Finally... a cure for my 6G2 trem thump

Discussion in 'Shock Brother's DIY Amps' started by King Fan, Nov 10, 2019.

  1. King Fan

    King Fan Friend of Leo's

    Posts:
    4,112
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    The 6G2, with its famous tremolo, also seems to be infamous for tremolo thump. Search for the term on the internet, and it seems *many* of the cases occur in this otherwise superb amp (although the problem also occurs in other bias-wiggle trem circuits). Believe me, I searched the internet... over a couple of years.

    Lots of solutions are suggested in lots of threads. A popular fix that helps some folks is to solder three (in some threads just two) 47pf 'snubber caps' at specific points in the trem circuit. Sadly, this didn't help mine much. It may be a cure for a different type of trem noise.

    Pulsing trem noise has lots of possible causes. To be clear, mine wasn't optical roach 'ticking' (no roaches here) and it wasn't the common (maybe even intrinsic) "whoof-whoof-whoof" of hiss amplified by bias-wiggle. It was like a drummer with a tom playing along with the trem: "thump thump thump."

    I've read threads on several sites where some poor guy tries a *ton* of solutions with very little luck. Lower bias, swapping 6V6s L for R, better matching, worse matching, shielded cable to the trem grid, lead dress (tho this sometimes works), and on and on. For sure I tried lower bias, a popular suggestion, but it did zero to mine.

    Finally I saw a different fix from a guy who, IME, is seldom wrong, Steve Luckey. In this el34world thread (see Reply #1), he suggests a diode across the intensity pot (something he borrows from a PR trem fix). I tried it today, and the thump is *gone.*

    upload_2019-11-10_14-6-59.png

    IMG_3967.jpeg
     
    Last edited: Nov 10, 2019
    John How, RatBug, Wally and 8 others like this.
  2. schmee

    schmee Poster Extraordinaire

    Posts:
    7,523
    Joined:
    Jun 2, 2003
    Location:
    northwest
    Cool... thanks!
     
    King Fan likes this.
  3. kingofdogs1950

    kingofdogs1950 Tele-Holic

    Age:
    69
    Posts:
    685
    Joined:
    Sep 10, 2006
    Location:
    Franklin, Texas
    I used this fix about fifteen years ago, and it works perfectly.
    I have a Mojotone 5f11 vibrolux (built by MT), close relative to your 6g2. My tremolo works perfectly with no issues.

    Mark
     
    King Fan likes this.
  4. theprofessor

    theprofessor Friend of Leo's

    Posts:
    4,444
    Joined:
    Aug 8, 2016
    Location:
    Chattanooga, TN
    Fantastic! That's all it took? One diode? Great solution!
     
    King Fan likes this.
  5. King Fan

    King Fan Friend of Leo's

    Posts:
    4,112
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    Good point -- the 5F11 is a kissing cousin, and it does seem prone to the familial thump.
     
  6. King Fan

    King Fan Friend of Leo's

    Posts:
    4,112
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    Yeah, amazing, huh?

    IIRC, Prof, in that thread the snubber caps had worked for you, and you passed the idea on to others who liked 'em too. I wonder if we had different diseases needing different cures. :)
     
  7. tubelectron

    tubelectron Tele-Holic

    Posts:
    544
    Joined:
    Nov 25, 2010
    Location:
    France
    It also works well on Princeton and Princeton Reverbs.

    -tbln
     
    King Fan likes this.
  8. King Fan

    King Fan Friend of Leo's

    Posts:
    4,112
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    Yes, and in fact it sounds like there you can do a couple other things as well. Steve Luckey's scheme:


    upload_2019-11-10_15-49-57.png
     
  9. Mongo Park

    Mongo Park Tele-Holic

    Posts:
    662
    Joined:
    Nov 28, 2010
    Location:
    Winnipeg
    beauty thanks for sharing. I sort of gave up and moved on but this will be a nice fix.
    Cheers Ron
     
    King Fan likes this.
  10. 82LesPaul

    82LesPaul TDPRI Member

    Posts:
    43
    Joined:
    Mar 9, 2019
    Location:
    Nashua, NH
    Glad it worked out. Wonder if the diode should be a going in position on the 6G2 layout? Steve Luckey is a wealth of knowledge. Helped me solve a nagging issue on my Gibson Falcon.
     
    King Fan likes this.
  11. King Fan

    King Fan Friend of Leo's

    Posts:
    4,112
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    Thanks, Ron, your thread helped me in my research. Hope this can help you back...

    Yeah, well, it's staying in my 6G2 layout! :) AFAIK not everyone gets the thump, so I'm not sure it should be universal.
     
  12. Mr Ridesglide

    Mr Ridesglide Tele-Afflicted Ad Free Member

    Posts:
    1,902
    Joined:
    Dec 11, 2009
    Location:
    Bloomington, MN
    Very good information there!
     
    King Fan likes this.
  13. Mongo Park

    Mongo Park Tele-Holic

    Posts:
    662
    Joined:
    Nov 28, 2010
    Location:
    Winnipeg
    I tried a few things and in the end installed a switch to turn it off when not in use to remove the unwanted effect, but this did not really seem total right and the effect was present when using this feature, which in the end was a part of the amp. It sounded gre4at but the negative effect bothers me. So I am hot to apply the above, goog on Ya for perservering.
    Cheers Ron
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.