Low Frequency Response Audio Level Meter

This project is an output level meter which is similar to the one in project Audio Output Meter in Testers section. Can you explain the differences?

This project has the same basic characteristics of the other project. The Meter circuit is the major change. This circuit uses the 50K Control as a combination shunt-series resistance, the other circuit uses it as a variable series resistance only. Can you determine which circuit is capable of reducing the Meter output to zero, and which circuit is not?

This Meter circuit has a much improved low frequency response compared with the other circuit. This is obtained by an input Capacitor of larger value and the elimination of the filter Capacitor.

Another important change is that this circuit responds to the average signal level, the other circuit tends to respond to the peak of the signal. This is due to the action of the filter Capacitor in the other circuit.