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- 4 Liquid Pre-amps - 40 classic emulations
Focusrite's proven Liquid technology delivers unmatched sonic pre-amp variety and quality - Remote control software via ethernet
Liquid 4CONTROL enables comprehensive standalone pre-amp control of multiple units, direct from your DAW - Pro Tools Remote control plug-in
A TDM/RTAS Liquid 4CONTROL plug-in provides remote control as an integrated part of your Pro Tools session - Full recall of every parameter
99 Unit setup memories provide instant back-up of all settings, including pre-amp selection and gain. - Adjustable harmonic distortion
Accounts for variance in vintage originals whislt providing additional variance over the sound of every pre-amp emulation. - Optional Eight channel EtherSound output card
Effective connectivity for large studios, post production installs and live sound engineers using EtherSound.
Software System Requirements
WINDOWS
Operating System
• Windows XP Service Pack 2 (all versions) or Windows Vista (all versions)
• Pro Tools 7.1 or higher (only if using the Liquid 4Pre TDM / RTAS plugin)
Computer
• Windows XP compatible PC (Pentium© 4 1GHz or higher recommended)
• Network card supporting ethernet 10Base-T, 100Base-TX, or 1000Base-T
CPU/Clock
• 1.0 GHz Intel or compatible
• 2.0 GHz Pentium© 4 or Xeon recommended
Memory (RAM)
• 256MB or more
• 512MB or higher recommended
APPLE MAC
Operating System
• Mac OS X Panther (10.3.9 or later) - OS Version subject change
• Pro Tools 7.1 or higher (only if using the Liquid 4Pre TDM / RTAS plugin)
Computer
• Apple Mac Power PC G4, G5 or Intel Mac (any)
CPU/Clock
• G4/800 MHz (minimum)
• G4/1.5GHZ or higher recommended
Memory (RAM)
• 256MB or more
• 512MB or higher recommended
Specifications
Converter performance
• Sample rate: 44.1, 48, 88.2, 96, 176.4 and 192kHz
• Bit depth: 24-bit
A/D
• Signal to Noise Ratio: 120dB measured with 20 Hz/22 kHz bandpass A-weighted filter
• Frequency Response: ±0.05 dB between 20 Hz – 20 kHz
• Maximum input level: +22 dBu
• THD+N: 0.0007% (-103 dB)
D/A
• Dynamic Range: 118 dB measured with 20 Hz/22 kHz bandpass A-weighted filter
• Frequency Response: ±0.05 dB between 20 Hz – 20 kHz
• Maximum output level: +22 dBu
• THD+N: 0.001% (-100 dB)
Jitter
• Internal Clock: less than 50 ps
• AES Output: less than 1 ns
• External Clock: less than 3 ns
Mic Pre
• Gain Range: +14 dB to +80 dB, switched in 1dB steps
• Frequency Response: Frequency response and harmonic distortion
variable, set by pre-amp emulation and harmonics setting chosen
(figures shown for FLAT setting with zero harmonics)
• THD+N at analogue out: 0.001% measured with a +1 dBu 1 kHz input signal with 20 Hz/22 kHz bandpass filter, gain +14dB
• THD+N at AES out: 0.0007% measured with a +1 dBu 1 kHz input signal with 20 Hz/22 kHz bandpass filter, gain +14dB
• Mic Noise: EIN = -128 dB measured at 60 dB of gain with 150 ohm source impedance and 20 Hz/22 kHz bandpass filter
• Noise Analogue Out: -92 dBu measured at +14 dB gain with 20 Hz/22 kHz bandpass A-weighted filter
• Noise AES Digital Out: -119 dBFS measured at +14 dB gain with 20 Hz/22 kHz bandpass A-weighted filter
• Maximum Input Level: +8 dBu
• Input Impedance: Variable, set by pre-amp emulation chosen
• CMRR: Electronic: greater than 85 dB @ 60 dB of gain
Line Input
• Gain Range: +32 dB to –10 dB, switched in 1 dB steps
• Frequency Response: 0 dB ±0.1 dB between 20 Hz and 20 kHz
• THD+N at analogue out: 0.001% measured with a +18 dBu 1 kHz input signal with 20 Hz/22 kHz bandpass filter
• THD+N at AES out: 0.0007% measured with a +18 dBu 1 kHz input signal with 20 Hz/22 kHz bandpass filter
• Noise Analogue Out: -92 dBu measured at 0 dB gain with 20 Hz/22 kHz bandpass A-weighted filter
