Analog Electronics Lab #9

1. For the circuit below, if the signal is loud enough to distort, which of these will the output signal look like?

If the signal is loud enough to distort, the output signal will look like answer A, the symmetrical distortion.

2. For the circuit below, if the signal is loud enough to distort, which of these will the output signal look like?

If the signal is loud enough to distort, the output signal will look like answer B, the asymmetrical (single-sided distortion).

3. Is it safe to assume that the output of these two circuits will sound the same and be the same volume?

The output of these two circuits will not sound the same or be of the same volume because the second circuit has a buffer, and the first circuit does not. Without a buffer, the resistance of the speaker/headphones and the resistance of the diodes interact in a strange way, behaving as though they are in parallel, which can result in a significant decrease in volume, or some bizarre distortion effect that we do not want. However, with a buffer, we are able to avoid this through the nature of the feedback loop, which produces a strong output signal without the strange, undesired effects of the diodes’ resistance or a great volume decrease. To achieve this, plug the input signal into the positive input, and plug the output signal into the negative input. From here, it will be possible to properly hear and control the distortion effects. Overall, the distortion effects will sound correct with the buffer like in the second circuit, and the sound will be strange or very quiet without a buffer like in the first circuit.

4. Fill-In-The-Blank Question:

Below is the schematic for the circuit I made in the video. I’d refer to the potentiometer at the end, right before the output circuit, as the “crossfader.” With this circuit, if you turn the crossfader all the way to one side you’ll hear a completely clean signal.  If you turn the crossfader all the way to the other side you’ll hear the signal at its maximum level of distortion.

5. If you turn the potentiometer to its halfway point, you’ll hear…

If you turn the potentiometer to its halfway point, you’ll hear a blend between the distorted signal and the clean signal. So, the signal is not completely clean, but it’s not at its maximum level of distortion either, it is at a balanced blend between the two. You’ll hear the exact average of the voltages of the two signals.