Condenser microphones usually specify different requirements for their phantom power. These ratings can range from 48 Volts all the way down to 9 Volts. Fortunately, theres a certain amount of flexibility with matching Phantom Power voltage to your mic. A rough rule-of-thumb would be more is better.
For example, a 24-volt condenser mic usually works perfectly with a 48 Volt Phantom Power Suppy. Some mics rated at as little as 9 Volts can operate on voltages up to 48 Volts (check with the manufacturer first). Conversely, a mic will generally perform best driven by not less than its rated voltage. So, for a 48 Volt mic, you would get best performance with 48 Volts of Phantom Power. For all the above, check out the Phantom II.
ART Phantom 2 (code 20145)
Dual Phantom Power Adaptor
£44.99 (inc vat)