• Noise AES Digital Out: -120 dBFS measured at 0 dB gain with 20 Hz/22 kHz bandpass A-weighted filter
• Maximum Input Level: +22 dBu
High Pass Filter
• Roll-off frequency: 75 Hz, frequency measured at –6 dB down point. 12 dB per octave roll-off
Harmonics
• Distortion Range: 0 to 15 where maximum (15) = 10% of 2nd-, 20% of
3rd- and 10% of 5th-order at 0dBFS (level-dependant distortion)
Rear Panel Connections
• Mic Inputs 1 to 4: XLR female
• Line Inputs 1 to 4: XLR female
• Line Outputs 1 to 4: XLR male
• AES Digital Input: XLR female
• AES Digital Outputs (CH 1+2 and CH 3+4): XLR male
• Wordclock Input: BNC, hi Z or 75 ohm input impedance (soft switchable)
• Wordclock Output: BNC, Low Z input impedance
• ADAT From Slave: Toslink optical Input socket
• ADAT Main Output and Aux Output: 2 x Toslink optical Output socket
• Ethernet Control: Ethernet (10baseT on RJ45)
• Ethersound (optional): Ethernet (RJ45)
Weight
• 5.3kg
• 11.7Ibs
Dimensions
• 484mm (W) x 85mm (H) x 270mm (D)
• 19" (W) x 3.5" (H) x 10.6" (D)
• 2U rackmount
FAQs
Q: What is Liquid4Pre™?
A: Liquid4Pre™ is a 4-channel pre-amp, capable of
emulating the sound of any pre-amp in history. Up to 4 mic/line-level
or 2 AES signals (or any combination of these) can be connected and
each have their own separate emulations individually selected on the
front panel. It’s like constructing your very own hybrid 4-channel
pre-amp from the most popular and priceless pre-amps from around the
world!
Q: How many different pre-amp emulations come with the unit?
A: There are 40 that ship with the unit as standard, but more are available for free online and are updated several times a year.
Q: Are The Liquid Channel emulations compatible with the Liquid4Pre™?
A: Yes. They are identical files so any pre-amps currently available for The Liquid Channel can be uploaded into Liquid4Pre™.
Q: How does it emulate classic pre-amps?
A: Like The Liquid Channel, Liquid4Pre™ uses a
combination of analogue and digital techniques to emulate the sound of
other pre-amps. The analogue stage is all about creating the same
interaction with a given microphone, that is the amplitude and spectrum
of the response caused by the input circuitry and impedance. After
converting to digital, all of the sonic character of the pre-amp being
emulated is applied to the signal using a process called dynamic
convolution.
Q: What is dynamic convolution?
A: Dynamic convolution is an intelligent process that
involves the acquiring of multiple level-dependent impulse responses of
each pre-amp, which are then added to the signals being processed in
Liquid4Pre™ to create the sound of every emulation. Just like
microphones and speakers, pre-amps can have their impulse response
measured by firing impulses (short bursts of noise) through them to see
how they are modified. This provides all the information required to
learn how the pre-amp behaves across the frequency range at one level.
The only difference being that pre-amps are dynamic so, rather than
inputting a single impulse, an entire impulse train is used, starting
at peak excitation and ending at the noise floor.
This lengthy ‘sampling’ process has been carried out at Focusrite HQ
with a great number of classic pre-amps (and compressors and EQs – see
the other Liquid range products) to build up a huge database of samples
for all the processors being emulated. Liquid4Pre™ stores these banks
of samples for every pre-amp in the digital board of each input and
loads up the relevant one when an emulation is selected. For anyone
needing assurance of how much sample application is actually going on
in Liquid4Pre™, when all inputs are being used and the sample rate is
set to 192kHz, the device is processing 256 million samples per second!
