Focusrite ISA TWO

Description

The history of ISA modules dates back to 1985, when Sir George Martin commissioned legendary designer Rupert Neve to create new modules for the AIR Montserrat console. They were so successful that many more were commissioned for AIR London. These original modules form the basis for today's Focusrite ISA series - delivering the legendary Focusrite sound to leading studios, artists, producers, and engineers worldwide. Hundreds of hit records have been created - and continue to be created - with the Focusrite ISA Range.

The Focusrite ISA Two brings together a pair of legendary, fully independent ISA microphone preamps, derived from the original ISA 110 module, combining the best of traditional solid-state electronics with the original input transformer specified by Rupert Neve - the Lundahl LL1538. Two is a pleasant number - ideal for recording vocals and instruments, or a stereo piano. And even if you only need 2 microphone preamps, you absolutely must choose the best. (And if you need more, we also have the 4-channel ISA 428 Mk II and 8-channel ISA 828 units).

Focusrite has made a small change to the microphone preamp. The original ISA 110 had a unique input impedance, ideal for the microphones of the time. The ISA Two boasts 3 additional impedances, allowing you to get the best out of all your microphones, vintage or modern. Give a vintage microphone the input it expects, and you'll get a warm, traditional sound. Pair the ISA Two with modern microphones, and you'll get the most transparent sound imaginable. Or experiment, bringing out the hidden character from each microphone. Combine all this with up to 80dB of gain, and you're ready for anything.

In addition to the microphone preamps, there are instrument inputs on the front panel for quick access, and line inputs on the rear panel. There is also a balanced insert point on the rear panel, activatable with a button on the front panel for inserting EQs, dynamic effects, and other processors. Add an 8-LED user-calibratable meter and a high-pass filter with variable cutoff, and you have everything you need to achieve the best quality in your audio recordings.

3-year warranty on all new Focusrite products purchased from January 1, 2018 onwards. The Focusrite Warranty is synonymous with peace of mind for the user, it represents a professional service that minimizes waiting times in the event of a manufacturing defect, and confirms that the products of the British company are built to high quality standards.

Key features

Lundahl LL1538 input transformer

Rupert Neve originally chose the Lundahl LL1538 as the input transformer for the ISA 110. It remains the best input transformer available and is used in every microphone preamp in the ISA series.

Up to 80 dB of gain

The ISA Two offers up to 80 dB of clean, distortion-free gain. The ISA design ensures low noise, even at the highest gain levels. The transformer provides 20 dB of gain, while the ISA input stage offers up to an additional 60 dB, for a total of 80 dB of maximum gain on the microphone input.

Variable input impedance

4 selectable input impedances, including the original ISA 100 setting, allow you to match the preamp to your microphone, even if it's vintage, to get the best possible sound. The impedance is selected via the switch on the front panel, and the chosen value remains in memory even after turning the unit off and on again.

User-calibratable meter

Each channel has an 8-LED row that clearly shows the level of your 2 signals. Align the levels of your ISA Two by matching them to your DAW converters with the calibration knob on the rear panel.

Front panel instrument inputs and rear panel line inputs

Two ¼-inch jack sockets on the front panel of the ISA Two provide immediate access to a transparent DI input. TRS line inputs are also present on the rear panel, and you can switch through them directly to select what you want.

High-pass filter with variable cut-off

Integrated and easily accessible thanks to the large knob and illuminated button, it is the same extremely smooth-sounding 18dB per octave high-pass filter as the original ISA 110 module. It is ideal for removing rumble, thumps, and other unwanted low-frequency sounds, and with a range from 16 to 420 Hz, it is easy to decide what to eliminate and what to keep.

Balanced inserts on the rear panel

Each channel of the ISA Two has its own balanced insert point. Thanks to the 1/4 TRS connections, you can connect the signal processor of your choice and activate/deactivate it via the illuminated switch on the front panel.

Technical specifications:
2 transformer-based preamplifiers from the ISA Series
2 front panel instrument inputs
Selectable impedance
Dedicated analog insert points for each channel
80 dB of clean gain
Variable high-pass filter
8-segment LED meter

Maximum output level
+24dBu with a THD +N <0.01% at 1kHz measured with a 0dBu input, with a 150 Ohm impedance source and 22Hz -22KHz bandpass filter

Maximum level obtained from the transformer on the microphone input
+7dBu with a THD +N <0.7% at 1KHz measured at 0dB gain, with a 150 Ohm impedance source and 22Hz -22KHz bandpass filter

Microphone input response

Gain range
0dB to +60dB in 10dB steps, plus 0dB to +20dB of continuously variable trim

Input Impedance
Selectable impedance settings
Impedance setting equivalent value at 1kHz
Low 600?
ISA110 1400?
Med (Medium) 2400?
High 6800?

EIN (Equivalent Input Noise)
-127dB, measured at 60dB gain, with a 150 Ohm impedance source and 22Hz -22kHz bandpass filter

Noise
-97dBu, output noise, at unity gain (0dB) and 22Hz -22kHz bandpass filter

Signal-to-noise ratio
121dB, relative to maximum output of +24dBu, measured with a 150 Ohm impedance source and 22Hz -22kHz bandpass filter

Total Harmonic Distortion + Noise
<0.0007% at 1 kHz, measured with a -20dBu signal, at +30dB gain with a 150 Ohm impedance source and 22Hz -22kHz bandpass filter

Frequency response
Frequency response at minimum gain (0dB): -0.5dB at 10Hz and –1dB at 135kHz, relative to 1kHz
Frequency response at maximum gain (60dB): –6dB at 10Hz and –1dB at 115kHz, relative to 1kHz

CMRR
-94dB for microphone input at 60Hz for maximum output = +24dBu
-91dB for microphone input at 10kHz for maximum output = +24dBu

Channel-to-channel crosstalk
Mic input, with I/P=0dBu, gain=0dB, at 1kHz with input on channel A, output on Channel B =-85dB

Line input response
Gain range
-20dB to +10dB in 10dB steps, plus 0dB to +20dB of continuously variable trim

Input Impedance
10Kohm from 10 Hz to 200 KHz

Noise
-97dBu, noise on the main output, at unity gain (0dB) measured with a 50 Ohm impedance source and 22Hz – 22kHz bandpass filter

Signal-to-noise ratio
121dB, relative to maximum output of +24dBu, measured with a 50 Ohm impedance source and 22Hz – 22kHz bandpass filter

Total Harmonic Distortion + Noise
<0.002% at 1 KHz, measured with a 0dBu signal, at +10dB gain and 22Hz -22kHz bandpass filter

Frequency response
Frequency response at unity gain (0dB): -0.3dB at 10Hz and –1dB at 80kHz, relative to 1kHz

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

Instrument input response
Gain range
+10dB to +40dB with continuously variable trim

Input Impedance
>2Mohm

Noise
-95dBu, at minimum gain (+10dB) measured with 22Hz 22kHz bandpass filter

Frequency response
Frequency response at minimum gain (+10dB): -0.1dB at 10Hz and –1dB at 115kHz, relative to 1kHz
Frequency response at maximum gain (+40dB): –2.5dB at 10Hz and –1dB at 110kHz, relative to 1kHz

High-pass filter
Slope = 18dB per octave
Frequency response = continuously variable between 16Hz and 420 Hz (-3dB)