I'm currently using piezo ceramic discs to amplify my acoustic guitars but there is an annoying bump at about 100-200 Hz.  Also the output is quite low so I would like to build a Mosfet Boost with some sort of variable bass roll-off. What are some low part count suggestions.
Thanks,
Jun

Would a 'varitone' type circuit work for this?
Jun

Great build for those who have not yet.
 Check out the links...Geo, AMZ, capacitors  in the signal path can roll of lows, try different [smaller] values

Does it have to be MOSfet? If yes, i guess you could stick a variable low pass filter before the AMZ MOSfet booster. If no, there are tones of small BJT/FET boosters with low parts count.

Thanks for the tip Pete.
I would like to build the Mosfet Boost since I've read so much about it  being a great non-coloring boost on this forum.
By 'low part count' I was referring to the tone section.  I didn't want to add a parametric eq but something passive like this:

http://www.muzique.com/lab/tone3.htm

Would the version 2 AMZ control work after the Mosfet Boost?
Jun

I just found the filter calculator
http://www.muzique.com/schem/filter.htm  
I'm gonna try a pot and cap after the Mos Boo.
Thanks,
Jun