Boris Landoni from Open Electronics has written an article about the design of a microphone preamplifier:
This Mini Microphone Preamplifier could be used as the first stage to amplify any audio signal. The device is equipped with a microphone plus clips to be connected to a 9V battery. Amplification is achieved by using an operational LM741 amplifier. The volume level could be adjusted via a trimmer.
I love this and believe its the smallest yet effective mic pre-amp I have ever come across. Thanks!
That’s neat, but I’m kinda curious why he used a 741 op-amp over a more modern audio op-amp like a NE5534. In fact, if my understanding of op-amp bandwidth is correct, I don’t think this circuit would have enough bandwidth to be useful for audio purposes.
I can’t find the actual component values for this design on the linked page. Maybe I’m missing something. Without the component values (and ideally the component manufacturer part numbers, especially for the electret mic and capacitors). I cannot comment on how this amplifier will work. So much for a post on a site named open-electronics, that seems to be not so “open” at first-glance. Also, the choice of a 741 variant is suspect. There are so many “fake” 741’s out there (from you know where), YMMV – big time.
Thank you for sharing the article! Do you think I would be able to use an XLR port instead of the mini mic show on the board?