This circuit can be used to setup
their home-cinema set adjusting all the loudspeaker outputs to the same
level when heard from the listening position. The circuit is very simple
(though linear and precise) ac millivoltmeter, using an existing
multimeter set to 50 or 100µA fsd with the probes connected to J1 and J2
to read the results.
Skema Rangkaian Pengukur Suara Speaker
The precision of the measure is entirely depending on the frequency response of the microphone used but, fortunately, for the main purpose of this circuit an absolutely flat response is not required. Therefore, a cheap miniature electret microphone can be used.
Note:
Please be careful and set the volume control very low, to avoid loudspeakers' damage. Switch-on the Sound Pressure Level Meter and increase the volume of the amplifier in order to obtain an approximate center-scale reading. Repeat the same steps with all channels.
Skema Rangkaian Pengukur Suara SpeakerList coponent R1................................... 10K 1/4W Resistor R2,R3............................... 22K 1/4W Resistors R4................................... 100K 1/4W Resistor R5................................... 100R 1/4W Resistor C1................................... 1µF 63V Polyester or Electrolytic Capacitor C2................................... 100µF 25V Electrolytic Capacitor C3................................... 220µF 25V Electrolytic Capacitor D1-D4............................... BAT46 100V 150mA Schottky-barrier Diodes IC1................................... CA3140 Op-Amp IC MIC................................... Miniature electret microphone (See Notes) J1,J2................................. 4mm Output sockets SW1.................................. SPST Toggle or Slider Switch B1................................... 9V
The precision of the measure is entirely depending on the frequency response of the microphone used but, fortunately, for the main purpose of this circuit an absolutely flat response is not required. Therefore, a cheap miniature electret microphone can be used.
Note:
Please be careful and set the volume control very low, to avoid loudspeakers' damage. Switch-on the Sound Pressure Level Meter and increase the volume of the amplifier in order to obtain an approximate center-scale reading. Repeat the same steps with all channels.
