Bias Point for Fuchs ODS 100?

Discussion in 'Amps and Cabs' started by Burst59, Aug 17, 2008.

  1. Burst59

    Burst59 Member

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    I was just wondering what you fellow Fuchs owners are setting your bias at.
    I have Fuchs ODS 100 loaded with TAD 6L6's. My current bias is 27mv but the manual lists the factory setting at 30.
     
  2. scottl

    scottl Member

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    Try 32 to 35. 27 is too low IMO.
     
  3. Burst59

    Burst59 Member

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    Well that explains my constant tweaking of the trimmers and tone knobs and swapping out speakers. That should improve the tone allot.
     
  4. Blue Strat

    Blue Strat Member

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    Try the 25-35 range and use your ears to decide. There's absolutely no consensus on what sounds best.
     
  5. scottl

    scottl Member

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    True... But in my Fuchs 100 with the same tubes, 27 sounds a little thinner and not as warm as 32 or so.... The amp has individual bias adjustments for each tube btw. So, you can safely set it in the mid 30s if you want.

     
  6. Blue Strat

    Blue Strat Member

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    ...to you.

    It's always best to experiment rather than rely on subjective opinions if for no other reason than experiencing "it" for oneself.
     
  7. Dave_C

    Dave_C Supporting Member

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    Andy recommends 36mA across the 1-ohm cathode resistors (assuming your input voltage is 120VAC). 27mA is WAY too low. Surprised the amp doesn't sound like poop at that level.
     
  8. Dave_C

    Dave_C Supporting Member

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    That's true, but I've found that there's very little audible difference between approx 55%-70% max idle Pd for most amps/tubes. Above that and it gets harsh to most ears (not to mention the risk of red plating). Below that and it gets dull and lifeless to most ears. Anywhere in the middle of that range is pretty much the sweet spot. So, for most ears, it's a pretty safe bet to recommend a number around around 60-65% and then forget about it. Heck, using a lousy cable will a affect your tone a lot more than worrying about the bias point within a few mA of the center of that range.
     

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