DRRI Mod?

Discussion in 'Amp Central Station' started by MerleJam, Sep 11, 2019 at 4:53 PM.

  1. MerleJam

    MerleJam TDPRI Member

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    hi, I know nothing about modding amps...I have a 65 DRRI and I would like it to break up sooner. I’ve heard about pulling V1, but heard something about putting a 12ax7 in v6..will doing those two things be noticeable? Any cons? And is it something I can do or does it require other changes being made to the amp. Thank you
     
  2. uriah1

    uriah1 Telefied Ad Free Member

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    The gear page has billions....but, you can get early break up
    with some good stomps too..spark drive,etc...and maybe a lower watt
    alnico speaker...beware of speaker hole screw count.
    imho

    have fun.



    From billions on gear page.

    SS rectifier (DO NOT do this with 6V6's)
    - 6L6 power tubes
    - clip bright cap
    - remove V1
    - better tubes in V2 and V4 (NOS or good new tubes)
    - AX7 in PI slot
    - disconnect Vibrato (or make it switchable)
    - not sure what comes stock, but upgrade the power tubes to NOS or JJ's (if you stay with 6V6's)
    - Speaker replacement
     
    swany likes this.
  3. Paul G.

    Paul G. Friend of Leo's

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    You can add dirt, but you can't add clean. The DRRI takes pedals well, plenty of very nice overdrives and boosts that will make your amp sound quite good.
     
    Hbom likes this.
  4. schmee

    schmee Poster Extraordinaire

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    Well, a couple things, but yeah, pedal helps.
    -What speaker? If you have the Jensen C12K that's a very clean speaker. Get something less robust.
    -Try the 12AX7 in V6, you can try that with no adjustments.
    -Turn the Bass way up, on DR's anything above 4 or 5 usually just adds breakup rather than more bass.
    -Clip the bright cap if it has one.
    -A 5Y3 in the rectifier slot might help but that would require rebiasing the power tubes.
    -What guitar? Try plugging into jack 2 and diming the guitar.
     
    uriah1 likes this.
  5. reckless toboggan

    reckless toboggan TDPRI Member

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    Sure you can.

    Not to sidetrack this thread too much but:

    For more clean you can use tubes with a lower gain factor.

    For more clean you can use a pedal like the the Mad Professor Underdrive.

     
  6. t-luxe

    t-luxe Tele-Afflicted

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    You can try it for yourself. Pull V1 and substitute it for V6 and see how you like it. Won't hurt anything.

    Or:
    A low sensitivity speaker.
    Power tubes rated for low transconductance(early breakup; eg, the ''Soft" rating on Tung Sol 6V6's. Your tube dealer can advise you here on other brands.).
    Adjust the Bias accordingly.
    Increase the value of the NFB resistor.
    Humbuckers.

    OR:
    Just use a pedal.
    Get an attenuator so you can crank it.
    Get a different amp.
     
    Last edited: Sep 12, 2019 at 4:25 PM
  7. 11 Gauge

    11 Gauge Doctor of Teleocity

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    I had a '79 DR for a little less than a decade. When I received it, it had already had all of the nasty factory stuff like the pull boost feature removed. Just the same, it took a bit more work to get it to sound how I thought it should have. I pushed it both in the cleaner and more overdriven directions, really leaving no stone unturned along the way.

    As a result of that, IMO it's probably mostly a matter of diminishing returns with modding a DR(RI), especially if someone isn't technically versed in what to alter. If you want earlier breakup that comes from the amp itself, and you don't know what to do under the hood, you're probably going to be happier with another amp.

    Aside from that, IMO, the one thing that can have the biggest effect w/o having to lift the hood, is to get a speaker that breaks up much earlier. Assuming you want an "American sound" type of breakup, I'd simply go for a 12" speaker that tries to replicate a Jensen design from yesteryear, with a small voice coil, and a cone that's known for early distortion. I found that I could maximize that effect with something from the Weber Signature series, and they happen to be pretty affordable, too. That said, there's a lot of other choices beyond the Weber stuff.
     
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