Taming the wild 6G15 reverb...

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by jawjatek, Feb 21, 2012.

  1. jawjatek

    jawjatek Member

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    I have a nice "65 Fender 6G15 reverb unit that has too much reverb. LOL. Actually I have to keep the mix knob way down or SURFS UP, and I was thinking of trying to get a more useable mix out of it. It has that Dick Dale thing going on in spades if I just turn the mix knob up a little, and I'm looking for a more blues-friendly reverb like Hollywood Fats, for example. I run it into either a tweed 5E3 Deluxe or a tweed Bandmaster (Clark Tyger), depending on room.

    Some background: I got it off Ebay a couple years ago ( a screaming deal at $500) and went thru it like I would an amp, replaced the electrolytics, added a NOS RCA 6k6GT. It came with RCA and Telefunken preamp tubes that test fine. The original Gibbs pan had a broken wire that I fixed but eventually it failed and I replaced it with first a 2 spring and then a 3 spring pan, keeping the 3-spring cause it sounds slightly better.

    So it works, but a little too well, so I'm trying to tame it. Any suggested tweaks, y'all? TIA
     
  2. TimmyP

    TimmyP Member

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    1) The Dwell appears to be nothing more than a tank drive level control, so run it low. If you don't like the way it sounds when lightly driven, you need to drop the gain of the recovery circuit. This would be most easily done I think by removing the 250/6 cathode bypass on the 7025.

    2) Another possibility would be to change the Mix pot (250K-L) to an audio taper. With the L, at 12:00 each signal (dry, wet) is attenuated 6dB (ignoring loading). With an A at 12:00 the attenuation of the wet will (I think) be 20dB, and almost none on the dry. However when you want it very wet, the dry will drop in level.
     
  3. jawjatek

    jawjatek Member

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    Thanks. As soon as I get done fixing everyone else's amp, I'll try a few things on the old tank.
     
  4. jetlag

    jetlag Member

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    I would start off much less invasive. Inside the reverb pan, put some silicon RTV on the joints where the springs meet (2 places). The two-spring pan is really a 4 spring pan and the spot I'm referring to is in the middle of each spring pair. Also, put some weather stripping on the back of the pan, two or three strips running the entire length of the pan. Next, place the unit on some foam. With old units, I don't turn the mix and dwell up that much, so be more judicious in your use of the knobs. If all of that doesn't get it, then consider trying an equivalent 3 spring (6-spring) pan. Going with the 3 spring pan generally lets you turn the mix and dwell knobs up quite a bit more before it surfs out. One other thing to consider is that if your unit still has the original electrolytic caps, they need to go. Since you mention that you're fixing everyone else's amps, you problably knew that. Same with yellow astron caps, if there are any in there (usually by '65 there are few if any) they should be tested for leakage and replaced as required. My '65 had one in it, the rest were the blue paktrons and, as you probably already know, they are rock solid.
     
  5. jawjatek

    jawjatek Member

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    What does putting "some weather stripping on the back of the pan, two or three strips running the entire length of the pan" do? This would interfere with the pan transport lock bracket. I understand doing this for pans in the bottom of combo amps in vinyl bags, but I don't think this would do anything in a 6G15.
     
  6. jetlag

    jetlag Member

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    I stopped the weather stripping for about 1.5 " or so - so as to not interfere with the bracket. I did the rtv and the weather stripping at the same time so I can't say for sure which thing did what.
     
  7. guitarcapo

    guitarcapo Senior Member

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    I've had problems with Fender reverb being to overblown and every mod I've heard about and tried seemed to reduce the amount or quality but not the duration. I've come to the conclusion that the only real answer is a different tank with a shorter decay or fewer springs.
     

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