Coil Windings

Just wondering if theres a formula to figure out the amount of coil windings one should have if building a dynamic mic.  Is it dependent on magnet size or diaphragm size wire gauge, all of the above?

Also, would it be better to have a diametrically charged magnet or regular?

With how cheap dynamics are, why would you waste the money to build one from scratch? You could modify a real mic on the cheap. Just my two cents.

Not trying to build one, im just interested in the math or lack thereof behind it. I like to experiment with different theories and ideas and this had come up with no answer to be found anywhere.

Hello !!!
You find a lot of different Moving Coil Mic Concepts out there.The Coils may have a dc resistance(in this cases it represents the Outputimpedance of the Coil, I think?.)varies from 10 to 600 ohm ,so a big difference in Coilturns,Wiresize and Weight .A few turns glued on a big Diagramm,10 ohms  than feed into a step up Transformer for 200/600 or even 50k output for hify Tape machine mic input(Mics like the Sm58,RE 20 etc have a capsuleimpedance of a few 10 ohms,than feed into a stepuptransformer for 150/200 ohm Output), or much more turns on a small Diagramm with 600 ohm Out, etc .A blank dynamic Mic capsul hold in the Air sounds crappy    freq response 100-5kHz with many peaks and dips.    so,exssesive mechanical eq like the use of a resonantdisc,ventilation holes, a resonating Grilldesign for the Highboost and flatening,Resonating Tubes in the Body for Bassboost, etc (sometimes 6-7 different resonators-Dampers are build in a single Mic.)  is required for more or less flat freq response .The Magnet used is important as well.The stronger the more Output ,but also has a influence in Sound(Modern neodym    high output but can sound harsh sometime , very fast attacs,Alnico -lower Output can sound very musical) the size is a factor too. The bigger the Magnet, the bigger- thicker the diagramm,more mass , more output because of the bigger Coil -Magnetic field,theoretical but more damping is required to control the move of the Diagramm ,slower Transientresponse ,when you reach the size of the Soundwave  like  10k = 3.4 cm you can create a accustical short on the Diagramm  ,greater Soundshadow from behind ,worse off axis behave etc.So it s like most of the time a compromise you get 1 thing better,you discrease the other parameter.
.In the the old days they had 2 way mics with 2 optimised capsule size, with a phase/ corrected L C  Network and passive summing (Telefunken M611/811, Akg 221 etc) with Freq ,phase,Transient Response and off axis sound almost like a Condenser.They also don t have a proximity effect because for the Bass they use a pressure and for the mid-high a pressuregradient capsule.Today a Mic like this would cost probably a few $$$$ because it s a lot of aktion to desingn ,to get the Mechanical and electronic Parts together- probably hand mounted -alignment ,needs to be accurate like a Swiss Clock.
Greatings from Berlin
Sorry for my bad written english.
Lothar

Your english is fine.  So basically you're saying that size matters for the coil impedance then the transformer steps it up and changes that impedance. And the body/grill (physical properties of the mic) can help determine the frequency response.  Very interesting.

I've been reading Microphones: Design and Application by Lou Burroughs (Electro Voice guy...) and there is a lot of detail on how dynamic microphones are made. Goes into a lot of detail on mechanical EQ.

Worth picking up i guess.  Could probably get it from the library as well... hmm good call.  Thanks

There a PDF book from the Neumann website which is the only accurate and useful tome on mike design I've come across.

Also "Microphone Engineering Handbook" - ed. Gayford from the Unobtainium Book Co.

http://www.leonaudio.com.au/cohen.htm has the chapter on preamps.