Hello. I have a question pertaining to analog circuit THEORY/sense, using a guitar preamp circuits just as an excuse. I will use the MXR MicroAmp schematic found here: http://www.generalguitargadgets.com/index.php/projects/15-boostersrouters/70-mxr-microamp-project. I'm doing things on these lines and plan to continue and evolve on them, however I'd like to know the why's along with that what's as well.
1. In engineering, compromise is always present. I can see R7 and R8 being used to bias the input to half the DC voltage, but why do they have the values that they do? Why not higher, say 1M? Wouldn't that result in even LESS power consumption? Potential dividers are used a lot so this a very important question. In its crux, the question becomes: in circuits dependent on RATIOS of impedances, what is the drawback to having higher impedances? What is the advantage and disadvantage to having them lower (aside from higher power consumption)?
2. Most the caps here are coupling or decoupling. But my question is similar to the previous one - why do they have the values that they do? Why not higher, or lower? Also, what purpose does C3 serve?
3. What purpose does R1 serve? Wouldn't it be better to leave it out? It only ends up loading the guitar (tonal degradation). Also, what is the point to R9 and R10? They, too, only end up loading the opamp (current/power consumption). What is the purpose to R3?
1. In engineering, compromise is always present. I can see R7 and R8 being used to bias the input to half the DC voltage, but why do they have the values that they do? Why not higher, say 1M? Wouldn't that result in even LESS power consumption? Potential dividers are used a lot so this a very important question. In its crux, the question becomes: in circuits dependent on RATIOS of impedances, what is the drawback to having higher impedances? What is the advantage and disadvantage to having them lower (aside from higher power consumption)?
2. Most the caps here are coupling or decoupling. But my question is similar to the previous one - why do they have the values that they do? Why not higher, or lower? Also, what purpose does C3 serve?
3. What purpose does R1 serve? Wouldn't it be better to leave it out? It only ends up loading the guitar (tonal degradation). Also, what is the point to R9 and R10? They, too, only end up loading the opamp (current/power consumption). What is the purpose to R3?
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