Bypass Cap on Filter cap ?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by rreiser, Mar 27, 2008.

  1. rreiser

    rreiser Supporting Member

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    My amp tech suggested I try putting a .1 bypass cap in parallel with a filter cap. It has something to do with keeping the impedance thruout the freq range more stable. I do notice a difference when I tried it. Anyone experiment with this and different values ? Thanks
     
  2. phsyconoodler

    phsyconoodler Member

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    Never heard of that one.Interesting though.
     
  3. rreiser

    rreiser Supporting Member

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    He read about it in a Audiophile magazine many years ago. I like what it does personally. I'm still curious if different cap values would make a difference. Anyone play around with this ? Thanks
     
  4. ClinchFX

    ClinchFX Gold Supporting Member Vendor

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    In the general electronics field, this has been common practice for a long time. The inherent inductance in large electrolytic caps reduces their filtering efficiency at higher frequencies. The small cap in parallel bypasses the high frequencies. Now that low ESR (Effective Series Resistance) electros are getting cheaper, you don't see it as much.

    As far as guitar amps or effects go, I've only used this technique with a switchmode supply in a pedal, to get rid of high frequency noise. I expect that it may give a smoother top end in a guitar amp, but I haven't tried it.

    Peter.
     
  5. rreiser

    rreiser Supporting Member

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    Thats what I hear. Thanks for your input. I hope we get more people chiming in that have tried it.
     
  6. Nolatone Ampworks

    Nolatone Ampworks Silver Supporting Member

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    Haha. Sounds almost like Goldilocks and the three bears :)
     
  7. donnyjaguar

    donnyjaguar Member

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    I've heard people say it gets rid of some of the hiss inherent with the rectifiers. There's not a lot of joules of energy storage capacity in a .1uF so its not going to have a profound effect on dynamics, IMO.
     
  8. VikingAmps

    VikingAmps Member

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    I usually put snubbers across the rectifier, that eliminates it at the source. Another good place is across the OT primary. That'll really smooth out an amp that has a bit to much of the nasty on top.
     
  9. rreiser

    rreiser Supporting Member

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    What are snubbers ? Thanks
     
  10. EarlTX

    EarlTX Member

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    There a variety of snubbers, the basic ones are like .1uF cap and a 47 ohm resistor in a small package. Good for any kind of HV switching, like yer standby switch, relay contacts, etc. .
     

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