JJ's and an AD200B: Was that a no-no?

Discussion in 'Amps [BG]' started by P-oddz, Aug 21, 2013.


  1. P-oddz

    P-oddz Supporting Member

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    Milwaukee, WI
    Just had my power tubes replaced due to wear and a microphonic issue in my AD200B. Being my first tube amp (and first set of tubes), I was talked into going the cheaper route with a quad of JJ 6550's (what the shop had available) instead of the Winged C's that were previously in it.

    Sparking up my amp back from repair - I noticed a slight tonal difference, obviously expected from different tubes, that wasn't bad, just different. After 15 minutes of warmup time - my amp goes to sh*t. No headroom, unwanted distortion, lack of punch and clarity. It also seemed it was running hotter than the previous set of tubes. It's going to go back to shop for diagnostic (to make sure one of the tubes didn't fail on me right away or that a preamp tube coincidentally burned out). All-in-all it was a bummer.

    I know this could be a symptom of biasing or possibly of more failed tubes - but my question to TB is this:

    • Does anyone have experience with the JJ's? Were they a bad choice for a bass amp, or this amp in particular?

    • Should I just replace them with a matched quad of the Winged C's and try to make up my losses by selling the JJ's somehow?

    • Any other tube experience on a decent (not ridiculously priced) set?

    Also, how does everyone deal with consistency issues and tube replacement? Is it just a sad truth to tube amp operation, or do I need to get to know my amp tech better for him to dial it in for me?
  2. chadds

    chadds

    Joined:
    Mar 18, 2000
    Did you keep the old winged Cs?
    Seems something else is wrong.

    Not to malign your tech at all but where I live it's advantageous to go to an old head who has serviced tube amps for decades. I find that whoever has been fixing your town's vintage player's amps is who you need. (Yeah, the players are vintage) :):)
  3. Mr. Foxen

    Mr. Foxen

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    If a place says replacing all the valves is the way to fix your amp, go find a new place.
  4. Chef

    Chef Moderator Supporting Member

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    So: you think the tubes are the problem; and you want to yank them and sell them to someone else?

    Not. Cool.

    Why not take the amp back to the shop that did the work and get them to stand behind it?

    JJ's, IME, and good, reliable tubes; but there's a bad one of every brand now and then. The tubes should have a short warranty period; especially when installed by a qualified tech.

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  6. P-oddz

    P-oddz Supporting Member

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    The problem is, that I really don't know anyone that services amps in my area (at least any that come by recommendation). The shop is a very reputable guitar shop in the area and the amp tech was pretty highly regarded (albeit a newer friend of a friend type situation). I'm sure it'll all get sorted out - and I'm not at the point of selling tubes and being screwed on amp repairs yet, just more so I was wondering if JJs were a bad choice with a amp like the AD200, and are just more prone to breaking up really early (something I wouldn't really want).

    I did get the Winged C's back, I guess it was my choice to replace the quad. One power tube was microphonic, and another in it tested for almost at fail so I was under the assumption (perhaps falsely) that it was a better option to replace the power tubes with a newer matching quad and I wouldn't have to worry about them for a bit. I don't know how much biasing needs to be done on replacing a new set of tubes - perhaps he biased the amp to run too hot?
  7. Mr. Foxen

    Mr. Foxen

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    AD200 is prone to breaking up and not having much headroom, for a supposedly 200w amp. Valves aren't to blame for that though. When power valves are going, there is a lot of scope for other fun going on in the amp that will need sorting, especially on ones made of minimal spec components, faulty valve can draw too much current through a resistor and damage it and such, it will sort of work, but not be right, and wreck newer valves faster, all this should be checked up by a proper tech. some amps are not made to be thoroughly serviced easily, and it is easy to skip that out and bung new valves in and call it good.
  8. Mr. Foxen

    Mr. Foxen

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  9. coreyfyfe

    coreyfyfe Supporting Member

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    I don't think the JJs are your problem, but I'd certainly take it back to the tech and see if they can work it out to sound better. It's possible you had the amp biased colder with the Winged Cs and this tech biased it closer to "normal" with the JJs. I've had both in my SVT and there wasn't a huge difference in headroom like this.
  10. P-oddz

    P-oddz Supporting Member

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  11. P-oddz

    P-oddz Supporting Member

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    I'm hoping that this is just the issue. But as I'm reading the responses, it seems like it might be more than that.

