Orange Squeezer Question

[Rayman]

How importatnt is it to use 82K for R2 and 2.4K for R5?  Could I substitue 100K for 82K and 2.2k for 2.4K?  What would the be the affect?

[Mark Hammer]

R2, and Q2+R7 act like a voltage divider.  Where R2 joins Q2 can be considered as the "wiper" of this virtual pot.  Instead of having both R2 and Q2's resistance be fixed and move a wiper around, the amount of attenuation is a function of how much resistance is on either side of the R2/Q2 junction at any given moment; i.e., their ratio.  As a result, raising R2's value will mean that changes to Q2 resistance will have more impact.  In other words, there will be more noticeable volume drops (moment to moment, in response to picking) when R2 is higher.

Ths may or may not be to your liking.  The "cure", if it isn't to your liking, is probably to reduce the gain of the op-amp a little, so that you aren't forcing the JFET to drop resistance as much.

Alternatively, if you had a couple resistors you could put in parallel to get the needed resistance, you wouldn't have to change anything about the design.  E.g., 150k and 180k in parallel get you 81.8K - more than close enough for rock and roll.

As for R5, you got me there.

[Rayman]

Got it, thanks Mark.