The ISA428 MkII from Focusrite is a four-channel microphone preamp featuring Focusrite's transformer-based preamps.
The ISA428 MkII from Focusrite is a four-channel microphone preamp featuring Focusrite's transformer-based preamps. With selectable input impedance, direct instrument inputs and an optionaleight channels of high-quality analog to digital conversion, the unit is a perfect front end for the audio professional, whether utilizing digital or analog recording.
The ISA microphone preamp holds a reputation for delivering transparency along with subtle warmth derived from transformer core saturation. The addition of a variable impedance circuit allows users to perfectly match the preamp with any microphone, or to use different settings creatively to shape the sound of the microphone.
The extremely broad frequency response of Focusrite preamps (close to 200kHz at the top end) guarantees accurate phase response across the range of human hearing, with the roll-off point being moved entirely outside of the audible hearing range. Warmth, plus beautifully open, unrestricted high frequencies, is a classic hallmark of the mid 80's Focusrite designs to which this preamp owes its design.
The optional eight channel analog converter utilizes high-quality Burr-Brown amplifiers and PCM4220 A-D converter chips seated within Focusrite's custom analog circuitry. Specifications include a dynamic range of 122dB and jitter performance below 250 picoseconds. The card can be retrofitted at any time and due to the convenient 25-pin D-type connector, it integrates seamlessly with most digital workstations, including Pro Tools.
|Number of Channels||4|
|Inputs||4 x XLR Microphone (rear panel)
4 x 1/4" TS phone Instrument (front panel)
4 x 1/4" TRS phone Line (rear panel)
4 x 1/4" TRS phone Insert Return (front Panel)
4 x XLR ADC Input for optional AD converter card (rear panel)
|Output||4 x XLR Line (rear panel)
4 x 1/4" TRS phone Insert Send (rear panel)
|Phantom Power||+48V individually switchable|
|Multi Function||Has provision for optional analog to digital converter|
|Gain Range||Microphone: 0dB to +60dB in 10dB steps, plus 0dB to +20dB continuously variable trim
Line: -20dB to +10dB in 10dB steps, plus 0dB to +20dB continuously variable trim
Instrument: +10dB to +40dB continuously variable
|Input Impedance||Microphone: 600Ω, 1.4kΩ, 2.4kΩ, 6.8kΩ
|Maximum Output Level||Microphone: +7.4dBu
|Frequency Response||Microphone: -0.35dB at 20Hz and -3.0dB at 122kHz (0dB gain) and -2.5dB at 20Hz and -3.0dB at 103kHz (60dB gain)
Line: -0.3dB at 20Hz and -3dB at 94kHz (0dB gain)
Instrument: -0.2dB at 20Hz and 0dB at 200kHz (+10dB gain) and -3.0dB at 20Hz and -3.0dB at 38.4kHz (+40dB gain)
|THD + N||Microphone: 0.0009% (measured at 1kHz, -20dBu input signal, at 30dB gain setting, with a 20Hz/22kHz bandpass filter)
Line: 0.002% (measured with +4dBu input signal, 0dB gain setting, with a 20Hz/22kHz bandpass filter)
Instrument: 0.006% (measured with -20dBu input signal, at minimum gain (+10dB), with a 20Hz/22kHz bandpass filter)
|Meters||Each 6-LED meter is calibrated 0dBFS = +22dBu (the maximum level which can be correctly converted by the optional internal A/D converter before overload occurs). The meter calibration points are as follows:
Meter panel calibration value in dBFS / Equivalent dBu value:
|Dimensions (WxDxH)||19 x 11 x 3.5" (483 x 279 x 89mm)|
|Weight||12.2 lbs (5.5kg)|
|Specialties||High Pass Filter
Roll off = 18dB per octave 3 pole filter
Frequency range: 16Hz to 420Hz (continuously variable, measured at the 3.0dB down point)
|Package Weight||17.55 lb|
|Box Dimensions (LxWxH)||25.0 x 18.0 x 9.0"|