Search found 2 matches

by AntK
Fri Mar 08, 2019 9:46 am
Forum: Pro Audio Design
Topic: Preventing mic preamplifier HF oscillation
Replies: 7
Views: 918

Re: Preventing mic preamplifier HF oscillation

Came into my mind that the circuit, stray capacitances included, looks frighteningly similar to an emitter follower type Colpitts oscillator. http://axotron.se/blog/wp-content/uploads/2015/01/colpitts1.png I found an old mixer service note which recommended adding BE capacitors (470pF) to kill the p...
by AntK
Mon Mar 04, 2019 9:42 am
Forum: Pro Audio Design
Topic: Preventing mic preamplifier HF oscillation
Replies: 7
Views: 918

Preventing mic preamplifier HF oscillation

A long time reader, but never had the courage to participate. This is a PRO forum anyway:) But here we go. The mic preamplifier that I recently built follows the idea of this classic circuit, except the transistors which are PNP type 2N4403. http://www.muzines.co.uk/images_mag/articles/hsr/HSR_84_08...