the tone cap myth...

[salvarsan]

What do you think of tantalum caps? (not for tone controls of course)

They last forever if you treat them well.

I know of one effects builder (Barber Electronics)
who likes them in the signal path of one of his pedals
because of their mild hysteresis distortion.

-drh

[Possum]

...

I will try to dig out my "before" and "after" audio clips of these pickups going from the ceramic .047uf to singlecoil.com .022uf cap. Believe me the difference was remarkable, you WILL hear it.

[David Schwab]

They last forever if you treat them well.

I know of one effects builder (Barber Electronics)
who likes them in the signal path of one of his pedals
because of their mild hysteresis distortion.

I used them instead of the aluminum cans when I can. I had always read they were better then regular electrolytic caps.

[Steve A.]

I remember seeing some audiophile website where they claimed if you remove the shrink wrap label from the aluminum can, it will improve the tone! They reasoned it was because plastic sounds bad.

What do you think of tantalum caps? (not for tone controls of course)

When I was building all of those Craig Anderton kits back in the 80's, tantalum caps were like the gold standard for coupling caps... a big step up from those cheap electrolytics! In guitar amps you can use them for the cathode resistor bypass caps but that's about it (for the higher voltage ratings they get very HUGE and very expen$ive).

Steve Ahola

P.S. The plastic shrink wrap could introduce static electricity, perhaps if there was a fan passing air currents over the board. Other than that I'd probably file it away with the vintage rubber bands that Eric Johnson uses to hold the bottom plate on one of his pedals... cough! cough!obsessive compulsive disorder! cough!

P.P.S. The loading down of a pickup with a 250-500k tone pot set to 10 using a typical 0.022uF cap is perhaps most noticeable when you really crank up your amp. One of my early custom tele harnesses used a push-pull pot to select between volume and tone control functions, and a friend took me to task on that- I ended up hard wiring a 270k resistor and a .022uF cap to the switch for the volume control position... and had to agree that it did sound much better that way!

[Possum]

...

Yeah some of this stuff is more noticeable when you play loud, thats where it really shows the differences....

[David Schwab]

When I was building all of those Craig Anderton kits back in the 80's, tantalum caps were like the gold standard for coupling caps... a big step up from those cheap electrolytics! In guitar amps you can use them for the cathode resistor bypass caps but that's about it (for the higher voltage ratings they get very HUGE and very expen$ive).

Yeah, it was Anderton that I was referring to. He always steered people away from ceramic caps. I use tantalum for polarized coupling caps and use aluminum cans for power filtering, etc.

P.S. The plastic shrink wrap could introduce static electricity, perhaps if there was a fan passing air currents over the board. Other than that I'd probably file it away with the vintage rubber bands that Eric Johnson uses to hold the bottom plate on one of his pedals... cough! cough!obsessive compulsive disorder! cough!

I figured maybe it produced another level of capacitance, but that's kind of reaching for straws! I appreciate high quality audio gear, but some of these people swear by painting "special" lacquer ($80 a half ounce) on their gear to improve the tone, and one guy was selling home made varnish that had carbon dust in it to paint on your plastic IC's to make them sound like vacuum tubes!

Then there were the $600 wooden knobs one place used to sell to improve the tone of the $1200 passive volume control they sell. They still sell these ridiculous wire wound resistors where they wind silver wire on a wooden dowel... sounds like an inductor to me! And they are only about 5 Ohms or whatever.

[David Schwab]

Yeah some of this stuff is more noticeable when you play loud, thats where it really shows the differences....

Dave, you went from a .047 to a .022 cap. That's why you heard a difference. You can do that with two ceramic caps and you will hear a difference.

You need to try that with two .022 caps.

I find better quality caps sound better when you have the control on zero, but on 10 I don't notice it.

[Mike Sulzer]

Yeah some of this stuff is more noticeable when you play loud, thats where it really shows the differences....

I think that a 250K resistor placed across a pickup is audible as long as it is loud enough to hear the guitar clearly, whether or not there is a .02 microfarad capacitor in series. It is easy to measure the effect of the resistor, too.

Measuring the difference between a .02 or a .047 or an infinite capacitance (short across the cap) is futile as this shows:http://www.naic.edu/~sulzer/jpToneComp.png.

Computing this is like walking along the diagonal to save steps (Pythagorean theorem). The current through a resistor is in phase with the voltage across it. The voltage across a capacitor lags the current by 90 degrees. When you put a resistance in series with a capacitive reactance, you use the Pythagorean theorem to compute the magnitude of the total impedance. We have a large resistance and a small capacitive reactance. The square root of( 500000 squared + 2500 squared) = 500006.25. You cannot hear this tiny difference in the amplitude at the peak. You cannot measure it. The tone pot is intended to remove the effect of the capacitor when it is on 10. It does its job well.

