Focusrite ISA 828 User manual

User Guide
www.focusrite.com
FA0145-04
Eight channel mic pre and optional A-D card with Dante
ISA828
MkII

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CONTENTS
About this User Guide ..................................................................... 3
INTRODUCTION .............................................................................. 4
ISA 828 MKII CONTROLS AND FEATURES .................................................... 5
Front Panel ................................................................................ 5
Channel Controls .......................................................................... 5
Input Selection.......................................................................... 5
Mic Input ............................................................................... 5
Line Input .............................................................................. 6
Instrument Input........................................................................ 6
Z In (Input Impedance)................................................................... 6
+48V ................................................................................... 6
Phase .................................................................................. 6
HPF (High-Pass Filter) .................................................................. 6
Insert .................................................................................. 6
Channel Meters ........................................................................... 7
Meter Calibration ....................................................................... 7
Rear Panel ................................................................................ 8
AC Mains Inlet .......................................................................... 8
Microphone Inputs ...................................................................... 8
Line Inputs ............................................................................. 8
Analogue Outputs ....................................................................... 8
A-D inputs.............................................................................. 8
Meter Trim ............................................................................. 8
A-D Option Card Slot .................................................................... 8
A-D Option Card ........................................................................... 9
A-D Card Clock and Sync Switches ......................................................10
PHYSICAL CHARACTERISTICS ..............................................................11
Power Requirements .....................................................................11
APPENDICES ................................................................................12
1. Connector Pinouts .....................................................................12
2. Preamp Input Impedance ..............................................................14
3. Pro Tools Interfacing ...................................................................16
PERFORMANCE AND SPECIFICATIONS .....................................................17
Focusrite RedNet Warranty and Service ..................................................19

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About this User Guide
This user guide applies to the ISA 828 MkII mic pre. It provides information about installing and using
the unit, and how it can be connected into your system.
Also included is information relating to the optional ISA ADN8 A-D interface card, which will allow
audio from the Mic pre to be added to a Dante network.
If you feel that additional information might be of assistance, be sure to consult the site:
https://pro.focusrite.com/technical-support, which contains a comprehensive collection of common
technical support queries.
Pro Tools® and Pro Tools | HDTM are trademarks or registered trademarks of Avid Technology, Inc. or its subsidiaries
in the United States and/or other countries.
Dante® and Audinate® are registered trademark of Audinate Pty Ltd.
Box Contents
• ISA 828 MkII unit
• AC power lead
• Safety information cut sheet

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INTRODUCTION
Thank you for purchasing the Focusrite ISA 828 MkII.
The ISA 828 MkII is a high quality eight channel microphone preamplifier, which can be used to
record microphone, line-level or instrument sources. Microphones and line-level sources for all
eight inputs are connected via the rear panel, whilst instrument inputs, available on channels 1–4,
can be plugged directly into the front panel jack sockets.
The front panel also features gain and other settings such as phantom power and impedance for
each of the eight analogue inputs. LED metering is provided on each channel in dBFS, to indicate
when the level is reaching the digital clipping point – a dial for calibration is provided on the rear
panel.
To maintain pristine Focusrite quality in the digital domain, an Analogue-to-Digital interface card
may be fitted into the option slot on the rear panel. This provides access to a Dante network and
features AES3, S/PDIF and ADAT signals.
With the A-D card installed, the internal/external clock sample rate and sync source can be selected
using the switches on the front panel.

