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Focusrite ISA828 8-Channel Mic Pre-amp  (Open Box)
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Product# 180187
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Focusrite signature sound from the legendary Forte console made affordable.

You can enjoy the benefits of Focusrites classic heritage sound in many ways, but one of the most cost-effective is with the ISA 828, which includes eight Focusrite transformer-based mic preamps in a compact 2U package, along with front panel instrument ins and rear panel line inputs.

The Focusrite ISA mic preamp is based on the original design created by Rupert Neve in 1985 for Sir George Martins AIR Studios. Virtually unchanged over the years, the ISA mic preamp delivers the warm, full sound that could be just what youre looking for “ and if you use a significant number of microphones at once, the ISA828 is for you.

We made one significant alteration to the design, and that was to add three additional input impedances to the original vintage ISA110 setting. Ranging from low to high impedance, the four settings enable you to get the very best sound from a vintage mic “ its after all what the ISA was originally designed for “ but also get a clean, transparent sound from the microphones of today. Or you can enhance a particular feature of your favourite microphones. Indeed, ISA makes the perfect match for any mic. Theres also a vintage design 75Hz / 18dB per octave high pass filter on each channel for detailed control of the bass end.

Four front-panel direct instrument inputs are also provided, with high and low impedance settings for extra versatility, and the input side is rounded out by eight TRS rear-panel line inputs. With convenient 25-pin D-type output connectors, ISA 828 is easy to interface with Pro Tools HD and other popular recording systems and consoles. Theres also an optional 8-channel A/D converter available with 122dB dynamic range and sampling up to 192kHz. An insert is available on each channel between the preamp and the A/D. 6-LED meters let you know exactly what is going on, and use the same reference points as Avid Pro Tools HD.

Eight ISA series transformer-based preamps
Optional eight-channel 192kHz A-D converter
Interface easily with Pro Tools and other systems
Direct instrument inputs
Inserts available on every channel
Switchable impedance
High pass filter, polarity reverse and phantom power
Six LED input meter
Eight Lundahl LL1538 mic input transformers
Mic Input Response
Gain range = 0dB to 60dB in 10dB steps
Input Impedance, variable as follows:-

Switched Impedance setting Equivalent Input Impedance at 1kHz
Low 600
ISA 110 1400
Med (Medium) 2400
High 6800

EIN (equivalent input noise) = -126dB measured at 60dB of gain with 150 Ohm terminating impedance and
22Hz/22kHz bandpass filter
Noise at main output with gain at unity (0dB) = -97dBu measured with a 22Hz/22kHz bandpass filter
Signal-to-noise ratio relative to max headroom (9dBu) = 106dB
THD at medium gain (30dB) = 0.0008% measured with a 1kHz -20dBu input signal and with a 22Hz/22kHz bandpass filter
Frequency response at minimum gain (0dB) = -0.5dB down at 10Hz and ”3dB down at 110kHz
Frequency response at maximum gain (60dB) = ”3dB down at 16Hz and ”3dB down 85kHz
CMRR=91.8dB (Channel 1, 1kHz, maxiumum gain)
Crosstalk Channel to Channel: with 10dB@1kHz input to chA, chB output =102dBrA. With 10dB@10kHz input to chA,
chB output = 84dBrA

Line Input Response
Gain range = -20dB to +10dB in 10dB steps
Input Impedance = 10k
Ohms from 10Hz to 200kHz
Noise at main output with gain at unity (0dB) = -96dBu measured with a 22Hz/22kHz bandpass 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 bandpass filter
Frequency Response at unity gain (0dB) = 0.3dB down at 10Hz and ”3dB down at 122kHz

Instrument Input Response
Gain range = 10dB to 40dB continuously variable
Input Impedance:
High >1M Ohms
Low > 300k Ohms
Noise at minimum gain (+10dB) = -90dBu measured with a 22Hz/22kHz bandpass filter
Noise at maximum gain (+40dB) = -62dBu measured with a 22Hz/22kHz bandpass filter
THD at minimum gain (+10dB) = 0.002% measured with a 10dBu input signal and with a 22Hz/22kHz bandpass filter
Frequency Response at 10dB gain with -10dB input = 10Hz-200kHz ± 0.6dB
Frequency Response at 40dB gain with -40dB input = -2.5dB down at 10Hz and 0dB at 200kHz

High Pass Filter
Roll off = 18dB per octave 3 pole filter
Fixed Frequency 75Hz measured at the 3dB down point

Input Meter
Calibrated in the detent position for 0dBFS = +22dBu and indicates the level after the High Pass Filter and before the
Insert Send output. LED levels are as follows:
0 = +22dBu
-2 = +20dBu
-6 = +16dBu
-12 = +10dBu
-18 = +4dBu
-42 = -20dBu
Calibration is adjustable to allow 0dBFS to equal +10dBu to +26dBu
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