Microphone Preamplifiers: how I designed the D.W. Fearn preamps and how you can get the most out of them

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Microphone preamplifiers are essential for almost all recording.
In this episode, I look at the requirements for a quality preamp,
and how preamps are designed and used.


Although this focuses on the D.W. Fearn VT-1, VT-2, and VT-24 mic
preamps, the principles are applicable to any preamp.


We look at the extreme range of levels a preamp has to deal with,
and the techniques used to accommodate this range. Why is there a
20dB pad on most preamps, and how best to use it (or not)? Many
modern mics have a transformerless out, and a non-standard output
impedance. How do we deal with that?


Do mic preamps introduce distortion? What kinds? And which add to
the sound and which distortions are annoying?


How does phase shift through the mic preamp affect the sound?
What can be done in the design process to minimize phase
shift?

How do we use the "Phase" (polarity) switch on a mic input, and
where is it most useful?


What exactly is “phantom power?” How did that come about? What
are the advantages, disadvantages, and potential problems?


Using a mic preamp on a mix buss is also covered, along with the
special requirements for that application.


How about installation of your outboard preamp? What do you need
to consider in cooling, wiring, and AC power in order to get the
maximum audio quality?


How can mic patch panels create potential serious problems, not
only for the audio quality but also for the safety of your
expensive microphones?


I take you through the history of the design of the VT-1 preamp,
which is the basis for all the D.W. Fearn mic preamps and also
influences the sound of our equalizers and compressor.


Understanding some of the technical details will help you to use
your preamps better. I avoid a lot of technical jargon and
theory, and just focus on the aspects that will be helpful for
most recording engineers.


Thanks to everyone who has contacted me with your comments and
suggestions. I have already added some topics for future
episodes, based on listener feedback. You can contact me at
dwfearn@dwfearn.com


email: dwfearn@dwfearn.com
www.youtube.com/c/DWFearn
https://dwfearn.com/