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Tonal Differences between Mylar, Ceramic, and Poly tone and Treble-bypass caps?

Discussion in 'Luthier's Corner' started by Skips, Jan 23, 2004.


  1. Skips

    Skips

    Feb 19, 2003
    I guess the title says it all.
    I know when recapping amps, it's important to replace ceramics with ceramics, polys with polys, etc, because the sound different. Is that also true with the tone control on a passive bass, and with the treble bypass on a volume pot? All basses I've looked at seem to have polypropelene caps, which are twice as expensive as ceramics (a whopping 49 cents or so ;) ) Is there a reason for this?
     
  2. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    I've never heard any knowledgeable person claim convincingly that the type of cap used made any difference at all to the sound of passive bass. I've heard a bit of hearsay, or myth-mongering, but nothing that made any sense to me.

    The one reason I've heard for using polypropylene caps over ceramic in a bass that seemed plausible to me is that *supposedly* manufacturing tolerances are tighter with poly, so that if you're buying a .022 mfd cap, you have a better chance of getting a value close to .022 with poly than with ceramic.

    FWIW, Chris Kinman (the Aussie guitar PU maker) claims something similar with respect to pots: he says that cheap pots can often vary wildly from their rated value (e.g., 117 kohms for what's supposed to be a 250 kohm pot).
     
  3. Skips

    Skips

    Feb 19, 2003
    Thanks--didn't know that.
    I've tested one or two cheap pots, and always found them to be very close to their rated values (249 or so for 250--maybe I was just lucky). However, Cheap pots get scratchy and go bad so much that I'll stay away from them anyway. :)
     
  4. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
  5. Skips

    Skips

    Feb 19, 2003
    none of those graphs load for me.:(
     
  6. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Nor for me. Drag. But anyway, what he thinks is pretty clear from the written summary.
     
  7. Skips

    Skips

    Feb 19, 2003
    yeah, and the other site with the scopes also says a lot.
    Thanks a lot :)