1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

Putting back in tubes

Discussion in 'Amps and Cabs [BG]' started by xampworshipx, Sep 4, 2008.

  1. xampworshipx


    Jul 13, 2008
    I just recieved in the mail one of my dream heads, a Sunn 300t.

    The seller took the tubes out to ship it. Which is wonderful, they're all perfectly intact. However, he didn't mark which tube was where.

    My question is does it matter if the tubes are in a different order than they were initially? For instance, does it matter what order the Power Amp tubes are in as long as they're all in there? Will it throw off the biasing?
  2. scotch

    scotch It's not rocket science! Supporting Member

    Nov 12, 2006
    Albany, NY USA
    Please see Profile for Endorsement disclosures
    It definitely matters with the preamp tubes. One of them is an 12at7 (as opposed to an ax7a). Be sure to put it in the appropriate socket - see manual link below, last page for chart: http://www.sunnamps.com/pdfs/manuals/bass/300T.pdf

    Also, it is possible that you will need to re-bias after reinstalling the power tubes. They work in pairs, so each pair needs to be matched, ideally. The good news is that you can easily re-bias the 300t yourself! All you need is a digital multimeter (worth owning, but easy to borrow) and follow the directions in the above .pdf link. Make sure you always have a cabinet (load) properly connected when turning the amp on & biasing!!!!!
  3. xampworshipx


    Jul 13, 2008
    yeah. got all that. I just wasn't clear if the actual order of the same tubes (the 12ax7s or the 6550s) counts. i figured it did.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.