Expanding the stereo base
I want to offer you one version of such a device, which in its simplicity is completely inferior counterparts.
The scheme was taken in some of the ancient issues of the journal "Radio" for years, don't remember what exactly. Was assembled, tested in the case.
The width of the stereo is regulated by a variable resistor R1. On the right side of the engine - the stereo base is minimal and the result is a monaural signal. In the left position of the stereo base is expanded twice.
The scheme is not critical to detail, however, the variable resistor is recommended to use a slide, type JS3-23B. Connects this device, for example, between a pre-amplifier and power amplifier.
It feeds the stereo expanderfrom bipolar stabilized power supply voltage +/-15 volts.