Recommended Picofarad Capacitors

Outfitter03
Outfitter03 Posts: 563
edited February 2011 in DIY, Mods & Tweaks
Any recommendations for type and vendor for Picofarad Capacitors. The values that I need to replace are 22pf, 47pf, 100pf, 330pf. The current capacitors are Polystyrene. Thanks for your input.
Post edited by Outfitter03 on
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  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited February 2011
    Hello,
    There might not be a need to replace them if they seem to be in good shape. I usually use Panasonic small value caps (sounds like a money market fund). Other folks use CDE with good results.
    What are these caps doing in the circuit? Phono EQ? Feedback loop?
    Cheers, Ken
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  • Face
    Face Posts: 14,340
    edited February 2011
    They only have the larger values you need: http://www.partsconnexion.com/capacitor_film_amtrans_amch.html
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • Outfitter03
    Outfitter03 Posts: 563
    edited February 2011
    Thanks Face for the information. Those look good and aren't too expensive.

    I guess the originals may be fine. These are in an Adcom gfa-545ii and from the production dates that I looked at the unit would be coming up on 20 years old.

    The individual I bought it from claimed to be the original owner and only used this amp less than 100 hrs before switching to tubes. I guess the shorter heat history may have left the caps in better condition, but while I am replacing some resistors and electrolytic capacitors just wanted to do everything that needed to be done at one time.

    330pf is in the input network
    The 47pf appears to be in the feedback loop.

    My ckt. theory is too rusty to tell you the function of the 22pf. The service manual says the 100pf provide high frequency compensation in the open loop gain, if that makes sense to you.
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  • [Deleted User]
    [Deleted User] Posts: 7,658
    edited February 2011
    In my opinion the ones to consider are the Rel-Caps Teflon series. I've used them in the RIAA feedback loop of my preamp with good results. You might want to try finding them at Sonicraft.com. I used to get them from a small supplier, but haven't contacted him in along time.
    Cheers, Ken
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