Tightening the bass on a DRRI

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by PedalFreak, Jan 24, 2008.


  1. PedalFreak

    PedalFreak Supporting Member

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    Has anyone done the "Dumble" Mod's to a Deluxe Reverb Reissue? I guess Alexander doesnt make them into a Dumble, but he tightens the bass up which is what I'd like to do to my DRRI.

    Any idea's where to start? I've put a Scumback H75 65watt speaker in it. Getting a complete Mercury Magnetics kit for it next. But internally what do you think should be done?

    Thanks in advance.
     
  2. Blue Strat

    Blue Strat Member

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    I don't think it's realistic to expect tight bass from a 20 watt amp with the volume above 3 or 4 max. If this is what you're looking for, you need a 40 watt amp.
     
  3. PedalFreak

    PedalFreak Supporting Member

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    Thanks TKS, That's some of the things that I've been told on another page :BEER

    Dumble actually does mods on Deluxe Amps that gets this done, just don't have the money to send him my amp :)
     
  4. Blue Strat

    Blue Strat Member

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    Right, almost anything can be done with the right amount of time/money. That's why I recommended a 40 watt amp.
     
  5. PedalFreak

    PedalFreak Supporting Member

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    Talked to my amp tech last night, we are going to start working on the DRRI soon. Looking at Dumble moded schematics, and talkin to some people on another forum.
    When I'm done I'll post what we did.
     
  6. Blue Strat

    Blue Strat Member

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    Installing Allen Upgrade transformers and using 6L6s will certainly help and increase the power output to 30+ watts. At least half of the Dumble mods are oriented toward having an overdrive channel which might be nice but doesn't address the "tight bass" issue.
     
  7. vibroverbus

    vibroverbus Member

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    nice.
    probably a lot of collateral tone changes of course, but would accomplish the 'tighter bass' goal.

    a quick & dirty alternative could be to slap a closed back extension cab on it.

    kinda sounds like PF is hankerin' to be able to say 'Dumble Mods' to his groupies though, so that might be too easy. :D
     
  8. slider313

    slider313 Silver Supporting Member

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    I always change the phase inverter cap from the stock .001 to a.002.
    If I'm doing an amp for someone who plays single coils exclusivly, I make it a .02. I also install a switch pot for the vibrato intensity which allows better fidelity and allows the bass to be turned up without it mudding up.
    A good 50 watt speaker like a Eminence Cannibis Rex or Weber 12F150 helps. For Celestion style speakers, I like the 50 watt Ceramic Blue Dog or Silver Bell.
     
  9. Rick1114

    Rick1114 Supporting Member

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    I put .01 a (silverface value) phase inverter cap in my DRRI and I found it increased the bass but muddied it as well. I'm going to try .0022 next and maybe even .0047 (stock is .001). If his amp is stock he may not get "tighter" bass by changing the PI cap if what I have been reading is correct. Some good info here:

    http://people.cornell.edu/pages/mt24/Amp/mm/SFBFPI.html

    Maybe the better MM iron will help?
     
  10. Bonenut

    Bonenut Member

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    You could double the first power filter stage. That would tighten up the bass. And/or raise the power rail voltage to the preamp tubes by changing the two dropping resistors from 10k/10k to 1k/4.7k like most BF Fenders have. That would give you more headroom.
     
  11. PedalFreak

    PedalFreak Supporting Member

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    Nah, I've got a ODS 1x12 Combo, If I wanted to show off to groupies I'd bring that out :BEER

    Just tweaking a new amp, like the sound Robben Ford get's out of his Deluxe.
     
  12. killer blues

    killer blues Member

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    the best way to tighten bass is to increase the plate and screen filtering. Go with 50uF on the plates and 40uF on the screens. This should help alot.
     

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