Eight ISA series transformer-based preamps

In a single robust 2U chassis, offering the classic Focusrite pre at its lowest cost-per-channel to date.

New optional eight-channel 192kHz A-D converter

Not Included

Embodies cutting-edge conversion technology, incorporating Focusrite analogue circuitry to deliver the best A-D performance 

Convenient 25 pin D-type connectors

The ISA828 integrates quickly and seamlessly with ProTools HD, as well as other popular hard disk recorders and mixing desks.

Switchable impedance

Selectable per channel; choose one of four carefully selected input impedances, including the original ISA110 setting, to suit any microphone.

Direct instrument inputs

Each instrument input features high and low impedance options to provide a comprehensive and accessible DI solution.

Inserting available on every channel

Allows external devices to be inserted between the preamp and the A-D converter, using the 25-pin D-type cable.

High pass filter, phase reverse and phantom power

Each has a dedicated switch, independent on each channel.

Six LED input meter

Complete with precise meter trim - Designed to utilise the same reference points as Avid Pro Tools HD™.

Overview

The ISA828 eight-channel microphone preamplifier provides eight original ISA transformer-based preamps in a single robust 2U chassis, offering the Focusrite signature sound at its lowest cost per channel to date.

The eight ISA-series transformer-based microphone preamps feature the same classic microphone preamplifier design as the original ISA110 module from Focusrite's critically acclaimed Forté console (including the original Lundahl L1538 transformer and bespoke zobel network).

The preamps are complemented by eight line inputs, eight line outputs and an optional eight channel 192kHz A-D converter boasting a dynamic range of 122dB. Thanks to its convenient 25 pin D-Type connectors, the ISA828 also integrates quickly and seamlessly with ProTools HD, as well as other popular hard disc recorders and mixing desks. More information about the ISA828 A-D converter option can be found here<=link to ISA428/828 ADC option page>.

The microphone input stage additionally includes a variable impedance circuit, allowing the user to switch between four carefully selected input impedance settings. The original ISA110 setting is supplemented by three further impedance settings to either perfectly match the preamp with any microphone, thus maximising level, or to use different settings creatively to shape the sound of the microphone being used.

The four front panel instrument inputs also feature high and low impedance options to provide a comprehensive and accessible DI solution. Insert switches are also featured on every channel, should the need arise to place extra processing between the preamp and converter. Vintage design 75 Hz / 18dB per octave high pass filters are also provided on every channel, ensuring unwanted low frequencies are effectively eliminated. 

Finally, every channel features a six LED input meter, complete with global precise meter trim. Metering has been designed to utilise the same reference points as Digidesign’s Pro Tools HD™ system and provides clear and accurate input metering, independent of the DAW.

Specifications

We always quote 'real world' performance figures (measured to the AES17 standard). Some companies choose to quote chipset performance, which is misleading, and here's why.

Mic Input Response

• Gain range: 0dB to 60dB in 10dB steps

• Input Impedance, variable: 600?, 1k4?, 2k4?, 6k8?

• 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? 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: 1M? or 300k?

• 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

Weight

• 8.84kg

• 19.5Ibs

Dimensions

• 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)