Focusrite ISA428MKII and Sterling ST69 Microphone  

Product #H78711

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Item Note:

This product has been discontinued but may be available as a Open Box item.

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Quality tube condensor microphone with a bank of four legendary microphone preamps.

This is a superb front end for your recording system, whether for a home studio or a professional recording suite. The Focusrite ISA428 MkII provides four of Focusrite's prestigious transformer-based microphone preamps in one convenient rackmountable chassis. It features the same classic circuitry and renowned audio quality found in the original Focusrite ISA mic pre at a new level of affordability. With selectable input impedance, direct instrument inputs and an optional eight channels of high-quality analogue to digital conversion, the ISA428 MkII creates the perfect front end for the discerning recording professional. Add to that a Sterling ST69 microphone and you have the beginning of a very sweet signal chain.

Sterling ST 69
Sterling Audio's ST69 Tube Microphone is an excellent choice for recording engineers and musicians looking for a superior studio microphone. A combination of new and traditional technology, blended with our Disk Resonator system, yields wide frequency response and quick transient response without sacrificing warmth and tone. It's ideal for capturing the full, detailed sound of vocals, acoustic & electric instruments, and drums. And its precision machined, brushed stainless-steel finish complements the ST69's technical brilliance.

First introduced in 1985, the ISA microphone preamp holds a reputation for outstanding transparency along with subtle warmth contributed by transformer core saturation. The addition of a variable impedance circuit allows ISA users to perfectly match the preamp with any microphone, or to use different settings creatively to shape the sound of the microphone. Unchanged for decades, the ISA microphone preamp topology offers incredible clarity and the signature Focusrite sound that makes it the top choice among many audio professionals today.

The optional class-leading eight-channel A-D converter option used with the ISA828 is also compatible with the ISA428 MkII. Along with the four mic preamp inputs, four additional inputs allow you to route other line signals through the converter. More information about the ISA428 MkII A-D converter option can be found here.

Four instrument inputs, instantly accessible on the front panel, allow quick and easy connection without the need for a separate DI box. Extra processing can be placed between preamp and conversion via the units dedicated insert points, featured on every channel. Finally, accurate six-segment LED metering is designed to catch even the fastest transients on every channel.

Over 25 years, Focusrite has earned a reputation for bringing superb audio quality and engineering excellence to an array of audio professionals. Whether you're looking to preserve the sound of your classic microphones, or searching for the perfect front end for your digital studio, the ISA428 MkII brings legendary tools to your studio at an exceptional new price.

  • Focusrite ISA428 MkII
  • Four ISA series transformer-based preamps
  • Eight-channel optional A-D converter
  • Selectable impedance
  • Four front panel instrument inputs
  • Dedicated analogue insert points
  • Variable high-pass Focusrite filter
  • Accurate LED meters for every channel
  • Sterling ST69
  • Cardioid, Omni, and Figure-8 patterns
  • Low noise, low heat, 6205 tube circuit
  • Double-sided 1" all brass capsule, hand assembled and oven baked for long term stable operation
  • Ultra-thin 3-micron gold-evaporated Mylar diaphragm provides sonic detail and accuracy
  • Disk ResonatorTM design extends high-frequencies naturally
  • High pass filter and -10dB pad
  • Custom-wound nickel core output transformer, optimized for the ST69
  • Brushed stainless steel body and head

Order now for a versatile bank of classic preamps for microphone or instrument along with a beautiful tube microphone.


ISA428MKII and Sterling ST69 Microphone Specifications:

