Lundahl LL1538 mic input transformer
Rupert Neve originally chose the Lundahl LL1538 to be the input transformer on the ISA 110. To this day the Lundahl transformer remains the best microphone input transformer available, and is used in every ISA Series mic pre. Rupert Neve also perfected the Zobel network found in the ISA circuit; something which takes a lot of knowledge and a golden set of ears. This allows the ISA mic pre to maintain an extremely flat frequency response across a very wide bandwidth.
Up to 80 dB of gain
ISA Two offers up to 80 dB of clean, distortion-free gain. The much-heralded ISA topology also ensures low-noise even at the highest gain levels. The transformer alone supplies 20 dB of gain, while ISA’s input stage offers up to 60 dB in addition, giving an astonishing 80 dB of maximum gain on the microphone input.
Variable input impedance
Four choices of input impedance, including the original ISA 110 value, allow you to match the preamp to your microphone, even if it's a vintage type, giving you the best possible sound. The impedance is selected using a switch on the front panel, and the impedance choice is remembered even once the unit is switched off and back on.
Each channel has an eight-LED array to clearly display the level of your two signals. You can line up your analogue evels with your converters or DAW by using the calibration knob on the rear panel. You will be safe in the knowledge that you have avoided clipping on the way in.
Front-panel instrument and rear panel line inputs
Two 1/4in jack sockets on the front panel of ISA Two give you instant access to a transparent DI input. TRS line inputs are available on the rear panel too, and you can step through them instantly to select the one you want.
Variable cut-off high-pass filter
Built in, and easily accessed with its own large knob and illuminated button, is an extremely smooth-sounding 18 dB/octave high-pass filter of the same design as the original ISA 110 module. This is ideal for cutting out rumble, thumps and other unwanted low-frequency sounds and with a range of 16 to 420 Hz, it's easy to lose what you don’t want, and keep what you do.
Rear panel balanced inserts
Each channel of ISA Two has its own balanced insert point. With 1/4" TRS send and receive connections, your choice of signal processor can be connected and switched in and out using the illuminated switch on the front panel.