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My first sucessful tube amp build!


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  • My first sucessful tube amp build!

    I now have a fully functional and quiet of hums and buzzes "cake pan" amp under my belt. It looks cool and sounds amazing!!
    I used an Ironsounds 18 watt Marshall clone circuit board kit and used some old iron I had laying around. It really didn't take too long to wire all the resistors, caps,diodes and such to it. It took longer to punch the bagillion holes in the baking pan and I also bolted in two two inch wide by 16 guage aluminum flat stock into the pan to stiffen it up and act ad a grounding plate. It buzzed like crazy on first fire up but after reading around I found that I needed to create a "virtual center tap" for the filament winding (the PT I used had no CT on the filament winding). After doing this and neatening up some of the grounding I fired her up and tested some voltages as per the instructions for the kit. Lo and behold all tests were within a percent or so of the chart they had for various test points. Then I plugged in my Les paul and turned it up. BLISS!!! I also got the wattage control option with this kit and will certainly add the FX loop kit too!!
    something I learned is that the Chasis is the most work. I also now see the advantages of a PCB is that even an idiot like me can put one together. The heater wiring is sort of taken care of by someone who knows how to keep it quiet. All I really had to do is hook the filament wires to the right spot on the board.
    Also it is noticable that the layout of this kit makes it inherently quiet as the ac wires remain so far from the signal path with a modicum of care. Also I had a chance to put this amp on top of my Marshall 4x12 and ran it flat out dimed for a good while and it never hiccuped and sounds excellent. I also if I were to do it again. I'd overdrill the tube holes (and more accurately centered ;-) and put a grommit there too to neaten it up a little bit. I also need to wire in the second input ( I wanted to make sure the amp worked first) ahd add a second speaker out in parallel with the one in there now.
    Attached Files
    If only I was all thumbs

  • #2

    very cool...ha!  great use of resources


    email josh@atlas-stands.com


    • #3

      Nice work on the amp and I am so happy it worked the first time. Now complete this amp and get started on your next project. GOOD LUCK !!!

       I did a hi-fi amp like that with one cake pan back in the mid-80s. Mine was a hand-wired triode-strapped KT-90 stereo and it buzzed like mad. It took a lot of work to get it to to run silently, but finally it did. It was not my first project either as I had built several Audio by Van Alstine stereo hi-fi  tube pre-amplifiers prior to the KT-90 amp build.

      HCGB #115

      "With every mistake we must surely be learning..."
      George Harrison


      • #4

        Now I also know why these were so liked back in the day.  This one sounds unbelievably good.

        It has VERY nice punchy cleans and needless to say that famous Marshall KKKEEEERRRRRRAAAAAAANNNGGGGGGG!!!!!!!!  When stressed.

        If only I was all thumbs


        • Rg505bk
          Rg505bk commented
          Editing a comment



          That voltage control is basically a vvr variant? I just finished a tube amp project and added a vvr type voltage control to it, only thing is that it adds a slight buzz on top of the note - and the troubleshooting is driving me crazy