Q: What’s the difference between dynamic convolution and other modelling techniques?
A: We compare the two processes by likening dynamic
convolution to sampling and modelling to synthesizing. Modelling
techniques vary drastically as there are no standards and the process
is very difficult to do accurately. Complex analytical experiments need
to be conducted to examine exactly which properties characterise how
the device behaves and then the most significant of those properties
need to be selected and recreated. Like synthesizing, there are many
different ways to recreate the sound and some do it very badly, often
producing the poor alternatives to the original that give digital
emulations a bad name.
However, dynamic convolution is much more like sampling. There is only
one way to do it and the result produces an impressive emulation that
pinpoints the most important sonic characteristics.
Q: Does Liquid4Pre™ use the same pre-amp design as The Liquid Channel?
A: Not entirely. The Liquid Channel was the first
pre-amp of its kind, engineered to be as transparent as possible but
capable of emulating the action of any pre-amp, by switching in and out
a multitude of different capacitors, resistors and other circuit board
components. As with all new technology, the size and cost were both
high. Over the last three years, Focusrite have been busy redesigning
the board to achieve the same performance with a smaller and more
efficient pre-amp board.
The main difference is the absence of a transformer, as research
concluded that the effect of a transformer could be cleverly emulated
using much more affordable components. After all, it is the action of
the transformer (the way it interacts with the microphone) and not the
sound that is important; the Liquid4Pre™ pre-amp itself should be as
transparent as possible so that all the sonic character can be added
after the signal converts to digital and the emulation’s samples are
added.
Q: What are the other differences between Liquid4Pre™ and The Liquid Channel?
A: The main difference is that Liquid4Pre™ can process
4 signals, whereas The Liquid Channel can process only one. However,
The Liquid Channel is a complete channel strip rather than a pre-amp
alone and so has a compressor section, which also uses dynamic
convolution to emulate the sound of any compressor (up to 40 onboard
with more online), and a single digital EQ for corrective shaping or
sideband compression.
On the pre-amp side, however, the controls are virtually identical
(listed below) but with the Liquid4Pre™ having a range of available
metering for each channel, rather than a single LED strip (listed
below) and a high impedance switch. There are also some differences to
the digital i/o (listed below).
Q: What front panel controls are there for each channel?
A: Phantom power (+48V) switch, phase reverse switch,
HPF switch, HiZ switch (sets the input impedance of that channel to the
maximum value, nominally 10k), gain dial, input selector switch
(selects mic, line or digital from the connectors on the rear panel),
session saver switch (for protection against clipping) and harmonics
switch (for adding more colouration), pre-amp select switch (for
choosing emulations), set-up switch (for setting up channel specific
features).
Q: What is the session saver switch?
A: This is a circuit that can be activated to protect
each input from exceeding the digital clipping point (0dBFS). Whilst
‘armed’ (session saver switch illuminated), if the signal level reaches
0dBFS, the input gain will be turned down by 1dB and the session saver
indicator LED will illuminate ‘active’. If the signal continues to clip
then the Liquid4Pre™ will continue to turn down the signal in 1dB steps
until it is below clipping point. When the gain is changed manually
using the dial, the session saver resets to zero – where it is now
placed in the ‘armed’ state.
Q: What is the Harmonics control?
A: The harmonics control is a dial that allows
additional harmonics to be added to the signal to add extra warmth and
colour. The exact harmonics that are added are emulation-dependent but
the first half of the dial rotation, 1-8, generally adds even harmonics
(normally 2nd) and the second half, 9-15, applies odd (mainly 3rd and
5th).
Q: What is the HiZ switch for?
A: The HiZ switch allows even more control over the
exact sound obtained from the pre-amp. Pressing it sets the input
impedance to the maximum value for that pre-amp (typically 10k), which
reduces the load on the microphone. The spectral effect on the signal
from the mic will vary according to the emulation loaded (so as to
behave in the same way as the original device) but, as a rule, the
level will increase as will the high frequency content (the signal will
become brighter). Other frequency related variations may become a
little flattened though.
