IFA inline amplifier
$54.00 – $79.00
The IFA is an inline phantom power adaptor and amplifier designed to connect dynamic microphones to standard phantom-powered microphone inputs. The IFA offers two low-noise input options with gain for dynamic ribbon and moving-coil microphones. The IFA is also available with a high-impedance instrument “DI” input.
The IFA can also be configured to adapt certain low-voltage, “active” remote capsule, or 12V T-powered microphones for use with standard phantom-powered microphone inputs.
Input polarity and output configuration
The IFA is available in a wide range of input connectors and may be customized as required for each microphone type. The IFA can support noninverting or inverting input from a balanced or unbalanced microphone.
An unbalanced input IFA will provide an impedance- or electrically-balanced output. The IFA can also support balanced interconnection for any microphone via independent noninverting and inverting inputs. Note that an IFA in this 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.
Low-voltage microphone 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 IFA for a positive polarity output from the IFA. Most three-terminal microphones have a positive polarity output, and thus should be connected to a noninverting input IFA.
Some three-terminal low-voltage microphones may be connected to a balanced input IFA 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. This “pseudo-balanced” configuration will be supplied with compatible microphone formats, including Audio-Technica TB3M and Shure TB4M formats, unless otherwise requested.
Dynamic microphone input
For dynamic microphones, the IFA offers two options; either a transformer-balanced or transformerless input. The transformerless input version draws 4mA current vs. 1.2mA for the transformer-input version. Either version offers low input noise and +26dB gain. The dynamic microphone input versions do not pass phantom power to connected microphones.
For T-power microphones, +12V power can be applied to either input pin on the XLR-3-F connector. A T-power adaptor IFA will be wired for balanced, noninverting input, unless inverting input is requested. Please indicate powered pin and input polarity in the order notes. A minimum phantom power supply voltage of +24V is required for T-power input.
“DI” instrument input
The IFA can support high-impedance instrument “DI” input using a special high-impedance amplifier, with either a ¼” TS (unbalanced) or TRS (balanced) phone jack input connector. The DI input version of the IFA uses an extended XLR-3-M connector for its output. The DI input version does not pass phantom power to connected instruments.
“Active” remote capsule microphones and polarization voltage
The IFA can support a range of “active” remote capsule, externally polarized condenser microphones that require a high polarization voltage. An IFA configured to support “active” remote capsule microphones will contain a polarization circuit that outputs a fixed voltage (between +40V and +60V), as required by the microphone, at any phantom supply voltage (+12-48V).
tinybox format input
An IFA can be supplied with a TB6M connector in “tinybox” format input, as follows:
- low-voltage supply
- right noninverting input
- left noninverting input
- polarization voltage supply
- right inverting input
- left inverting input
Each signal input pin may also provide a low-voltage microphone supply, as required. Please specify microphone type in the order comment field.
In this format, the IFA will have either an XLR-3-M (stereo unbalanced) or XLR-5M (stereo balanced) output connector.
Note that an IFA 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 IFA must be configured for a single microphone type.
The Lectrosonics®-compatible TB5M configuration does not support Lectrosonics’ “Servo Bias” function; however, the IFA can be made compatible with mics wired for “Servo Bias”. Please specify your microphone’s wiring format according to the Lectrosonics schematic.
The Shure®-compatible TB4M configuration may support both microphone and instrument input upon request. To enable this feature, the high-impedance amplifier is used (see specifications below).
Output configuration and polarity
The IFA is available with the following outputs:
- XLR-3-M: mono input, impedance- or electrically-balanced output
- XLR-3-M: stereo unbalanced output
- XLR-5-M: stereo input, impedance- or electrically-balanced output
- XLR-5-M: four-channel unbalanced output
The XLR-5-M output uses an extended connector for its output. TBxM and 1/4″ input connectors also require an extended XLR-x-M output connector. Extended XLR-3-M connectors are available as an option for other configurations, if direct connection to microphone amplifiers is desired.
Special output cables are available in these formats:
- XLR-3-F to dual XLR-3-M (impedance-balanced)
- XLR-3-F to stereo XLR-5-M (impedance-balanced)
- XLR-5-F to dual or quad XLR-3-M
IFA inline adaptor and amplifier specifications
Type: inline phantom power adaptor and amplifier for dynamic, T-power, low-voltage, and “active” remote capsule microphones; DI instrument adaptor.
Phantom Power: +9-52V; +24V minimum required for 12T and +16V “active” microphones.
Voltage Supplied to Microphones: low-voltage; +8V, “active”; +6-16V; 12T, +12V.
“Active” Polarization Voltage: +60V maximum
Current, low-voltage microphone, electrically-balanced output: 2mA typical
Current, low-voltage microphone, impedance-balanced output: 1mA typical
Current, low-voltage microphone, stereo electrically-balanced or four-channel output: 4mA typical
Current, transformer-input dynamic mic or DI input: 1.2mA
Current, transformerless dynamic mic input: 4mA
Polarization voltage circuit: 1.2mA
Input Impedance: 6KΩ or as specified
Input Impedance, dynamic microphone, transformer input: 6KΩ
Input Impedance, dynamic microphone, transformerless input: 12KΩ
Input Impedance, DI input: 1.6MΩ
Output Impedance: 150Ω
Recommended Preamp Input Impedance: 1.5KΩ or higher
Maximum Input Level, 1kHz @ 1% THD: +6dBV (8V mic supply) to +13dBV (16V mic supply)
Maximum Input Level, 1kHz @ 1% THD, +26dB dynamic mic input: -15dBV (with P48 supply)
Maximum Input Level, 1kHz @ 1% THD, transformer input: -12dBV (with P48 supply)
Total Harmonic Distortion, 1kHz @ -30dBV: less than 0.005%
Total Harmonic Distortion (transformer input) 1kHz @ 0dBV output: 0.01%
Total Harmonic Distortion (transformer input) 100Hz @ 0dBV output: 0.1%
Frequency Response: 20Hz to 40kHz
Frequency Response (transformer input, 150Ω source): 30Hz to 20kHz
Equivalent Input Noise: -121dBV unweighted, -124dBA
Equivalent Input Noise: -121dBV unweighted, -124dBA
Equivalent Input Noise (low-noise dynamic microphone version): -125dBV unweighted, -128dBA
Equivalent Input Noise (transformer-input dynamic microphone version): -127dBV unweighted, -130dBA
Equivalent Input Noise, high-impedance input: -114dBV unweighted, -117dBA
Weight: 81g (2.8oz)
Dimensions: 87mm x 32mm x 25mm (3 1/2″ x 1 1/4″ x 1″)
Dimensions (extended output): 106mm x 32mm x 25mm (4 1/8″ x 1 1/4″ x 1″)
Notice of FCC compliance
Pursuant to section 15.103(h), the IFA with polarization circuit 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 IFA 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 an IFA with polarization circuit connected to a phantom power supply or microphone preamplifier that is operated from the AC power lines is strictly prohibited under Part 15.
|Dimensions||4 × 1 × 1 in|