Running SVT-CL On less tubes

Discussion in 'Amps and Cabs [BG]' started by RushofBlood, Apr 27, 2005.

  1. RushofBlood


    Apr 27, 2005
    Is it safe to run the SVT-Classic on 4, or even 2 power tubes?
    I know this works well with guitar tube amps, but what about bass? Anyone heard of it?
  2. xshawnxearthx


    Aug 23, 2004
    new jersey
    instead of doing this, why dont you trade me your cl for my 3 pro, then you wont have to worry about tubes. :smug:
  3. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    On some amps you can get away with that OK, especially if you also change taps.

    On most amps, if you pull half the tubes (one each from the two groups), and then use the next lower impedance tap, you are probably OK. (use 8 ohm speaker on 4 ohm tap)

    On the SVT, its different....I don't recommend it.

    For starters, you can't pull "half" because there are two groups of three. There isn't a tap to match 1/3 or 2/3 the tubes to a standard impedance speaker. So you start out with a mismatch, and we have just had a discussion on that....

    Also, I don't recommend it because of the fact that the SVT is pushing the tube ratings to start with. Changing operating conditions gets into variables that would take a little study.

    Not recommended for SVT.

    (P.S.....yes I know that it does happen inadvertantly if a tube decides to quit working....which isn't often. But it isn't a good plan to intentionally do it.)
  4. and thats onle one, imagine 3 of em being out :rollno:
  5. I'm not sure if you are in fact, biased, but I believe your tube amp circuits ARE indeed biased.... :D

  6. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY
    Is it two groups of three, or three groups of two?

    Doesn't really matter, I'm just curious. I had always assumed it was three push/pull pairs parallelled.

    I just picked up an old Hammond amp. Two pairs of 2A3 driven by a pair of 56. I figure it should be good for about 20W of all-triode goodness, if my guy can get it running.
  7. TheChariot


    Jul 6, 2004
    Boston, MA
    Yeah, and you'll also never have to worry about being too loud :spit:

    But yeah... I think I recall this idea on TB once before, and it just wouldnt be too safe with the impedance mismatch for tubes. Two groups of 3... kinda spoils the whole idea from the get-go.
  8. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Not sure I see the difference/distinction that you do......But there are 3 tubes paralleled in each group, each group connecting to a single wire on the transformer.

    So that would be two groups of three....
  9. Trevorus


    Oct 18, 2002
    Urbana, IL
    You could look into an attenuator, if you want tube tone at lower volume.
  10. RushofBlood


    Apr 27, 2005
    eh, oh well. I'm just on limited income and after all the money spent on the classic (even though it was an amazing deal), i was seeing if i could get around buying $200 worth of new tubes for the thing for a little while :-\

    in that case, anyone have a good place to get 6550's?
  11. Ben Clarke

    Ben Clarke Liquidating to fund a new business. Buy My Gear!

    Jan 6, 2005
    Western NY

    Gotcha. Thanks.