A simple microphone circuit with tube stage pre-amplifier.
The circuit runs on a 9v Battery, i have used a wall wart plug pack to power this as well.. the electret mic is a just a cheap insert from Jaycar, we also have some generic capsules in our store. This is a fun project and initially i used some plumbing pipe to make the housing, with aluminium tape wrapped around it to stop EMI. This project was designed in 2010 long before i bought my first 3d printer. Keep an eye on this space as we develop this project more and include 3D printer files for a custom enclosure.
You can replace the 0.1uf caps with 0.47uf for a wider frequency range… the sound is warm and picks up sound from rooms away once you amplify it a little via your mixer or audio interface.
The inductor has to be similar in appearance to the coil in the photo these are usually 1.5A or more type… the MC34063A chips tends to create noise and using the wrong inductor will create hiss and other noise.
The future of this circuit is to use large diaphragm capsules and to run it on Phantom 48v directly from your mixer or audio interface.. i have not worked on this circuit in 9-10 years and was originally from our website for our eBay store (www.dystopiantone.com)
You can download the PDF for this project, including the Etching template HERE.