Playing with microphone transformers, variable microphone setup ratios passive amplifier

At your risk. Take all safety precautions.


Many modern microphone preamplifiers may have a input impedance of the order of 2KΩ to 20KΩ.


Most microphones have an output impedance of typically 200Ω.


It can be fun to make a small turn ratio step up transformer acting as a passive mic booster amplifier.


It can be wound on a ring core. Suitable cores may be made by Arnold, Magmet, Magnetec etc.


Or a transformer could be bought. For example a Hammond 600Ω to 2400Ω, 2 primary windings, 2 secondary winding.


4 pole switches can be used for primary or secondary.


In this way all four terminals per primary or secondary windings can be administered to other terminals of the switch so that either series or parallel connection is implemented.


So then by just using 2 switches all 4 combinations are possible such as:


150Ω to 600Ω


600Ω to 600Ω


150Ω to 2400Ω


600Ω to 2400Ω


And it is even more important as at first glance since direct windings (number of turns of wire) have a different inductance. So the interaction of such inductance and microphone output impedance may create the right low cut response for getting rid of the so annoying bass heaviness. So they may aid to the goal of flat frequency response from producer's brain to listener's brain.


The transormer can be housed inside a Neutrik module box. So everything is small, elegant, professional looking, with Neutrik XLR input and output connectors.