The ISA One from Focusrite is a single channel, transformer-based microphone preamp, based on the original ISA 110 preamp that formed the cornerstone of each channel of the legendary Forte console. It features classic vintage topology and includes the Lundahl L1538 transformer and a custom Zobel network.
In addition to switchable input impedance settings for the microphone preamp, the unit includes a line input on XLR and 1/4" TRS phone jacks. An independent DI channel features a dedicated gain control, active or passive impedance switch, a 1/4" TRS output for routing to an amplifier, and an independent XLR output on the rear.
The ISA One features an insert point should the need arise to place extra signal processing between the preamp or DI, and the optional analog-to-digital converter. Phantom power, phase reverse and a 75Hz, 18dB/octave high-pass filter are also available from the angled front fascia.
Independent input metering for both channels is provided by a moving coil VU meter with variable calibration to suit analog and digital recording media, alongside two six-LED peak meters. Inputs can be metered either pre- or post-insert. The meter calibrations utilize the same reference points as Digidesign's Pro Tools HD systems, allowing effortless integration with Pro Tools.