I was about to build the Geo "quick & dirty oscillator" ( http://www.geofex.com/FX_images/q+dosc.gif )
which produces an approximate sine wave of 1kHz, with outputs of 1V, 100mV, and 10mV.

Schematic states that the 100mV is the closest to a newly struck string.  Fine; that's what I thought too, actually.

I checked the schematic for my amp, a Fender Blues DeVille, ( http://www.mrgearhead.com/faq/schematics/fender/Blues%20DeVille%20Schematic.pdf ) and it appears that the test signal they use is 4mV.

So me slightly worried.  Why, if I'm reading it correctly, would Fender use only a 4mV test signal?  Also, (not terribly important), the Geo circuit states, "in a pinch, you can leave off the emitter follower t".  Great!  Which one's that?

Eden

the emitter follower is the right hand transistor and all of its support components (three resistors and three caps.)  you can just use the oscialltor and attach a cap right where the signal would have gone into the base of the right-hand transistor.

to get a small signal like 4 mV, you'll need to put in another resistor divider.  keep the emitter follower circuit, change the bottom resistor from 100 ohms to two resistors like 33 ohms and 68 ohms (33 at the bottom.)  add one more output cap between those two resistors.

after a string dies down, it easily goes down to 4 mV.