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One last tube question

Discussion in 'Amps and Cabs [BG]' started by JJd2sc, Feb 9, 2006.

  1. JJd2sc


    Jul 31, 2003
    Marietta, Georgia
    I just got off the phone was Mesa. I called a number i recieved from them a week or so ago to get directly to a person. I left a message, and about an hour later I got a call back of him offering to answer all my questions.

    Mesa has stopped making 6550s, and Im in need of some. The man told me that I needed to find the most "rugged, durable and strong" tubes I could find, seeing how older 400s run off of 6 tubes and need stronger tubes. He had no suggestions. I mentioned JJ tubes, and he responded that Mesa once tried JJ tubes and did not like their quality or preformance and didnt sell them. All i hear about are people raving about JJ tubes, so I dont know if I should take that with a grain of salt or not. I dont really know how to look for a "rugged" tubeset, but maybe some of you guys here do. Thanks in advance.
  2. BbbyBld


    Oct 13, 2005
    Meridian, MS
    JJ makes pretty good power tubes. Another good choice would be Sovtek.

    If you are rich and want to go all out, buy a NOS set of Tung Sol 6550s. That's the ultimate 6550. That would set you back....a lot!
  3. They NEVER made 6550's. The ones they rebranded and sold under their name were first Philips 6550A's in the 80's, and then later trash Chinese 6550's. Your Bass 400 was most likely sold new with Philips 6550A's installed. Out of curiousity, why do you think you need new tubes?

    Most ANY modern 6550 will be just fine. The Bass 400 is FAR easier on 6550's than most other bass amps that use the type. Ruby's ( www.magicparts.com ) new Chinese 6550 the closest thing to the sound of the original tubes in your amp and is reasonably priced.

    More likely, Mesa didn't get them as cheap as they'd like to make money for rebrand sales. JJ's are usually pretty good quality. I have heard of failures with them, but they are no more numerous than any other currently made tube. Mesa is famous for spreading lots of BS about their amsp and the tubes they use to try and keep up the "Mesa mystique."

    Old Tungsols are nowhere near what they're cracked up to be. They're not BAD tubes, but their reputation is more the result of hi-fi tube dealers looking for a 6550 type to overcharge for than performance. Since there aren't enough Genelex KT88's in circulation for regular sales, the Tungsol 6550 'aquired' coveted status in the mid 1990's. Previously they were regarded as trash tubes by most of the hi-fi crowd.

    There is even a new version of the Tungsol made in Russia by New Sensor (Sovtek) which is a VERY good tube, and better in some respects than the original US made Tungsol! (You can get them cheaper if you just look for a Sovtek KT88, though. ;) )
  4. JJd2sc


    Jul 31, 2003
    Marietta, Georgia
    My amp got damaged by what seems to be a power surge during a thunderstorm, even though off and through a surge protector. Fried
    some connectors and burnt out a tube or two. I was just looking up Sovtek. Does the KT88 fit or work like a 6550? Or am I supposed to just look for a 6550? Sorry for the ignorance, I guess thats why i made this thread :]
  5. A power surge shouldn't even TOUCH the output tubes if the amp is off. Did a tech tell you this? If that is what happened, I SERIOUSLY doubt just getting new tubes will fix your amp, and you may end doing even more damage to to it just by installing them.

    Modern KT88's and 6550's are pretty much the same thing. It wasn't always the case in past times, though. Befroe you go buying tubes which you may or may not even need, let someone who knows electronics get ahold of your amp. I know someone who's even local to you. PM me and I'll give you their address.
  6. KT-88s and 6550s are usually interchangable in most amps. I have JJs in my 400+; JJ and Mesa sound good together. I hated the rebranded Mesa ones (probabally cheap ones, dunno from where) when I tried the Mesa for the first time, but with JJs it sounded a lot better.
  7. JJd2sc


    Jul 31, 2003
    Marietta, Georgia
    I appreciate the concern, but I have already taken my amp in to a reputable place called northwest speaker. The tubes werent the only thing wrong, but two different people said that id need to get new ones before using it again. I have to buy new tubes on top of the repair :[ The place that is fixing it doesnt sell tubes, so I am fairly sure they arnt trying to get more money out of me.

    PM sent.
  8. If you buy new power tubes, make sure they are matched as far as measurement is concerned (logo and other labels matching doesn't matter).
    I believe, like in the SVT, that the signal is split out of phase (read: divided in two) and sent to 2 rows of three power tubes each.
    Each row amplifies its half of the signal and then both half are summed.
    If the tubes are not matched, again spec-wise, one side of the signal will be distorted in comparison to the other.
    6550 are pretty easy to find on ebay, or I also recommend the tube depot (www.tubedepot.com). The 6550 are also called KT88. New tubes will make a difference.
  9. seamonkey


    Aug 6, 2004
    "matched" tubes won't match after a month of actual use.
  10. I thought you said you were going to stick to talking about things you actually knew something about... :rolleyes:

    If the tubes have been burned in prior to matching, they WILL still be matched. You could take emission readings off a s/s power amp's individual transistors sometimes, though. You MIGHT learn something.
  11. BbbyBld


    Oct 13, 2005
    Meridian, MS
    What makes you say that?

    I'm not surprised.:rolleyes:
  12. I've been through many examples of them and even have a couple of NOS and a few used ones right now. Similarly, I've also found Mullard EL34's and Genelex KT88's to be overrated. While vintage US and European tubes ARE generally better, the hype surrouding certain types is just pure BS. "Traditional" tube dealers who cater to hifi nuts use this mystique to charge outrageous prices for them, and unfortunately, the rest of the market follows.

    I'd rather have Sovtek KT88/ Russian Tungsol 6550's for a modern 6550 type bass amp than the 'real' ones. However, for a Hammond/Leslie, which IIRC, you have, nothing comes close to the original coke cottle Tungsol for tone, but the Leslie isn't running 700+ volts of B+ either.

    As recently as five or six years ago, I'd have said the JAN Philips 6550A was the king of 6550's, followed closely by GE's JAN 6550A, but modern 6550/KT88's have really stepped up in terms of voltage handling and current capability. The ONLY current 6550 that I do not recommend is the Svetlana/ Flying C 6550C because they just don't handle voltage and have to be biased FAR too cold to be useful.

    Until the early 1990's, most Tungsol 6550's were trashed because they were 'just industrial junk tubes.' It wasn't until Genelex KT88's became scarce that they suddenly became desirable. Hifi guys grudgingly accepted the GE 6550A because of Conrad Johnson. It's really funny, too, because I've seen people pay exhorbitant amounts of money for Chinese counterfeit "Philips 6550's" thinking they're getting Tungsols, and give them rave reviews while trashing their other honestly labelled 6550 brethren. Like a lot of things, the appearance is MUCH more important than reality, especially to people who have no idea what they're dealing with.
  13. JJd2sc


    Jul 31, 2003
    Marietta, Georgia
  14. Kelly Lee

    Kelly Lee Yeah, I'm a guy! Supporting Member

    Feb 17, 2004
    Marana, AZ, USA
    I have been thinking of the Sovtek 6550we or JJ's KT88 for my Trace Quatra head.

    Anybody have experience with the Sovtek 6550we?

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