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Do I have a dying tube in my Boogie D-180?

Discussion in 'Amps [BG]' started by Webtroll, Dec 4, 2013.


  1. Webtroll

    Webtroll Rolling for initiative Supporting Member

    Apr 23, 2006
    Austin, TX
    Do I have a dying tube? I've owned tube amps for years and never had a tube fail, so I'm not sure if the sound is what I should expect from a failing tube. Hell I used an SVT for over a decade without a single problem (other than it weighing so damned much).

    Last practice my new SUB Sterling didn't sound great and I chalked it up to a cheap bass needing new strings. Tonight my go-to US SUB sounded bad and a little farty. Swapped cables, new battery, same. Looked at the tubes, one of them is glowing blue, but in the way that online descriptions says is normal (photo 1):

    http://www.thetubestore.com/Resources/Matching-and-other-tube-info/Blue-Glow

    The tube glowing blue is the leftmost Sovtek 6L6WXT, and it's the only one glowing blue. The tube is also labeled 04 03, the next one 04 05, and the rest 04 03; I'm not sure what these numbers mean nor if it makes a difference at all.

    The preamp tubes, left to right, are 12AX7 (labeled MADE IN HUNGARY), 2 matching 12AT7 tubes, and a Philips 12AX7.

    I'm thinking about a set of JJs replacing the 6L6WXTs with 6L6GCs. There are other brands of tubes out there and I'm willing to listen, but some of the prices on tubes are nuts!

    I seek opinions and am all ears. Thank you.
     
  2. B-string

    B-string Gold Supporting Member

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  4. Webtroll

    Webtroll Rolling for initiative Supporting Member

    Apr 23, 2006
    Austin, TX
    Those tubes are significantly more expensive than JJs, are they that significantly better? In what ways?
     
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    You will have to have the new power tubes rebiased unless you buy mesa tubes with the same colored dot as what you have in your amp now.
     
  6. SirMjac28

    SirMjac28 Patiently Waiting For The Next British Invasion Gold Supporting Member

    Aug 25, 2010
    The Great Midwest
    Have you tried switching the tube positions?
     
  7. Webtroll

    Webtroll Rolling for initiative Supporting Member

    Apr 23, 2006
    Austin, TX
    I have not tried shuffling them. The 6L6 tubes that are in there are from the Tube Depot (based on stickers) so I'm assuming it's had at least one tube job in the past. As for biasing I didn't see where it would be set, is this self biasing with matched tubes or will it need manual biasing?
     
  8. Primakurtz

    Primakurtz Registered Nihilist Supporting Member

    Nov 23, 2011
    Denver, Colorado
    Like (almost) all Mesa amps, you cannot bias it. You can use any sturdy 6L6's, so long as they are within the correct range. Most good tube sellers know what this is, and can give you what you need. IME, you can swap in a good Mesa bias range tube for a bad one without causing any problems - especially in a six-tube bass amp like the D-180. Mesas are built this way, and for good reason.
     
  9. Webtroll

    Webtroll Rolling for initiative Supporting Member

    Apr 23, 2006
    Austin, TX
    All righty, seems I could use a tube checker. Thanks for the info folks!
     
  10. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    The small tubes are self biasing but the 6L6GC power tube's bias should be checked. In these amps, bias is changed by changing the resistance. Since there isn't a pot that allows you to adjust the bias, a resistor needs to be soldered into place. A tube seller can sell you a tube based on the colored dot.

    Unless you are confident in the tube seller, I think that it's still a good idea to have a tech check that the bias is optimally set after the new power tubes are installed. This is different that testing the tubes with a tube tester.
     
  11. chaosMK

    chaosMK Supporting Member

    May 26, 2005
    Albuquerque, NM
    Disclosures:
    Hi-fi into an old tube amp
    The bias range for Mesa tubes is not some mystical thing. It's around 35mA for 6L6 (around the "average" range for a 6L6).

    JJ's in the power section is a great idea, they rock. For my preamps I use a mix of Tung Sol RI, JJ 83 and JJ 803 in all of my amps (these are all inexpensive current production tubes). Tung Sol RI is a great (and currently popular) tube for V1.

    I am surprised you have 2 12AT7's. You should probably just have one at most. My D180 is all 12AX7's. These old school Mesa heads can have a little variation though.
     
  12. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Disclosures:
    Endorsing: Ampeg Amps
    I've not had much good luck with JJ 6L6's except for my new V4B. Two months in and they're still doing well.
     
  13. Webtroll

    Webtroll Rolling for initiative Supporting Member

    Apr 23, 2006
    Austin, TX
    What problems have you had with JJ 6L6s? It would be hard to beat the price, most other options are more than twice the cost.


    The chassis is actually labeled for that, and when I search for tube kits for the D-180 that's the default configuration.
     
  14. JimmyM

    JimmyM

    Apr 11, 2005
    Apopka, FL
    Disclosures:
    Endorsing: Ampeg Amps
    One set went crackly within 3 months, another set was microphonic right out of the box.
     



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