peavy classic 400 tube question

Discussion in 'Amps and Cabs [BG]' started by hombrelobo, Nov 21, 2005.

  1. hombrelobo


    Sep 28, 2005
    I just purchased one of these through mf and ive been reading that the stock tubes in it are no good. Just wondering if another owner of one of these could tell me if this true and what would be some good replacement tubes. I am recieving this amp sometime today and i cant wait to try this beast out!
  2. It depends on what kind of power tubes are actually in the amp. Peavey shipped it with TWO different types, both labelled "Peavey 6550." Both types are Chinese. The true 6550 has a "coke bottle" shape with a bulbous top tapering to a slightly skinnier bottom and is a TOTAL piece of crap. The other type is a Chinese KT88 and has a fat bottle with straight sides. It's a good tube. The preamp tubes are cheap Chinese stock and pretty much ANYTHING will be an improvement over them.
  3. Thornton Davis

    Thornton Davis

    Dec 11, 1999
    I put 8 new matching Sovtek 6550WE's in the power section almost 6 years ago now and last summer I put 5 new Electro-Harmonix 12Ax7-EH and 1 new Electro-Harmonix 12AT7-EH in mine.

    If you put new power tubes in yours, make sure that you have the amp re-biased or you'll do some major damage to the amp.

    Good luck.

  4. SubMonkey


    May 3, 2004
    Denver, CO
    I have the same power tubes in mine and am very pleased with the result :D .

  5. and I the Sovtek KT88 and I'm very pleased as well :bassist:
  6. Thor

    Thor Gold Supporting Member In Memoriam

    Any suggestions for the rest of us how to
    rebias this on our own work benches?

  7. <-- all the service docs AND bias proceedure are there for download :smug:
  8. Quadzilla

    Quadzilla Supporting Member

    Hey James, can you put a link to the Peavey magazine ads that you have somewhere on your classic 400 website right on the front page?
  9. I'll try to get to something tonight. I've no FTP access at the moment.
  10. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
    Any thoughts as to how this tube compares to the mighty Sovtek KT-88?

  11. The Chinese KT88 is good, but not as good as the Sovtek KT88. The Sovtek can handle more voltage, puts out slightly more power and is less compressed sounding. The Chinese KT88 is low-end heavy and relatively inarticulate in the mids and highs. It works well for bass amps because of it.
  12. tombowlus

    tombowlus If it sounds good, it is good Gold Supporting Member

    Apr 3, 2003
    North central Ohio
    Editor-in-Chief, Bass Gear Magazine
  13. Thor

    Thor Gold Supporting Member In Memoriam

    Very interesting, thanks PBG !
  14. I have all the stock tubes in mine right now. I have what PBG calls the "crap" power tubes. I think the amp sounds fine as is. Of course I know I can improve on it with better tubes but keep in mind that a complete retube and bias, unless you can do it yourself, isn't a cheap thing to do. I'm gonna try to get some more mileage out of my tubes before I swap them out.

  15. The biggest problem I (and many others also) have had with Chinese 6550's is their relaibility. They have a dangerous tendency to short, which damages an amp badly. I've never had a single set work so I could make tonal observations.
  16. Thor

    Thor Gold Supporting Member In Memoriam

    I guess we can stop worrying about their
    space program then. :p
  17. I guess that I've just been lucky then! :eek:
  18. They've not made those 6550's in at LEAST 15 years, probably more, but lots of American distributors (cough- Mesa, cough- Peavey, cough Penta) bought tons of them in the late 80's because they were so cheap and never bothered to check their reliability beforehand. They were originally counterfeit copies of old US Tungsols that were sold to the Japanese hi-fi market. You can see them on eBay pretty often bearing lots of labels, usually Philips. The gold base band is the giveaway that they're fake. Real Tungsols were plain metal.

    Anyhow, after their attempts at counterfeiting were discovered, they retooled, made the tubes even more poorly (tales of cigarette butts inside the tube envelope are common) and sold them even more cheaply. Peavey bought and relabelled some of them, too

    BUT after 1997 Richardson Electronics sold off their old tube making equipment form the old Ken Rad/GE plant in Owensboro, Ky to the Chinese, including lots of plate material and they have been producing 6550A's and KT88's that are at least equal to Richardson's 6550A quality and possibly even GE's. (Richardson may have made tubes in the old GE plant, but their QC was terrible.)

    As far as their space program, the Chinese can ALREADY plant an ICBM on the continental US if they so choose.
  19. Thor

    Thor Gold Supporting Member In Memoriam

    Excellent tale of the tube tribulations! Very interesting!

    I was under the impression that all components for new missiles were already being produced in China. ;)

    Of course, landing one here would eliminate their biggest
    market, very politically incorrect! And the Waltons wouldn't
    stand for it! :D

    I actually had heard that the Chinese were interested in a
    Moon shot. That would be a NASA wake-up call.

  20. timv


    Jun 7, 2000
    Chandler, AZ
    PBG, are the ones that are crappy the old chinese ones shaped like a tung sol? Are these the ones considered, coke bottle? Are the ones shaped like the JJ KT88 the good ones?