PURPOSE: To improve the operability by controlling an ALC by detecting a voltage or a level of a tap provided on a clock point of a volume.

CONSTITUTION: When a sound recording level adjusting vomume RV1 is in a click point, a tap becomes the ground potential, and an input level of a comparator 3 becomes the ground potential, therefore, a comparison output becomes an "H" level, and an ALC circuit 1 becomes on and becomes an ALC mode. Also, when the RV1 is set to other position than the clock, the comparator input becomes an "H" level, the comparison output becomes an "L" level, and the ALC circuit 1 becomes off, and becomes a manual sound recording level adjusting mode.