Cap Value Question

[Stew]

Ok, I have a set of vintage designed pickups. Alright, Fender LTD Masterwound pickups. Fender says it does not matter what cap you use. If you have a .022 cap then that's fine. I say not true. I had a set of Custom 54's a few years back that replaced my American Standard Delta pickups. OMG, it was horrible how brittle and bright these pickups were. I almost returned them until I read a review on Harmony Central about using a .1 cap (.1 is the same as .10?). I got some pancake ceramic .1 mfd capacitor and it really helped. Now it sounded like a nice 60's set of pickups.

Now I've heard the argument over and over as to the .1 cap should have made things brighter, not the reverse. But it did. I even did a comparision with some Custom Shop '56 Time machine pickups. The .045 cap with those pickups sounded bright. Looked like a mylar foil cap. I swapped out with the .10 ceramic cap and everything was perfect.

So now, I've installed my Masterwounds which have about a 6.5K resistance, alder body, maple w/rosewood neck (Custom Shop Relic neck), and the .10 mfd ceramic cap. It sounds way too thin. Has the spank of a Tele bridge pickup. Theh only normal sounding pickup is the neck which sounds woody but with some Hendrix high end sparkle to it. Well, to me the .10 mfd cap is not working. I have some .10 mfd mylar foil caps as well as a .010 mfd mylar foil cap.

Confirm for me if you can: .022, .033, ......= brighter? .10 and less is darker until you hit .022 mfd? I'm sure all I need is just one step value in the appropriate direction to trim some of this high end off. I'm turning my amp treble down to 4 and bass to 10 on my Fender Princeton Reverb. I'm getting a nice strong volume too so it's not the pickup height which are at 8/64" bass side, and 6/64" on treble.

What's the electronics theory on caps and tone? I understand the theory about the cap affecting how much high frequency is bled off on the pot. I'm just mentally stuck on values and how they affect tone and how some materials can have an effect also (i.e, paper/foil, ceramic, electrolytic, mylar/foil, etc)?

[jnewman]

Increasing the capacitor value decreases the corner frequency - so more highs are rolled off, making it sound darker (darker=less highs). Anyone who tells you any different hasn't taken physics.

The different materials in caps affect how linearly they respond to frequency changes. The bottom line is that some (particularly ceramic) capacitors introduce more noise into the signal. Otherwise, there is NO DIFFERENCE in this application. In ultra-high end stereo equipment, you can maybe kind of make an argument for it (I've done a bit of audio amplifier building), but in a system already as noisy as a guitar? Use whatever's handy.

You only really use electrolytic caps when you need really high capacitances (above 1 microfarad), and most have the unfortunate problem of being polar (they only work properly one direction, which is bad for an AC signal). Below that level, good 'ole film capacitors (the little orange ones that are EVERYWHERE) are nonpolar, cheap as hell, and work great. There's not any reason to use anything but a cheap polyester film cap in a guitar (unless you're trying to do something like the $800 solid silver power cables you find in idiot hifi circles - in which case buy the hundred dollar oil-filled caps and charge your customer until he's dead from blood loss).

Edited September 30, 2005 by jnewman

[lovekraft]

Couldn't have said it better myself! "...Until he's dead from blood loss.." - that's perfect!!

Actually, standard electrolytics are not particularly reliable in circuits that don't keep a DC bias voltage on them most of the time (for instance, a guitar tone control) - just don't use 'em!

[Southpa]

Just an example of what sort of effect this will have. I recently built an all maple tele and was expecting it to sound a bit bright so I substituted the usual .022 mfd cap for a .047 cap. Guitar sounds great!

[jnewman]

Couldn't have said it better myself!  "...Until he's dead from blood loss.." -  that's perfect!! 

Actually, standard electrolytics are not particularly reliable in circuits that don't keep a DC bias voltage on them most of the time (for instance, a guitar tone control) - just don't use 'em!

←

True... I always forget about that part . I only ever use them in power supplies anyway, so I guess it's fine. Heh.

[Stew]

Ok, lets get back to values. So a .10 will have a huge effect over a .010, .022, .033, .047? I think I better double check the value of the .10 mfd cap, unless it the material that's making the difference. I'll swap out for the mylar .10 cap. Who knows that might sound way too dark.

[Southpa]

The only sure way is to just try them all out and see (or hear) what happens. In my experience I've found that variables like body and neck wood density, pickup type/positioning and potentiometer value will dictate the cap value for your best (or most desired) output frequency range.

Edited October 1, 2005 by Southpa

[JohnH]

The only sure way is to just try them all out and see  (or hear) what happens. 

I agree with that - I have two guitars, one (a Shergold with fairly low output humbuckers and 100k pots) sounds just fine with the original 0.047 cap. My other, a recently rewired Hondo Strat, with quite dark sounding ceramic single coils and 500k pots, was dead sounding when I put in a 0.033 cap, and is much better with a 0.01. I couldnt have guessed the best values without trying them.

John