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1970 SVT blue line head: tube replacement ideas?

Discussion in 'Amps and Cabs [BG]' started by jmjbassplayer, Jul 6, 2005.

  1. jmjbassplayer

    jmjbassplayer Justin Meldal-Johnsen

    Mar 25, 2005

    I just got a hold of a fairly beat 1970 SVT head with the blue line front panel graphics. It's working but has noisy pots and is faintly microphonic, and the power tubes probably need replacement, and maybe all the preamp and driver tubes as well.

    Anyone have any ideas? What sounds great in that amp? I'm definitely willing to go NOS if it's substantially better. And what sort of cost might I expect for a full re-tube with some good stuff?

  2. 8mmOD


    Mar 20, 2005
    I endorse & use Tech 21 pedals, Eminence loaded cabs, EMG pickups, Jim Dunlop picks & Ernie Ball Strings, BC Rich Basses.
    There's lots of places to get tubes, I get them from www.tubedepot.com

    TOLL FREE Phone: 877-289-7994 ask for Christian.

    or EMAIL FOR INFORMATION (info@tubedepot.com)

    I would just email or call & tell him exactly what you wrote in your post, it pretty much says it all.
  3. I really like the Svetlanas I have in mine, a marked improvement over the magnavoxes that were in it prior.
  4. the dude

    the dude Supporting Member

    Sep 19, 2004
    Despite what some will tell you, "old" does not necessarily mean "bad" in the world of tubes.

    I'd say take it to a good tech and see what he says.

    I bought the same amp and the tech had to replace only a few tubes - and it sounds friggin' great!
  5. Wasn't there someone on here at one time who said he came into a warehouse's worth of NOS tubes? I think it was here. I would LOVE to see whatever became of that.

    Oh, and a sextet of 6550's wouldn't hurt either. :smug:
  6. Wesley R

    Wesley R Supporting Member

  7. Ive got Sylvania 6550A's ( rebranded as Philips ECG's) in my SVT II, they are nice, and apparently very good :)

    But ill agree with 8mmOD, email christian at tubedepot
  8. DaveMcLain


    Jun 19, 2005
    Cuba MO
    I've used the Sevetlana tubes in an old SVT head that I repaired for a customer several years ago and they were great. BUT..... the Sevetlana tubes avaliable today are NOT THE SAME as the ones make before about 2002 sadly. Today's Sevetlanas are made in the Reflector factory the same place where Sovteks are made, for some reason the quality just isn't as good as the older versions. If I had the amp I think I would experiment with several versions of that tube and decide what sounds best, there are numerous versions on the market including several excellent KT-88's that might be awesome in that amp.

    The old SVT I was working on began it's life as a 6146 equiped amp, it was in rough shape electronicly when I started working on the thing. It had about 3 or 4 of the blowout resistors open from being run with lousy tubes for years, thus it was down about 50% or more on power and sounded terrible. Getting that fixed up, a new set of output tubes and drivers in there, bias set, pots cleaned etc, it sounded very nice and the guys been using it ever since.
  9. That's good to know, I thank you. Honestly, the last time I had mine retubed was right around that time. Late 2001 actually. I had no idea. Luckily, mine sounds and responds well. Moving forward, I guess I'll have to ask my tech what else he'd recommend for the future.
  10. All in all, I'd say it's a worthwhile investment to get sompletely cleaned up.

    A full retube I paid just over 300 bucks. I had it fully cleaned by way of lubed pots and all the niceties, and had the standy switch replced, and that only ran me @ 60 bucks.

    As long as the transformers are sound in that head, the rest is cake.

    If you're ever in the area and need a loaner, look me up.

  11. robd

    robd Supporting Member

    I had a 1970 SVT back in the early 80's. Bought a matched set of "Groove Tubes" 6550's and it sounded the best it ever had. Don't know if groove tubes is still around or if someone else actually made the tubes for them and they just marketed them but that was the best sounding amp with those tubes in it.....

    Sold it for $350 in the late 80's, (same price I bought it for with an 8x10 cabinet included) I should have kept it. now I just want to cry everytime I think about it :crying: :bawl:
  12. throbgod13


    Mar 26, 2005
    get NOS tubes *if* the tubes are bad.. you might just need to have it rebiased using the same tubes..

    the problems with older tube heads are the caps and resistors.. the ones that are closest to heat are the ones who drift from thier values the farthest..

    other than that, you have a nice amp..
  13. Anyone care to list the names of manufacturers currently or recently building 6550s? Or provide a link to such a list?

    I'd also love to see a current assessment regarding brands of 6550 tubes. This is something that could be referenced to for future threads.


    XYZ 6550 built by/in ABC factory in country X that has a build quality of Y and sounds like ..........

    I'll post some pics of some modern day 6550s I'm really curious about.
  14. 8mmOD


    Mar 20, 2005
    I endorse & use Tech 21 pedals, Eminence loaded cabs, EMG pickups, Jim Dunlop picks & Ernie Ball Strings, BC Rich Basses.
    My first reply to this thread has a link to www.tubedepot.com. I will expand on it even more just for you...

