by GP49 Mon Jul 19, 2010 6:14 pm
The VU meters you salvaged: what did they come out of?
In most cases it's best to drive such meters with a small transistor amplifier stage, to buffer the meter coils from the output of the amplifier and to provide a means to calibrate them. Even with that, however, it's doubtful that you would ever be able to determine the peak power your amplifier is putting out from the meter reading. Most power peaks are almost instantaneous in nature and are long gone by the time that slow, sluggish meter needle is going to be able to respond; by the time the needle gets a short distance up, the peak is gone and the meter needle goes back down again.
That's why there is a specific calibration and damping standard that applies to standard vu meters and their circuitry.