Matchless DC30 half power switch question

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by tedwoods, Jun 5, 2005.

  1. tedwoods

    tedwoods Member

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    I usually run my DC30 at the half power switch setting.
    This supposedly disengages two of the power tubes(?).

    Is it possible to determine which ones,middle two or the ones on both sides or some other combination,and more importantly is it then possible not to have any tubes at all at the unused positions without any adverse effects to the amp or sound?

    Thanks,

    Ted
     
  2. drbob1

    drbob1 Silver Supporting Member

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    I'm not sure about the DC30, most amps that do this use either the inner or outer pair. You wouldn't hurt the amp by pulling one or the other and seeing which made the sound go away (of course, turn the amp OFF before removing tubes). There's not much advantage to not having the tubes in the unused positions but it should be safe (unless the heaters are in series, which I doubt).
     
  3. tedwoods

    tedwoods Member

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    Thanks!

    I was thinking that if I use the amp in half power(2 tubes on) , when I do decide to use it at full power the rest of the tubes might not be matched anymore since they remain unused.

    So,I figured it would be best to keep a set of two for dedicated half power use and a set of four for full power.

    I believe some people use to "share" tube duties,swapping the two used with the two unused pairs everytime they play, but I figured two different sets would be more practical.

    I also wanted to make sure no extra strain is placed on the components...

    Ted
     
  4. Kiwi

    Kiwi Silver Supporting Member

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    I'm pretty sure it's the inner two that get used at half power, but here's the easy way to tell:

    In a darkened room, warm it up on Standby on half power. Then flip the amp to Power On. Two tubes should light up with the blue glow. Those are the "hot" ones.

    I play at half power a lot. I rotate the two "used"tubes every six months or so to try to even out the wear. Who knows if it's worth the effort, since modern EL84s are not expensive.

    Kiwi
     
  5. Swarty

    Swarty Member

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    Another thought is to touch them after the amp has been on for awhile. The tubes being used will be too hot to touch.
     
  6. tedwoods

    tedwoods Member

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    Thanks guys!

    It also occured to me that since I use only two I could then also use some Brimars that I had found...
    Trouble is,I've only found two matched duets that can't be used together...so that's the rest of the story!

    Ted
     
  7. TheAmpNerd

    TheAmpNerd Member

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    Ted,

    Sure you can. Use one duet for the inner,
    and the other duet for the outer.

    Then, each pair is matched. That actually
    might sound very good, you might like it.
     

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