Bo Deadly
Well-known member
The gain is maximum at 10 ohms which will be 60dB or so. But if you vary the series resistance with a potentiometer like you're looking at doing, the gain can be adjusted. I'm not sure what's confusing about that.
The 3300u cap makes an RC with the 10 ohms for a roll-off at 5Hz. But at lower gains, the series resistance is higher and so the roll-off is lower accordingly. If you switch the capacitor to a smaller size, the roll-off frequency goes up. At 1000u, it's 16Hz. But the recommended cap is oversized because even at 16Hz, a mediocre electrolytic capacitor might translate to distortion in the output.
I used 100u for the smallest cap in my circuit and my gain is trimmed to 67dB which equates to a roll-off of 200Hz or so. But as Abbey and I were discussing, the gain and roll-off interact with each other. As the gain is increased, the series resistance gets smaller and so the roll-off frequency shifts up.
The 3300u cap makes an RC with the 10 ohms for a roll-off at 5Hz. But at lower gains, the series resistance is higher and so the roll-off is lower accordingly. If you switch the capacitor to a smaller size, the roll-off frequency goes up. At 1000u, it's 16Hz. But the recommended cap is oversized because even at 16Hz, a mediocre electrolytic capacitor might translate to distortion in the output.
I used 100u for the smallest cap in my circuit and my gain is trimmed to 67dB which equates to a roll-off of 200Hz or so. But as Abbey and I were discussing, the gain and roll-off interact with each other. As the gain is increased, the series resistance gets smaller and so the roll-off frequency shifts up.