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Thread: Orange AD200b Bass head- but guitar cap values?!

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    Senior Member Guitarist's Avatar
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    Orange AD200b Bass head- but guitar cap values?!

    I just repaired one of these. Now I see the .022 preamp caps. are these big enough to allow some good bass frequencies to pass? The owner has some nice basses so I'm tempted to add or parallel some bigger caps on V1,

    Also the PI CF calls for a 12at7 but how abut a 12au7 there and move the 12at7 on the PI? I could parallel another 100K 1/2 Watt or 1 Watt cap on the u7.
    Nice iron inside. But the board's star grounds all rely on a small Phillips screw that mounts to the chassis. Even after cleaning and a torque, it sure seems iffy.
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    Supporting Member The Dude's Avatar
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    Was there something he didn't like about it? If not, I see no reason to redesign it.

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    “Yeah, well, you know, that’s just, like, your opinion, man.”

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    Lifetime Member Enzo's Avatar
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    Amen.

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    Education is what you're left with after you have forgotten what you have learned.

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    Old Timer J M Fahey's Avatar
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    Quote Originally Posted by Guitarist View Post
    I just repaired one of these. Now I see the .022 preamp caps. are these big enough to allow some good bass frequencies to pass? The owner has some nice basses so I'm tempted to add or parallel some bigger caps on V1,
    Capacitors by themselves mean nothing, you always analyze them combined with some resistor.
    In this case .022uF coupling cap driving some 470k load gives you a Bass cut below 16Hz.

    Way lower than any Bass Guitar frequency.
    Also the PI CF calls for a 12at7 but how abut a 12au7 there and move the 12at7 on the PI? I could parallel another 100K 1/2 Watt or 1 Watt cap on the u7.
    Nothing to gain and probably a botched design, why would you do that?

    As said above: "do not fix what´s not broken"

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    Juan Manuel Fahey

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    Senior Member Guitarist's Avatar
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    OK cool, just what I was hoping — fine answer and we have three here. Thank you.
    I did no know about the cap + resistor setting that frequency.

    May it serve him well...

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    Old Timer J M Fahey's Avatar
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    Any time you want to calculate the cutoff frequency for an RC combination:

    http://www.sengpielaudio.com/calculator-RCpad.htm

    Not only that, they have TONS other useful tables and calculators.

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    Juan Manuel Fahey

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