rectifier questions

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by frank52, Oct 15, 2004.


  1. frank52

    frank52 Guest

    i have an amp with a magnavox 6CA4 rectifier. i have noticed it "pings" when i tap the tube. also my power transformer seems to be running hotter than usual. when should a rectifier be replaced and do they have any effect on tone? i have read that some "sound better" than others. should i go for a high quality nos or use a current prodution? how important is this? i see them anwhere from 10 bucks to over 100 for a gold lion. is this just because of the rarity or is it really that much better? all other tubes in the amp are new. what is the story? thanks.
     
  2. Roccaforte Amps

    Roccaforte Amps Member

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    Any NOS 6CA4/EZ81 will do, its not in the signal path.
    If it pings, its microphonic. As far as the power transformer running hot, that could be just the nature of the transformer,
    OR your filter capacitors need replacing, and are loading down the supply.
    Does this amp hum? What kind of amp is it?
     
  3. frank52

    frank52 Guest

    thank you doug. it is a univox U155R. it does not hum at all. i have noticed you use this tube in some of your amps. i really like the sound of this thing and use it on gigs. just recently it has started making "static type noise" as well. i suspect it is time for a cap job as well. just wondering if it is safe to use it with this tube until i can find another one.
     
  4. Roccaforte Amps

    Roccaforte Amps Member

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    The worst that can happen is the tube shorts
    and blows the fuse.
    I wouldn't be too worried about it.
    Being that its a Univox, I would certainly have it recapped,
    Japanese capacitors used back then we not too good.
     
  5. frank52

    frank52 Guest

    thanks for your time and advice. it is great to hear this from someone who knows instead of the local shade tree amp techs.
     
  6. Roccaforte Amps

    Roccaforte Amps Member

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    Yeah, there are a few armchair techs floating around here lately.
     
  7. frank52

    frank52 Guest

    i just pulled the chassis and the amp has the atlas oil and Ace caps in it. bad news. even a fool like me knows they are junk. i can see that the electrolytics are bad for sure. i will replace all of them. what brand should i use? sprague atoms? allied says about 30-40 bucks for all of them. does this sound right? thanks again.
     
  8. Roccaforte Amps

    Roccaforte Amps Member

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    Too much. Go to Mouser Electronics, they sell retail, and use Xicon capactors. They're good quality, and won't dime your wallet.
    PS, Mouser is online.
     

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