Replacing tubes in my Matchless DC30, which ones should be NOS?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Weekendwarrior, Jan 25, 2012.

  1. Weekendwarrior

    Weekendwarrior Member

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    Although i only purchased my DC30 a month ago, the tubes have already started giving me problems. The EF86 is extremely microphonic, and the rectifier tube also suffers heavy amounts of rattle. I know I could simply go back to my retailer but I figured now is as good a time to replace them with some tubes that won't be so problematic, and a selection that can hopefully also sweeten up/soften the highs of the amp.

    I plan to replace these tubes with either higher quality or NOS tubes. Seeing I use channel 2 exclusively, I figure its not worth replacing the 12ax7. However, I was looking to replace the EF86, 5ar4 (i think thats the recto tube) and the EL84s.

    I've read up on recommended tubes but I have a few questions.

    First off, I know the DC30 is notorious for burning through tubes, but are the preamps or power amp tubes most likely to go first? I'm alright with purchasing NOS tubes but If they will all burn out in 3 months I am definitely going to think twice.

    Would some NOS tubes be more beneficial? Would a NOS Mullard Longplate EF86 serve to improve the tone more than some NOS EL84's?
     
  2. mcdes

    mcdes Member of no importance

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    start with a NOS rectifier, then a NOS EF86, and it will sing. then the 12AX7's, then the power tubes.......... but thats just from my experience.
     
  3. Blue Strat

    Blue Strat Member

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    +1 on the order of priority with the possible exception of starting with the EF86.
     
  4. Weekendwarrior

    Weekendwarrior Member

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    Good to know! i see you are a tube distributer. I will be grabbing a NOS mullard long plate (assuming thats the best), but what do you think is the best option for the 5AR4? I will most likely be purchasing through you :)
     
  5. Blue Strat

    Blue Strat Member

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    Anything NOS is way better than anything new and tend to last 30 years, on average. The JAN Philips would be the most cost effective.

    Please contact me directly as this is not MY website.;)
     
  6. twangbanger

    twangbanger Supporting Member

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    NOS Dario Miniwatt EF86 , getting harder to find but worth it.
     
  7. Blue Strat

    Blue Strat Member

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    Those are great but mostly gone. There are other great ones. No one had even heard of Darios until about 8-10 years ago.
     
  8. guitarcapo

    guitarcapo Senior Member

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    Matchless amps seem to have heavy plate voltages on the power tubes. 350 volts for an EL84 amp like Spitfire or Lightning for example.
     
  9. Blue Strat

    Blue Strat Member

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    350V is in spec for EL84s. The problem is usually the idle current which can run the idle POWER (plate voltage minus cathode voltage TIMES idle current) over 100%.
     
  10. ScioBro

    ScioBro Supporting Member

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    Vintage rectifier makes lovely feel difference, lasts forever.

    sweeten the 12ax7 ch by using a 5751 or 12AY7 in V1
    you'll have to turn up the pre vol. more to get to a sweet spot (if you're used to doing that with the 12aX7)
    but it should be a sweeter gain....less harsh
    My Lightning sounded sweetest with 12AY7s in V1 AND V2 spot.
    Got a 5751 in a Spitfire
    just leave the 12AX7 PI tube alone, (I didn't like a 12AT7 in there)
     

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