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Vintage SVT and power tubes

Discussion in 'Amps and Cabs [BG]' started by lefty, Nov 16, 2012.

  1. lefty


    Sep 25, 2004
    I have a vintage 1974 SVT and have 6550 power tubes. Looking to re tube pretty soon and was wondering if there is a difference with tubes Groove tubes, G E, Russian is there a difference.
    What's the deal?
  2. B-string

    B-string Supporting Member

    GE's or "Winged C"'s will out last and out-perform GT's as a general rule. GT does not make tubes. Groove Tubes only buy, test and re-brand tubes from current production suppliers like China, Yogo, Russia.
  3. JimmyM


    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Ampeg uses Sovteks stock in their SVT's except for the Heritage, which comes with JJ's. Honestly, I like the Sovteks just fine. Not experienced with JJ 6550's but I have NEVER had good luck with JJ's of any kind that I've bought.
  4. JCM800


    Jan 22, 2009
    Austin TX
    Have used winged C's in my mud 70s SVT and was pleased.

    Currently using ValveArt 6550 and pleased as well. Have used the hell out of them over past year/half of touring and constant gigging. Happy with them ad well
  5. Bassmec


    May 9, 2008
    Ipswich UK
    Proprietor Springvale Studios
    What's wrong with the tubes you have in it?.
    If you must buy new production tubes then winged C will be ok:meh:but saying that the last matched set of these tubes I bought for a customer and biased very carefully, two had drifted out of quiescent current range of the others, sufficient to cause sight red plating after about six months.
    If you find it's full of RCA, GE or something else quality and old:)and the amp runs fine. New tubes are just going to make it less reliable and probably won't make any difference to the output power before distortion.
    A lot of the 6550 tubes that were made in the USA were made to government standards for linear motors used by the Navy.
    In the sort of service life a bass amp gets they will last for ages.:hyper:
  6. bassdude51

    bassdude51 Supporting Member

    Nov 1, 2008
    Central Ohio
  7. iiipopes


    May 4, 2009
    I played an SVT in the early '90's. The only reason to retube is if the amp is starting to run really hot, you have to turn up the volume more than you used to, or tone is suffering, either quality overall or more perceived distortion at the same volume level. Even then, it could be a bias drift issue, not a tube issue.

    And even at that, it's not always the power tubes going. To kill a 6550, it has to be run pretty much full on every night for several months. Informal rule of thumb: if you're running it at a level that you can still stand in front of it, you're not pushing the power tubes that hard, and 6550's last a very, very long time indeed.

    More than likely, if something is going, it will be one of the preamp tubes. Now that is something that might need to be planned for in advance, since Ampeg are notorious for specifying tubes that are not the most common, like the 12DW7 in the middle of the tone stack as a buffer stage & line out tube, and the 12BH7 phase inverter (as opposed to most amplifiers that use 12AX7's for preamp tubes of all stages and 12AT7's for purposes such as reverb driver, phase inverter, etc. - for example, the classic Marshall amplifiers used three 12AX7's for everything, etc., but I digress....)

    Check this link:
    http://books.google.com/books?id=O3...d=0CEEQ6AEwAw#v=onepage&q=ampeg 12dw7&f=false
  8. Blair101


    Nov 14, 2012
    I had an older SVT that needed new power tubes, I found a matched set of Russian KT100's. I thought they gave the amp clearer headroom.
  9. coreyfyfe

    coreyfyfe Supporting Member

    Nov 19, 2007
    boston, ma
    I normally get winged C but with the price increase i ended up going with JJ for my latest set (ordered yesterday). The winged Cs I have in my SVT now are just about done, they're 2-3 years old and sounding a bit weak at this point*. I was going to get some kt-88s but I want sure if I'd have to room for the wide bottles. I've never had an issue with JJ tubes before but I've also had fairly limited use of their power tubes and haven't tried the 6550s so we'll see how it goes.

    *Long story. I've had some noise problems so i swapped the tubes with another set. That cleared up the noise and were much clearer, but one tube was red plating so I ended up ordering a new set for now.

    Edit: And to add, this is from the studio earlier this year. The top amp belonged to the studio owner and was NOS tubes top to bottom including GE 6550s. Mine has a mix of NOS and new production pre-amp tubes and winged C 6550s. Both had been recapped. We play tested both and went with mine ;)

  10. Blair101


    Nov 14, 2012
    The KT100's wasn't a calculated choice, but they did sound nice. I was just trying to find the nicest matched set of power tubes for the price. I had a mid 90s SVT that I put kt88 in and that sounded great too.
  11. Winged C (SED is the real name) are the best current production.
    Sovtek/new sensor/EH tubes seem to burn through much faster than NOS GE or current production SED.
    I kind of like how EH sound, at least in guitar amps.
    My current SED tubes in my Mesa are about 4 years old and still good. And my last band was super loud, so they took a beating.
  12. ThisBass


    Aug 29, 2012
    I don't like the GE's made in the 80s

    the big bottles sounds great ... GE / Magnavox ... ?
  13. B-string

    B-string Supporting Member

    Maybe because GE wasn't making tubes in the 80's? They were re-brands if they sold any.
  14. ScottTunes

    ScottTunes Gear-A-Holic Supporting Member

    Feb 7, 2011
    So Cal
    I still have my NOS GE 6550s I kept as spares for my V-9 SVT... Don't have the head anymore, but tested them before going on the road with it in the early 80s (just after purchasing the tubes). I've used the same brand and vintage in Sunn heads as well. Haven't found an equivalent (haven't tried in 5 yrs however).

    The GEs are seemingly more potent, and last far longer, with fewer "bad" tubes - IME/IMO/ YMMV, etc, etc...
  15. iiipopes


    May 4, 2009
  16. ThisBass


    Aug 29, 2012
    It was in the late 80s (or early 90s) when I purchased a sextet of GEs 6550.
    That was because I thought it was time to retube the amp after more then 10 years of playing the amp.
    The bottle of these GEs was a bit smaller then the bottle of the older ones.

    After plying the retubed amp for a couple of ours I retubed the power amp again with the old 10 years used 6550s (GE+Magnavox) I still had.

    I did not liked the sound of these (80s) GE's ....