PFA phantom power adaptor

PFA phantom power adaptor for plug-in power and low-voltage microphones

PFA phantom power adaptor


SKU: PFA Category:


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The PFA phantom power adaptor allows low-voltage, “active”, or 12V T-power microphones to connect to standard phantom-powered microphone inputs.

The PFA phantom power adaptor is also available for unpowered high-impedance instrument “DI” input, and a low-noise +26dB version for dynamic ribbon and moving-coil microphone input.  These versions do not pass phantom power to connected instruments or dynamic microphones.

Please confirm that your microphone will be compatible with the PFA phantom power adaptor wiring configuration selected before ordering.

PFA phantom power adaptor 3.5mm minijack adaptor wiring configuration

There are several common methods of wiring input jacks for miniplug microphones, which are not compatible:

  • Mono PC microphone (Soundblaster® format): tip = signal (6.8KΩ termination to ground); ring = power (+8V across 2kΩ); sleeve = ground.
  • Mono plug-in power (“PIP”): tip & ring = signal + power (+8V across 6.8KΩ); sleeve = ground.
  • Mono Sennheiser® compatible: tip = signal + power (+8V across 6.8KΩ); ring = no connection; sleeve = ground.
  • Stereo plug-in power (“PIP”): tip = left + power (+8V across 6.8KΩ); ring = right + power (+8V across 6.8KΩ); sleeve = ground.

A microphone wired with separate signal (tip) and power (ring) leads will only be compatible with the PC microphone format.

Some microphones intended for use with PCs are wired with tip and ring as common for signal and power.  Such microphones will work with any of the above PFA formats, but will work best with a mono PIP or Sennheiser® format adaptor.

Mono microphones wired with tip-sleeve (no ring) connectors or with tip-ring-sleeve with ring and sleeve in common will only be compatible with Sennheiser® format.

Mono microphones wired with tip-ring-sleeve connectors with ring unconnected will not work with the PC adaptor format, but will work with mono PIP or Sennheiser® format.

Stereo PIP miniplug microphones are normally wired as:

  • tip: left signal + power
  • ring: right signal + power
  • sleeve: ground

That format is only compatible with the stereo minijack PFA phantom power adaptor.  The PFA will have two XLR outputs; the XLR connected to the 3.5mm minijack ring will be identified with a red ring on the XLR boot.

The voltage and resistance on the PFA’s microphone power supply can be customized as required.


Input polarity and output configuration

The PFA can support noninverting or inverting input, and can support unbalanced or balanced input.

Low-voltage microphones are wired as either two-terminal (signal + power and ground) or three-terminal (power, signal, and ground) devices.  Most two-terminal microphones have a negative polarity output, and thus should be connected to an inverting input PFA for a positive polarity output from the PFA.  Most three-terminal microphones have a positive polarity output, and thus should be connected to a noninverting input PFA.  Those configurations will be supplied with each type of microphone, unless otherwise indicated in the order notes.

The PFA may also be configured for a balanced output microphone, in which each input of the PFA (noninverting and inverting) are independent.  Note that a PFA in that configuration is not a differential circuit (and thus will not cancel interference by itself), but when connected to a standard differential input microphone amplifier will complete a fully balanced circuit from microphone to amplifier.  It is also possible to invert polarity with the balanced input option, if required.

Some three-terminal low-voltage microphones may be connected to a balanced input PFA in a “pseudo-balanced” configuration–the impedance on each terminal may not exactly match, but this configuration can still offer some rejection of interference compared with the unbalanced three-terminal configuration.

“Active” remote capsule microphones will also be one of the above input types, with the addition of a terminal for the high-voltage polarization supply.  However, since there are a range of schemes for polarizing the capsule (positive vs. negative polarization voltage, and whether the voltage is applied to the diaphragm or backplate), either PFA input polarity may be required to generate a positive polarity output from the PFA.  Please confirm the required input polarity with the microphone’s manufacturer.

For T-power microphones, power can be applied to either input pin on the XLR-3-F connector.  A T-power adaptor PFA will be wired for balanced, noninverting input, unless inverting input is requested.  Please indicate powered pin and input polarity in the order notes.

An unbalanced input PFA will provide an electrically balanced, differential output with nominal 6dB gain into a standard differential input microphone amplifier.  An impedance-balanced output is also available, which does not provide 6dB gain, but instead reduces current consumption to 1mA (typical).  Please request the impedance-balanced output in the order notes.

Please obtain information on microphone polarity from the microphone’s manufacturer and indicate as required in the order notes.


“Active” remote capsule microphones and polarization voltage

The PFA can support a wide range of “active” remote capsule, externally polarized condenser microphones that require a high polarization voltage to operate.  The standard barrel PFA can provide a +40V rail for the polarization supply when used with a standard P48 phantom power supply.  The polarization voltage will be correspondingly lower with low-voltage phantom power.

The extended barrel PFA may be ordered with a polarization circuit that outputs a fixed voltage (between +40V and +60V), as required by the microphone, at any phantom supply voltage (P12 to P48).

