Focusrite Pro ISA828-MKII Users Manual
ISA828
MkII
Eight channel mic pre and optional A-D card with Dante
User Guide
FA0145-04
www.focusrite.com
CONTENTS
About this User Guide
INTRODUCTION
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ISA 828 MKII CONTROLS AND FEATURES
Front Panel
Channel Controls
Input Selection
Mic Input
Line Input
Instrument Input
Z In (Input Impedance)
+48V
Phase
HPF (High-Pass Filter)
Insert
Channel Meters
Meter Calibration
Rear Panel
AC Mains Inlet
Microphone Inputs
Line Inputs
Analogue Outputs
A-D inputs
Meter Trim
A-D Option Card Slot
A-D Option Card
A-D Card Clock and Sync Switches
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PHYSICAL CHARACTERISTICS
Power Requirements
APPENDICES
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1. Connector Pinouts
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2. Preamp Input Impedance
3. Pro Tools Interfacing
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PERFORMANCE AND SPECIFICATIONS
Focusrite RedNet Warranty and Service
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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 | HD
in the United States and/or other countries.
Dante® and Audinate® are registered trademark of Audinate Pty Ltd.
TM
are trademarks or registered trademarks of Avid Technology, Inc. or its subsidiaries
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
Input channels 1–8
LED meter
source
Instrument inputs
for channels 1–4
Channel Controls
Selects the high (30-60 dB) mic gain
range for the Gain switch
Applies +48V phantom power to the
mic input XLR
Inverts polarity (Phase) of the
selected input
Applies a 75 Hz high-pass filter
(HPF) to the selected input
Swaps the A-D option card‘s input
between channel out and external
input ‘A-D Input’
A-D option card: clock
and sync selection
10 dB stepped Mic/Line Gain switch
Mic: 0-30 / 30-60 Line: -20 +10
LED meter for signal level at channel
output or external input
Input Trim pot Mic/Line: 0 +20 dB
Instrument: +10 +40 dB
Selects the input impedance (Z In)
for the Mic and Instrument inputs
Input source selection
Power
switch
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.
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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.
Low
ISA 110
Med 2.4 kΩ
High 6.8 kΩ
Mic Impedance
600 Ω
1.4 kΩ
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
Low
High 2.4 MΩ
Instrument Impedance
470 kΩ
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.
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