ISA 828 incorporates eight of Focusrite's renowned mic pres in a simple-to-operate 2U enclosure, placing four mic preamps, instrument inputs and line ins at your fingertips. The original Focusrite mic pre was designed to suit the microphones of the time; today's model makes one small change, adding three additional input impedances to the classic ISA 110 setting, allowing you to match any microphone, old or new, and access a wide range of sounds, from the character and warmth of a vintage mic to the clear transparency of a modern design.
Each mic pre has the option of mic, line or the front-panel instrument input, with variable input impedance to ensure you are getting the best performance from the source. Up to 60dB of gain is available on the four-position rotary and gain range switches, with a further +20dB of continuously variable trim, meaning a huge 80dB of gain is available should it be required. The high-pass filter features variable cut-off frequency between 16 and 420Hz. An array of 6-segment LED meters show peak signal level for the four mic pres, in addition to the four direct inputs to the optional A-D card. Switchable rear-panel insert points allow the use of inline processors such as compression.
Product Specifications
Mic Inputs
| Gain range | 0 dB to 60 dB in 10 dB steps |
| Input Impedance | Variable, 600Ω, 1k4Ω, 2k4Ω, 6k8Ω |
| EIN (equivalent input noise) | -126 dB measured at 60 dB of gain with 150 Ohm terminating impedance and 22 Hz / 22 kHz bandpass filter |
| Noise at main output with gain at unity (0 dB) | -97 dBu measured with a 22 Hz / 22 kHz bandpass filter |
| Signal to noise ratio relative to max headroom (9dBu) | 106 dB |
| THD at medium gain (30dB) | 0.0008% measured with a 1 kHz -20 dBu input signal and with a 22 Hz / 22 kHz bandpass filter |
| Frequency response at minimum gain (0 dB) | -0.5 dB down at 10 Hz and –3 dB down at 110kHz |
| Frequency response at maximum gain (60 dB) | –3 dB down at 16 Hz and –3 dB down 85 kHz |
| CMRR | 91.8 dB (Channel 1, 1 kHz, maxiumum gain) |
| Crosstalk Channel to Channel | With 10 dB @ 1 kHz input to chA, chB output = 102 dBrA. With 10 dB @ 10 kHz input to chA, chB output = 84 dBrA |
Line Inputs
| Gain range | -20 dB to +10 dB in 10 dB steps |
| Input Impedance | 10 kΩ from 10 Hz to 200 kHz |
| Noise at main output with gain at unity (0 dB) | -96 dBu measured with a 22 Hz / 22 kHz bandpass filter |
| Signal to noise ratio relative to max headroom (24 dBu) | 120 dB |
| Signal to noise ratio relative to 0dBFS(+22dBu) | 118dB |
| THD at unity gain (0dB) | 0.001% measured with a 0 dBu input signal and with a 22 Hz / 22 kHz bandpass filter |
| Frequency Response at unity gain (0dB) | 0.3 dB down at 10 Hz and –3 dB down at 122 kHz |
Instrument Inputs
| Gain range | 10 dB to 40 dB continuously variable |
| Input Impedance | 1 MΩ or 300 kΩ |
| Noise at minimum gain (+10 dB) | -90 dBu measured with a 22 Hz / 22 kHz bandpass filter |
| Noise at maximum gain (+40 dB) | -62 dBu measured with a 22 Hz / 22 kHz bandpass filter |
| THD at minimum gain (+10 dB) | 0.002% measured with a 10 dBu input signal and with a 22 Hz / 22 kHz bandpass filter |
| Frequency Response at 10 dB gain with -10 dB input | 10 Hz - 200 kHz +/- 0.6 dB |
| Frequency Response at 40 dB gain with -40 dB input | -2.5 dB down at 10 Hz and 0 dB at 200 kHz |
Instrument Inputs
| Roll off | 18 dB per octave 3 pole filter |
| Frequency | Fixed 75Hz measured at the 3dB down point |
Weight and Dimensions
| Weight | 8.84 kg | 19.5 lbs |
| Dimensions (W x H x D) | 484mm (W) x 85mm (H) x 305mm (D) (350mm depth with heat sink) | 19" (W) x 3.5" (H) x 12" (D) (13.8" depth with heat sink) |
