Hello.This is my inverting preamp schematic.Is R11 needed when a bjt opamp such as NE5532 is used? Should its value be equal to the parallel combination of (R1+R2) and R11 ?
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If i leave it in place and use it with a jfet opamp will there be any problem? or just increased noise?Is the value of this resistor equal to the parallel combination of (R1+R2) and R11 or just equal to R11?
Apart from the offset at the opamp output caused by the imbalance ,does this imbalance affects the distortion of the preamp?
The resistor is to balance out the bias current. While this is a little bit of an
issue with the 5532, it's negligible with the 2134. Its bias current is worst
case +/- 100 pA, that's PICO Amps, 0.1 nano Amp. Typical is 5pA. I'm
running a 2134 nearly the same as yours and no output blocking cap and
it's just barely detectable under worst case conditions. Try shorting that
resistor and see if it's a problem. My guess is it's not.
G²
In this case, it is just adding thermal noise.
Depending what this module is doing, a 100R in series with the output might be a good idea for load stability
Depending what this module is doing, a 100R in series with the output might be a good idea for load stability
