Using the PFA
The PFA is a phantom power adaptor for plug-in power mics, which enables the mics to be connected to standard professional microphone preamplifiers. The PFA supplies the appropriate voltage to the plug-in power microphones, and provides a balanced, low impedance output to the microphone preamplifier.
The left and right channels of the PFA operate independently, so phantom power must be supplied to both channels for stereo operation. The PFA requires +9V to +48V phantom power to operate (supply voltage to microphones will be reduced with phantom power supply of less than +12V).
In standard configuration, the PFA supplies +9V across 5.6KΩ resistors to each microphone channel. For "three-wire" lapel-style mics, the PFA is available in a mono configuration, with either a balanced or unbalanced input via minijack or mini-XLR connectors. The supply resistor values may be customized to suit various microphones.
IThe PFA is also capable of supplying polarization voltage for "active" externally biased microphone capsules. The bias voltage supplied is dependent upon the current draw of the "active" capsule's FET, but due to the very low current draw of the PFA's buffer circuit the bias voltage will typically exceed +40V. 4-pin mini-XLR connector is required for mono PFA with "active" capsule connection; 5- or 6-pin is required for stereo.
The low-voltage supply for the capsule FET is regulated, and may be supplied at +5V to a maximum of +16V (standard setting is +9V). Headroom of the PFA's buffer circuit is also determined by that voltage.
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PFA Specifications
Type: phantom power adaptor for plug-in power microphones
Phantom Power: +9V to +48V required
Current: 1mA minimum
Input Impedance: 4.8Ω
Output Impedance: 150Ω
Recommended Preamp Input Impedance: 600Ω minimum
Total Harmonic Distortion, 1kHz @ -30dBV: less than 0.05%
Maximum Level, 1kHz @ 1% THD: +6dBV
Frequency Response: 20Hz to 20kHz
Self-Noise: -117dBA
Weight: 2.9oz (83g)
Length (cable): 9" (23cm)
Dimensions (XLR): 2 3/4" x 3/4"ø (70mm x 19mmø)
Dimensions (minijack): 1 3/8" x 3/8"ø (35mm x 9mmø)
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