  15. The microphony could easily be in the pots themselves. Besides what most people know as microphony is preamp tube microphony, so it sounds like you have no reason to replace your power tubes.

    However, if you do, I cannot recommend AGAINST Svetlana strongly enough. Yes, I mean the "old" Svet, aka SED, ( now against Svetlana, BTW). They sounds great at first, but have terrible mechanical stability and don't handle voltage well. I have about 100 in sextets of them from when they first came out and NOT a sinlge sextet of them will even bias up right in an SVT!!! Best bang for the buck tube is the Sovtek KT88, which is truly a great tube regardless of price.
  16. Thanks but that's mainly a source to buy. I'm looking for more details like countries of origin, factory locales, associations among brands, lineage, and feedback based on experience, etc. I'm sure only a few here can provide this kind of insight.
  17. DaveMcLain


    Jun 19, 2005
    Cuba MO
    The new Sevetlanas are built in the Reflector factory in Russia, the same on that makes the Sovtek stuff. The JJ's are made in Slovakia and the Shughang are made in China. Using the KT-88's opens up many more options for you to experiment with. I myself have not had trouble with the old Sevetlana but I have with the new, but my experience is mostly with 6L6 stuff, not 6550's, the ones I used were great. I would say that they are probably very inconsistent from Sevetlana, new or old and buying them from a vendor who checks them closely is the secret to getting good results.

    My use of the Sevetlana 6550 in an SVT was about 10 years ago, whenever they first came on the market through Audio Glassic. The lady who I delt with there sent me a set to try and they worked great, maybe they were specially selected or "cherry picked", who knows...
  18. So they come out of the same factory. But the Sovtek is considered better by some?

    Where does "New Sensor" fit into this?? A tech told me that the Svets I got recently were from New Sensor. What is/was New Sensor?
    What's JJ stand for and have they ever gone by another name?
    No need to tell me about anything Chinese
    In what way? Quality?
  19. Edit part II: I edited this post with respect to the names of parties and facts that were made plain in the court case KOA linked. My sources were all mixed up, and if you'll read any of the conflicting internet news reports on this case, it's easy to see why.

    Svetlana's WERE being made in the Saratov factory because Mike Matthews (owner of New Sensor/Sovtek) bought the rights to the name from the bankrupt American "Svetlana" distributor a couple years ago and began importing "his" (read Sovtek) tubes in the "Svetlana" trademarked red and black packaging.

    The factories that make the tubes aren't "owned" in the US. They're independent former Soviet state factories that make contract production runs. JSC Svetlana is where 'Svetlana's' (the ones you guys like so much) are made, and Reflektor is the origin for MOST of Sovtek's line, although there are other Russian factories that New Sensor uses for its Sovtek/EH/ Tungsol/ Mullard brands.

    Since this left JSC Svetlana without an American distributor of its Svetlana tubes, CE Electronics(Antique Electronic Supply is their consumer arm) picked up the line and called the tubes "S.E.D." for "Svetlana Electron Devices." (Again, these are the tubes everyone but me seems to like.) They were sold in white boxes with red writing.

    To confuse the issue even further, CE Electronics sued Mike Matthews for use of the name "Svetlana" in the US. He 'lost,' BUT the judge ruled that New Sensor could use the SED trademark and 'Svetlana' (the 'real' ones) would go back to being distributed in the US AS Svetlana in their original red and black boxes. So now, the NEW Svetlana tubes are 'real' Svetlana's once again. (Got all that?) At least to Matthews' credit, New Sensor is NOT currently selling an "SED" 6550 to the best of my knowledge.

    Anyone with a passing familiarity with the two types' build can instantly tell which tube is the 'real Svetlana' regardless of what the packaging says. 'Real' Svetlana/SED tubes have rectangular plate holes and dark red/orange plastic base caps and well-hidden grids. Sovtek/EH/Tungsol 6550/KT88's all have small round plate holes and fairly visible grids and usually have black base caps, but not always.

    There are also at least three different Chinese factories making a 6550/KT88. Shugang is the most famous, and theirs is the least expensive. The "Golden Dragon" 6550/KT88/KT99 are made in another factory and the "Ruby" 6550/KT88 is made in the same factory that Groove Tubes uses for it's "US made" 6L6"GE" and 6CA7"GE" using the original GE tube jigs purchased from Richardson Electronics.

    JJ Electronics is unique in that the factory IS actually owned by "JJ Electronics" but it still shares floorspace with its former 'parent' factory which was "Tesla", which was the Czeckoslovokian state tube factory. JJ's are distributed via "Eurotubes." They produce an excellent, but pricey, KT88.

    Ei, a former Philips plant, produces KT90's in Serbia, and evidently does not have a single US distributor. They also have VERY infrequent production runs and severe problems with microphony in their preamp tubes, which are basically Philips/Sylvania copies.

    Edit: I wrote all of this before reading KOA's post and to clarify- New Sensor is the US distributor/owner of several brands, Sovtek, Electro Harmonix, and most recently, they bought the rights to the "Mullard" and "Tungsol" brand names.
  20. illidian


    Jul 2, 2004
    If I recall correctly, the poster went to the warehouse only to find out it was recently cleaned out.

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