Focusrite Liquid 4PRE User Manual

Liquid 4PRE

User Guide
Mode d’emploi
Bedienungsanleitung

FA0186-01

2

Introduction

Thank you for purchasing The Liquid 4PRE™ brought to you by the Focusrite team. The chaps at Focusrite are a jolly hard
working bunch and take a great deal of pride in designing, building and delivering products which are considered 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 email us at: [e-mail]

Contents

Introduction 3

Contents 3

Important Safety Instructions 4

Power Connections 4

Liquid 4PRE™ Architecture 5

Front Panel Quick Reference Guide 7

Rear Panel Connections 9

Basic Channel Operation 10

The Setup Pages: Basic Operation 16

Program and Channel Memories 18

Channel Setup Options 21

System Setup Options 23

Frequently Asked Questions (FAQs) 26

Technical Specification 29

Mode d’emploi 36

Bedienungsanleitung 67

Liquid4Control™ Software

Please visit www.focusrite.com to download the latest version of the free Liquid4Control™ software application, for
Mac OS X or Windows XP. The application allows you to edit Liquid 4PRE™ remotely, plus load, save and archive the
mic pre emulations and program memories. The Liquid4Control™ user guide is available to download in PDF format.

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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. Ensure adequate ventilation
at all times.

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 is
provided for your safety. When the plug provided does not fit into your outlet, consult an electrician for replacement of
the obsolete outlet.

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.

WARNING:

THIS UNIT MUST BE EARTHED BY THE POWER CORD. UNDER NO CIRCUMSTANCES SHOULD THE MAINS EARTH BE
DISCONNECTED FROM THE MAINS LEAD.

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 & Yellow

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Liquid 4PRE™ Architecture

The Liquid 4PRE™ is the third product in the Liquid range and is a multi-channel version of The Liquid Channel™, which
won numerous awards across the globe. Although Liquid 4PRE™ is extremely simple to use, please take a moment to
read this section of the user guide, which gives a brief overview of the signal path and storage capabilities of the unit.

Overview

Like The Liquid Channel™, Liquid 4PRE™ utilises Focusrite’s groundbreaking, hybrid ‘Liquid Technology’, which
transports classic front-end processing into the digital age, removing the need for endless patching and adding fluidity
and reliability to the studio environment. Quite simply, Liquid 4PRE™ is capable of emulating the finest mic pres in
history, providing a total of 4 independent and configurable input channels all inside a single 192kHz, 2U device.

This is achieved through a unique two-part process. In the digital domain, Liquid 4PRE™ employs Dynamic Convolution
techniques, using lightning-fast SHARC chips to apply unique level-dependent impulse responses to every sample of
audio. However, whilst this is more than sufficient to closely emulate a pre-amp’s sonic behavior, the way in which the
physical front-end interacts with a given microphone also plays a large part in creating that pre-amp’s distinctive sound.
As such, Liquid 4PRE™’s analogue front-end involves highly sophisticated and over-engineered design, incorporating a
large number of circuit board components that can switch in and out as required. This means that each one of the inputs
on Liquid 4PRE™ can match the input impedance and other signal path characteristics of the device being emulated.
Every emulation employs both the complex analogue front-end switching and the digital application of recorded samples
to emulate the sound of the original pre-amp.

With entirely digital front panel controls, settings can be saved in one of 99 program memories, meaning that entire
session setups can all be recalled at the touch of a button. An Ethernet port on the rear panel links to a computer
running the free Liquid4Control™ software application, enabling the archiving of both emulations and surplus program
memories, as well as providing full editing and remote operation of the unit itself. The Liquid 4PRE™ comes complete
with emulations of 40 classic mic pres but is infinitely expandable, since the Ethernet port also facilitates the upload of
further emulations downloaded from the Focusrite website.

Finally, to account for variances in amounts of 2nd-, 3rd- and 5th- order harmonic distortion (usually perceived as
warmth) from one pre-amp to the next, a dial is included to permit control over this value. This essential feature ensures
satisfaction for even the most hardcore vintage enthusiast, bringing accurate control over the key sonic attributes.

Liquid Assets

Liquid 4PRE™ ships with 40 pre-amp emulations as standard, but there are many more available online at
www.focusrite.com. Visit the Liquid Assets pages for access to all pre-amp emulations, with detailed information
about each one. Once downloaded, emulations can be sent to Liquid 4PRE™ using the free Liquid4Control™ software
application, after connecting to the computer using the supplied Ethernet cable.