Q: How do I meter the input levels?
A: There are several metering options available for
each input. As default there is always a vertical strip meter running
down the right side, for observing the peak level. In the main display
there are two options, the ‘old-style’ VU meter, displaying the average
level in VU (0VU may be calibrated to line up with various levels of
dBFS), as well as a horizontal strip VU meter showing peak level in
dBFS, which may be preferable if recording high level signals, and is
more suitable when working further away from the device.
Q: Is there a 'lock' function to protect the unit when used in remote locations?
A: Yes. There is a front panel disable mode that allows all front panel controls to be deactivated.
Q: Does the unit have full recall including gain control?
A: Yes. There are in fact three ways to recall the
front panel settings. One is to load the panel from a previously saved
memory, this can be done per channel or for the entire unit. The second
allows all the channel settings apart from phantom power to be reset to
the default position (emulation, gain, phase, input type, HPF etc.).
The third allows all front panel settings for all four inputs to be
reset to the default position, as well as the digital settings such as
sample rate and synchronisation. The unit always saves the panel
settings every 10 seconds so that, should you switch off the unit by
accident, your last set position will be as it was when you power back
up (as long as no settings were changed within 10 seconds prior to the
power down).
Q: What’s the status display on each input all about?
A: The status display indicates any errors that are
occurring, primarily to do with the digital configuration, e.g. loss of
input or system lock, or any data errors. It also displays when the
session saver has reduced the level and by how much. When it reads
‘OK’, there is nothing to report and everything is functioning
correctly.
Q: What digital i/o is available?
A: There are inputs for ADAT (8 channels) and AES/EBU
(2 channels) that can be fed to any of the four front panel inputs, as
well as an optional EtherSound card for use with EtherSound systems.
This optional card provides a further 8 channels to choose from. As
standard, there are AES/EBU (4 channels) and ADAT (8 channels) outputs,
and then a further optional 8 channels on the EtherSound card. The
additional channels of ADAT and EtherSound are used for digitally
sending the outputs of two linked Liquid4Pres™ combined. At higher
sample rates, the number of channels falls as they link together to
allow for double the number of samples (see next question).
Q: Does the digital channel count decrease at higher sample rates?
A: The AES/EBU remains the same. However, the ADAT and
Ethersound halve as the sample rate doubles. So, at 88.2/96kHz, the
number of input channels falls to 4 and output channels remains at 8
utilising both optical outputs. At 176.4/192kHz, the number falls to 2
inputs and 4 outputs.
Q: What are the master/slave options all about?
A: There are options for slaving together two units so
that the audio outputs can be combined and sent down the same digital
cable (ADAT or EtherSound). In this case, the units must be connected
together using an ADAT link cable and the Setup Cluster modes set to
‘Master’ and ‘Slave’ accordingly. This will ensure that the audio from
the two units is correctly synchronized.
Q: Will it use USB for SW control like TLC?
A: No. The device uses 100Base T Ethernet network
connection as the number of devices that can be controlled is much
greater, as is the distance Liquid4Pre™ can be remotely controlled.
Q: Can I link multiple units to build bigger systems? If so, what's the limit?
A: If wanting to control multiple Liquid4Pres from one
computer using Liquid4Control™ software then up to 32 devices can be
linked, as 128 channels are possible simultaneously.
Focusrite’s new LIQUID4PRE™ four-channel microphone pre-amplifier
utilizes The Liquid Channel™’s proven Liquid™ technology, marrying a
hugely flexible analogue front end with cutting-edge dynamic
convolution DSP to deliver the sounds of 40 vintage and classic
microphone pre-amplifiers across all four channels. Augmented by fully
digital controls and remote software control over Ethernet, LIQUID4PRE
provides the ultimate fluid multi-channel front-end.