The connected microphone’s sensitivity, self-noise, and SPL handling will vary with the polarization voltage, such that +40V supply will yield -3.5dB sensitivity (and 3.5dB higher self-noise and SPL handling) compared with a +60V supply.  A low-voltage supply will yield even lower sensitivity.

A standard PFA connected to a microphone amplifier with selectable phantom voltage can thus offer two sensitivity levels, acting as a capsule attenuator and resulting in increased SPL handling at the lower phantom voltage.  For example, a P12 phantom supply will yield -12dB sensitivity (and thus 12dB higher SPL handling) as compared to a P48 phantom supply.  This effect will not occur using a PFA with polarization circuit, as that circuit will generate a fixed polarization voltage irrespective of phantom supply voltage.

tinybox format input

A PFA can be supplied with a TA6M connector in “tinybox” format input, as follows:


  1. low-voltage supply
  2. right noninverting input
  3. left noninverting input
  4. polarization voltage supply
  5. right inverting input
  6. left inverting input
    chassis: ground

Each signal input pin may also provide a low-voltage microphone supply, as required.  Please specify microphone type in the order comment field.

Note that a PFA cannot support multiple microphone types by providing two different low-voltage microphone supplies (on pin 1 and pins 2-3, 5-6), as was possible with a tinybox.  Thus, each PFA must be configured for a single microphone type.

It is also not possible for a PFA to supply 48V phantom power to a connected microphone, although a PFA can be configured to provide 12V or 16V phantom power to a connected microphone with limited current draw (3mA or less).

Schoeps® KCY compatible input

A PFA can be configured to support the Schoeps KCY format via a Binder series 711-5-F input.  However, the Binder connector does not have adequate size to support a stereo Y cable.  Thus, it is necessary to have the stereo PFA terminated to a 5- or 6-pin mini-XLR (TA5M or TA6M), and use a short Binder to mini-XLR adaptor cable.  The TA5 option is wired in the same pin configuration as the Schoeps KCY Binder (that is, pin 1 to pin 1, pin 2 to pin 2, etc.), whereas the TA6 option will be wired in a compatible “tinybox” format, as described above.

Lectrosonics®-compatible input

The Lectrosonics®-compatible TA5M configuration does not support Lectrosonics’ “Servo Bias” function; however, the PFA can be made compatible with mics wired for “Servo Bias”.   Please specify your microphone’s wiring format according to the Lectrosonics schematic.


Shure®-compatible input

The Shure®-compatible TA4M configuration may support both microphone and instrument input if the high-impedance amplifier option is selected.


PFA phantom power adaptor specifications

Type: phantom power adaptor for plug-in power, “active” remote capsule, dynamic, and T-power microphones; DI instrument adaptor.

Phantom Power: +9V to +48V; +24V minimum required for 12T.
Voltage Supplied to Microphones: low-voltage; +8V, “active”; +8V, +12v, or +16V; 12T, +12V.
“Active” Polarization Voltage, standard barrel: +40V (with P48 supply)
“Active” Polarization Voltage, extended barrel: up to +60V (with P12-P48 supply)
Current, per amplifier: 2mA typical for low-voltage microphones; 4mA for +26dB dynamic mic input;
1mA typical for impedance-balanced output.  Extended barrel polarization voltage circuit adds 1.5mA.

Input Impedance (low-volt microphone, typical): 6KΩ
Input Impedance (DI): 500KΩ
Output Impedance: 150Ω
Recommended Preamp Input Impedance: 1.5KΩ or higher

Total Harmonic Distortion, 1kHz @ -30dBV: less than 0.005%
Maximum Input Level, 1kHz @ 1% THD: +6dBV
Maximum Input Level, 1kHz @ 1% THD, +26dB dynamic mic input: -10dBV (with P48 supply)

Frequency Response: 20Hz to 20kHz

Equivalent Input Noise: -123dBA
Equivalent Input Noise, +26dB dynamic mic input: -129dBA
Equivalent Input Noise, high-impedance input: -117dBA

Weight (typical): 83g (2.9oz)
Dimensions (XLR): 70mm x 19mmø (2 3/4″ x 3/4″ø)
Dimensions (extended XLR): 100mm x 19mmø (4″ x 3/4″ø)
Dimensions (minijack):  35mm x 9mmø (1 3/8″ x 3/8″ø)


Notice of FCC compliance

Pursuant to section 15.103(h), the PFA with +60V polarization voltage is only intended to be run from a battery-powered phantom power supply or microphone preamplifier.  It is thus exempt from Part 15 of the FCC rules.  The PFA qualifies for exemption as the highest frequency generated by the device is less than 1.705MHz, and it may not be operated from the AC power lines.  Use of a PFA with +60V polarization voltage connected to a phantom power supply or microphone preamplifier that is operated from the AC power lines is strictly prohibited under Part 15.

Additional information

Weight 0.4 lbs
Dimensions 4 × 4 × 1.3 in