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5F1 Triode Layout

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  • 5F1 Triode Layout

    Hey guys,

    Just wondering if you can give this layout a lookover for my upcoming build. I'm mainly worried about grounding scheme as I have heard/read that the 5F1 can be a real problem child when it comes to ground loops/ground noise.

    Also if you have another layout I should be using feel free to post it up!

    Here is the link:

    http://site.triodestore.com/5F140-18027120V.pdf

    Thanks!

  • #2
    That layout uses a star ground which works in theory, but fails in practice because of an imperfect star.

    Do the input jacks you have connect ground to the chassis? How about the speaker jack?

    Study this thread: http://music-electronics-forum.com/t16311/
    WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
    REMEMBER: Everybody knows that smokin' ain't allowed in school !

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    • #3
      Originally posted by loudthud View Post
      That layout uses a star ground which works in theory, but fails in practice because of an imperfect star.

      Do the input jacks you have connect ground to the chassis? How about the speaker jack?

      Study this thread: http://music-electronics-forum.com/t16311/
      I ordered Switchcraft jacks which ground to the chassis for both inputs and speaker jack.

      Comment


      • #4
        Read through the thread you linked me to needless to say it is a little bit above my level. Do you have a layout w/ grounding scheme you would recommend?

        Thanks

        Comment


        • #5
          I'd do it like this:

          http://i45.tinypic.com/i1lbbb.gif

          ideally, the 470 ohm + 25uF should be grounded directly to the first filter cap (blue 16uF), but you would need another turret for that

          this layout is per Merlin's article, I hope I didn't f***k something up

          http://www.freewebs.com/valvewizard2/Grounding.html
          Last edited by frus; 07-18-2012, 06:47 AM.

          Comment


          • #6
            Following the layout you edited wouldn't some things be grounded twice for example the volume pot and 220k resistor would be going to the speaker jack and the input jack. Also, I would need to remove the jumpers connecting the (-) on the capacitors so that I could ground them as you mentioned correct?

            Originally posted by frus View Post
            I'd do it like this:

            http://i45.tinypic.com/i1lbbb.gif

            ideally, the 470 ohm + 25uF should be grounded directly to the first filter cap (blue 16uF), but you would need another turret for that

            this layout is per Merlin's article, I hope I didn't f***k something up

            The Valve Wizard

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            • #7
              oh, I thought the speaker jack was isolated
              never mind, just ground it to the chassis then (so no ground wire), I think you can take a chance for it not making a ground loop (I have non-isolated jack on my 5F4, and no buzz)

              all the (-) legs of the filter caps have to be connected, don't remove the jumpers (I just added one more). That's where the ripple current is flowing. we just have to make sure that the signal current is not flowing through the same wires

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              • #8
                Originally posted by LJay942 View Post
                Hey guys,

                Just wondering if you can give this layout a lookover for my upcoming build. I'm mainly worried about grounding scheme as I have heard/read that the 5F1 can be a real problem child when it comes to ground loops/ground noise.

                Also if you have another layout I should be using feel free to post it up!

                Here is the link:

                http://site.triodestore.com/5F140-18027120V.pdf

                Thanks!
                Gentlemen,

                Here is the approach I would take to such a layout. The layout in this link is one I put together for the Gibson GA-5, but it is, for all intents and purposes the same thing, with only very minor differences. I have added in some optional stopper resistors, and a heater elevation point.

                Note that this is a "tube socket-centric" layout designed to minimize wire runs to the bare minimum. Note that I haven't built this layout, but I have used the same design principles for very much more complicated amps - barring any oversights or errors, I have every reason to believe that it would perform well. Note that there is one and only one ground reference to the chassis, and that the PT CT returns directly to the negative side of the reservoir cap.

                EDIT: Oh, and it's a fabulously bad idea to have the 120VAC switch incorporated into the volume pot as shown in the triode diagram. Not only are most such switches not rated for that much voltage, but you are also putting the very noisy AC immediately adjacent to your preamp signal. That almost guarantees a bad result with respect to noise.
                Last edited by Wombaticus; 08-30-2012, 02:38 AM.

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                • #9
                  Just an update on this -- here's a similar layout, but showing values specific to a Fender 5F1 Champ style circuit (and omitting a couple of non-original additions in the Gibson layout above, such as the filtered divider for elevating the heaters: Wombat Amplification: Layout for circuit similar to 5F1 Champ

                  Comment


                  • #10
                    Originally posted by Wombaticus View Post
                    Gentlemen,

                    Here is the approach I would take to such a layout. The layout in this link is one I put together for the Gibson GA-5, but it is, for all intents and purposes the same thing, with only very minor differences. I have added in some optional stopper resistors, and a heater elevation point.

                    Note that this is a "tube socket-centric" layout designed to minimize wire runs to the bare minimum. Note that I haven't built this layout, but I have used the same design principles for very much more complicated amps - barring any oversights or errors, I have every reason to believe that it would perform well. Note that there is one and only one ground reference to the chassis, and that the PT CT returns directly to the negative side of the reservoir cap.

                    EDIT: Oh, and it's a fabulously bad idea to have the 120VAC switch incorporated into the volume pot as shown in the triode diagram. Not only are most such switches not rated for that much voltage, but you are also putting the very noisy AC immediately adjacent to your preamp signal. That almost guarantees a bad result with respect to noise.
                    Hmm, first of all your design still has flaws....I have build 5F1 and GA-5 amps and are virtually hum free. This is what I do...

                    Firstly if the on/off switch is not rated for 120V you reckon. I use it for 240V...never had a problem. Secondly I run the hot to the fuse first then to the switch.

                    The original filter caps are under valued to eliminate completely AC ripple, I use 20/20/20 you could still raise the screen filter cap for better results.

                    Always separate the B+ filter cap ground to the PT side. The other caps ground go to the input side.

                    Connect the heater CT to the cathode of the 6V6 (I've never noticed a great deal of difference to having it to ground, I just prefer it)

                    I run a shielded wire from the volume pot to the 12Ax7 (some builders found it made no difference) But I found it does reduce hum from severe interference.

                    Also use Switchcraft jacks, they ground to the chassis (star washers are recommended for extra security)

                    Jobs done

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