Focusrite ISA 220 Session Pack Instructions Manual

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1

Introduction

Thank you for purchasing the ISA 220 Session Pack brought
to you by the Focusrite team – Trevor, Peter, Martin,
Helen, Raf, Tom, Mick, Phil, Chris, Micky, Pauline, Jo, Chris,
Bryn, Giles, Rob and Simon.
The chaps at Focusrite are a jolly hard working bunch and
take a great deal of pride in designing, building and delivering
the best audio units around. We hope your new Focusrite
unit lives up to that reputation, and that you enjoy many
years of productive recording.
If you would like to tell us about your recording
experiences then please email us at: [e-mail]

The Focusrite Team

Contents

Introduction..............................................................................................1

Contents.....................................................................................................1

Important Safety Instructions.............................................................1

Power Connections...............................................................................1

Signal Connections.................................................................................2

Getting to know the ISA 220.............................................................3

Metering.....................................................................................................3

Input Stage.................................................................................................4

EQ Module................................................................................................4

Compressor..............................................................................................6

De-esser.....................................................................................................7

Limiter.........................................................................................................8

Output.........................................................................................................8

Stereo A/D................................................................................................8

Applications...............................................................................................9

FAQs.........................................................................................................11

Specifications.........................................................................................13

Warranty.................................................................................................14

Accuracy..................................................................................................14

Copyright................................................................................................14

Focusrite Distributors.......................................................................71

Reset Sheet

.............................................................................................72

Important Safety Instructions

Please read all of these instructions and save them for
future reference. Follow all warnings and instructions
marked on the unit.

• Do not obstruct air vents in the rear panel. Do not
insert objects through any apertures.

• Do not use a damaged or frayed power cord.

• Unplug the unit before cleaning. Clean with a damp

cloth only. Do not spill liquid on the unit.

• Unplug the unit and refer servicing to qualified service
personnel under the following conditions:

If the power cord or plug is damaged; if liquid has
entered the unit; if the unit has been dropped or the
case damaged; if the unit does not operate normally or
exhibits a distinct change in performance. Adjust only
those controls that are covered by the operating
instructions.

• Do not defeat the safety purpose of the polarised or
grounding-type plug. A polarised plug has two blades
with one wider than the other. A grounding type plug
has two blades and a third grounding prong. The wider
blade or the third prong are provided for your safety.
When the plug provided does not fit into your outlet,
consult an electrician for replacement of the obsolete
outlet.

WARNING:

THIS UNIT MUST BE EARTHED BY THE POWER

CORD.

UNDER NO CIRCUMSTANCES SHOULD THE

MAINS EARTH BE DISCONNECTED FROM THE

MAINS LEAD

This unit is capable of operating over a range of mains
voltages as marked on the rear panel. Ensure correct mains
voltage setting and correct fuse before connecting mains
supply. Do not change mains voltage settings while mains
supply is connected. To avoid the risk of fire, replace the
mains fuse only with the correct value fuse, as marked on
the rear panel.
The internal power supply unit contains no user serviceable
parts. Refer all servicing to a qualified service engineer,
through the appropriate Focusrite dealer.

Power Connections

There is an IEC mains lead supplied with the unit, which
should have the correct moulded plug for your country.
The wiring colour code used is:

For units shipped to the USA, Canada, Taiwan and Japan:

Live - Black Neutral - White Earth - Green

For units shipped to any other country:

Live - Brown Neutral - Blue Earth - Green and Yellow

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2

Signal Connections

(Optional A/D Card shown fitted)

XLR (Audio) Inputs and Outputs

All 3-pin XLR audio connectors (Output, Mic IP, Line IP,
and EXT A/D IP) are wired as follows:
Pin 1 Screen/Chassis
Pin 2 Audio 0°
Pin 3 Audio 180°

Inst. Hi Z IP, Comp Key IP, Int A/D Direct
Input and Dynamic Link

1/4” jack wired as follows:
Tip Audio 0°
Ring Audio 180°
Sleeve Screen/Chassis

Mic IP/Line IP/Inst. Hi Z IP

Any one of these inputs may be used as the main input to
the ISA 220. Signals routed to these inputs are referred to
as the ‘internal’ or ‘Int’ signal path.

Int A/D Direct Input

The ‘Internal A/D Direct Input’ is used to route an external
signal directly to the A/D card via the Limiter. It is fed to
the left channel of the A/D card and thus it replaces the
‘Internal’ signal feed to the A/D card (i.e. replaces whatever
is connected to the mic, line or instrument input.)

Ext A/D IP

The External A/D input is used to route an external signal
to the optional A/D card via the Limiter. The signal is fed to
the ‘spare’ side of the A/D card (the right channel, i.e. the
channel not being used by the internal signal) and so does
not replace it. Using this input, two ISA 220 units can be
used to create a stereo recording channel using only a single
A/D card.

Output

This output is used as the main analogue internal signal
output, and is fed by whatever is connected to the Mic IP,
Line IP or Inst IP, after this signal has been routed through
the EQ and dynamics modules.

Dynamic Link

You can connect two ISA 220 units (using a standard stereo
jack to jack lead between the DYNAMIC LINK sockets) to
allow the compressor sections to behave as a stereo pair of
processors. When connected in this way the dynamics
processors behave as if both units were receiving the same
level of signal, with both units responding to the higher level
of the two signal paths. The EQ channels can be matched
visually or aurally to be used as a stereo pair if required.

