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Circle "D" Ceramic Disc Capacitors?

Discussion in 'Amp Central Station' started by Josey, Dec 4, 2013.

  1. Josey

    Josey Tele-Meister

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    Where have all these little guys gone? Have technicians completely exhausted any stock that remained? When trying to do some modifications to my blackface and silverface amps I originally planned to use vintage parts so that to the naked eye, everything would seem original under the hood. That has become quite a challenge. Do you guys have any advice on where I can find them or what makes the best replacement?
     
  2. David Barnett

    David Barnett Doctor of Teleocity

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    Those are Cornell Dubilier, they're not making single layer ceramic disk capacitors anymore.
     
  3. Glen Smith

    Glen Smith RIP

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    You can find a few on ebay but very pricey for what they are.
     
  4. Josey

    Josey Tele-Meister

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    I can't find the proper values needed on eBay. What's my next best option?
     
  5. mojo2001

    mojo2001 Tele-Holic

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    Circle 2. Don't be vague, ask for Sprague.
     
  6. Josey

    Josey Tele-Meister

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    I'm confused at what your saying here. I use Sprague for my electrolytic caps.
     
  7. mojo2001

    mojo2001 Tele-Holic

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    Well, Sprague made ceramic disc caps too. Often marked 2 inside a circle.

    If you're looking for USA made ceramic cap, these should be equivalent quality to CD.
     
  8. mojo2001

    mojo2001 Tele-Holic

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    Come to think of it, I have a couple [email protected] CDs sitting on my work table right now if you need a few.
     
  9. rsi106

    rsi106 TDPRI Member

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    Looks like mojo2001 has you covered. For future reference, there's an ebay store called "audiograde" that I get caps from. He usually has some. The trick is finding the value you need.
     
  10. FenderLover

    FenderLover Poster Extraordinaire

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    "Don't be vague, ask for Sprague."

    (That used to be their advertising catch phrase back in the day)
     
  11. Josey

    Josey Tele-Meister

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    Ahhhh. Gotcha. I did not know that. I really appreciate your offer mojo, but the values are what I'm having trouble finding. I'm trying to modify my 66' Bassman to the older AA864 like they discuss on Fender guru. They suggest replacing the 0.1uF coupling cap between the second gain stage and the phase inverter with a .001uF or .003uF. The original AA864 circuit used a 500pF here instead. Honestly I would be satisfied if I could find any one of the three.
     
  12. TNO

    TNO Friend of Leo's

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    I'm in the middle of doing that mod myself and decided to go with the .003 value. If am amp has ceramic disc coupling caps and sounds fine I'll leave them but I would never put one in an amp in that position.
     
  13. Josey

    Josey Tele-Meister

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    I guess it's just a matter of preference. I'm pretty sure Leo used a ceramic disc there.

    What type cap did you end up using TNO? Right now I'm using a 500pF circle "D" that I salvaged when I removed it from the pre amp section. There are two ceramic disc caps across the 100k plate load resistors that rob some of the amp's tone. One's a 500pF and the other is a .01uF. Taking these out will open it up.
     
  14. muchxs

    muchxs Doctor of Teleocity

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    The ceramic discs are generally in the trem oscillator in Fenders. The trem oscillator isn't in the signal path. There may be one in the tone controls and another as a snubber in the power amp.

    Typical Leo... he spec'ed good parts almost everywhere but saved a buck where he could.

    By contrast my old Supro had nothing but ceramic discs all in the signal path.
     
  15. Josey

    Josey Tele-Meister

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    Well I kinda wanted to keep anything "bright orange" from showing up on my board but if that's what gives me the best results then I'm all for it.
     
  16. mojo2001

    mojo2001 Tele-Holic

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    I switched out a ceramic disc coupling cap in a drip edge Vibrochamp with a nice plastic molded.

    I could hear NO difference.

    I have been in the tube audio business for 30 years and know what caps do, so I'm not flinging the "the only thing that matters is the value" line, which is some kind of weird fundamentalist Electronics 101 stance that does not jive with my experience.

    Ceramic caps of this ilk are junky five-cent microphonic parts but they somehow rise above their station in musical instrument applications at times. Still, it is hard for me to choose these out of my stock of new and NOS caps to install willingly.

    Shoulda just left that disc in there but it had a small chip on the coating and OCD took over.

    I should take those .015 CDs and build a 5C1 with them and give them a shot to do their trashy ceramic thang.
     
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