Capacitor Test: Polyester Film vs. Paper-in-Oil (PIO) in Guitar Tone Circuit


Does capacitor kind (paper-in-oil -- PIO, polyester film, ceramic) matter in guitar tone circuits? If so, how much? A short test, downloadable samples, and my opinion below.

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33 thoughts on “Capacitor Test: Polyester Film vs. Paper-in-Oil (PIO) in Guitar Tone Circuit

  1. Did you mark both of the capacitors for the outer foil and inner foil, then hook the outer foil to the ground?

  2. I listened FLAC test and difference was there on my Beyedynamic DT-770 headphones,but maybe that got to do with the fact that PIO cap value always vary notieably in compare to polyester.

    Did you play with the same pick and strum at the same place?
    Best regards.

  3. Some engineers a did a scientific test of 26 caps of different types and values. They graphed the values and then took the same sound file and ran it through filters that were based on the actual results of each individual capacitor. You can listen to all the results. The bastids used science. Its all just about the value. Just dont use disc ceramics (microphonics)

  4. Interesting conclusions! and having the guts to say your opinion. From a High Frequency background involving Radio, Multiplexing and audio, The paper in oil were the sad cousin to anything modern! I know from building IRAA eq networks that say polyester green caps measure identically to the Paper in oil variety but on blind listing tests I seemed to pick the Paper in oil as a choice 8 out of 10 times My supply of Paper in oils where salvaged from old equipment and graded by measurements so I was building with the same measured values! But I for one could never get a scope trace on the filter to say they where different! The Guitar world is like the Audiophile world going on whispered rumors as to what is best and is not! As for my electronics work it is now limited to fixing what I built and nothing new has been made in 20+ years

  5. If you can’t easily hear the difference between caps:

    A) You’re deaf
    B) Your system is too crappy to reveal the differences.

  6. Thanks for the test. I’m not a guitarist but am an “audio nut” :) in a good way and try not to get hung up on gear but instead focus on the music.

    Taking your “test” without watching what I noticed right away was how one sounded a tad sharper and had a little more “bite” and “air” while reproducing the sound with lightness.
    While another had more “body” a fullness or more weight to the guitar pluck.
    The latter being my preference and betting that it was PIO I was correct. This was especially noticeable on the first & second track.


  7. Listenening to the comparison, two things are clear : There are quite big differences in volume due to variations in strumming. Secondly, the sound has some distortion and ‘warbling’ which is particularly noticeable at the end of the clips. I find it strange that some people claimed the PIO sounded ‘better’ yet made no mention of the obvious. If they didn’t notice the dynamics and distortion, they can hardly be trusted to detect a difference in tone.

    Leaving that aside, even if there was a difference it can’t be claimed that one sounds ‘better’ than the other because tone is subjective.

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