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ISA 828 MKII CONTROLS AND FEATURES
Front Panel
Applies +48V phantom power to the
mic input XLR LED meter for signal level at channel
output or external input
Inverts polarity (Phase) of the
selected input Input Trim pot Mic/Line: 0 +20 dB
Instrument: +10 +40 dB
Applies a 75 Hz high-pass filter
(HPF) to the selected input Selects the input impedance (Z In)
for the Mic and Instrument inputs
Swaps the A-D option card‘s input
between channel out and external
input ‘A-D Input’ Input source selection
Selects the high (30-60 dB) mic gain
range for the Gain switch
10 dB stepped Mic/Line Gain switch
Mic: 0-30 / 30-60 Line: -20 +10
Channel Controls
Input Selection
Each press of the Input button steps through the available input sources: Mic/Line/Instrument for
channels 1–4, Mic/Line for channels 5–8.
Mic Input
The Gain switch sets the mic gain in 10 dB steps. Its range is either 0–30 dB or 30–60 dB when the
30–60 switch is pressed. An additional 0–20 dB of fine gain adjustment is available by using the Trim
control.
To avoid an excessive jump in level, It is recommended that the stepped Gain switch is turned to minimum before
pressing the 30-60 switch.
Before starting a recording, or if used for PA work, set the Trim control to near its centre position.This will allow for
some gradual gain adjustment up or down without the use of the stepped control.
Input channels 1–8
Power
switch
Instrument inputs
for channels 1–4
LED meter
source
A-D option card: clock
and sync selection

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Channel Controls...
Line Input
The Gain switch sets the gain at between -20 dB and +10 dB in 10 dB steps. Continuous gain adjustment
of up to 20 dB can be added using the Trim control.
Instrument Input
The Instrument inputs are accessed via standard 1/4” mono jacks on the front panel. The level is set
using the Trim control only and is continuously adjustable from +10 dB to +40 dB.
Refer to the appendix on page 12 for connector pinouts.
Z In (Input Impedance)
With Mic input selected, pressing the Z In button steps through the four
transformer preamp input impedance options. The values are shown in the
table.
For additional information on impedance selection see Appendix 2, “Preamp Input
Impedance” on page 14.
With Instrument input selected, pressing the switch toggles between High and
Low impedance settings, as shown in the lower table.
The Line input impedance is fixed at 10 kΩ and is not affected by the Z In
switch.
+48V
Pressing the +48V button applies phantom power to the Mic input XLR. This switch does not affect
the Line or Instrument inputs.
If you are unsure whether your microphone requires phantom power please refer to its handbook. Certain
microphones (most notably ribbon and unbalanced mics) could be damaged by applying phantom power.
Phase
Pressing Phase inverts the polarity of the selected input. This can be useful when multiple mic are
used in close proximity (ie., on a drum kit).
HPF (High-Pass Filter)
Pressing HPF inserts the 18 dB/octave 75 Hz high-pass filter into channel path; it is applied to
whichever input is selected.
The HPF is useful for removing any unwanted low frequencies, eg., rumble transmitted through oor mounted
mic stands, etc.
Insert
Pressing a channel’s Insert button switches the A-D option card’s input source from the channel
output to the external input – ie., the same channel in the ‘A-D Inputs’ connector.
The channel’s output is unaffected, allowing its signal to be processed externally and then returned
to the A-D card for conversion.
The return signal levels can monitored on the channel LED meters when the Meters Pre A-D switch is pressed
– see Channel Meters on the next page.
Low 600 Ω
ISA 110 1.4 kΩ
Med 2.4 kΩ
High 6.8 kΩ
Low 470 kΩ
High 2.4 MΩ
Mic Impedance
Instrument Impedance

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Channel Meters
The LED meters can be switched to display signal level at two different audio paths,
determined by the setting of the Meters Pre A-D switch on the front panel:
• Meters Pre A-D switch OFF – LEDs show the signal at the channel output. This is
the default setting and shows the level being sent to external recorders/outboard
effects.
• Meters Pre A-D switch ON – LEDs now show the signal level received at the A-D
Input connector on the rear panel. This mode is useful when the A-D option card is
installed and allows the incoming signals to be monitored before being converted
by the digital card.
The LED meter scale is in dBFS, ie., the dB level relative to maximum output (reached
when the red ‘0’ LED illuminates).
The default calibration for the meters is for ‘0’ to indicate a signal level of 22 dBu (which is
the A-D card’s maximum input level). See Meter Calibration below.
Meter Calibration
The signal level at which 0 dBFS is displayed can be adjusted by using the Meter Trim
control on the rear panel.
The default setting of 0 dBFS = 22 dBu occurs when the knob is in its central, detent
position – to correspond with the maximum input level of the A-D card.
Rotating the Meter Trim knob will set the value at between 0 dBFS = 15 dBu (fully
anticlockwise) and 0 dBFS = 26 dBu (fully clockwise).

