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5F2-A with master volume schematic?

Discussion in 'Shock Brother's DIY Amps' started by klobasa, Mar 9, 2013.

  1. klobasa

    klobasa Tele-Meister

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    Hi,

    I tried google, but didn't find a schematic....

    If you have the knowledge, could you please show me how to add a master volume to a classic 5F2-A circuit? What kind of pot does it have to be?

    Many thanks if you can help me.
     
  2. JohnnyCrash

    JohnnyCrash Doctor of Teleocity Gold Supporter

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    You can replace the 220k grid leak from the 6V6 to ground with a 250k pot.
     
  3. klobasa

    klobasa Tele-Meister

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    Thanks! Like this?
     

    Attached Files:

  4. Jcn3

    Jcn3 Tele-Meister

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    you really think you'll need one -- they're just not that loud. i'm using a texas heat with mine and it's surprisingly quiet. also if you're using a guitar with humbuckers, you can make one crunch very easily.
     
  5. klobasa

    klobasa Tele-Meister

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    Yeah, I need it. I just want to knock down few db's. Master volume will cost me 5€, an attenuator at least 100€.
     
  6. FenderLover

    FenderLover Poster Extraordinaire

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    No...

    The right pot connection is correct, except the dotted line on the layout goes to the center (wiper). You'll have to lift the board to get at that wire.

    The left pot terminal goes to ground (where the green line goes to).

    The pot can be 250K or 500K audio taper.

    P.S. Oddly enough, your drawing will work, but it's not a good idea. The pot will short the preamp signal to ground with zero impedance. Wired as I suggested, the load is constant for the preamp, and the output taps what you set it to.
     
  7. klobasa

    klobasa Tele-Meister

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    Thank you, I am trying to figure out how does your corrections look like... ;)

    BTW, I don't have this same layout, but seeing this layout with MV helps me to realize how to do it in my amp.
     
  8. hackworth1

    hackworth1 Friend of Leo's Vendor Member

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    Remove 220K resistor

    .022uF blocking capacitor (by itself) connected with a wire to right lug (hot) on pot.

    Wire from 6V6 pin 5 to center lug (wiper) on pot.

    Ground on the left lug on pot like you have it.
     
  9. Fatknuckle

    Fatknuckle Tele-Holic

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    How would this work with a 5C1?
     
  10. FenderLover

    FenderLover Poster Extraordinaire

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    Good eye, Fatknuckle. It wouldn't apply to a 5C1 because there is only one gain stage in the preamp, but that's the schematic to follow to add a Master to any 2-stage Champ.
     
  11. Fatknuckle

    Fatknuckle Tele-Holic

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    Adding a second gain stage then?
     
  12. FenderLover

    FenderLover Poster Extraordinaire

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    Sure: Gain>vol>gain>Master>output
    The 5C1 with two 6SJ7's would have a boatload of drive. I love that tube. There should probably be a resistor before the Vol to trim some of the gain, or add a tone pot to add some loss. Not a 5C1 any more though, but so what. I had thought about trying that arrangement once, driving an 8417.

    edit:
    found this schematic
     

    Attached Files:

    Last edited: Mar 13, 2013
  13. Fatknuckle

    Fatknuckle Tele-Holic

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    No, that is definitely a different animal. Interesting.
     
  14. Ibazen

    Ibazen TDPRI Member

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    Total necrothread, but for anyone else thinking about putting a master volume on a 5fa2, I did it and found it wasn't worth it. I got some overdrive, but not much and pretty fizzy. YMMV. Hackworth's advice is correct. I just went back to check this thread before reverting the master volume, to make sure I didn't miss a step.
     
  15. robrob

    robrob Poster Extraordinaire Ad Free Member

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    You need to add some drive at the input to make the master volume work for you in a 5F1. Hot guitar pickups, a clean boost pedal or even a graphic equalizer with all the tone sliders up a little can get the preamp into overdrive to give the master volume something to work with.
     
    D'tar likes this.
  16. Mongo Park

    Mongo Park Tele-Holic

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    Build it with different tubes. Lots of old radio power tubes that are lower output than 6v6.
    Smarter minds can list some, Inwill kooks up some
    Even a 12at7 preamp will chang things as well.
     
  17. Mongo Park

    Mongo Park Tele-Holic

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    Something like a 6K6 would work.
    Lots of them around
     
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