[Joe Gwinn]

I know of one effects builder (Barber Electronics)
who likes them in the signal path of one of his pedals because of their mild hysteresis distortion. -drh

Does he use wet-slug tantalums, or dry pellet? It makes a big difference.

[HoaglandBrothers]

Wilkinson caps?

Has anyone had any experience with Wilkinson mylar caps? One of my suppliers just offered them to me so I bought 10 of each to check them out.

[salvarsan]

Does he use wet-slug tantalums, or dry pellet? It makes a big difference.

Could be either. Dave Barber is purely empirical in his approach --
if he likes the component sound in a particular circuit, he uses it.

-drh

[Mark Hammer]

While the skeptical side of me would be quick to pooh-pooh this thread, the other side of me that is fond of saying "Context is everything" is pleased by what I've been able to learn here.

In a perfect world, where the maxed tone pot would present enough series resistance to preclude ANY loss of bandwidth, I would be very quick to roll my eyes at the suggestion that tone cap type on the guitar itself can have any impact.

On the other hand, as someone who has equipped my own guitars with tone switches that completely lift any tone cap entirely from the circuit, I can attest to the fact that a 500k pot is not exactly a brick wall when it comes to bleeding treble. And I thank Possum for reminding me of that and allowing me to soften my hardass views.

All of that being said, what this thread makes the strongest argument for is a simple no load tone pot, rather than the rabid pursuit of exotic caps. At one time, I suppose the bumblebee type were simply what you could buy. But with the emphasis on production of miniaturizeable caps, things like bumblebee types become a rarity, and with that their price skyrockets. Enough that it is simply more prudent and cheaper to install a switching or no-load tone pot that can lift the cap out of circuit, than it would be to spend big bucks to let the cap itself do all the heavy lifting. So, the "tone cap myth" can have some substance to it, but that does not necessarily imply that the "tone cap problem" MUST be solved by the tone cap itself.

I suppose the most difficult task would be persuading dangerously misinformed customers that this does the same thing at lower cost, and that if the cap is disconnected it should not matter what the cap type is. Once objects take on mystical qualities, and find a willing community of believers, it can become hard to shake such beliefs out of people's heads, and hard for them to recognize that the desirable aspects of that component type are confined to a very specific set of circumstances which can be sidestepped.

Incidentally, one wonders if what Dave observed is not an argument for higher-value reverse-log tone caps. That is, something like a 2-meg pot that passes through the first meg and a half after maybe 15% of the pot's rotation, and spreads the remaining 500k over the other 85% of rotation. Remember that "no-load" pots provide open circuit or infinite resistance, and at some point along the way a high-enough load is functionally equivalent to no load.

[salvarsan]

Hail, Marcus.

On the other hand, as someone who has equipped my own guitars with tone switches that completely lift any tone cap entirely from the circuit, I can attest to the fact that a 500k pot is not exactly a brick wall when it comes to bleeding treble. And I thank Possum for reminding me of that and allowing me to soften my hardass views.

We agree that the tone circuit loading effect is audible, reproducible,
remediable, and that solutions have been available for years.

This is what I call "settled" technology in that the issue was settled over
10 years ago when people started disconnecting the tone control circuit
or using the no-load tone pot that you described.

Mystical tone capacitors are a tad more subtle but a heuristic is that
inexpensive microphonic caps have no place in an audio signal path.
Ciao, .022uF disc caps, hello .022uF polyester.

For me to doctrinairely argue from assumptions of electronically ideal
components is to invite large toothmarks on my backside from ferocious
Reality bites. I will not speak for others on this point.

-drh

[Mark Hammer]

The microphonic qualities of some caps is something I have no personal knowledge of since the only playing I do is generally something a person could talk over, or at least shout over easily enough to make me turn down. At those sorts of levels, NOTHING is microphonic.

On the other hand, I ask myself "At the volume levels that a cap could become microphonic, is anyone going to notice something deleterious?". I mean, jeez, aside from Hank Marvin just exactly who DOES play pristine clean at high levels?

[Mike Sulzer]

Hail, Marcus.
We agree that the tone circuit loading effect is audible, reproducible,
remediable, and that solutions have been available for years.

But I do not think we are agreed on what the tone loading effect (tone pot on 10) is the result of. I claim it is the resistance of the pot that is making the effect with the cap acting as a low impedance path to ground. This effect is then the same as the loading that a volume pot does. But so far, no one with any electronics experience has agreed with this explanation, or said that it is wrong because....