capacitors and their function
- Thread starter iuserneim
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It depends on how is the capacitor connected. It can cut lower frequencies as well. In some preamplifier designs it sets gain or midrange frequency (a pair of capacitors is actually required).
In a generic passive tone control it really cuts higher frequencies - use higher values to cut more highs and get a boomier tone.
In a generic passive tone control it really cuts higher frequencies - use higher values to cut more highs and get a boomier tone.
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A capacitor's function depends on how it is connected in a circuit. In a power supply (including a battery powered circuit), the capacitor's job is to help regulate the voltage by opposing changes. If the DC voltage goes up, the capacitor charges, taking on more energy. If the applied voltage goes down, the capacitor discharges, releasing energy attempting to hold voltage constant. This has no effect on sound, unless, of course, the capacitor fails.
In a signal path, however, the capacitor behaves differently. In a coupling hookup, the capacitors job is to pass AC frequencies while blocking DC voltage. In this application, the capacitor presents a frequency-variable 'resistance' to the AC signal. The lower the frequency, the more 'resistance'. It's really called capacitive reactance. At zero Hertz (DC) it's reactance approaches infinity. In this sense, a capacitor behaves like a frequency-variable resistor.
In a passive tone control (typically a low-pass filter), the capacitor has reference to ground through a potentiometer. Because reactance reduces as frequency increases, more high frequencies are passed to ground, thereby making the remaining signal contain more low frequencies (This makes the sound more and more bassy as the resistance of the potentiometer is decreased.) Increasing resistance of the potentiometer allows less signal through the capacitor, thereby making the tone contain more high frequencies.
In signal path/tone control circuits, the larger capacitor can pass the lower frequencies.
Hope this helps,
Omar
In a signal path, however, the capacitor behaves differently. In a coupling hookup, the capacitors job is to pass AC frequencies while blocking DC voltage. In this application, the capacitor presents a frequency-variable 'resistance' to the AC signal. The lower the frequency, the more 'resistance'. It's really called capacitive reactance. At zero Hertz (DC) it's reactance approaches infinity. In this sense, a capacitor behaves like a frequency-variable resistor.
In a passive tone control (typically a low-pass filter), the capacitor has reference to ground through a potentiometer. Because reactance reduces as frequency increases, more high frequencies are passed to ground, thereby making the remaining signal contain more low frequencies (This makes the sound more and more bassy as the resistance of the potentiometer is decreased.) Increasing resistance of the potentiometer allows less signal through the capacitor, thereby making the tone contain more high frequencies.
In signal path/tone control circuits, the larger capacitor can pass the lower frequencies.
Hope this helps,
Omar
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True in the sense that you would receive the full spectrum of the signal (full lows; full highs), but there would be no means of rolling off highs to change the sound. Passive tone controls are typically low-pass filters.
Active filtering using op-amps is quite a different concept.
O
Active filtering using op-amps is quite a different concept.
O
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iuserneim said:
Assuming potentiometers of equal value, the larger capacitor would allow more lows, however we would see values more in the range of .01 microfarads.
The trick here is, if the larger capacitor is connected to ground, it will pass more lows (and highs) to ground, thereby making the resultant signal more bassy. If the larger capacitor is in series with the signal path, it will pass more lows and high frequencies, thereby allowing the tone to keep more of it's full spectrum. This case would let the tone contain more treble.
The truth is, passive circuits can only cut, not boost.
Confusing? You bet!
O
