My booster project questions?

[Curtis]

Ok so im new here (actually this is my first post) and this is the schematic for a booster pedal i want to build, it'll be my first, and i just have a few questions. Its just a Fetzer valve and an output buffer



1) Is there anything that can be omitted with out changing the overall tone?
2) I've seen in the Xotic RC Booster that the third lug on the pot is connected to the bias voltage. What does that do? Will it work with this?
3) Is the output buffer necessary? I figured that i wouldn't need an input buffer cuz jfet have such high input impedances but i didn't know for outputs.
4) Should i increase the volume pot to 100K?

[amptramp]

1. I would say everything there is worthwhile although some people would find a favourite value for the 20K gain pot (in the FET drain circuit) and substitute a fixed resistor.  But I would leave it in - you never know when you need a different sound and it allows you to compensate for variations in FET characteristics.  You have a boost switch at the FET source that causes the high frequencies to be boosted when it is closed.  You may want to make it permanent or delete it ind the 0.15 µF capacitor.  But I would keep my options open and leave it in.  There are things that are not shown such as the divider for 4.5 volts for the base resistor for the bipolar transistor and any protective or filter circuitry for the power input.  This design is pretty simple - a FET load control and a volume control with two transistors and no op amps.  There is not much point in trying to simplify it.

2. I assume you are talking about the 50K pot.  Connecting the 50K pot to anything above ground would cause the right-hand diode to turn on.  The Xotic design would be just as good (or better) if the pot went to ground.  The Xotic has an input buffer followed by asymmetrical clipping based on a tube screamer op amp stage followed by a Baxandall tone control and a buffer.  The Xotic design is here:

http://schematic.exteen.com/xotic-rc-booster-ac-booster

3. You may find other stompboxes that would work without an output buffer (such as those with a 50K input impedance), but the advantage of the buffer is that you have complete control of what the diodes see regardless of what is connected externally.  The low output impedance is a good thing - it reduces the sensitivity of the performance characteristics to the next pedal or amp input characteristics.

4. You could increase the volume pot, but the impedance is dominated by the drain load of 5.1K to 25.1K anyway.  You might get better bass response but with the turnover at 31.8 Hz in the existing design, there would be little effect even for a bass guitar.

[Curtis]

Thank you so much  that was wonderfully stated