Focusrite ISA TWO - 2 Channel Preamp

Focusrite ISA Two Dual Channel Mono Mic Preamp

The Focusrite ISA Two Dual Channel Mono Mic Pre offers two independent channels of premium Focusrite mic preamp heritage sporting line in and instrument front panel inputs; eliminating the need for DI boxes. As its built FROM the classic Focusrite ISA 110 ethos, the ISA Two features four impedance settings, including the classic ISA 110 setting, that lets you blend between a clean transparent signal or bringing out the character of your favourite mic.Plus, with an 80dB range of low noise gain, the ISA Two can perform under any stressful setting, offering a stable platform to let your mics shine. Additionally, rear accessed TRS sockets allow you to plug in your outboard gear, be it a compressor, EQ or limiter.

Each channel's high-pass filter has a variable cut-off frequency of 16 to 420 Hz selected from the front panel and has an attenuation of 18 dB/Octave - the same design as used in the ISA110 module introduced during the 80's. The high pass filter, phase-invert, insert point and phantom power can all be switched in and out per channel using front panel controls.

Eight-segment LED arrays provide clear metering of both signals, and a calibration knob on the rear panel allows lining up of analogue signal levels to prevent clipping and optimize your signal path to any DAW or recording system.

Focusrite ISA Two Features

• Transformer-based mic preamplifiers
• Variable input impedance
• Up to 80 dB of clean, low-noise gain
• Variable cut-off high-pass filter
• Eight-segment user-calibrated LED meter per channel
• Two front panel instrument inputs
• Dedicated per-channel insert point
• 1U 19" rack-mount format

Specifications

Front and Rear Pannel 

Front panel, per channel:

Maximum Input and Output Levels

Mic Input Response

Input Impedance
Switched Impedance setting - Equivalent Input Impedance at 1 kHz Low = 600 Ω

• ISA 110 = 1.4 kΩ
• Med = 2.4 kΩ
• High = 6.8 kΩ

EIN (Equivalent Input Noise)
Measured at 60 dB of gain with 150 Ω source impedance and 22 Hz-22 kHz band pass filter: -127 dB

Noise
Noise at output with unity gain (0 dB) and 22 Hz-22 kHz band pass filter: -97 dBu

Signal-to-Noise Ratio
Measured with 150 Ω source impedance and 22 Hz-22 kHz band pass filter 121 dB relative to max output: +24 dBu

Total Harmonic Distortion + Noise
Measured with a -20 dBu input signal at +30 dB of gain and with a 22 Hz-22 kHz band pass filter: < 0.0007% at 1 kHz

Frequency Response
At minimum gain (0 dB)

• -0.5 dB at 10 Hz,
• -1 dB at 135 kHz,
  (relative to 1 kHz)

At +60 dB gain

• -6 dB at 10 Hz,
• -1 dB at 115 kHz, 
  (relative to 1 kHz)

CMRR (Common Mode Rejection Ratio)

• -94 dB for mic input at 60 Hz for max. output = +24 dBu
• -91 dB for mic input at 10 kHz for max. output = +24 dBu

Crosstalk Channel to Channel

Line Input Response

Gain Range : -20 dB to +10 dB in 10 dB steps, plus 0 dB to +20 dB continuously variable trim

Input Impedance: 0 kΩ from 10 Hz to 200 kHz

Noise
 Noise at main output with gain at unity (0 dB) measured with 50 Ω source impedance and a 22Hz - 22 kHz band pass filter: -97 dBu

Signal-to-Noise Ratio
Measured with 50 Ω source impedance and a 22 Hz-22 kHz band pass filter: 121 dB relative to max output +24 dBu

Total Harmonic Distortion + Noise
Measured with a 0 dBu input signal, +10 dB of gain and a 22 Hz-22 kHz band pass filter: < 0.002% at 1 kHz

Frequency Response
At unity gain (0 dB)

• -0.3 dB at 10 Hz,
• -1 dB at 80 kHz, relative to 1 kHz

Crosstalk Channel to Channel

Line input, with I/P = 0 dBu, gain = 0dB @ 1 kHz input to channel A: Channel B output = -91 dB

Instrument Input Response

Gain Range: +10 dB to +40 dB continuously variable trim

Input Impedance: > 2 MΩ

Noise: >Measured with 22 Hz-22 kHz band pass filter Minimum gain (+10 dB) = -95 dBu

Frequency Response
At minimum gain (+10 dB)

• -2.5 dB at 10 Hz, 
• -1 dB at 110 kHz
  (relative to 1 kHz)

High-Pass Filter

General