Program and Channel memories

Liquid 4PRE™ has 99 program memories plus 99 channel memories to allow storage of preferred pre-amp combinations
and settings. A program memory stores the complete settings within the Liquid 4PRE™ unit (all 4 channels and any
system settings) providing a convenient way of resetting the unit for a particular application or location. A channel
memory stores settings for an individual channel. Channel memories can be loaded to any channel within the unit,
for example to copy settings from one vocal channel to another.

Program and channel memories can also be archived and reloaded from a remote computer using Liquid4Control™,
via the Ethernet connection.

Using Liquid4Control™, a virtually unlimited number of emulations and memories can be stored on your PC or Mac and
uploaded to the Liquid 4PRE™ hardware as required. You can also email your favourite Liquid 4PRE™ emulations and
settings to other users anywhere in the world – the ultimate in session recall.

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Signal Path

The Liquid 4PRE™ features both analogue (mic and line) and digital (AES-EBU and ADAT) inputs, plus analogue (line)
and digital (AES-EBU and ADAT) outputs. Analogue signals connected to the mic input are routed through an analogue
mic pre stage, before passing through an A/D and entering the digital pre-amp convolution section. The unique sonic
characteristics of the selected pre-amp emulation are then applied to the signal. The signal then routes to the digital
output, and via the D/A to the analogue output.

Analogue signals connected to the line input follow the same signal path as above, but bypass the initial mic pre stage,
routing directly to the A/D. With Line input selected on the front panel, the pre-amp type is fixed at FLAT elec (electronic).

Digital signals connected to the digital input are routed directly to the pre-amp convolution section.

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Front Panel Quick Reference Guide

Master Controls

On the left of the front panel you will find the unit’s master controls:

Power Press to power the unit on or off. Turn on the Liquid 4PRE™ before you power up devices to

which the outputs are connected.

Sample Rate LEDs These LEDs show the current sample rate of the unit. The sample rate, which can be set from

44.1kHz to 192 kHz, is selected from the System Setup pages. Note that if you are locking to
external clock, the sample rate must be set to match that of the clock source.

External Clock Press the External Clock button to lock the unit to an external clock source. The external clock

is pre-selected within the System Setup pages, and may be set to Wordclock, ADAT, AES or
Ethernet.

Lock LED When the unit is correctly locked, the Lock LED lights steady state. If the external clock source

is not connected, or invalid, the Lock LED will flash.To lock the unit to an internal clock source,
turn off the External Clock button; both the External Clock button and Lock LED will extinguish.

System Setup Press this button and the LCD on CHANNEL 1 updates to access the System Setup pages.

Here you can set options such as the sample rate of the unit and external clock source; save
and load program memories; lock out the front panel controls; define a cluster (for linking 2
units for single ADAT link operation); define a unit name; set metering options; and define the
unit’s Ethernet parameters. See Page 21 for details.Press the System Setup button again to
return the LCD to CHANNEL 1 mode.

Channel Controls

The remainder of the front panel is divided into the 4 individual channels; each channel features:

Clip LED Illuminates (red) if the channel input overloads (exceeds 0dBFS).

+48V Press to apply +48V phantom power to the corresponding MIC XLR input on the rear panel.

Ø Press to invert the phase of the input.

HPF Press to switch the High Pass Filter in or out of circuit. (Mic/Line inputs only).

Input Press to switch the channel between Mic, Line or Digi input; the selected source is indicated

by the appropriate LED and on the channel’s LCD.

Session Saver Press this button to arm the Session Saver function, useful for avoiding digital clipping at the

channel input. Once armed (the button illuminates), if the input signal exceeds 0dBFS, then the
analogue input gain is automatically turned down in 1dB increments.

Session Saver LED The Session Saver LED illuminates to indicate that the gain has been automatically adjusted.

See Page 10 for more details.

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Channel Controls (continued)

DATA Encoder This push-switch rotary encoder works in conjunction with the Pre-amp Select, Harmonics,

Setup buttons and the channel’s LCD to operate the following:

Input Gain When no buttons are selected, the encoder adjusts input gain. Turn the control to adjust gain in

1dB steps; the relative gain is shown using the LEDs around the control, and more precisely, in
dB, on the channel’s LCD.

