Quieting Down a Pignose G40V

Discussion in 'Amp Tech Center' started by Platefire, Jun 30, 2020.

  1. Platefire

    Platefire Friend of Leo's

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    For any Pignose G40V owners out there who have a loud hum when you crank up your Master Volume. That has been a problem with mine since I got it used in 2006. It has really just sat in a closet all these years mostly because I like a quiet amp and can't stand a loud hum.

    Well I have now got mine quieted down sounding great and more usable than ever. It is quiet as a mouse and has better tone than ever.

    What did I do? I bypassed the extra gain stage V1B and that did it. I didn't figure that out myself but was suggested by another Amp Tech guy that helps me on a lot of my projects.

    It was pretty simple. Disconnect the output grid from V1B by disconnecting the green wire going to V2A input grid pin #2. Cap it off with some shrink wrap. Run a jumper wire(hookup wire) from C21 at the junction
    of C21 and Volume pot output to V2A pin #2 where you disconnected previous green wire.

    I will post the schematic my friend made for me. He shows also disconnecting R14 and R15, but I didn't do that. I just left them connected. One thing I should say also is I use a 12AY7 in V1.

    So basically the G40V is a JCM-800 2204 with 6L6's. After this mod it will be a Plexi with 6L6's. IMHO, this makes it a lot more usable amp for my purposes and very happy with it now. Platefire
    Sluckey Suggested Experment.jpg
     
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  2. Timmay

    Timmay TDPRI Member

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    Hmm. Interesting. Thanks for the post. I've been thinking about buying another G40V. I had one years ago, and it's one of the few amps I regret selling. Awesome little grab and go amp with plenty of volume to hang with a loud drummer. I had a weber Chicago in mine and it sounded GLORIOUS cranked up. Mine had a little hum, but not too bad.
     
  3. radiocaster

    radiocaster Poster Extraordinaire

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    People do that when they want to get a clean channel. It's kind of like a Bassman now.
     
  4. Jon Snell

    Jon Snell Tele-Meister

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    If you replace C12 with a 470pF 250v if gives more stretch to the treble control. At the moment it can be a bit 'boxy' sounding.
     
  5. Javier668

    Javier668 TDPRI Member

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    A new cap job i think was you needed.
     
  6. Platefire

    Platefire Friend of Leo's

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    If it was bad caps, it wouldn't be silent now. I like a MV amp that if you want to, you can turn the MV up full and just use your preamp volume like a vintage amp. I couldn't before but now I can. I read other post from G40V users that got a lot of noise when they turned their MV up---so this is a possible fix for those if you really don't need that extra gain and want it more clean and quiet. I play clean and use pedals for dirt. This made the amp usable for me, for others it may be no good. Platefire
     
  7. Lowerleftcoast

    Lowerleftcoast Tele-Afflicted

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    Thanks for posting about the Pignose. I was beginning to think they had gone from the endangered list to extinct. I have both the G40V and the G60VR.

    If memory serves me, they were built with a ground loop on the small board that holds the artificial CT. The grounding and heater wiring can be cleaned up as well. I haven't been inside the G40V for a while so I don't remember exactly what I did to the little beast. I run 12ax7s and a 12at7 for the PI and 5881 power tubes.

    I modded my G40V to be more 5f6a with some JTM character. I call it my Mini-Marshall. With a little boost the OD has that great Marshall sound. No OD pedals needed.

    The G60VR is still stock.

    I have my G40V dead quiet. This looks like an interesting mod though. You have me thinking of a possible Plexi on a switch. Hmm.
     
  8. Platefire

    Platefire Friend of Leo's

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    I was seriously considering making mine switchable but after considering it a few days decided I would never use it. Especially considering it would be bringing that old hum back. If I ever change my mind I could still go back and make it switchable but right now I'm just totally happy with it as is. I was thinking of using a SPDT switch. Have the center pole wire going to V2A Pin #2, one end pole with the jumper wire going to it and the other end pole the output grid of V1B going to it. Here is a schematic of it(attached).
    Switchable G40V Gain Stage.jpg


    The main mod I did to my Pig was built another speaker baffle so my G40V could take a 12" speaker.
    The original pig speaker was shot. It also had the original Chinese tubes, that I changed out. The reason I want to keep it because its small size and portability yet powerful, makes it a good grab and go amp.
    In my Senior way that works real good:>) Here is also some picture of the speaker and baffle mod. Platefire
    6d82bc6b-56d3-4561-be91-bd53707a2ef5.png

    ddd7dbab-4934-4dc3-987e-9e6804089dfc.png
    5a75fffb-1185-4de8-97dc-e4fea0925b46.png
     
    Last edited: Jun 30, 2020
  9. Lowerleftcoast

    Lowerleftcoast Tele-Afflicted

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    Same here. The weight and small footprint makes it perfect for quick jam sessions. It has more than enough power to handle anything I do. If it only had onboard reverb...

    I still have the original speaker. I was thinking of putting a 12" on a different speaker baffle, but recently I heard that a Celestion G10 vintage is a good match. I'm not sure I will pull the trigger as the original works with the mods I have done.
     
  10. Platefire

    Platefire Friend of Leo's

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    If you ever decide to make yours switchable, please let me know how it turned out. Reverb would be nice but I can get by with just a slap back delay just fine. Platefire
     
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