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single el84 driving two reverb tanks

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  • single el84 driving two reverb tanks

    I built an amp in a junk chassis that is essentially two blackface champs in one box (with dual gang pots). I added an extra 12ax7 as verb recovery driving the wiper of a 1 meg pot- the top of the pot connects to the grid of v1b with a 270k resistor. The verb sound clear and has plenty of volume and if I plug a guitar into the verb inputs they have plenty of clean gain to distort the power section...so not an issue, recovery is taken care of.

    I originally tried foldback reverb (left tank driven by right power amp and vice-versa) and while it works OK, it doesn't sound amazing like previous mono and stereo amps I've built using the blackface fender design or the single tube design favored by Tubenit and others.

    I'm thinking about connecting a pair of .01 uf caps and 220k resistors from the outputs of V1a (left and right) summing to a single 1 meg dwell pot driving a single el84 and SE transformer driving both reverb tanks. I'm concerned with having enough drive, thus the choice of an el84 since it requires very little grid drive.

    So...I've only got to add 1 pot, 3 resistors, 3 caps, one tube and one transformer to try it so I will but I just thought I'd ask if anyone had any thoughts.

    jamie

  • #2
    I was planning on using an EL-84 as a reverb driver myself. From I have read, you would want to drive it through a 500pF cap, and maybe [maybe] run it in triode mode. I was going to run it in pentode mode because I can power scale a pentode.

    -g
    ______________________________________
    Gary Moore
    Moore Amplifiication
    mooreamps@hotmail.com

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    • #3
      The 6BQ5 should run two tanks, no different than running two speakers. I'm just wondering that if you've gone this far for a dual signal path, why not use something like a 6CG7/6FQ7 with each triode driving its own tank? or try and find a dual power triode...maybe a 6N7? You could drive the tanks through caps instead of Xformers if you're trying to save space. I'm trying to imagine the intro to 'Wipeout' in stereo!

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      • #4
        Just wondering if you ever listen to your reverb driver with a 8 ohm speaker load or not. I tried it with my Deluxe reverb and was not impressed. A good lead drive tone, but I was hoping for a clean reverb drive. I'm only guessing, but wouldn't a clean drive signal yield a clearer reverberation sound?

        How hard should one blast the tank? The VibroKing uses a 6V6 for a driver. the transformer is a 10W SE unit. Huge!

        The first version of the VibroKing used an EL84 and got bad reviews before going to the 6V6. I'm guessing (again) because it takes a little more level to drive a 6V6, the EL84 was overdriven and distorted. Kinda makes sense after hearing my Deluxe.

        I would advise a P-P reverb drive. Amp your tank up with a clean drive and give Lexicon a run for their money...!
        Black sheep, black sheep, you got some wool?
        Ya, I do man. My back is full.

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        • #5
          Originally posted by GibsonLover View Post

          I would advise a P-P reverb drive. Amp your tank up with a clean drive and give Lexicon a run for their money...!
          A P/P circuit would have more clean headroom..... so what, maybe a 12au7 running self-split Class A/B into a small P/P output transformer driving a 10 ohm tank ? or the other way would be a pair of el84 or 6v6. . . . .
          ______________________________________
          Gary Moore
          Moore Amplifiication
          mooreamps@hotmail.com

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