Hey guys,
Occasionally I get the urge to like...you know...do some learnin'. At the moment I'm looking at some basic op-amp circuits and I have 2 things I'm not totally sure about. Lets use the Dist+ as an example:
(http://www.freeinfosociety.com/electronics/schematics/audio/pictures/mxrdistp.gif)
1) For biasing the positive input of the distortion plus there are the 1meg resistors coming from +9v. I would have assumed that we'd want the positive input of the opamp to sit at +4.5v? As far as my knowledge of voltage dividers go, +4.5v should be a the middle junction of those 2 (3) 1 meg resistors. Wouldn't the point where the positive input is actually connected to be closer to ground?
2) The low pass filter on the feedback loop of the dist+ (the distortion pot) is connected to ground. I have seen some circuits (the love pedal for example) connect this to the +4.5v point of the voltage divider as I described in the last point. Is there a reason for this? Is it effectively achieving the same thing? (your guitar signal sitting at a +4.5v bias point).
Hope this isn't too complicated a question(s) to be asking, thanks for any help!
Paul