Tue Dec 7 13:55:04 EST 2010
Guitar output voltage and AC/DC coupling.
Measuring both guitar and bass with DVM AC mV gives me just below
200mV max output. The quiet voltage is about 2.2mV which is probably
hum due to the unshielded cable hookup (I have no scope yet...).
So I think it's safe to conclude that guitar signals do not really
need any boost when working with 9V or +- 4.5V circuits; the level is
fine as it is.
Next: Can a guitar be DC-coupled to the half-way ref voltage? This
depends on the power supply use in other circuits. It seems to be the
convention to tie the signal ground to negative power. In that case
the ref voltage would be shorted. Answer: no, AC coupling is
necessary. If box uses batteries (power supply is local) there is no
Next: What resistors should be used for a R/R voltage divider for the
1/2 ref voltage? Should there be a cap from ref to ground if there is
a unity gain buffer? It seems the reason for the cap is to short AC
noise to ground.