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The preamp that was part of the package I was getting for my acoustic was no use to me on my own so I lent it to a friend who was complaining about the low output from his Martin. He said it had much more gain, but he couldn't fit it onto his Martin without enlarging the hole in the side.

I've taken his (80s?) Martin preamp apart and traced the circuit, and I can't see that anything can have gone wrong with it. It has a JFET source-follower buffer feeding a three-band passive EQ. Output from the EQ goes via the volume control to a 10dB JFET gain stage. I reckon overall gain as designed is probably 5 with the EQ centred and the volume up full.

Does anyone have any figures for typical acoustic preamp gain?

I asked SIRI and she said 42.

Great, I've set it up for 40.3, closest I could get with preferred values.

desertan wrote:I asked SIRI and she said 42.

lmfao

I told my sister to tell SIRI I'd give her one yesterday and she replied "I don't even know who your brother is."

Only guy I know with a 4s is on holiday atm.

I would point out that my reply was meant to be deadpan, but purely by coincidence I'd settled on that value for the output stage so the overall gain on the Martin preamp with EQ flat is now maybe 13. It's enough to drive my colleague's compressor to even out his Martin's levels a bit.

I'd say that 14 would be more accurate.

14 X 3 = (you guessed it) 42.