A condenser microphone works by actually converting sound energy into an electrical voltage, but this voltage is much lower than the voltage coming out of your keyboard or other line level sources.  If you plug a condenser microphone in to audio interface then the signal it generates will be very quiet unless the signal is boosted. This is why you will need for a preamp. 

On a consumer sound card you will have a mic preamp, but it's only designed for speech and cheap mic--totally unsuitable for audio recording. 

You can add a Microphone Preamps to your set up via:

• Mixer (eg Behringer UB 802)
• Sound Card with built in Preamp (eg Tascam US-122)
• Mic Pre (eg ART Tube MP Studio V3)

On the bottom of this page you will see a lot of different preamps that will boost a microphone signal without adding lots of noise.  We have Pre Amps for every budget, however, bear in mind that the Mic Pre is one of the most important links of the chain that will effect the sound quality of your recording system.

Phantom Power

"Phantom powering" is a method of providing power to microphones by applying a voltage to the same wires that carry the audio signals. Phantom power can be generated from mixing consoles, mic preamplifiers, or in-line phantom power supplies.

In general, phantom voltages are used to power electronics within condenser microphones. Condenser microphones require power for various parts of their operation, including impedance converters, preamplifier circuitry and, in some cases, to polarized microphone capsules. Phantom is usually a DC voltage ranging from 12 to 48 volts. Microphones draw current from this voltage based on their needs.