Note that the position of the input gain stage varies according to the type of input. For example,
for MIC inputs, you are adjusting the analogue mic pre-amp gain; for DIGI inputs, you are
adjusting digital gain within the convolution stage. Therefore, the amount of gain varies
depending on the input selection.

Pre-amp Select Press the Pre-amp Select button (it flashes green) and turn the rotary encoder to select a

mic pre emulation. The channel’s LCD shows the name and a brief description of the emulation.
To load your selection, press the rotary encoder. Note that you will not hear your selection until it
is loaded.

Harmonics Press the Harmonics button (it flashes green) and turn the rotary encoder to dial-in the amount

of harmonics you wish to add to the signal; the amount, from 0 to 15, is shown in the hmncs
area of the Channel LCD.

Setup Press the Setup button (it flashes green) to access the Channel Setup pages. Here you can set

options such as the channel name; save and load channel memories, select the type of digital
input and select a Link Bus for control linking. See Page 19 for details.

Press the Setup button again to exit the Channel Setup pages.

Hi Z Press to set the mic impedance to high. This button allows you to bypass the automatic

impedance setting recalled by the mic pre emulation - for example, if you are splitting a
microphone signal to two different mic amplifiers.

Channel LCD During normal operation, the channel display provides feedback on channel parameters, such

as input gain, choice of pre-amp emulation, amount of harmonics, etc. In addition, the display
includes two input meters:

A vertical bargraph meter showing peak levels up to 0dBFS.

A horizontal meter which may be set either to Peak level or VU operation from the System Setup
pages. See Page 9 for details.

When the Setup button is pressed, the display changes to access the Channel Setup pages.
On CHANNEL 1, the display also accesses the System Setup pages.

As all controls are digital, settings can be saved and recalled with ease, and edited from the Liquid4Control™ software

application (available from www.focusrite.com). Please refer to the Liquid4Control™ User Guide for details.

Note that when the unit is turned off, the hardware’s onboard memory stores the last front panel settings to have been
unchanged for over 10 seconds. These settings are recalled when the unit is powered on.

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Rear Panel Connections

Analogue Inputs 1-4 Each channel (1 to 4) provides separate female XLR connectors for Mic and Line inputs,

and a male XLR for the Line output. All 3-pin XLR audio connectors are balanced analogue
connections, and are wired as follows:

Pin 1: Screen/Chassis

Pin 2: Audio 0°

Pin 3: Audio 180°

Ethersound Card (optional) An optional Ethersound card may be fitted to this expansion slot. The card is manufactured

by AuviTran™ and provides 8 digital audio inputs and 8 digital audio outputs on Ethernet
(CAT 5) connectors. For more details on this card please visit the AuviTran™ website at
www.auvitran.com. ADAT Three optical ADAT connections offer multi-channel digital audio
inputs (FROM SLAVE) and outputs (MAIN OUTPUT and AUX OUTPUT). These can be used to
input digital audio signals to the unit, output the 4 channels of the unit to an external recorder,
or to daisy chain units using the Cluster option. See Page 22 for details.

Note that the maximum number of digital audio channels is dependent on the sample rate
of the unit:

8 channels at 44.1kHz or 48kHz.

4 channels at 88.2kHz or 96kHz.

2 channels at 176.4kHz or 192kHz.

AES A single AES/EBU input carries two channels of digital audio plus AES clock, on female XLR.

Two AES/EBU outputs carry channels 1+2 and channels 3+4 on individual male XLRs.

Each AES/EBU input and output connector carries two channels of digital audio at any sample
rate from 44.1kHz to 192kHz.

Wordclock The WORD-CLOCK IN BNC allows the unit to be locked to an external clock source. Note that the

unit can also lock to any of the other digital inputs (AES, ADAT or Ethersound) or Internal clock.
The WORD-CLOCK OUT BNC allows the Liquid 4PRE™ to supply a clock source to external equipment.

The input and output range of the Wordclock signal must be between 44.1kHz and 192kHz.

Ethernet Control This connector allows the Liquid 4PRE™ to be connected to a computer running the free

Liquid4Control™ software. Using this software you can operate the unit remotely, download
new mic pre-amp emulations and archive or recall program memories. Please refer to the
Liquid4Control™ User Guide for details.

