What is the circuit diagram of a preamplifier using 741 opamp?
http://burningsmell.org/ shows a schematic for a dynamic mike preamp circuit based on a “741, or just about any op-amp” The caption reads as follows: This circuit is capable of amplifying the output from a 150-ohm dynamic microphone to line level in a single stage, courtesy of a little thing called an instrumentation amplifier. They’re like op-amps but with settable gain and much better common-mode rejection. They can have very high gain, high precision, low noise, and decent cost per chip; not particularly fast, but there’s no such thing as a free lunch, and it’s good enough for audio anyway … They’re designed for circuits with a positive, negative, and ground supply, so a virtual ground is needed, a constant 4.5 volts when operating off a convenient 9v battery. The sole purpose of the 741 op-amp is to buffer this virtual ground, since the things feeding into it would easily overwhelm a pair of 1K resistors. A side-effect of this virtual ground is that this circuit MUST operate from