Retrofitting the Optional A/D Card

The optional A/D card can be retrofitted to a standard ISA
220 at any time. The card can easily be fitted by the user –
no engineering experience is required. Full fitting
instructions for this option are included with the card.

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Getting to know the ISA 220

Power

Applies power to the unit. Turn on the ISA 220 before
powering up devices to which the outputs are connected.

Bypass

The processing modules can be globally switched out using
the BYPASS switch, providing a direct route (except for the
signal overload protection of the multi-band limiter, which
remains in the circuit) from the main inputs or External
input, to the A/D inputs. (This enables the unit to be used
as a 24-bit, 96kHz stereo converter for final mastering or
for analogue transfer to digital.)

Metering

VU Select

The VU meter can display input level or the compressor
gain reduction. Press VU SELECT to toggle between the
two sources as indicated by the corresponding LEDs. With
‘Input’ selected, 0VU corresponds to +4dBu. With
‘Compressor’ selected, the meter indicates the amount of
gain reduction caused by compression, from 0VU (no
compression) to -20VU (corresponding to 20dB of gain
reduction).
Note: the VU meter is calibrated at operating temperature.
An ISA 220 will typically take up to 30 minutes to reach
operating temperature. Prior to this the meter may give
slightly lower readings.

Digital Output Meters

Two 16-LED bar graph meters monitor the Internal signal
and the External signal (whatever is connected to the “Ext
A/D IP” XLR input) at a point after the Limiter but before
the A/D input. The meters cover a wide range, with the O/L
LED (see below) acting as an Overload indicator to warn of
excessively high levels at the input of the A/D converters.

O/L LED

This LED illuminates when the peak signal level reaches or
exceeds +20dB, or when the peak signal level reaches 6dB
below clipping. The signal is monitored at three points: after
the input gain TRIM, after the EQ module and after the
Dynamics module, since each module could cause clipping if
incorrectly set up. Occasional short-duration peaks which
may cause the LED to blink will not normally cause audible
distortion, but if the LED is lit constantly, the level in the
appropriate module should be reduced to prevent
overloading.

Inst I/P

Instrument sources may either be connected via the rear
panel ‘Inst Hi Z IP’, or via the front panel ‘Inst I/P’ jack.

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4

Input Stage

Three input options are provided to give compatibility with
microphone, line or instrument level sources.

Select

Pressing SELECT steps through each of the three inputs as
indicated by the corresponding LEDs. When the Mic LED is
lit, the Mic input is active etc.

Mic Input Gain

With the mic input selected, the user has access to the full
gain range, from 0dB to +60dB, in 10dB steps. With the ‘30­60’ switch off, 0dB to +30dB settings are accessible. With
the ‘30-60’ switch on (illuminated), +30dB to +60dB settings
are accessible (yellow legend).

Line Input Gain

With the line input selected, the user has access to gain
settings ranging from –20dB to +10dB (white legend). The
‘30-60’ switch is inactive when the line input is selected.

Instrument Input Gain

With the instrument input selected, gain changes can be
made using the trim control only (see below) which allows
+10dB to +40dB of additional gain. This input is suitable for
high impedance sources such as guitar or bass pickups
(which may be connected directly without the need for an
external DI box), or vintage synthesisers with high
impedance outputs.

Trim

The Trim control provides additional variable gain of 0dB to
+20dB (with mic or line inputs selected – white legend) or
+10dB to +40dB (with instrument input selected – yellow
legend).

+48V

This provides +48V phantom power for condenser mics
when pressed. This switch does not affect the other inputs.
If you are unsure whether your microphone requires
phantom power, refer to its handbook, as it is possible to
damage some microphones by providing phantom power.

Phase

Pressing PHASE inverts the phase of the selected input, to
correct phase problems when using multiple microphones,
or when incorrect wiring polarity has occurred.

EQ Module

All EQ

Pressing ALL EQ activates all sections of the EQ module
(including the Hi and Lo Pass Filters), placing the whole
module in the audio path. (Also note that each section may
also be switched out of circuit individually.) Toggling ALL
EQ allows A/B comparison of EQ settings without having to
use BYPASS, which switches both EQ and Dynamics
modules in or out of the audio path.

Filter In

Press in to make the Hi and Lo Pass Filters active in the
audio path. Both filters provide 18dB/octave rolloff, and
since the filter frequencies overlap they may be configured
as a very tight band-pass filter.

Low Pass Filter

A variable control sets a rolloff frequency from 400Hz to
22kHz.

High Pass Filter

A variable control sets a rolloff frequency from 20Hz to
1k6Hz.

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5

PARAMETRIC EQ

Two separate bands of parametric EQ are provided, each
with continuously variable boost/cut with centre detent,
sweep control with two ranges, and variable Q. The first
band covers the range 40Hz to 400Hz (120Hz to 1k2Hz
when x3 is pressed) and the second band covers 600Hz to
6kHz (1.8kHz to 18kHz when x3 is pressed).

Param EQ In

Press in to switch the Parametric EQ into the signal path.

X3

The Sweep controls have two ranges; the higher being
selected when the x3 switch is pressed (frequencies shown
in yellow on the panel).

SHELVING EQ

High and Low frequency shelving sections are available, each
with continuously variable boost/cut with centre detent, and
a four position rotary switch for selection of rolloff
frequency.

Shelving EQ In

Press in to switch all the Shelving EQ into the signal path.