Note that each channel of the Liquid 4PRE™ can be switched between Mic, Line or Digital input. The Digital input for
each channel is pre-selected from the Ethersound card (1-8), ADAT FROM SLAVE (1-8) or AES (Left/Right) within the
Channel Setup pages, see Page 19.

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Basic Channel Operation

This section covers channel operations in more detail. Each of the 4 channels is identical.

Input Select

Press the Input select button to step through the 3 input options for the channel:

Mic – the MIC input XLR on the rear panel.

Line – the LINE input XLR on the rear panel.

Digi – the pre-selected digital input. This can be any digital input (Ethersound

1-8, ADAT 1-8, or AES Left/Right) as defined within the Channel Setup.

The Mic, Line or Digi LED illuminates to indicate your selection.

In addition, the type of input (e.g. MIC) is shown on the channel’s LCD.
For digital inputs, you see the name of the pre-selected digital input (e.g.

AES Left, Adat 1, etc.)

Input Gain

Turn the channel’s DATA encoder to adjust the input gain. Note that to adjust input gain, the Pre-amp Select, Harmonics
and Setup buttons must all be turned off.

Note that the position of the input gain stage varies according to the type of input. For example, for MIC inputs, you are
adjusting the analogue mic pre-amp gain; for DIGI inputs, you are adjusting digital gain within the convolution stage.
Therefore, the amount of gain varies depending on the input selection:

+14dB to +80dB for Mic inputs.

-10dB to +32 dB for Line and Digital inputs.

Gain is adjusted in 1dB intervals and is shown using the LEDs around the encoder. In addition, the exact numeric value
is displayed on the channel’s LCD – in our example above, 14dB.

Input Metering and Levels

The Channel LCD provides two input meters:

The first is a vertical peak level bargraph meter which is

always

visible, even when

accessing Channel or System Setup pages.

The meter displays the digital peak input level, with a scale from -40dBFS to 0dBFS.

When adjusting input gain, take care to avoid input levels exceeding 0dBFS or
digital clipping will occur. Remember that you can use the Session Saver function,
as described on Page 10, to help avoid digital clipping for unpredictable signals.

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Input Metering and Levels (Continued)

The second is a horizontal meter which is visible within the main channel display. This meter can be set to one of two
modes from the System Setup pages:

Meter Type = Peak Meter Type = VU

Meter Type = Peak - a digital peak level input meter with a scale from -40dBFS to 0dBFS. This mimics the operation

of the vertical bargraph meter. Note that if the signal is below -20dBFS then peak hold is inactive (because the
resolution of the meter is too low below this point).

Meter Type = VU - a VU input meter with variable scale.

By default the VU scale is set so that 0VU = -10dBFS. Since 0dBFS = +22dBu, this means that 0VU represents +12dBu at
a line level output for an input with unity gain. However, from the System Setup pages, you may adjust the 0VU sine level
allowing you to optimise the VU scale for different operating levels.

Note that the VU meter models a time varying RMS measurement of the input signal, much like a real VU meter.
Therefore, it displays levels more “musically”, like a listener’s perception, rather than registering every digital peak.
However, to avoid digital clipping at the input remember to observe the vertical peak bargraph and the CLIP LED when
working in this mode.

The horizontal meter options are set globally for all 4 channels of the unit from the System Setup pages.

Clip LED

In addition to the input meter, a separate LED lights if the channel input overloads. This indicates that digital clipping
has occurred. To avoid clipping, reduce the input gain or use the Session Saver function.

Hi-Z (Input Impedance)

Press the Hi-Z button to change the input impedance of the rear panel MIC input XLR from low to high. This raises the
input impedance to the maximum (approximately 10k resistive) so as not to load the microphone excessively.

Note that the input impedance circuitry does not affect Line or Digital input connections, and will continue to be applied
to the MIC input XLR at its configured setting even if the input select is toggled to Line or Digi.

+48V (Phantom Power)

Press the +48V button to apply 48V phantom power to the corresponding rear panel MIC input XLR. Phantom power is
usually required for condenser microphones. If you are unsure whether your microphone requires phantom power, refer
to its handbook, as it is possible to damage some microphones (most notably ribbon microphones) by providing phantom
power.

Note that the +48V button does not affect Line or Digital input connections, and will continue to be applied to the MIC
input XLR even if the input select is toggled to Line or Digi.

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