What is it?A microphone pre-amplifier incorporating Focusright’s ISA transformer-based design in a “rugged and portable” chassis. DetailsThe ISA One is built around the same vintage microphone pre-amplifier topology as the original ISA110 module, including the Lundahl L1538 transformer and bespoke zobel network. The pre-amp is complemented by a line input (XLR and TRS Jack) and an independent DI channel, complete with dedicated gain control, active or passive impedance switch, a TRS jack output for routing to an amp and an independent XLR output on the rear. The design features variable impedance circuitry – allowing the user to switch between four selected input impedance settings – plus phantom power, phase reverse and a 75Hz, 18dB/octave high-pass filter. Frequency response for the mic input at minimum gain is -0.5dB down at 10Hz and -3dB down at 125kHz; at maximum (60dB) gain, it is -3dB down at both 16Hz and 118kHz. Signal to noise ratio is quoted as 106dB and THD (at 30-db) at 0.0009%. Input metering for both channels is provided by moving coil VU meter – with variable calibration to suit analogue and digital recording media – plus dual 6-LED peak meters. Inputs can be metered either pre- or post-insert.