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6G3 Deluxe Micro Preliminary Schematic

Discussion in 'Shock Brother's DIY Amps' started by jmp81sc, Mar 5, 2021.

  1. jmp81sc

    jmp81sc Tele-Meister

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    Hi Everyone,
    I am really liking my recent Brown Deluxe/ Brown Super build. I have a boatload of 12AU7 Tubes, so I thought I would build a 6G3 Deluxe Micro amp using Rob Robinette's 5F6a Bassman Micro for the power amp.

    I am hoping to get drive and distortion at lower volumes.

    Posted below is a schematic of my proposed build. Any feedback on design issues or errors would be greatly appreciated.
    Thanks
    John

    6G3 Micro Schematic V1.png
     
    Sam VanLaningham likes this.
  2. willholt92

    willholt92 Tele-Meister

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    That sounds like an awesome project. Look forward to seeing more
     
  3. Uncle Daddy

    Uncle Daddy Tele-Afflicted

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    Looks interesting. I'd prefer to see a DPST main switch; it's a European convention. Brown Deluxes are great, but quiet they're not!

    My recent build-
    P1130224.JPG
     
  4. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    The 220k resistor before the second stage is a left over from the original 6G3 circuit. It is not needed.

    The 100K/15K voltage divider dumps signal to ground. You may find different values to your liking. Use of a bypass cap on the 100k would retain some highs if wanted. @robrob has a *Fender Deluxe Models* site where he mentions using a 100k pot as a master volume at this location. I caution against installing a pot in this location, as there would be high voltage on that pot. Other options could be utilized if a master volume is desired.
     
  5. _Steve

    _Steve TDPRI Member

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    I was just reading Rob's JCM micro page the other day.

    He probably knows a lot more than me, but I would be inclined to raise the LTP tail resistor substantially (like to 56K+ to reduce its output swing) which would then allow you to reduce the size of those huge 'grid stoppers' on the power tubes.
     
  6. jmp81sc

    jmp81sc Tele-Meister

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    Hi Everyone,
    Very strange that my original post should show up now, as I just finished my build. My first post did not get much attention so I wasn't sure if anyone was interested.

    I tried to use as many recycled parts from my organ donor as possible. I used new transformers, pots and electrolytics. Everything else came from my leftover parts stash, or radio shack stuff. I used wood cut offs from the organ for the case along with some plywood I had on hand.

    I am very pleased with the amp. It is very touch sensitive and can go from clean to dirty with just pick attack. I also like how it just opens up the sound being able to push the 12AU7 power tube. All of my bigger watt amps are just to loud to really open them up at home. The master volume works well for low volume bedroom playing.

    The amp is very sensitive to speaker choice and guitar pickups. With ASAT MFD pickups I need to crank up the tone knob. With fender single coils I have it at noon or so. I think it sounds better through a brighter speaker, through a CRex it can sound a little too mid range or woofy.

    I have a bunch of 12AU7's and a few 12BH7's. Rolling the power tubes made a big difference in sound. I did not like the 12BH7 I tried and I don't need the extra watts, so I ended up liking a Raytheon 12AU7 best. I only have one older 12AX7 and I didn't hear much difference between it and new JJ's, so I just left those in.

    Below is my final schematic with voltages, and a few pics.
    Take Care
    John

    6G3 Micro Schematic wVoltages.png

    IMG_1050.JPG

    And with my 5F2a

    IMG_1058.JPG
     
    robrob, 2L man and King Fan like this.
  7. David Barnett

    David Barnett Doctor of Teleocity

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    Where are the wobbly bits? That's an essential part of a 6G3.
     
  8. jmp81sc

    jmp81sc Tele-Meister

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    I thought about doing a Vibro Champ trem, but decided to just keep it simple. I have 5G9 Tremolux and 6G4a Super clones to cover the Trem side of things.

    I also want to thank Rob Robinette for all of his fantastic work, such a great resource. These micro amps are really nice for home use.
     
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  9. robrob

    robrob Poster Extraordinaire Ad Free Member

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    Very cool amp build, congrats.
     
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