David, it depends in what part of the circuit the coupling cap is located.
If the cap is between two amplifying stages within the same amplifier/pre-amplifier, it is safest to keep the capacitance as close as to standard as possible. Going bigger can cause some amps to oscillate, going smaller may cause the amp to roll off some of the bass signals early.
If you are referring to an output coupling cap, Optimationman is correct in that the value depends on the input impedance of the next device. I have reduced a 8uF output coupling cap to 1uF on a phono preamp with no negative impact, mainly because the input impedance of my pre-amp was sufficiently high to allow this.
Most pre-amp designers go big on output coupling caps to ensure compatibility with other equipment.
Regards
Paul
If the cap is between two amplifying stages within the same amplifier/pre-amplifier, it is safest to keep the capacitance as close as to standard as possible. Going bigger can cause some amps to oscillate, going smaller may cause the amp to roll off some of the bass signals early.
If you are referring to an output coupling cap, Optimationman is correct in that the value depends on the input impedance of the next device. I have reduced a 8uF output coupling cap to 1uF on a phono preamp with no negative impact, mainly because the input impedance of my pre-amp was sufficiently high to allow this.
Most pre-amp designers go big on output coupling caps to ensure compatibility with other equipment.
Regards
Paul