This circuit, to add the ambience effect, was suggested by National Semiconductor in documentation from the 90s. The amplifier needs an appropriate power source.
We found this circuit in an old documentation from the 70s. The text is the original one of the...
The circuit shown in figure is suggested by Maxim in an application note. The operational...
We found this amplifier in a 1990 documentation. The transistors are common, having been made...