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The basics of tube amp circuit layout to avoid components interfering with one another.

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  • #16
    Originally posted by Jazz P Bass View Post
    Wow !
    Nice build.
    A Boutique Blues Junior.
    That my friend is how Fender should have built the amp.
    Although it probably would have them cost too much.
    Agreed, that's a really nice build indeed. I really like the Blues Jr and always thought it deserved to be better constructed than the factory product. That build is a 'keeper'.

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    • #17
      Just found this excellent article by one of our members: https://dalmura.com.au/static/Hum%20article.pdf
      - Own Opinions Only -

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      • #18
        Originally posted by Jazz P Bass View Post
        Wow !
        Nice build.
        A Boutique Blues Junior.
        That my friend is how Fender should have built the amp.
        Although it probably would have them cost too much.
        Thanks!

        If you're interested I posted the full build here...

        https://music-electronics-forum.com/...n-eyelet-board

        If it ain't broke I'll fix it until it is...
        I have just enough knowledge to be dangerous...

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        • #19
          Originally posted by Mick Bailey View Post

          Agreed, that's a really nice build indeed. I really like the Blues Jr and always thought it deserved to be better constructed than the factory product. That build is a 'keeper'.
          Thanks!

          It's definitely a keeper.
          When I'm gone, whomever gets this is gonna be surprised.

          From the outside it looks like a stock Blues Junior.
          If it ain't broke I'll fix it until it is...
          I have just enough knowledge to be dangerous...

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          • #20
            "When I'm gone, whomever gets this is gonna be surprised.
            From the outside it looks like a stock Blues Junior"

            You should put a note in the amp of what you did and when.
            Otherwise, I can just imagine the posts in the far future as someone looks for information on this 'rare' Fender BJ.

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            • #21
              Originally posted by Jazz P Bass View Post
              "When I'm gone, whomever gets this is gonna be surprised.
              From the outside it looks like a stock Blues Junior"

              You should put a note in the amp of what you did and when.
              Otherwise, I can just imagine the posts in the far future as someone looks for information on this 'rare' Fender BJ.
              Ya, I taped a schem and layout in an envelope inside.
              If it ain't broke I'll fix it until it is...
              I have just enough knowledge to be dangerous...

              Comment


              • #22
                Originally posted by mozz View Post
                Find old tube books, earlier the better, 30's-40's-50's.
                http://www.jumpjet.info/Pioneering-Wireless/

                https://nvhrbiblio.nl/biblio/boek/

                https://www.vintage-radio.info/books

                https://worldradiohistory.com/

                https://worldradiohistory.com/Bookshelf_Bernards_Babani.htm

                https://worldradiohistory.com/BOOKSHELF-ARH/Bookshelf_Hobbyist.htm
                Who does not know and knows that he does not know - teach him Confucius)
                Who knows and does not know that he knows - wake him Confucius)

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                • #23
                  Regarding if you "got lucky" with a quiet amp. I would say no. If you followed what KOC outlines in TUT3 then you will get a quiet amp as far as grounding goes. I've been using that approach for 12 years and never had a problem with grounding hum. Honestly I wouldn't even be able to recognize it!

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                  • #24
                    Originally posted by Gaz View Post
                    Regarding if you "got lucky" with a quiet amp. I would say no. If you followed what KOC outlines in TUT3 then you will get a quiet amp as far as grounding goes. I've been using that approach for 12 years and never had a problem with grounding hum. Honestly I wouldn't even be able to recognize it!
                    Thanks!

                    Yes, I used his "distributed filtering" scheme from TUT3.
                    All grounds are "wired" on the board, each section/stage to it's respective node, and the entire circuit is grounded to the chassis "only" at the input jack.

                    You can sorta see the distributed filtering by how the big filter caps are spaced across the board, rather than all bunched together like most production amps.
                    If it ain't broke I'll fix it until it is...
                    I have just enough knowledge to be dangerous...

                    Comment


                    • #25
                      Originally posted by galaxiex View Post

                      Thanks!

                      Yes, I used his "distributed filtering" scheme from TUT3.
                      All grounds are "wired" on the board, each section/stage to it's respective node, and the entire circuit is grounded to the chassis "only" at the input jack.

                      You can sorta see the distributed filtering by how the big filter caps are spaced across the board, rather than all bunched together like most production amps.
                      Yeah, that's how I've always done it too. Merlin Blencowe advocates the same (which makes sense because it's technically the most proper way). I would say a lot of "production" amps do it that way too, but often don't decouple every node. Also it's not really necessary to have the cap physically so close, it just makes the wiring easier. There are lots of ways to make an amp quiet, but the "Galaxy Ground" method is fool-proof. Take it from this fool.

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                      • #26
                        Henry Ott's book is one of my bibles as well. Add to that Low Noise Electronic Design by C.D. Motchenbacher & F.C. Fitchen. and Grounding and Shielding Techniques in Instrumentation by Ralph Morrison. Ott's book has so much excellent material about materials, and makes what Morrison's book presents easier to comprehend.

                        I'm sure there's some text or technical papers on the fine points of transformer design. That's another world of complexity that has everything to do with performance. Most of us that have been at this craft of audio electronics have been accumulating technical papers and books, adding to thick notebooks that continue to grow over time as we find additional information written, presented to a wide variety of technical societies, as well as in respected magazines and such. There's a wealth of information out there for any discipline you care to follow.
                        Logic is an organized way of going wrong with confidence

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                        • #27
                          Originally posted by Helmholtz View Post
                          Just found this excellent article by one of our members: https://dalmura.com.au/static/Hum%20article.pdf
                          Great article!! Thanks for posting that.

                          Tim, is this the second edition to that article? Great work. Unfortunately, the downside is now we're going to have to put you back to work writing more quality content for us.
                          If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

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                          • #28
                            I have put together 9 'general' articles over the last decade on things that have interested me (bottom of link below) but I hadn't found another similar 'document' to refer to. I update them as I come across new stuff (even just minor tweaks), but don't keep a revision list so its not easy to know what has been changed since you may have last looked, and also means the date on the top of the doc identifies the latest version (and anyone who has previously downloaded needs to clear their cache or they may still see an old version).
                            https://www.dalmura.com.au/projects/Valve%20Info.html

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