Tuesday, 8 January 2013
Info from circuit designer J. Nagy: The Supa Nova is a very low to pretty high gain, tube-ish, distortion pedal that relies on a MOSFET (BS170) to overdrive two JFETs (J201). The tone controls are designed to provide adjustment to the middle and upper frequencies. Voltage at the drains of Q2 and Q3 should be about 5.4 and 4.7, respectively, but make sure to tune by ear. Q4 can be a 2N5088 bipolar transistor or a JFET. The layout is meant to accommodate either. The JFET is smoother and mellower than the 2N5088, while the 2N5088 (my favorite) is clearer and has a bit more edge and attack. Silver-mica capacitors are recommended for the pF values, as these sound less smeared in this circuit than ceramic. All capacitors are in uF unless otherwise noted. Consider excluding D1 if a battery is your primary power source. You might notice that it sounds better this way. If you like to live dangerously, see if you can hear a slight increase in highs by removing D2.