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  • #46






    Quote Originally Posted by mblooper45
    View Post

    It's good to go man.

    And you misread, what was said was that both the depth and presensce circuit would equate to to much nfb on the stock feedback tap. Just switch taps like the schematic says and your good to go.




    Thanks man. I'm still getting my feet wet with the whole amp modding thing, and I just wanted to make sure.

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    • #47






      Quote Originally Posted by theDogger
      View Post

      Did I miss something on this board. The only schematic that I have seen was for an AstroVerb!!!!



      mblooper45 can you please shine more light on the choke mod for us newbee's....pics also..





      theDogger




      Its in deuse's thread (warning his schematic is not labeled the same as the pcb).
      Jca 50h/ 100h/ 22h Mod thread and Owners Club
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      • #48






        Quote Originally Posted by mblooper45
        View Post

        Its in deuse's thread (warning his schematic is not labeled the same as the pcb).




        Can you post the link to the thread? For some reason I do not have a link anywhere to search in FireFox. I have a link in Chrome but when hitting it takes me to the main page and keeps asking me to login..



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

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        • #49






          Quote Originally Posted by theDogger
          View Post

          Can you post the link to the thread? For some reason I do not have a link anywhere to search in FireFox. I have a link in Chrome but when hitting it takes me to the main page and keeps asking me to login..



          theDogger




          http://acapella-legacy.harmony-centr...0&d=1263560793



          That should be it.

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          • #50






            Quote Originally Posted by barden1069
            View Post







            Thanks it will be very helpful. I am not sure why the damn search link does not show up on top when I am logged in....



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

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            • #51
              How much are the mods? links website? kinda interested on this Amp..
              ------------------------------------------------------------------------------------------------------------------------------
              Great Deal(s) With - LoFiBrian, eyeball987

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              • #52






                Quote Originally Posted by Zhorellski
                View Post

                How much are the mods? links website? kinda interested on this Amp..




                It's very DIY So far. So the cost of mods is the cost of parts.

                The only other person that does mods is Dave Friedman.

                I think his mods run around $3-200.
                Jca 50h/ 100h/ 22h Mod thread and Owners Club
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                • #53
                  ARG!

                  MY light is failing me again, it's flickering on and off!

                  Also I'm adding the instructions for the choke mod.

                  My light just died going to see if its just faulty soldering on my part.

                  please, read the warning and safety measures before you start modding.

                  Jca 50h/ 100h/ 22h Mod thread and Owners Club
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                  • #54
                    Ok kool thanks for that. So to make sure that I understand in simple terms using a choke in the filter supply the result is less background hum and cleaner, better bass response. Using a resistor manufacturers save time and cost and there is a bit more background hum and a looser bass response.



                    I emailed Mercury Magnetic and they suggested the JTM45 -- 7H -- 150mA. Why did you choose the Hammond 156M 3h-100ma current and 86 ohm DCR??Would changing the output transformer make a difference int he choice of the choke?



                    So the R3 Resistor value is 1k? 5%



                    thanks



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

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                    • #55
                      I'd use a Fender (or replacement) choke for the Deluxe Reverb. 4H, 100R. Search Fender 125C3A. Its small and enough for the JCA20H.
                      Krampe Amplification.

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                      • #56






                        Quote Originally Posted by theDogger
                        View Post

                        Ok kool thanks for that. So to make sure that I understand in simple terms using a choke in the filter supply the result is less background hum and cleaner, better bass response. Using a resistor manufacturers save time and cost and there is a bit more background hum and a looser bass response.



                        I emailed Mercury Magnetic and they suggested the JTM45 -- 7H -- 150mA. Why did you choose the Hammond 156M 3h-100ma current and 86 ohm DCR??Would changing the output transformer make a difference int he choice of the choke?



                        So the R3 Resistor value is 1k? 5%



                        thanks

                        http://acapella.harmony-central.com/...ply&p=40352845

                        theDogger




                        A choke is used in place of a series resistor because the choke allows better filtering (less residual AC ripple on the supply, which means less hum in the output of the amp) and less voltage drop(higher B+, so a little more "clean" headroom).

                        In typical designs (such as this) the choke only regulates DC current to the screen grids of the pre and output tubes. each pre amp tube takes about 1-3ma and the output tubes about 10ma.

                        So following this formula a 50 watter would usually need only 50-60Ma.

                        The induction was chosen probably because even at the specs that it is at it is still over kill. You wont get much of a difference with 3h to 7h, once the induction is up to snuff going higher brings much much much much less return.

                        The choke part number I got from deuse, but I'm sure that it was chosen

                        because it was fairly inexpensive (30$ shipped) and it is perfect for the job, hell if anything it's already overspec'd.

                        I don't mean to blast Mercury, but the choke they suggested to you is probably over priced (when compared to the hammond choke) and will not affect the feel of the amp in a more positive way than the Hammond choke. If anything the higher induction of the mercury choke may make the amp feel more stiff, and make it harder to break up.
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                        • #57
                          Does anyone know where to get an A1M pot for the depth mod? I tried google but all I got was some confusing stuff and I'm a bit lost now...







                          Told you I'm a noob.

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                          • #58
                            Mouser, Mojo, Ruby . . .



                            Look for a Alpha 1M log pot. Or 500k. Doesn't really matter.
                            Krampe Amplification.

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                            • #59
                              Just thought I'd offer my experience with a little tube swapping I did;



                              I recently tried following tubes:

                              JJECC803S Gold Pins, Hi-Gain

                              JJECC83S Hi-Gain

                              Electro Harmonix 12AX7EH

                              Sovtek 12AX7LPS

                              Tung Sol 12AX7 RI

                              New Sensor Mullard RI 12AX7



                              I also replaced the power tubes with JJEL84's



                              I tried just about every imaginable combo with these tubes and my results:



                              Balanced Sovtek LPS sounded the best in PI (V3) spot...



                              Most of these I tried with the Hi-gain JJECC83S in V2...



                              803S Gold Pin - Had something weird going on in the mids. Hard to describe. Brighter than the JJECC83S, but still darker than a "normal" 12ax7...

                              83S - Sounded alright, seemed a little too "mushy" in V1.

                              Tung Sol - Pretty good. Articulate, smoother than stock, but a little bright/fizzy.

                              EH - Similar to the Tung Sol, a little less fizz maybe, good gain.

                              Mullard - I finally settled on this tube. I really liked it in my Blackstar. It seems to be pretty smooth, while still retaining good note to note articulation. Good, open, throaty sound.



                              I did try the Tung Sol in V1 with EH in V2. Seemed a touch brighter/fizzier than I wanted. With Mullard RI in V1 and EH in V2, didn't have quite as much gain as with the Hi-gain JJ in V2.



                              I'm really liking the tube combo I've got now. Good amount of gain, smoother with less fizz on the high end with max gain. I went from running almost no presence and treble/mids noon or below to running presence from 4-6 and treble and mids 5-5.5. I think the Mullard and JJ rolled off some of the high end, which is what I was trying to accomplish. Awesome sound when wound up too
                              SPAM:
                              Blackheart Little Giant Head
                              BG Dark Bucker Pickups - Brand new

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                              • #60
                                Thanks, BSS! That's some good info.
                                Originally Posted by buddhapaugh


                                Rocking the spandex AND the depends!

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