    I'm aware the Orange is known for breaking up earlier, but the truth of it is that before my amp went in for a tube switch it RIPPED. Punchy, growly, loud. Last night was just completely undesirable and unusable. Quieter, farty, fizzy.
  12. AL30

    AL30

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    Oct 15, 2009
    Take the amp back to the tech. It may or may not be the tubes. But, the problem occurred after the retube so the tech should take it back and give it a look over.

    I think it was a wise choice to retube. You will notice some tonal differences between tube brands. It's just the nature of things. I have no experience with 6550's but I have used both JJ's and Winged C's. While I like the Winged C's tone the price has gotten ridiculous. My experience with JJ's has been positive. They are solid tubes.

    AL
  13. WretchedExcess

    WretchedExcess

    Joined:
    Jul 29, 2013
    If you just had work done then you should have some warranty coverage for the work. This should include coverage for the tubes if you bought the tubes from the guy who installed them, but techs won't warranty the performance of tubes that you purchase elsewhere.

    From a practical standpoint it's good for your tech to do a burn-in test before giving back the amp so that problems like yours don't happen.

    My experience with JJ tubes is that they are reliable. I have not heard anything bad about the 6550, though I have heard a lot of people complaining on the tech boards about JJ 6L6 being microphonic when purchased from one particular distributor, and that one distributor refusing to honor warranty claims for microphonic tubes. The solution seems to be to shop with a different distributor.
  14. B-string

    B-string Supporting Member

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    While I have not installed the JJ 6550's I personally have found JJ power tubes inconsistent with early failures a little too common. Just my personal experiences many folks have good luck with them.
  15. P-oddz

    P-oddz Supporting Member

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    Update for anyone interested:

    Got the amp back at the end of last week after having to take it in for a second time (see original post), and she's running like a beaut so far - we just played a stage at Milwaukee's 110th Harley festival where the Orange rocked.

    So apparently this is what went down:
    The quad of JJs that I replaced the Winged C's with had a faulty tube. Upon playing it back from the shop the first time - the one bad from the factory tube failed, causing the other to compensate for power. At this point, the fail-safe should have tripped the fuse and shut off power to that pair, however (unbeknownst to me) it appears the previous owner had put in an improperly rated fuse. Ultimately it never cut power when it should have and I started to fry the other power tube in that pair. The "hot" I was experiencing was literally that - I cooked one of the tubes.

    Unfortunately, I was not able to receive any refund on the JJs since the mismatched fuse was technically my fault and not part of the amp operating as intended. My tech replaced the two bad JJs at no cost with some equally matched Sovteks he had around and tested the amp to make sure I didn't fry anything else. Seems to be right as rain at this point, and it's good to have it back.

    Words of wisdom: Don't let a cheap fuse ruin your expensive amp.
  16. chadds

    chadds

    Joined:
    Mar 18, 2000
    Tech should have checked fuse to be it's of correct value when it first came in! Some people use aluminum foil as a substitute. Probably why he gave you tubes.
    Glad it's all good.
  17. B-string

    B-string Supporting Member

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    IMO that all depends on how the tech is paid. If by the hour you have little trouble justifying spending extra time. If paid by the job (only on billable hours) it becomes very important to move on after the unit is fully functional unless you are having a very profitable week. I know that spending my time for free made me feel good about the work performed but I would also catch some guff for not getting as many billable hours as I could.
  18. VanillaThundah

    VanillaThundah Pleasantly plucky Supporting Member

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    What were the tubes rated on for breakup?

    I had a set of broken tubes replaced in my Traynor YBA200 with Groove Tube Golds (supposed to be Russian and high-quality stuff) by Guitar Center. They were medium distortion, because I didn't know the difference at the time and just went for the middle. They still sounded great, but broke up earlier than I'd like. Sounded awesome, but not as much clean headroom.

    Replaced them with a set of Tung Sols I got from Doug's Tubes, spec'd to be late distortion tubes. Difference was pretty noticeable. Nothing wrong with either set, just rated to break up sooner than the others. They may have replaced them with some early or middle distortion tubes that start the breakup earlier...and chances are the AD200B wasn't spec'd for tubes like that to sound ideal out of the box. I wouldn't worry too much about JJ being stamped on the tube, they make some pretty solid stuff.



    EDIT: NVM, read the update. Glad you guys got it figured out!!!
  19. Mr. Foxen

    Mr. Foxen

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    'distortion' ratings on valves is well dodge, they should work right, or they are broken.
  20. JimmyM

    JimmyM Supporting Member

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    +1. Distortion rating = "How weak are these tubes?"
  21. carbonfold

    carbonfold Supporting Member

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    +1


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