Nik Keefe
08-13-2005, 12:15 PM
This is a sort of intro/FAQ thread. Please ask questions, make corrections or add extra info to it. If you want more threads like this, just ask!
I have split this post into three sections - the Intro, the Technical Stuff and the Bottom Line. My technical knowledge is not great though, so don't be scared of the middle section!! Very Happy
The Intro
There are basically three types of microphone you will come across in live and studio settings. The good news is that we're not going to cover ribbon mics just yet, because they're a whole different kettle of fish! The other two, with which 99% of musicians are already familiar, are the dynamic microphone and the condenser microphone.
Both of these names are a little unhelpful for understanding how they work. A more helpful pair of descriptions would be moving-coil (dynamic) and capacitor (condenser). All mics do the same job - turning sound energy into electric energy - but these two concepts do it very differently.
Here are a few well-known models of each type:
Dynamic - Shure SM57/SM58, Sennheiser MD421, AKG D112 bass drum mic ('The Egg'). Most stage mics used for vocalists and guitar amps.
Condenser - Neumann U87, all of the Studio Projects range to date, AKG C1000S (yuk) and AKG C12 (yes please). The 'studio' microphone, often pictured in a metal and elastic shockmount.
The Technical Stuff
A dynamic mic capsule is a coil of wire suspended close to a magnet. The coil has a diaphragm which gets hit by moving air. This causes the coil to move on its suspension. Because it is in the field of the surrounding magnet, this induces a current into the coil, which becomes the electrical signal sent down your XLR lead to your preamp.
A condenser works quite differently, and is a little more complicated, so here's my simplified version. A capacitor is an electrical component which can temporarily 'store' charge. There are two elements - a rigid back-plate and a flexible membrane (the diaphragm). They are separated by a resistor, in this case air, and a voltage is applied across them, which in this case is a +48V Phantom Power supply. The 'capacitance' (how much it can store) changes when the diaphragm moves and so the amount of air between it and the back-plate changes. The diaphragm is moved, of course, by the incoming sound waves caused by your vocalist or instrument. The changes in capacitance essentially become the electrical signal sent to your preamp.
The Bottom Line
Because they have much lighter and more flexible diaphragms, condenser mics can be much more 'sensitive'. But this same capsule design also makes them more fragile to shocks such as being dropped or used to beat a tempo into your drummer's head. Also, should a very high sound pressure level (SPL) hit the membrane, it could become stretched, or even touch the back-plate, shorting out the mic.
Dynamics, then, tend to be the sensible choice for stage use and to sit close to big guitar amps or inside bass drums. The Shure SM58 has lasted for a number of decades not primarily because of its sound but because of its durability. But dynamics do tend to have a more pronounced resonant 'presence' peak, followed by a drop-off in higher frequencies, which makes them less ideal for accurate reproductions of instruments such as acoustic guitars, violins, cymbals and some female vocalists.
So there you have it. A bluffer's guide to dynamics and condensers. You should now understand why every condenser microphone needs phantom power, why dropping your brand new C1 is a bad idea, and why SM57s make your violin sound like it's being recorded with a sock over the mic.
Any questions? :)
I have split this post into three sections - the Intro, the Technical Stuff and the Bottom Line. My technical knowledge is not great though, so don't be scared of the middle section!! Very Happy
The Intro
There are basically three types of microphone you will come across in live and studio settings. The good news is that we're not going to cover ribbon mics just yet, because they're a whole different kettle of fish! The other two, with which 99% of musicians are already familiar, are the dynamic microphone and the condenser microphone.
Both of these names are a little unhelpful for understanding how they work. A more helpful pair of descriptions would be moving-coil (dynamic) and capacitor (condenser). All mics do the same job - turning sound energy into electric energy - but these two concepts do it very differently.
Here are a few well-known models of each type:
Dynamic - Shure SM57/SM58, Sennheiser MD421, AKG D112 bass drum mic ('The Egg'). Most stage mics used for vocalists and guitar amps.
Condenser - Neumann U87, all of the Studio Projects range to date, AKG C1000S (yuk) and AKG C12 (yes please). The 'studio' microphone, often pictured in a metal and elastic shockmount.
The Technical Stuff
A dynamic mic capsule is a coil of wire suspended close to a magnet. The coil has a diaphragm which gets hit by moving air. This causes the coil to move on its suspension. Because it is in the field of the surrounding magnet, this induces a current into the coil, which becomes the electrical signal sent down your XLR lead to your preamp.
A condenser works quite differently, and is a little more complicated, so here's my simplified version. A capacitor is an electrical component which can temporarily 'store' charge. There are two elements - a rigid back-plate and a flexible membrane (the diaphragm). They are separated by a resistor, in this case air, and a voltage is applied across them, which in this case is a +48V Phantom Power supply. The 'capacitance' (how much it can store) changes when the diaphragm moves and so the amount of air between it and the back-plate changes. The diaphragm is moved, of course, by the incoming sound waves caused by your vocalist or instrument. The changes in capacitance essentially become the electrical signal sent to your preamp.
The Bottom Line
Because they have much lighter and more flexible diaphragms, condenser mics can be much more 'sensitive'. But this same capsule design also makes them more fragile to shocks such as being dropped or used to beat a tempo into your drummer's head. Also, should a very high sound pressure level (SPL) hit the membrane, it could become stretched, or even touch the back-plate, shorting out the mic.
Dynamics, then, tend to be the sensible choice for stage use and to sit close to big guitar amps or inside bass drums. The Shure SM58 has lasted for a number of decades not primarily because of its sound but because of its durability. But dynamics do tend to have a more pronounced resonant 'presence' peak, followed by a drop-off in higher frequencies, which makes them less ideal for accurate reproductions of instruments such as acoustic guitars, violins, cymbals and some female vocalists.
So there you have it. A bluffer's guide to dynamics and condensers. You should now understand why every condenser microphone needs phantom power, why dropping your brand new C1 is a bad idea, and why SM57s make your violin sound like it's being recorded with a sock over the mic.
Any questions? :)