Silicon - Solid State Mic Preamp

Silicon is the Octa module version of the much loved Microphone Preamplifier of the Ark console.

For pure sonic clarity, Silicon’s transformerless, universal, solid-state amp can accept signals from any type of microphone whatsoever. 

Even older Ribbon microphones, synths or guitars can be directly connected (so yes, you can also use this mic input as a line input).

With an extraordinarily low Equivalent Input Noise of -138dBu, Silicon will not add any noise over and above that coming from the microphone itself.

The Mic trim pot gain range has been limited from +20 to +60 dB to allow fine level control. 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: 20k
• Maximum Input Level (unity gain): +20dBu (500 Module)
• Maximum Input Level (unity gain): +24dBu (Octa Module)
• Frequency Response (-1dB): 15Hz to 40kHz
• Frequency Response (-3dB): 7Hz to 80kHz
• Equivalent Input Noise (input shorted, 60dB gain): -134dBu
• Output noise at minimum gain (low Range): -100dBu
• Output noise at minimum gain (high Range): -83dBu
• Total Harmonic Distortion at +4dBu output: 0.0004%
• Inter Modulation Distortion at +4dBu output: 0.0004%
• Common Mode Rejection: -80dB
• Maximum Output Level: +26dBu (500 Module)
• Maximum Output Level: +32dBu (Octa Module)
• Current requirement: 65mA (maximum) per rail
• Size and weight: Standard 500 Series, 0.6 kilos

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