  • Sterling ST69
    preamp Class-A Tube
    polar patterns Cardioid, Omni, Figure-8
    frequency response 20Hz - 20kHz
    High pass filter Switchable 75Hz, 12dB/octave
    attenuation pad Switchable -10dB
    Sensitivity 30mV/Pa
    Maximum SpL 130/140dB SPL
    Equivalent noise 23dB SPL
    Typical Load impedance >1000 Ohms
    Output Source impedance 200 Ohms, transformer isolated
    dimensions 7.5" long, 1.8" max. diameter
    Weight 1.2 lbs.
    power Included power supply
    Focusrite ISA48 MkII
    Mic Inputs
    ¢ Frequency response at minimum gain (0dB): -0.35dB at 20Hz and -3dB at 122kHz
    ¢ Frequency response at maximum gain (60dB): -2.5dB at 20Hz and -3dB 103kHz
    ¢ Gain range: 0dB to +60dB in 10dB steps, plus 0dB to +20dB continuously variable trim
    ¢ Maximum headroom: +7.4dBu
    ¢ THD+N: 0.0009% (measured at 1kHz -20dBu input signal, at 30dB gain setting, with a 20Hz/22kHz bandpass filter)
    ¢ Noise EIN: -126dB (measured at 60dB of gain with 150Î termination and 20Hz/22kHz bandpass filter)
    ¢ Noise at main output with unity gain: -98dBu (measured with a 20Hz/22kHz bandpass filter)
    ¢ SNR: 123dB (relative to max output 25dBu)
    ¢ SNR: 120dB (relative to 0dBFS (+22dBu)
    ¢ CMRR: 88dB.
    ¢ Input Impedance, variable: 600Î, 1400Î, 2400Î, 6800Î
    Line Inputs
    ¢ Frequency Response at unity gain (0dB): -0.3dB at 20Hz and -3dB at 94kHz
    ¢ Gain range: -20dB to +10dB in 10dB steps, plus 0dB to +20dB continuously variable trim
    ¢ Maximum headroom: +25.4dBu
    ¢ THD+N: 0.002% (measured with +4dBu input signal, 0dB gain setting, with a 20Hz/22kHz bandpass filter)
    ¢ Noise at main output with unity gain: -91dBu (measured with a 20Hz/22kHz bandpass filter)
    ¢ SNR: 116dB (relative to max output 25dBu)
    ¢ SNR: 113dB (relative to 0dBFS +22dBu). Input Impedance: 10kÎ
    Instrument Inputs
    ¢ Frequency Response at +10dB gain: -0.2dB at 20Hz and 0dB at 200kHz
    ¢ Frequency Response at +40dB gain: -3dB at 20Hz and -3dB at 38.4kHz
    ¢ Gain range: +10dB to +40dB continuously variable
    ¢ Maximum headroom: +11.5dBu
    ¢ THD+N: 0.006% (measured with -20dBu input signal, at minimum gain (+10dB), with a 20Hz/22kHz bandpass filter)
    ¢ Noise at main output with minimum gain (+10dB): -95dBu (measured with a 20Hz/22kHz bandpass filter)
    ¢ Input Impedance = >1MÎ
    High Pass Filter
    ¢ Roll off = 18dB per octave 3 pole filter
    ¢ Frequency range: 16Hz to 420Hz (continuously variable, measured at the 3dB down point)
    ¢ 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
    0dBFS / +22dBu
    -2dBFS / +20dBu
    -6dBFS / +16dBu
    -12dBFS / +10dBu
    -18dBFS / +4dBu
    -42dBFS / -20dBu

    Front and rear connectivity
    Analogue Channel Inputs (Inputs 1-4)
    ¢ 4 instrument 1„4" TS jack inputs on front panel
    ¢ 4 microphone XLR inputs on rear panel
    ¢ 4 line 1„4" TRS jacks on rear panel
    ¢ 4 insert return 1„4" TRS jacks on rear panel
    ¢ 4 ADC XLR inputs on rear panel
    Analogue Audio Outputs (Outputs 1-4)
    ¢ 4 line XLR outputs on rear panel
    ¢ 4 insert send 1„4" TRS jacks on rear panel
    Other I/O
    ¢ IEC power input connector 100Vac - 240Vac
    Front Panel Indicators
    ¢ 8 output meters, 6 segment
    ¢ 4 30-60 mic gain range selection indicator
    ¢ 4 +48V phantom power indicator
    ¢ 4 Phase indicator
    ¢ 4 Insert In indicator
    ¢ 4 Filter In indicator
    ¢ 4 Input selection indicators (Mic, Line, Inst)
    ¢ 4 Z In microphone input impedance selection indicators (Low, ISA110, Med, High) Clock select indicators (44.1, 48, 88.2, 96, 176.4, 192)
    ¢ Ext clock indicators (Lock, Word clock, 256X)
    Dimensions (W x H x D)
    480mm (W) x 88mm (H) x 280mm (D)
    19" (W) x 3.5" (H) x 11" (D)

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