HELP I'm a bias virgin!!

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by nemp, Jan 26, 2005.

  1. nemp

    nemp Member

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    I have a Peavey classic 30 and want to give it a bias so as to not run the tubes too hot. I've never done this, can I do this by ear?
     
  2. ToneDog

    ToneDog Member

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    No, you'll need a bias meter. I have one of George Alessandro's Bias Meters and it works great. There may be others too, but it is definitely not something you can do by ear.

    But why am I thinking that the Classic 30 is an EL-84 cathode biased amp? If it is, you can not (nor do you need to) bias the amp - it would be self-biasing.
     
  3. Guinness Lad

    Guinness Lad Silver Supporting Member

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    I'm not sure if this true with all el-84 amps but most of them are class - A designs. Most of the el-84 amps I ever owned never needed bias adjustments. Given this as a train of thought, some tubes will inherently run hotter, so try to get tubes that are selected accordingly. Groove tubes and Sovtek have rating guides on their tube packages so you can choose if you want cooler running or hotter running tubes. Hotter running tubes will give you more midrange, breakup sooner and wear out sooner; they may also be louder then cold running tubes. Cold running tubes will be cleaner sounding, less midrange, and more clean headroom before breakup and tend to last longer. I'd suggest the middle groung, I think it's 4 to 7 for Groove tubes? and go from there. The Peavey classic 30 is a great amp, even better when you change out the speaker. Try a Celestion G12H30 or a Weber "Blue Dog" for starters both of these would probably sound great. :)
     
  4. John Phillips

    John Phillips Member

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    Not true. Almost all EL-84 amps are Class AB designs. Many of them are also cathode-biased. Cathode-biased and Class A are NOT the same thing, despite popular belief/marketing BS. The number of Class A amps with EL84s on the market can probably be counted on the fingers of one hand.

    In any case, the Peavey Classic 30 is a fixed-bias amp. I don't think it has an adjustment trimmer either, from memory.

    It doesn't matter. Just get a set of decent tubes and you're good to go. Don't worry about it.
     
  5. nemp

    nemp Member

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    Thanks John. BTW it has a Peavey "sheffield" speaker and it sounds cool. I think those are the speakers in the 5150s. There Peaveys answer to vintage speakers as Eddie likes the vintage tone.
     
  6. I have never heard a 5150 get a vintage tone! I was listening to balance the other day, and I have to say..early VH...nice..late stuff...the worst tone I can think of! I like the results that people get with 5150's for heavy stuff..but Eddies phaser crap has got to go!
     
  7. Igneous

    Igneous Member

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    Yeah dude, as much as I love Eddie unconditionally, I cant stand that"poundcake" sound. It might have a lot to do with that guitar.

    He should go back to jmp's and golden lions. IMHO -if he does anything at all.
     

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