will tungsol kt120s work in ampeg vr

Discussion in 'Amps and Cabs [BG]' started by Thunder B, Mar 20, 2011.

  1. Thunder B

    Thunder B

    Mar 20, 2011
    i do not know if this is the right thread to post this. i was wondering if someone could advise me if the tungsol kt120s would work in my ampeg vr without doing any kind of modes (called ampeg and could not get any definite answer) would greatly appreciate any input from anyone out there. thanks
  2. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Yamaha, Ampeg, Line 6, EMG
    before you even attempt anything like that, you must first ask yourself what you're hoping to get out of it, and if it's something you're not getting with 6550's. for me, the svt is the world's perfect bass amp, so i'd leave it.
  3. will33


    May 22, 2006
    I'm no tech but just because the 120 tube can run higher voltages doesn't mean you get that just by sticking them in the amp. The rest of the circuit has to be designed to make use of them.

    Have to +1 Jimmy here.....if it ain't broke....
  4. ZachM


    Nov 19, 2010
    Nashville, TN
    If I remember correctly, you may not be able to physically do that because those KT120's are significantly larger than 6550's are. Although I have not personally tried it, I don't think you actually have the space to do that inside the VR, for reasons of literal space, or because the tubes need a certain amount of room to be able to properly dissipate heat.

    And as the previous post said, if the amp can't take advantage of the increased power handling, you possibly stand to gain very little.
  5. AwkwardLoudness


    Jan 11, 2010
    MI USA
    I seriously doubt that an SVT power transformer could handle the higher current draw of KT120s.

    Like ZachM, KT120s are also taller than 6550s and likely would not fit.
  6. Thunder B

    Thunder B

    Mar 20, 2011
    Thanks for the replys. i was wondering if anyone of you know the sonic difference between kt88s and 6550s. i have read some threads that there is a difference and others say there is none.
  7. Mr. Foxen

    Mr. Foxen Commercial User

    Jul 24, 2009
    Bristol, UK
    Amp tinkerer at Ampstack
    In the same amp, there probably isn't much difference, until you are clipping the power section hard, in a 300 SVT, that will be too loud for you to appreciate the difference.
  8. AwkwardLoudness


    Jan 11, 2010
    MI USA
    In general, KT88s have louder cleans, i.e. more headroom, and clearer note definition when loud compared to 6550s which are a bit more fuzzy. The differences would be more noticeable in some amps and less noticeable in other amps...depends on the circuit. The differences are more apparent when the power section is pushed hard into really loud territory.

    KT88s draw a little bit more current than 6550s. KT120s draw even more current.
  9. Jerrold Tiers

    Jerrold Tiers

    Nov 14, 2003
    St Louis
    Let me say that I have absolutely NO idea.... but then I have no info on the KT120 part....

    it depends on a stack of things....... from basic tube base pinout to bias requirements, screen voltages, max current, optimum load impedance, and so on.