Well, again, we present a very simple circuit. As is also shown in the drawing, few parts. The circuit is based on a dual operational amplifier RC4558. But this is only half used, so there is only one using the op amp. Alternatively, you create an active tone control in the second operational amplifier section.
In this video you can hear a small taste of what kind of voice. We replaced the parts, which is how to cut the signal. The germanium diode harder and softer LED performs cutting. Look, listen:
Op amp and tone change:
In the drawing, R1, C3, and R7 are members of the potentiometer variable tone. a slight variation of R1 and C3 highlight the value of the tone can be adjusted. But who wants to experiment with feel free to skip. Instead, the second operational amplifier, the unused portion can build active tone regulator. A little help here: Tone stack circuits. Mission operations and the rc4558 amplifier instead of calmly you can test the TL072 possibly NE5532 type.