Cap material for guitar tone

[PhiloB]

Does it matter?  Know it is debated hotly.  I had reached the unscientific conclusion that it doesn't.  Got caught up researching it again last night and am asking the question again.  What do the collective genius of the Madbean world say?  Yes or no!


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[jkokura]

I've tried maybe 6 or 7 different types of caps (in at least two guitars I tired 4 or 5 different caps), and aside from finding ceramic caps noisy (surprise surprise) I haven't been able to hear any difference.

Jacob

[jubal81]

I just thought of a mnemonic device:
The ABCs of cap selection.
Anything
But
Ceramic

With the "U.Y.H.T.B.O.S.C.O.T.A.Y.H.H.A.Y.B" addendum:
Unless you have to because of size considerations or that's all you have handy at your bench.

[Govmnt_Lacky]

When it comes to cap selection... I tend to follow what the experts say (RG, Hammer, etc.)

Caps are caps! Film is film, poly is poly, and ceramic is ceramic!

As long as they measure within tolerance... use what you have! Too much mojo talk about caps. Some claim to "hear a difference" but I have found little or no evidence of this.

I use precision where it is called for and I use ceramic if I HAVE to. Often when space is limited (multi-layer) YMMV 

[jubal81]

I think this is a pretty good article:


Here's a link to the PDF

[mremic01]

But which cap stacks best with a Timmy?

[PhiloB]

Thanks for bringing me back to earth:) that said, a guy from CL gave me a bag of old capacitors and resistors and among them are a few .05 uF paper/oil caps and also some .033 caps.  I am changing my pickups on my strat and may 'upgrade' the tone cap:) Also just picked up a P90 guitar that needs the pots replaced - may put the .033 cap in there.
Is the .033 value too dark for a humbucker guitar?


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[davent]

Trust your ears, audition the guitar with your amp(s) with the caps available, you decide.

[angrykoko]

Youtube is your magic answerall

My 2 cents, unless I'm a/b'ing them, I'd never know unless one was noisy.

[PhiloB]

Yeah davent, you are correct.  I should use the wire + alligator clips to audition different values/types.  I need to stop being lazy about it!


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[lars]

The only place I've found in a guitar circuit where you definitely need to use a specific type of cap is for RF filtering. Tiny ceramics are the best choice for that.
I think the suggestions to just audition different caps in your guitar is a great idea/project. Set up a breadboard and switching system, so you can quickly change from cap to cap. Sometimes if we can't immediately A/B/C things for comparison, our ears can play tricks on us.

[gordo]

I decommed an old rotary telephone system for the Hancock building in Chicago years ago and saved a handful of the old Sprague black and orange caps (black cats?) and have used them in a handful of guitars.  I swear they sound a bit smoother than anything else I've used but I'm not convinced that my brain is telling my ears to like them because I WANT to like them.  Bottom line is that if there IS a difference it's certainly subtle.

[peterc]

Ceramic caps come in different variants. The most common are X5, Y7 and NPO/COG.

In this paper by Deane Jensen, he has researched these materials and found NPO/COG dielectrics to be very good for audio work. I use them regularly and I dont hear that 'thin harsh' sound associated with ceramics.

Deane Jensen and John Hardy are both rather brilliant audio designers....

http://www.johnhardyco.com/pdf/990.pdf

Peter

[culturejam]

I would be more inclined to worry about the cap type in my guitars if I played with the tone controls anywhere other than 10 for a decent amount of time. I'm usually wide open on the tone, unless the circumstance calls for otherwise.

If you're on 10, the pickups are only "seeing" a tiny bit of the cap. With a typical 500K tone pot and 22n cap, the cutoff frequency is ~14Hz, which is a few hertz below the generally accepted low-end threshold of human hearing. So all that mojo is happening in a frequency range well into the "haunting lows" territory. 

Obviously, if you play a substantial portion of the time with the tone control less than maxed out, maybe you'll notice some differences.

[pickdropper]

Ceramic caps come in different variants. The most common are X5, Y7 and NPO/COG.

In this paper by Deane Jensen, he has researched these materials and found NPO/COG dielectrics to be very good for audio work. I use them regularly and I dont hear that 'thin harsh' sound associated with ceramics.

Deane Jensen and John Hardy are both rather brilliant audio designers....

http://www.johnhardyco.com/pdf/990.pdf

Peter

NP0/C0G are definitely a higher grade and don't suffer the same capacitance fluctuations you can see with the other ceramic caps. X7R/X5R caps work fine for many audio applications, although the capacitance is reduced the closer they are used to their rated voltage.  They also drift down over time.  The problem with NP0/C0G is that they aren't always an option in the higher capacitances.  And if they are, they are usually fairly expensive; IE: you could probably just buy a nice film cap for the cost of a 1uF NP0/C0G MLCC cap.

Ceramic caps do have measurably higher distortion, but whether or not you could actually hear that is debatable.

For guitars, the cost of tone caps is so tiny compared to the cost of the rest of the guitar that I'd probably just throw some nice film caps in there and call it a day.  Then you don't have to worry about whether or not the cheap ceramic cap is having a negative effect.  I've put paper in oil caps in a couple of my guitars because I had them.  If nothing else, they look cool.

Now what I don't get is people putting NOS Ceramic Disc caps in their guitar.  That's pretty much the worst of all worlds there.