phantom power

[pellgarlic]

how is 'phantom power' applied? does it need a connection to mains electricity, or are batteries sufficient? will the microphone be unusable (even if just because of severely impede functioning) without application of phantom power, if it is needed? some mics have 'phantom power indicator leds', but do not state a need for phantom power in specs. is this different? how does phantom power improve functioning of mic? please answer any or all of these questions if you can - if not, i guess i'll have to just go for a straightforward dynamic mic instead.

[pellgarlic]

also - do all condenser mics require phantom power, or are there some which don't? cheers!

[mikemchargue]

Phantom Power simply means that 48v is sent across pins 1 and 2 of an XLR connection. Mics that require phantom power will not function without it. To my knowlege, all condenser mics need phantom power, but I could be wrong.

This link explains it quite well:

http://www.shure.com/support/technotes/ ... ntom1.html

[owel]

Dynamic microphones don't need phantom power because they generate their own electricity proportional to the sound level through the use of magnets and coil.... (kinda like a motor, except instead of running when electricity is applied, you turn it and electricity is generated.)

Condenser mics (i.e. condenser, another word for capacitor) senses the change in capacitance proportional to the sound level. Think of it as two plates, and the louder the sound, the more the plates are pushed near towards each other, which varies the capacitance, proportional to the sound level. These types require an external source of power... either from phantom power or batteries.

Some mics accept batteries and internally switch off when phantom power is detected.

[ron]

does it need a connection to mains electricity

Do not plug your microphone into the mains

As owel says-
All microphones work on essentially the same princple:

Sound pressure waves cause a mechanical vibration on a diaphram (or ribbon or such like). That mechanical vibration then gets converted into a very small electric current

1) by moving a coil of wire in the field of a magnet (dynamic microphones) which generates the current directly.

2) by changing the capacitance between the front and back of the diaphram. This is detected by applying a voltage to the front and back plates and measuring the change in the voltage or current. This needs an electrical supply to provide the bias voltage, but also to drive the amplifier circuit in the microphone head.

Phantom power is a voltage that is applied between the "hot" and "cold" connections of a balanced circuit - it should not affect a dynamic microphone, but will power a condenser mic. The voltage is usually +48v, although lower voltages can be used. Some microphones can use 9v or less (and usually have provision for batteries) - but the sound quality suffers.

Note that some microphones ("Tubes") run on thermionic valves and require a much higher voltage - they typically have a separate power supply (which is plugged into the mains), and don't require phantom power.

One thing to remember - 48V is much greater than the signal levels that audio equipment uses and should only be used for microphones.[/u][/i]

[Tweak]

Great Thread, guys. Thanks!

[pellgarlic]

cool - thanks for all the info, it helped a lot. i have just one more question though - as i don't have a mixer, is there an alternative for providing the phantom power, such as a small standalone unit that can be placed inbetween the mic and my computer? and are these, if they exist, more or less expensive than a low-budget mixer? thanks again to all who helped.

[mikemchargue]

Some preamps can provide phantom power and there are inline devices as well. Hear's what I could find at zzounds...

http://www.zzounds.com/prodsearch?form= ... submit.y=0