Back in the mid-1980s, the Focusrite Forte Recording Console was acclaimed as being among the finest designs of studio hardware to come along up until that time. Its legendary ISA110 mic pre and EQ was among the most revered and trusted amongst high-end studio professionals who demanded a clean, pristine, transparent sound but still yielding a bit of warmth to the signal. Over the course of many years, the same design was implemented in a slew of Focusrite products within their ISA and RED range of preamplifiers, favorites of discerning engineers the world over. The Focusrite ISA One Single-Channel Mic preamp makes it possible to own one of these fantastic preamps in the form of a portable, rugged chassis with a host of useful features, at a price that makes it accessible to engineers of all ilks. Lets begin with the ISA110 module. The very same topology used on the original design is faithfully implemented here. A flexible, independent D.I. channel, complete with dedicated gain control, allows you to blend the direct guitar or mono instrument signal with the micd signal, making for some very interesting creative options. The variable impedance control lets you properly match up your microphone to get the best possible signal into the ISA One. You can hook up a compressor or EQ at the units insert point, a handy feature enabling you to further enhance your signal on the way to your recording medium of choice. The line in jack allows for your active signal to pass through and a headphone jack with a dedicated volume control ups the ante, as you can monitor whatever signal (the whole stereo mix, for example) you route through it. Monitor your signal via the moving-coil VU meter together with two 6-LED meters. Inputs can be metered either pre or post input. The Focusrite ISA Ones rear panel analog outputs include 2 balanced XLR outputs (mic pre and D.I. output), as well as a TRS ? send. To further enhance the connectivity, Focusrite offers a digital output option with the ISA ADC providing 2 channels of the highest quality 24-bit conversion at all sample rates up to 192kHz. Digital output formats include 2 channel single/dual wire AES/EBU or 2 channel S/PDIF, all via a 9-pin D-type connector, as well as optical S/PDIF and ADAT. The ADAT (TOSlink) port is stereo and operates at 24-bit, up to 96kHz. Also available is the ISA One Digital, offering the ADC as a standard built-in feature, so remember to ask us about it. The same card can be used in Focusrites ISA 430 MKll channel strip. With all these useful features, together with pro sound quality packed into a single sturdy, portable box, youd be hard-pressed to find a better professional solution at a better value than the Focusrite ISA One. Specifications Mic Input Response Gain range = 0dB to 60dB in 10dB steps + 20 dB of variable gain Input Impedance, variable as follows:- (Switched Impedance setting Equivalent Input Impedance at 1kHz) Low = 600 Ohms ISA110 = 1400 Ohms Med = 2400 Ohms High = 6800 Ohms EIN (equivalent input noise) = -126dB measured at 60dB of gain with 150 Ohm terminating impedance and 22Hz/22kHz band-pass filter Noise at main output with gain at unity (0dB) = -97dBu measured with a 22Hz/22kHz band-pass filter Signal to noise ratio relative to max headroom (9dBu) = 106dB THD at medium gain (30dB) = 0.0009% measured with a 1kHz -20dBu input signal and with a 22Hz/22kHz band-pass filter Frequency response at minimum gain (0dB) = -0.5dB down at 10Hz and -3dB down at 125kHz Frequency response at maximum gain (60dB) = -3dB down at 16Hz and -3dB down 118kHz CMRR=98dB (Channel 1, 1kHz, maximum gain with +24 dBu input) Crosstalk Channel to Channel: with 10dB@1kHz input to chA, chB output =104dBrA. With 10dB@10kHz input to chA, chB output = 84dBrA Line Input Response Gain range = -20dB to +10dB in 10dB steps + 20 dB of variable gain Input Impedance = 10kO from 10Hz to 200kHz Noise at main output with gain at unity (0dB) = -96dBu measured with a 22Hz/22kHz band-pass filter Signal to noise ratio relative to max headroom (24dBu)=120dB Signal to noise ratio relative to 0dBFS (+22dBu) = 118dB THD at unity gain (0dB) = 0.001% measured with a 0dBu input signal and with a 22Hz/22kHz band-pass filter Frequency Response at unity gain (0dB) = -0.3dB down at 10Hz and -3dB down at 200kHz Instrument Input Response Gain range = 10dB to 40dB continuously variable Input Impedance: High = greater than1MO Low =greater than 300kO Noise at minimum gain (+10dB) = -92dBu measured with a 22Hz/22kHz band-pass filter Noise at maximum gain (+40dB) = -62dBu measured with a 22Hz/22kHz band-pass filter THD at minimum gain (+10dB) = 0.001% measured with a 10dBu input signal and with a 22Hz/22kHz band-pass filter Frequency Response at 10dB gain with -10dB input = 10Hz-100kHz +/- 0.6dB Frequency Response at 40dB gain with -40dB input = -2.5dB down at 10Hz and 0dB at 100kHz High Pass Filter Roll off = 18dB per octave 3 pole filter Fixed Frequency 75Hz measured at the 3dB down point Meters Moving coil (MC) meter is factory calibrated to 0VU = +4dBu with 1kHz sinewave. With the VU Cal button pressed the meter can be adjusted on the rear panel to allow 0VU to equal +10dBu to +26dBu with the centre detent being equal to +22dBu. Peak LED meters calibrated in the detent position for 0dBFS = +22dBu, calibration is adjustable on the rear panel to allow 0dBFS to equal +10dBu to +26dBu Routing for MC and Peak1 meter is after the HPF, pre insert send or switched post insert return. Peak2 is always pre ADC channel 2, which can be fed by external input or Instrument input. LED levels are as follows when peak calibration is set to center detent on the rear panel. (This is when using the internal ADC). 0 = +22dBu -2 = +20dBu -6 = +16dBu -12 = +10dBu -18 = +4dBu -42 = -20dBu FRONT AND REAR CONNECTIVITY Analogue Channel Inputs: Mic input: XLR x 1 Line input: XLR x 1 and TRS x1 Instrument input TRS Jack: XLR x 1 External ADC input: TRS Jack x 1 Return: TRS Jack x 1 Analogue Channel Outputs: Send: TRS Jack x 1 Balanced line output: XLR x 1 DI output: XLR x 1 DI through: TS Jack x 1 Analogue Channel Additional I/O: Cue mix left input: TRS Jack x 1 Cue mix right input: TRS Jack x 1 Headphones output: ? TRS Jack x 1