the bias, the amp sounds way better with the JJ's. The gain is much more defined, and the amp is overall a lot more clear and punchy. I imagine that my power tubes are only running about 50% as well... and I am excited to hear what they sound like at 70%
          Guitars
          Norman Acoustic
          ESP LTD EC-400VF
          Amp
          Jet City JCA20h
          Cabs
          Jet City JCA12S
          Custom 2x12 w/Eminence Governor+Private Jack

          Comment


          • #20
            i too am using JJs.



            im using high gain 12ax7s, and balanced HG JJ in the PI slot, and 2 early breakup JJ el84s.



            very happy with the change in tone, clean and dirty.



            i wonder how much adding reverb would cost...

            Comment


            • #21






              Quote Originally Posted by guitarmadman85
              View Post

              I have the same tube replacement from eurotubes, but I am ordering my bias probe today so I haven't biased it yet. It just took me a couple weeks before I felt comfortable biasing my own amp. The way you figured out the bias, and the way I did are a little different. I use 12 watts dissipation, instead of 11.5. So... my amp is running at 360 plate voltage. I would do 12/360=.033 *.7= .023 milliamps. I double checked this with the weber bias calculator on their website and the numbers come out right. The link for the weber bias calculator is:



              http://www.webervst.com/tubes1/calcbias.htm



              I'm not trying to tell you you're wrong, it's just a sincere question and pursuit of tone.



              I will post some pics... but there is a pretty big mar on one of the big traces on the pcb. I don't think it is changing the sound of the amp.... it just doesn't look as pretty inside. I'm hoping I can get a second opinion.



              Even without the bias, the amp sounds way better with the JJ's. The gain is much more defined, and the amp is overall a lot more clear and punchy. I imagine that my power tubes are only running about 50% as well... and I am excited to hear what they sound like at 70%




              That is not a huge issue. You can use 11.5 or 12 watts. the difference between 21ma and 23ma is not a big deal. If it was 16ma and 23ma then there would be a difference. A lot of guy think that 70% is too high and that 60-65% should be used.



              I just ordered the BitMo Surfa mod.........



              FYI - I am returning my amp to MUSIC123 for a replacement. They sent me a used amp that had an issue with the blue Power Light. Why do I say it is a used amp? Because there is a shipping label under my UPS label for a different party in Indiana. So I paid for a new JCA20H and got a returned open box with a power light issue...Called MUSIC123 an they have issue an RMA.

              This is the 2nd time that it has happened to me...the other time to was from SamAsh with a Bugera 6262.



              Really kinda pisses you off!



              theDogger
              - Ibanez MTM2(EMG-18Voltz) -
              - Mesa Boogie Single Rec -
              - Egnator Vengeance -
              - TC Electronics G-Major
              - Custom 4x12 Build DIY -
              - https://www.facebook.com/bfgcabs/

              Comment


              • #22
                I just ordered a few JJ's myself. 2 - EL84's, 1 - ECC803s (hi-gain), 1 - ECC83s (Hi-gain) and then I orderd a balanced Sovtek LPS and a Electro-Harmonix 12ax7EH. But, I can't play with them until I get home from a business trip on Friday



                I'm still probably going to try some regular gain JJ ecc83s too, depends on what I think of the hi-gainers. I had heard that regular JJ ECC83s' are a lower gain tube, which is why I went with the hi-gain version.
                SPAM:
                Blackheart Little Giant Head
                BG Dark Bucker Pickups - Brand new

                Comment


                • #23






                  Quote Originally Posted by theDogger
                  View Post

                  That is not a huge issue. You can use 11.5 or 12 watts. the difference between 21ma and 23ma is not a big deal. If it was 16ma and 23ma then there would be a difference. A lot of guy think that 70% is too high and that 60-65% should be used.



                  I just ordered the BitMo Surfa mod.........



                  FYI - I am returning my amp to MUSIC123. They sent me a used amp that had an issue with the blue Power Light. Why do I say it is a used amp? Because there is a shipping label under my UPS label for a different party in Indiana. So I paid for a new JCA20H and got a returned open box with a power light issue...Called MUSIC123 an they have issue an RMA.

                  This is the 2nd time that it has happened to me...the other time to was from SamAsh.



