TWANG
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Anyone ever read what Terry Downs @ TDPRI wrote about caps? Here's a post from him...
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I always dread getting into this, but here goes.
The capacitor thing IS A MYTH. I could write a book on it, but I'll only summarize here.
1. Capacitor Doesnt Contribute Much - Probably most significant misunderstanding about the tone network is that the capacitor is not a significant part of the circuit until you are near the most counterclockwise (CCW) range of the pot. Here's why. A resonance occurs between the inductance of the pickup and the capacitance of the pickup/cable/amp. It generally occurs in the treble region, especially on Teles with single coils. Check the plot below.
I believe I did this PSPICE simulation with a Tele bridge pickup, 500K pots, 10ft cable, and a Fender Twin input impedance. This family of curves is the frequency response of the guitar at the various 10 dial positions of the tone pot. Notice each curve has the dial position/resistance of the audio taper tone pot. Notice the resonance hump at the high dial positions is at about 3.4kHz. That's the Tele treble most of us love. With the tone pot at max, the resistance of the pot is 442kohms (this comes from actual test data I took on a 500K Alpha pot), well within the 20% tolerance. The reactance of a 0.05µF capacitor at above a few hundred Hertz is practically zero. It is only a few kohms down at 100Hz. So, the capacitor is just a low impedance coupling cap to a variable resistor. As you turn the pot down, the load that the pickup sees is a lower resistance. This damps out the resonance. The resistive load of the tone pot as it is turned down is a RESONANCE KILLER. Notice it doesnt shift the resonance frequency. Guess what, it takes capacitance to do that!!
As the tone pot approaches max CCW, the tone network is now purely capacitive and the resonance is back, but now at 300Hz (dial at zero).
If you use the tone pot at max CCW, then the capacitor makes a big difference. It decides where that low frequency resonance occurs. If you only turn down the tone pot slightly to lets say to remove the "icepick", then the pot is what's accomplishing that for you.
Prove it to yourself. If you slightly roll off highs with a tone pot, open your control cavity and use a clip lead and SHORT OUT YOUR TONE CAP. You won't be able to hear much difference in the tone pot's operation until it is turned down fairly low. At max CCW of course the signal is shunted to ground and nothing comes out.
2. Capacitor Types - As mentioned earlier with the twinkie analogy, the amplitude and frequency range of a guitar signal poses no challenge for any capacitor (except for a polarized cap). One of the reasons why ceramics get a bad rap is because many of the Fenders come with a the 503Z.
This a 0.05µF ceramic that has a tolerance of -20% to +80%. The actual capacitance of this part could be as high as 0.09µF !!! They are used because they are cheap. If you like using your tone control near max CCW, and you change that cap out with a tighter tolerance 0.05µF, you will hear a difference. It's only the capacitance value that matters, and that only matters in the lower fourth of the tone pot's range.
3. Psychoacoustic effects - Anyone that cares about what something sounds like will be a tinkerer. I have chased my tail on many things. It is easy to convince your mind that a changed part will affect the sound of something. It is only natural and normal. I'd venture to say that some of the folks that think they can hear the difference in a particular capacitor type (capacitance value being the same) are of a breed of folks that are sensitive to various changes in the acoustic environment and have better senses than I do. I've never understood how anyone could have perfect pitch, but they exist. So, I have no disrespect to any audiophile. I'm just stating the engineering facts.
4. Amplifer Impedance - This isn't mentioned much, but the amplifier input impedance is just like having another tone pot in parallel, although it has no series capacitor. That input impedance is also a resonance KILLER. Also the capacitance of the amp input and cable will shift the resonance. Oh yes, if there is a capacitor on the input of an amplifier, why isn't it paper in oil too?!?!?!?!?
5. Looks Good Under the Hood - If you like the looks of a $60 cap for your vintage vibe, then go for it.
Capacitor Upgrades - Myth? - Telecaster Guitar Forum
----------
I always dread getting into this, but here goes.
The capacitor thing IS A MYTH. I could write a book on it, but I'll only summarize here.
1. Capacitor Doesnt Contribute Much - Probably most significant misunderstanding about the tone network is that the capacitor is not a significant part of the circuit until you are near the most counterclockwise (CCW) range of the pot. Here's why. A resonance occurs between the inductance of the pickup and the capacitance of the pickup/cable/amp. It generally occurs in the treble region, especially on Teles with single coils. Check the plot below.
I believe I did this PSPICE simulation with a Tele bridge pickup, 500K pots, 10ft cable, and a Fender Twin input impedance. This family of curves is the frequency response of the guitar at the various 10 dial positions of the tone pot. Notice each curve has the dial position/resistance of the audio taper tone pot. Notice the resonance hump at the high dial positions is at about 3.4kHz. That's the Tele treble most of us love. With the tone pot at max, the resistance of the pot is 442kohms (this comes from actual test data I took on a 500K Alpha pot), well within the 20% tolerance. The reactance of a 0.05µF capacitor at above a few hundred Hertz is practically zero. It is only a few kohms down at 100Hz. So, the capacitor is just a low impedance coupling cap to a variable resistor. As you turn the pot down, the load that the pickup sees is a lower resistance. This damps out the resonance. The resistive load of the tone pot as it is turned down is a RESONANCE KILLER. Notice it doesnt shift the resonance frequency. Guess what, it takes capacitance to do that!!
As the tone pot approaches max CCW, the tone network is now purely capacitive and the resonance is back, but now at 300Hz (dial at zero).
If you use the tone pot at max CCW, then the capacitor makes a big difference. It decides where that low frequency resonance occurs. If you only turn down the tone pot slightly to lets say to remove the "icepick", then the pot is what's accomplishing that for you.
Prove it to yourself. If you slightly roll off highs with a tone pot, open your control cavity and use a clip lead and SHORT OUT YOUR TONE CAP. You won't be able to hear much difference in the tone pot's operation until it is turned down fairly low. At max CCW of course the signal is shunted to ground and nothing comes out.
2. Capacitor Types - As mentioned earlier with the twinkie analogy, the amplitude and frequency range of a guitar signal poses no challenge for any capacitor (except for a polarized cap). One of the reasons why ceramics get a bad rap is because many of the Fenders come with a the 503Z.
This a 0.05µF ceramic that has a tolerance of -20% to +80%. The actual capacitance of this part could be as high as 0.09µF !!! They are used because they are cheap. If you like using your tone control near max CCW, and you change that cap out with a tighter tolerance 0.05µF, you will hear a difference. It's only the capacitance value that matters, and that only matters in the lower fourth of the tone pot's range.
3. Psychoacoustic effects - Anyone that cares about what something sounds like will be a tinkerer. I have chased my tail on many things. It is easy to convince your mind that a changed part will affect the sound of something. It is only natural and normal. I'd venture to say that some of the folks that think they can hear the difference in a particular capacitor type (capacitance value being the same) are of a breed of folks that are sensitive to various changes in the acoustic environment and have better senses than I do. I've never understood how anyone could have perfect pitch, but they exist. So, I have no disrespect to any audiophile. I'm just stating the engineering facts.
4. Amplifer Impedance - This isn't mentioned much, but the amplifier input impedance is just like having another tone pot in parallel, although it has no series capacitor. That input impedance is also a resonance KILLER. Also the capacitance of the amp input and cable will shift the resonance. Oh yes, if there is a capacitor on the input of an amplifier, why isn't it paper in oil too?!?!?!?!?
5. Looks Good Under the Hood - If you like the looks of a $60 cap for your vintage vibe, then go for it.
Capacitor Upgrades - Myth? - Telecaster Guitar Forum
