Pulling Tubes in a Silverface Twin

Discussion in 'Amps and Cabs' started by 1kidc, Oct 6, 2006.

  1. 1kidc

    1kidc Member

    Messages:
    985
    Joined:
    Mar 17, 2004
    Location:
    Peoples Republic of Boulder
    I'm going to be working in a theater that has a mid 70's silverface twin in house. I thought I recalled a thread re: the removal of 2 tubes to let the amp work a little harder. Since it isn't my amp I don't want to fry it, can anyone tell me which tubes to pull and - more importantly - is it safe to do?
     
  2. JubileeMan 2555

    JubileeMan 2555 Member

    Messages:
    3,769
    Joined:
    Dec 12, 2005
    Location:
    Minneapolis, MN
    100% safe. Just be sure to pull either the INNER 2 ...OR... the OUTER 2 power tubes. Power tubes work in a Pull push fashion and you can't just pull any 2 you want.

    In theory, you need to change (half) the ohm setting of the amp when you do this (as in 4ohm out with 4 tubes, and 2ohms out with tubes pulled), but there is no ohm selector on fender amps so you can't. But fender amps are VERY VERY resiliant and some people actually prefer the slight ohm mismatch.

    Just give it a try, and see what you think. I used to run my twin reverbs that way for a while.
     
  3. 1kidc

    1kidc Member

    Messages:
    985
    Joined:
    Mar 17, 2004
    Location:
    Peoples Republic of Boulder
    Hi Guys - I'm bumping this thread once before I leave for nyc on monday. Could I get a confirmation from someone else that Jubilee is right about this? I talked to another guitarist this week who thought the opposite. I just want to be sure of the "safe" combo of tube pulls since it is not my amp.

    All the Best,
    dd
     
  4. Guitar Dave T

    Guitar Dave T Member

    Messages:
    9,419
    Joined:
    May 15, 2006
    Location:
    Living In The Palace Of The King, Big D of DFW
    Jubilee is 100% correct about this. Pull the outer two or inner two tubes. I've owned 3 Twin Reverbs - one a silverface, and have done it at one time or another on all three.

    I found it to be a decent solution for avoiding volume complaints in small rooms, but as far as giving the amp a lot less headroom and more punch, I was always less than satisfied with the results. In some ways, it seemed to weaken the output in more ways than I wanted.

    Besides, if it's a true mid-70's Twin Reverb, it will have a master volume control, which actually does a pretty good job of what you're trying to do, as long as you don't go overboard into Fuzz Territory. That can get pretty ugly.
     
  5. Blue Strat

    Blue Strat Member

    Messages:
    30,047
    Joined:
    Aug 2, 2002
    Location:
    Sterling, VA (not far from Washington DC)
  6. pete kanaras

    pete kanaras Member

    Messages:
    2,955
    Joined:
    Mar 24, 2004
    Location:
    baltimore, md
    yank the first preamp tube as well, and then plug into channel 2. it helps a wee bit; makes ch2 a little spongier feeling
     
  7. ericb

    ericb Silver Supporting Member

    Messages:
    8,331
    Joined:
    Jan 4, 2002
    Location:
    VT
    LIke Jubillee was saying , when you pull the 2 tubes you'd want to use the 2ohm out ,but they don't have one of course.. SO I just use 1 speaker with my Twin quite often with 2 tubes. That means you're using the 4ohm out (Which is what the SF TWIN is defaulted to and expects to see) into 1 8ohm speaker... Same as a 2ohm out into the 2 8ohm speakers (4 ohm load)

    SO , because you ain't gonna be able to PULL 1 of the speakers in the Twin this isn't really an option for you , BUT you could bring your favorite 8 ohm cab and just plug the 2 tube twin into that cab and you're all set.
    Just another idea. ERIC
     
  8. ericb

    ericb Silver Supporting Member

    Messages:
    8,331
    Joined:
    Jan 4, 2002
    Location:
    VT
    He's 100% EXACTLY CORRECT as LONG as you understood the post.. I tried to expand on it a little in my post above. Good luck

    ERIC
     
  9. Guitar Dave T

    Guitar Dave T Member

    Messages:
    9,419
    Joined:
    May 15, 2006
    Location:
    Living In The Palace Of The King, Big D of DFW
    Also, replace the 12AT7 phase inverter - it's the last preamp size tube next to the power tubes - with a 12AX7. Will help with dynamic response.
     
  10. Blue Strat

    Blue Strat Member

    Messages:
    30,047
    Joined:
    Aug 2, 2002
    Location:
    Sterling, VA (not far from Washington DC)
    Since, I assume, he wants less clean headroom, using both speakers (which results in an impedance mismatch) will get him less headroom. It won't deliver full power, but I think that's his objective.
     
  11. Blue Strat

    Blue Strat Member

    Messages:
    30,047
    Joined:
    Aug 2, 2002
    Location:
    Sterling, VA (not far from Washington DC)
    Also included in the article in the link I posted above.
     
  12. 1kidc

    1kidc Member

    Messages:
    985
    Joined:
    Mar 17, 2004
    Location:
    Peoples Republic of Boulder
    Right guys, I'm just trying to work the power tubes a little more. This theater only seats 100 people and I don't want to just set the volume at 1. I hate the way a Twin sounds when you do that - really thin. But the twin is there and it's free to use so I thought I'd give it a shot.

    If it ends up sounding like $hit I can always go around the block to Manny's and pick up a Roland Cube amp.

    Thanks for all the advice guys!

    d2
     

Share This Page