I need to amplify my guitar signal, which is in the milli-volt range and swings +/-.... I just need to boost it up with a gain of... I dunno maybe between 10-100... maybe 500 at most.... but I'm looking for a good op-amp to boost this audio signal and that I can operate from a 9V battery
... a gain ofbetween 10-100... maybe 500 at most....
That means the gain-bandwidth product is 10 MHz; you will want to cascade two garden-variety amplifiers (each with max gain of 22). TL072 is a suitable dual op amp for audio. Connect the midpoint of your 9V battery to your ground, so it makes a +/- 4.5V supply.
So... in order to use an opamp with a guitar signal (or audio signal) I will need to power one of the rails with a negative voltage... is this right? If I have one of the rails at ground, does that mean that I can't go lower than that with my output?
My intention was not to get the full gain with a single amplifier stage; two stages of amplification (22 being the square root of 500) means that neither stage needs get near the gain-bandwidth limit.
It's not a necessity, the signal can either go through a DC blocking capacitor OR the power supply can be ground-referenced at midpoint. It's easier to do to the power supply, though.
Not lower if your output is directly coupled to the operational amplifier; it'd take a transformer or capacitor, with some associated low-frequency rolloff. You need some low-frequency DC rejection in any case, with a gain as high as 500 volts out per volt in, but it can be a small capacitor that isn't signal-critical.