The amplifier itself is designed considering simple tone and distortion circuitry.
It’s a circuit that uses resistors, conductors, capacitors, and op amps, altogether to give you a very interesting audio effect.
It’s a very simple; three stage circuit with a Tone control front end that has some gain as well. And then there is a Gain distortion stage in the circuit that gives you kind of the guitar crunch sort of sound. And then the last part of this is the simplest power amplifier.
Two relatively low-resistance resistors are just set up to have a modest amount of gain, around 10 or so. And, the, capacitors work like just DC blocks. They're essentially short circuits for the signal, the AC, frequencies of the signal. But they, isolate, like the inverting input from whatever the DC voltage is coming. LEDs are used to indicate the ON/OFF status of the amplifier.
TL072 Op Amp is used, this is two Op Amps in one package. So they are used as Half of one of the Op Amps for tone control, and the other one for the gate control.So that's why it's one half of that, it's a dual Op Amp chip.
The tone control circuit is basically just a Op Amp setup in an inverting amplifier configuration, so the input goes through the input resister to the inverting input of the Op Amp.The non-inverting input is grounded, and then there's feedback from the inverting input from the output back to the inverting input.
And the network that goes on the, in the feedback path Is the parallel combination of a capacitor, 10 Nano-farad capacitor, and a 50 kilo-ohm resistor.The resistor acts like a potentiometer.And the center wiper on the potentiometer is connected to one den, one end of the capacitor.
The capacitor is going to look like a smaller impedance for higher frequencies. And therefore the total feedback impedance is going to be reduced, so the gain is going to go down. So, for high frequencies, so when the wiper is up at the end. Then the gain is turned down for the high frequencies. So that means that the low frequencies are accentuated. So that's like turning up the bass in, in this amplifier.Now on the other end, sliding, moving the slider all the way to other end then gives the circuit its full bandwidth.
There's no loss of gain for the higher frequencies because the capacitors just taken out of the circuit. And so that has the effect of turning up the treble control, so it kind of accentuates the high frequencies. So one end, its bass boost, other end, its treble boost.
Feedback Network:
As a function of the potentiometer settings, which is between 0 and 1.It's the series combination of the resistor. So this plus impedance. Now this impedance is the parallel combination of the feedback capacitor and this piece of the, resister, gRF. And so the parallel combination of those two is the product of their impedances.
The expression for the gate, the magnitude of the gate is just the feedback impedance divided by the input resistance.This is a function of frequency now. And so the gain is going to be a function of frequency.
