rp
Well-known member
I've attached a screenshot the 1178 preamp section with some elements removed for legibility.
I'm trying to understand what's going on between the inverting input of the op amp and ground and how that relates to the Fet. Can anyone recommend some resources or search terms that would help me get there? Or if you're up for it, can you explain what's going on here?
Things I don't understand:
1 - What's the point of R9 and R10?
5 - Why isn't C10 just tied to ground?
2 - What's the point of R6/C9 if they are mostly bypassed by R7/R8?
3 - How do I figure out the gain of IC2-B? Is it just 1+((R7+R8) / (R9+R10))?
4 - What's R5 doing?
6 - Why take the distortion-improving dry signal (R15,C12) from the output of the op amp instead of directly from the drain of the fet?
I'm guessing most of these features are related to feedback aimed at lowering distortion?
I'm trying to understand what's going on between the inverting input of the op amp and ground and how that relates to the Fet. Can anyone recommend some resources or search terms that would help me get there? Or if you're up for it, can you explain what's going on here?
Things I don't understand:
1 - What's the point of R9 and R10?
5 - Why isn't C10 just tied to ground?
2 - What's the point of R6/C9 if they are mostly bypassed by R7/R8?
3 - How do I figure out the gain of IC2-B? Is it just 1+((R7+R8) / (R9+R10))?
4 - What's R5 doing?
6 - Why take the distortion-improving dry signal (R15,C12) from the output of the op amp instead of directly from the drain of the fet?
I'm guessing most of these features are related to feedback aimed at lowering distortion?