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AC Mains Inlet
Standard IEC receptacle for AC mains. ISA 828 MkII features a ‘Universal’ PSU, enabling it to operate
on any supply voltage between 100 V and 240 V AC.
Microphone Inputs
Eight latching XLR-3 female connectors.
Line Inputs
Eight balanced 1/4” TRS jack sockets.
Analogue Outputs
Channel outputs 1–8 on DB25 female connector. These outputs are linked internally to the A-D option
card inputs, except when the Insert switches are pressed.
A-D inputs
Eight analogue inputs to the A-D option card on DB25 female connector. Inputs are enabled individually
by pressing channel Insert switches.
Both DB25 connectors are wired according to the AES59 Standard (also known as the TASCAM Analogue
standard). Refer to the Appendix on page 12 for connector pinouts.
Meter Trim
Allows the channel LED meter reading at full scale to be adjusted between 15 dBu and 26 dBu. At the
central detented position the reading will be 22 dBu, which matches the maximum input level of the
A-D card. Also see Meter Calibration on page 7.
A-D Option Card Slot
Slot for ISA ADN8 analogue to digital conversion card. The card allows audio channels from the ISA
828 MkII to be added to a Dante network. It also provides AES3, S/PDIF and ADAT signals.
See the following page for A-D card details.
Rear Panel
Mic input XLRs
1-8
Line input jacks
1-8
Mains
inlet
Analogue
outputs 1-8
A-D external
inputs 1-8
Meter Trim
control
Slot for A-D
option card

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A-D Option Card
The optional ISA ADN8 A-D card can be retrofitted to an ISA 828 MkII at any time. Engineering
experience is not required as the card can easily be installed by the user.
Note that the ISA 828 MkII does not support the earlier ISA 8-Channel A-D card.
Once fitted, configuration of the card is carried out over the network using either RedNet Control or
the Dante Controller software application.
The tting instructions and network software applications are included with the A-D card option.
Word Clock – Input
Allows the card to be synchronised to an external Word Clock source via the BNC connector.
Word Clock – Output
Provides an output of the external Word Clock source connected at the “Word Clock In” BNC connector
or, transmits the internal sample frequency of the A-D card.
• When the ISA 828 MkII is being used as a slave device within a larger digital system, the Word
Clock Out connector can be used to pass on the external word clock signal to the next device.
• When the unit is not slaved to another device and is in Internal Clock mode, the Word Clock
Out connector outputs the sample frequency selected on the ISA 828 MkII front panel.
Primary Network Port
Latching RJ45 connector for the Dante network. Use standard Cat 5e or Cat 6 network cable to
connect to a local Ethernet switch to connect the ISA ADN8 to the Dante network. Adjacent to each
network socket are LEDs which illuminate to indicate a valid network connection and network activity.
Secondary Network Port
Secondary Dante network connection where two independent Ethernet links are being used
(Redundant mode) or an additional port on an integral network switch on the primary network
(Switched mode).
ADAT I/O 1 and 2
Two independent 8-channel ADAT optical inputs and outputs using standard TOSLINK connectors.
AES3 Outputs 1-8
Eight AES3 outputs on DB25 connector.
See Appendix 1 on page 13 for connector pinouts.
See Appendix 3 on page 16 for Pro Tools interfacing information.

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A-D Option Card...
A-D Card Clock and Sync Switches
Clock select
Allows the user to select the internal sample frequency: 44.1kHz, 48kHz, 88.2kHz,
96kHz, 176.4kHz, or 192kHz.
Ext
Allows the ISA ADN8 A-D card to be slaved to an external Word Clock source. Press the
switch to toggle between standard and Dante clock.
Lock LED
Indicates that the unit is successfully synchronised to the external Word Clock.