[biasing issue, now resolved] Fatpants 2012: Increase headroom?

[thebigkevdogg]

Just finished a successful Fatpants build - I absolutely love how it sounds with my tele! The one issue that I'm having, however, is that I mostly play a pedal steel guitar with really high output pickups which is causing the pedal to distort quite noticeably. For example, I had to tweak the internal trims on my Keeley Compressor to keep it from clipping. I plan to use the fatpants as a tone shaper quite often instead of a volume boost, so keeping a pristine clean signal at unity gain is preferred.

My question - what's the best way to do this? I'm a bit of a noob - the way I know to do it would be to add a little trim pot between the 3pdt and the circuit board to cut down the input level. Is there a more elegant solution? If not, what's the best pot resistance value to use? The fatpants is always after a buffer (Cornish buffer clone) built into my pedal board.

Thanks in advance!

P.S. one little question, is the volume supposed to drop out when I max out the Fat control? The very last few degrees of travel in the knob completely cause the output to reduce to zero (no volume loss effect is seen elsewhere in the travel of the knob).

[midwayfair]

Sounds like it's biased incorrectly based on your P.S. Make sure you had the Fat control set to max AND that you had the fat switch in the "off" position before biasing.

Try that first -- if your steel guitar still distorts it, there are some fixes, but this thing has some SERIOUS headroom, so I'm surprised anything can distort it.

Maybe one of the active pickup folks on the forum will chime in, too.

[thebigkevdogg]

Well that was a stupid question, you are totally right. I biased it wrong. Now that I've done it correctly (and know how to read a JFET schematic symbol) the FAT knob issue is gone and there is ample headroom on tap. Thanks!