On Tone Caps and My Rudimentary Understanding of How They Work...

[Commodore 64]

It is commonly assumed that with the pot at max, the tone cap does not effect the signal from your guitar (i.e., it's not affecting the tone). In other words, if you have a .1 cap and a .01 cap, they would sound exactly the same with the pot maxed. I'm not 100% convinced of this based on personal experience.

Last week, I was working on a Ray Benson Samick (kinda like a tele with strat forearm contour). The neck PUP sounded really muddy and the bridge was nothing special. The neck PUP had no adjustment screws and I didn't want to take off the strings and PG. So I replaced the .047 cap with a .015 cap. I thought the guitar was noticeably brighter. The owner thought so too, and I didn't tell him I had replaced the cap.

Caveat: I don't know my *** from my elbow about electric engineering
It is my understanding that the resistance from the pot and the capacitance of the cap work together to roll-off high frequencies in your guitar signal. The resistance makes more of the signal "bounce off" the pot and head down to the amp input because the signal is like water and follows the path of least resistance. So, the only way that the capacitor would be out of the equation would be if the pot resistance was high enough to bounce ALL of the signal to the amp input. I don't know how to calculate whether this happens or not, and I'm not sure how much the resistance at the amp input factors into the equation either (I know 68k resistors are commonly used in front of the ground for the input jacks).

I just know what I heard with that Ray Benson Samick, and it has piqued my curiosity.

 

[Ch0jin]

Hey C64,
You have it all figured out by the sounds. How you've described it is basically spot on. The tone cap in a basic wiring scheme IS always in circuit, it's just the tone pot that's "diverting" varying amounts of signal to the output, or to ground. Varying the size of the pot (in value) and the cap will determine how much the "wide open" signal is effected by the cap.

What's the value of pot that would negate tone cap effects wide open? That's a cool question, but I'll have to get back to you on the math as it's been a long *** day

Actually, I just found this AWESOME spreadsheet.. This has all the math built in and you can absolutely simulate what you have heard. Varying the value of the tone cap with the tone wide open DOES affect frequency response.

http://people.smartchat.net.au/~l_jhewitt/circuits/GuitarFreak_2_2.xls

 

[deeaa]

FWIW I'm thinking of removing the tone pots and caps from all my guitars...I think they only worsen the sounds anyway. I have them on 3 or 4 guitars I think, right now...I think they might sound better without the tone pots...and I don't recall a single time I've ever used tone controls on my guitar. If I have tried, it has been trying to make it brighter, never darker. Never met a guitar that was too bright or even bright enough to start with.

 

[Tig]

Reminds me a little of Guthrie Govan's guitar:

"The Suhr Guthrie Govan signature model has a push-button "Blower" switch which allows you to go to a full-on bridge humbucker sound with a push of the button from whatever volume, tone, 5-way setting you're at. For instance, you can have an overdriven sound on the amp but with the volume and tone pots rolled back with the neck humbucker split for a clean rhythm sound. Instead of flipping the 5-way switch to the bridge position and turning up the volume and tone pots for a searing distorted lead sound, you can just push the button in a split-second for a fully open bridge humbucker that actually bypasses all circuits inside the guitar. You get yet another humbucker sound that is louder, brighter and raunchier than it going through the normal circuitry (the volume and tone pots as well as the 5-way switch). The Blower switch not only adds convenience when you need to make quick sound changes on the guitar, but yet another very useful and righteous sound at your fingertips."

 

[deeaa]

That's a pretty cool feature!

And yeah, that's what I always want...the non-restrained, full and raw output of a pickup with no restraints. Whether I want cleaner or dirtier, darker or brighter, I rather use amp controls than constrict the sound source - I want the widest spectrum possible from the pickups. Hence I also prefer actives which have much wider frequency response than passives.

 

[markb]

Modern Fenders have the "Delta" tone control. The CTS made pot has a notch at "10" which takes the tone control out of circuit. They are available as a spare. Here's the first retailer I found selling them. I had one in my 8502 Tele' and it worked well.

http://store.stellartone.com/prostores/servlet/Detail?no=86

 

[deeaa]

Mm, if there were 25K versions I might install such pots, sounds like a good idea indeed!

 

[FrankenFretter]

Thanks for posting this, C64. I've always thought that the cap was in play, even with the tone maxed.

 

[kiteman]

There's the "no load" pots as I used them in my tele copy. At "10" position it's straight through to the jack. Really bright and literally screams.

 

[Monkus]

good info....thanks for posting.

 

[Bookkeeper's Son]

I need to call in my dog for a consult on this stuff.

 

[poodlesrule]

He is out on a walk with Elvis....