99
Unit Setup Memories provide full recall of every parameter across all
four channels, delivering instant multiple user presets and a
comprehensive backup of session settings. These memories can be managed
either via the hardware, or via LIQUID4PRE’s dedicated control
software, LIQUID4CONTROL™. This intuitive software application places
comprehensive pre-amp control inside the DAW. Communication between
LIQUID4PRE and the DAW flows via Ethernet, with LIQUID4CONTROL
providing comprehensive management of multiple LIQUID4PREs. A similar
Pro Tools TDM/RTAS plug-in allows integrated remote control via Pro
Tools hardware and software, including Icon systems, providing all the
benefits of a Pro Tools TDM/RTAS plug-in, such as comprehensive
automation and session integration.
The unique ‘Harmonics’ and ‘Session Saver’ features from The Liquid
Channel are also provided across all four LIQUID4PRE channels. The
adjustable harmonic distortion circuit accounts for variance in the
vintage originals, but can also be used creatively to vary the sound of
each pre-amp. Session saver is a unique automatic gain control circuit
that intelligently reduces the input level to help avoid critical
overs. Each channel also features a classic Focusrite high-pass filter,
phantom power and phase reverse, available directly from the front
fascia independently for every channel. These controls sit alongside
the four large information display screens which, as well as providing
in-depth information of settings, also display huge digital VU meters,
providing accurate, responsive and easy-to-read metering. A further
feature essential for the LIVE sound arena is ‘Operator Lock’, which
guarantees secure use in public arenas by locking the front panel
controls to help avoid any unwanted alteration of pre-amps settings,
including gain.
AES and ADAT™ optical digital inputs and outputs are provided as
standard to integrate with a variety of digital i/o setups. However, an
optional EtherSound eight-channel card is also available, providing
effective connectivity for large studios, post production installs and
live sound engineers using EtherSound. Multiple unit set-ups are easily
configured for remote control via LIQUID4CONTROL utilising an Ethernet
hub. With a third ‘Slave’ ADAT input, audio from two LIQUID4PREs can be
routed directly to a single optional EtherSound card, or at 48kHz, all
eight channels can be routed to a single ADAT light-pipe output.
Finally, the Focusrite site is soon to feature its own dedicated online
emulations library, ‘Liquid Assets’, which will continue to be updated
with additional vintage emulations, available to the worldwide liquid
community as free downloads.
Reviews
Sound On Sound Magazine review quotes
March 2008
Hugh Robjohns
"Fortunately, technology moves on, and the Focusrite boffins have spent
the last three years locked away in darkened rooms trying to find a way
of reducing the size and complexity of the preamp circuitry without
changing the fundamental way in which it works, its flexibility or,
most importantly, its performance. The launch of the Liquid 4 Pre is
the evidence that they have achieved their goal."
"This is a very intensive number-crunching exercise, requiring a very
powerful DSP — and with all four channels running at 192kHz, the Liquid
4 Pre DSP is processing 256 million samples per second!"
"The Liquid 4 Pre is unique — there is nothing else on the market with comparable tonal versatility."
"So the Liquid 4 Pre sits amongst some venerable competition, but
certainly isn’t shamed by any of it. Furthermore, for the price of any
one of these units, the Liquid 4 Pre provides almost all of them at the
flick of a switch. Food for thought..."
* IMPORTANT INFORMATION: FOCUSRITE, the
FF logo, LIQUID TECHNOLOGY, LIQUID 4CONTROL and the LIQUID 4PRE logo
are trademarks of Focusrite Audio Engineering Ltd. DYNAMIC CONVOLUTION
is a trademark of Sintefex Ltd. All other product names, trademarks, or
trade names are the names of their respective owners, which are in no
way associated, connected nor affiliated with Focusrite or its LIQUID
4PRE product and which have not endorsed Focusrite's LIQUID 4PRE
product. These other product names, trademarks, and trade names are
used solely to identify and describe the third party products the sonic
behaviour of which was studied for the LIQUID 4PRE product, and to
accurately describe the functionality of the LIQUID 4PRE product. The
LIQUID 4PRE product is an independently engineered technology which
utilises the patented process of Dynamic Convolution to actually
measure examples of the sonic impact of original analogue products upon
an audio stream, so as to electronically emulate the performance of the
original product studied. The result of this process is subjective and
may not be perceived by a user as producing the same effects as the
original products studied. |
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