Focusrite ISA Two Microphone Preamp

The Focusrite ISA Two Microphone Preamp is a dual mono microphone preamp featuring transformer based microphone inputs with variable input impedance. Based on the legendary designs found in the Focusrite Forte and Studio consoles, the preamps provides up to 80 dB of gain, while two front panel instrument inputs allow for immediate access to two transparent DIs.

The microphone inputs feature a pair of Lundahl LL1538 transformers with a 3-section winding that results in very low leakage inductance, along with an extended frequency response. To shield them from stray magnetism, each is encapsulated in mu-metal cans. Each channel has a fully-balanced insert point, activated using a front-panel button, making it easy to insert a choice of outboard EQ, a compressor, or limiter.

Microphone Input Transformer

• Includes Lundahl LL1538 input transformers, originally chosen by Rupert Neve for the ISA 110 and one of the best microphone input transformers available
• Zobel network in the ISA circuit (perfected by Rupert Neve) allows the microphone preamp to maintain an extremely flat frequency response across a very wide bandwidth

Gain

• Offers up to 80 dB of clean, distortion-free gain
• ISA topology ensures low-noise even at the highest gain levels
• The transformer supplies 20 dB of gain, while the ISA's input stage offers up to 60 dB of additional gain on the microphone input

Variable Input Impedance

• Four choices of input impedance, including the original ISA 110 value, allow for matching the preamp to a different microphones, even a vintage type, for the best possible sound
• Impedance is selected using a switch on the front panel
• Impedance choice is remembered even when the unit is switched off and back on

User-Calibrated Metering

• Each channel has an eight-LED array to clearly display the level of the two signals
• Line up the analog levels with digital converters or a DAW by using the calibration knob on the rear panel
• Calibration avoids clipping on input

Instrument and Line Inputs

• Two 1/4" TS connectors on the front panel provide access to a transparent DI input
• TRS line inputs are available on the rear panel and a front panel switch allows for stepping through them to instantly select required input

Variable High-Pass Filter

• Smooth-sounding, built-in 18 dB/octave high-pass filter per channel
• Same design as the original ISA 110 module
• Ideal for cutting out rumble, thumps and other unwanted low-frequency sounds using the 16 Hz to 420 Hz range
• Easily accessed with a large knob and illuminated button

Balanced Inserts

• Each channel has its own balanced insert point via 1/4" TRS send and receive connectors
• Allows for a choice of signal processor to be connected and switched in and out using the illuminated switch on the front panel