                  Really kinda pisses you off!



                  theDogger




                  Forget Music123, Musicians Friend, etc.... Sweetwater is the only place that I will spend my money for new gear these days. Those other dealers hire monkeys for employees (no offense to anyone on here that works at either )
                  Guitars:Fender Jaguar HH, Fender MIJ Jazzmaster, Gibson Les Paul StudioAmps:2 Silverface 1970s Fender Pro Reverbs, Fender Blues Deluxe, Ampeg V4, 80s Roland JC-120Current Main RigFulltone Fulldrive II--> Keeley modded Rat--> Line 6 FM4--> EHX Deluxe Memory Man--> Line 6 Verbzilla--> Roland JC-120Other StuffKorg Electribe, iPad2 (Beatmaker 2, iSequence, Animoog)

                  Comment


                  • #24






                    Quote Originally Posted by Kidbs
                    View Post

                    Forget Music123, Musicians Friend, etc.... Sweetwater is the only place that I will spend my money for new gear these days. Those other dealers hire monkeys for employees (no offense to anyone on here that works at either )




                    I used to work for them. You are correct.
                    Originally Posted by buddhapaugh


                    Rocking the spandex AND the depends!

                    Comment


                    • #25






                      Quote Originally Posted by theDogger
                      View Post

                      That is not a huge issue. You can use 11.5 or 12 watts. the difference between 21ma and 23ma is not a big deal. If it was 16ma and 23ma then there would be a difference. A lot of guy think that 70% is too high and that 60-65% should be used.




                      Cool. I just wanted to make sure I wasn't doing my calculations wrong. I would be interested to hear your opinion on how much the bias helped the amp. I understand that they are biased a little cold from the factory.
                      Guitars
                      Norman Acoustic
                      ESP LTD EC-400VF
                      Amp
                      Jet City JCA20h
                      Cabs
                      Jet City JCA12S
                      Custom 2x12 w/Eminence Governor+Private Jack

                      Comment


                      • #26
                        I did a couple more clips today



                        http://www.netmusicians.org/files/33-JCpowerchords.mp3





                        http://www.netmusicians.org/files/46-JCkalmah.mp3
                        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


                        • rjonsolo1
                          rjonsolo1 commented
                          Editing a comment
                          Just listened to you sound clips. Is that stock and if so, what did you do to get that much gain. Mine is kinda mushy. More vintage sounding. But I'm running through a 412. Thanks

                      • #27






                        Quote Originally Posted by theDogger
                        View Post



                        FYI - I am returning my amp to MUSIC123. They sent me a used amp that had an issue with the blue Power Light. Why do I say it is a used amp? Because there is a shipping label under my UPS label for a different party in Indiana. So I paid for a new JCA20H and got a returned open box with a power light issue...Called MUSIC123 an they have issue an RMA.

                        This is the 2nd time that it has happened to me...the other time to was from SamAsh.





                        Someone had that same issue and Jet City sent them a new light. =/ but I understand they shouldn't send you a used an without telling you.



                        EDIT: I should've said that I love my JCA20H. Gonna get the two 212 cabs and another one for some stereo rig action

                        Comment


                        • #28






                          Quote Originally Posted by tlbs
                          View Post

                          Someone had that same issue and Jet City sent them a new light. =/ but I understand they shouldn't send you a used an without telling you.



                          EDIT: I should've said that I love my JCA20H. Gonna get the two 212 cabs and another one for some stereo rig action




                          That sounds hot! I plan to wait for the PicoValve to do much the same thing.
                          Originally Posted by buddhapaugh


                          Rocking the spandex AND the depends!

                          Comment


                          • #29






                            Quote Originally Posted by Yarbicus
                            View Post

                            That sounds hot! I plan to wait for the PicoValve to do much the same thing.




                            yeah and they finally posted their online store to their website. gotta get some slip covers, amp bags and some baffles for the beauties

                            Comment


                            • #30






                              Quote Originally Posted by tlbs
                              View Post

                              Someone had that same issue and Jet City sent them a new light. =/ but I understand they shouldn't send you a used an without telling you.



                              EDIT: I should've said that I love my JCA20H. Gonna get the two 212 cabs and another one for some stereo rig action




                              That was me, and doug made it right.
                              Jca 50h/ 100h/ 22h Mod thread and Owners Club
                              Jca20H Mod thread and owners club
                              Like me on facebook
                              Follow me on twitter

                              Comment













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