Iron - Transformer Mic Preamp

Iron is the Octa module version of the much loved Microphone Preamplifier of the Ark console, but with a custom high-quality input transformer added.

For pure sonic clarity, Iron’s universal amp can accept signals from any type of microphone whatsoever. 

The Mic trim pot gain range has been limited from +20 to +60 dB to allow fine level control.

To allow for lower input level boost, we added a 20dB [Range] switch, so the range can be changed to be 0 to +40 dB, keeping the same fine control of the input signal.

Note that the [Range] switch is not a “Pad”, but changes the gain range of the microphone amplifier by modifying the following parameters:
- the value of the gain pot
- the quiescent current of the input stage
- the amount of feedback used to stabilise the circuit accordingly
All of these are necessary to preserve the exemplary noise, distortion and headroom performance at all gains.
In short: While a “pad” and our “range” have a similar effect, a “pad” adds noise to the signal, our [Range] switch does not.

Specifications

• Input Impedance: 6k
• Maximum Input Level at 1kHz (unity gain):  +24dBu (Octa module)  /  +20dBu (500 module)
• Frequency Response (-1dB): 15Hz to 30kHz
• Frequency Response (-3dB): 7Hz to 40kHz
• Equivalent Input Noise (150 ohm source, 60dB gain): -128dBu
• Output noise at minimum gain (low Range): -100dBu
• Output noise at minimum gain (high Range): -93dBu
• Total Harmonic Distortion at 1kHz and +4dBu output: 0.007%
• Inter Modulation Distortion at 1kHz and +4dBu output: 0.0002%
• Common Mode Rejection: -80dB
• Maximum Output Level:  +32dBu (Octa module)  /  +26dBu (500 module)
• Current requirement: 85mA (maximum) per rail
• Size and weight: Standard 500 Series, 0.6 kilos

Iron features our reference bargraph meter and the High-Pass-Filter (Lo-Cut-Filter) from the EQ section of the Ark console.

Product page on the Interphase Audio website