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1 - AWS 900+ SOS 2005 - Mastering Mansion by jizhen1947


									SSL AWS900
Mixer & Control Surface
Published in SOS November 2005

Reviews : Mixer

With their latest Superanalogue console, SSL bring the sonics and functionality of their
flagship SL9000K to studios with smaller rooms and budgets. In the process, they've
incorporated comprehensive control-surface facilities for driving computer DAWs
remotely. But can the AWS900 really live up to its pedigree?
Hugh Robjohns
The acronym SSL is likely to be recognised
immediately by everyone reading this review. The
Oxfordshire-based manufacturer Solid State Logic
redefined the art of the large-format analogue mixing
console some thirty years ago when it launched the
original SL4000 desk. This console became a must-
have for almost every high-end recording studio around
the world, and it has maintained that position — albeit
with various updates and improvements over the years Photos: Mark Ewing
— virtually right up to the present day. While the
SL9000 series Superanalogue console took over as the flagship product nearly a decade
ago, the popularity of the venerable SL4000 has continued, and I noticed a brand-new
SL4000 being readied for delivery during my recent factory visit.

SSL recently passed through a rocky patch in the company's long history, but with new
management and funding now in place the future is looking bright once again, with four
main product lines. The flagship product remains the SL9000K Superanalogue console
for music recording and production, and is accompanied by a new generation of digital
consoles aimed primarily at the broadcast and post-production sectors: the C100, C200,
and brand-new C300.

The other two product lines are closely related to each other, and are both derived
directly from the SL9000: the XLogic rackmount equipment, including the
Superanalogue Channel which I reviewed back in SOS February 2004; and the AWS900
console, the subject of this review. In order to make the console commercially viable, a
way had to be found of reducing the production costs while retaining the Superanalogue
sound quality — and that meant moving to surfacemount technology and automated
circuit board production. In the process of redeveloping the SL9000 circuitry for the
AWS900, it became apparent that surfacemount circuit boards would also lend
themselves nicely to rackmounting applications, which led to the development of the
XLogic series.

What Exactly Is The AWS900?
The clearest way to look at the AWS900 is as a Superanalogue console in miniature,
combined with a bespoke HUI-compatible control-surface interface. It was designed as
a high-quality tracking console for use with Pro Tools DAW rigs and the like, but also
serves as a superb analogue mixdown desk. It features twenty-four highly specified
input channels with switchable E/G-series EQ, in-line functionality, and motorised
faders. Unlike the SL9000K desks, which incorporate dynamics in every channel, the
AWS is equipped with just two dynamics processors, but these can be assigned to any
two channels or outputs. The classic G-series buss compressor is also included, along
with very comprehensive 5.1 surround monitoring facilities. Bar-graph metering is built
in for all the inputs and outputs, while the two main outputs are displayed on large-
format VU meters. In addition to the 24 input channels, there are four stereo effects
returns and a pair of main buss direct (cascade) inputs, allowing up to 34 input sources
at mixdown. Full snapshot recall and fader/mute automation of the console are available
as cost options.

The very elegantly designed and fully integrated hardware control element of the
console surface is compatible with any system that supports multiple HUI-compatible
surfaces, allowing the console to appear as a continuous 24-fader surface to the DAW.
A similar approach is used by Yamaha with their DM2000, DM1000, and 02R96
consoles, and the necessary multi-port interfacing is currently supported by Pro Tools,
Logic, Pyramix, SADiE, and Soundscape. At the present time Nuendo and some other
DAWs only support a single HUI-compatible interface, and the AWS900 can only
provide eight control faders with these systems.

The desk and DAW are linked via multiple MIDI connections, a decision which initially
seemed odd — why not use a fast USB interface? However, it was explained that MIDI
is an established interface format to which the majority of DAW manufacturers conform
(thus maximising compatibility), and using multiple interfaces allows data transfer rates
much faster than actually required by the desk. MIDI can also be used over greater
distances than USB (up to 15m instead of 5m), which is very useful when the DAW
computer is located in a machine room away from the console.

The motorised Alps channel faders and the associated assignable rotary encoders can be
switched globally between controlling the console's analogue signal paths and various
DAW parameters, allowing a kind of virtual in-line working practice to be set up,
building up a monitor mix on the channel faders by remotely controlling the DAW's
internal mixer channels.

The AWS900 looks like a 'proper' SSL in every way. It works and sounds like an SSL,
and the bespoke DAW interface is extremely ergonomic and very cleverly engineered
so that controlling the DAW's signal-processing facilities becomes a natural extension
of the console, with the same immediacy and control resolution. Of course, none of this
comes cheap in the absolute sense, but it is certainly a lot more cost effective than a
fully featured traditional SSL console, and represents an ideal solution for many
'tapeless' studios and smaller post houses. In fact, some of the leading studios around the
world have already re-equipped tracking rooms with AWS900 consoles.

Superanalogue Circuitry
The AWS900 console is a single-box product which can be either built into the studio
furniture or supported with an optional floor stand. The internal mains power supply has
heat sinks running across the rear of the meterbridge, so there are no noisy fans.
Borrowing an idea from long-established telecommunications technology, the incoming
mains is converted to a high-voltage (400V) low-current supply for internal distribution,
with local conversion and regulation on each circuit board. Although unusual in the
professional audio world, this approach is reliable, efficient, and extremely cost
effective — although it does mean that service engineers have to be as careful working
on live AWS900 boards as anyone working with traditional valve equipment!

With the exception of dual engineer's headphone sockets, all of the console's I/O is
arranged along the back panel. Channel inputs and outputs are provided on XLR or TRS
sockets, as are most of the main outputs, while the monitoring section, buss outputs, and
cue/effects sends are accessed via 25-pin D-Subs in the familiar Tascam format. This
enables the console to be quickly and easily installed, and also allows it to be used
without a patchbay, should this be necessary.

The audio circuitry is derived directly from the SL9000K series, but redesigned to use
mainly surfacemount components. SSL claim that the sound quality has not been
compromised in any way during this redesign, and in some cases it has actually brought
extra benefits thanks to the easier introduction of ground planes and the shorter circuit
track paths. It uses the same DC-servo technique throughout to avoid coupling
capacitors in the main audio path, and provides the same wide bandwidth and
uncoloured signal quality as the flagship console. The specifications claim a response
that is 3dB down at 135kHz and 4dB down at 200kHz, so 'wide bandwidth' is definitely
an appropriate phrase here! The desk also boasts headroom of +27dBu, distortion of
0.002 percent at +24dBu, and noise below -90dBu (providing more than a 110dB
dynamic range when feeding professional A-D converters).

Channel Facilities

Each channel has three inputs: mic, line, and instrument — the first two on XLR and the
last via a quarter-inch socket. The mic/line selection can be controlled globally from the
console's master section, or overridden locally with a Flip switch. The mic input is
essentially the same as that used in the SL9000K-series consoles and XLogic channel
strip, and provides continuously variable gain from +15dB to +75dB. A 20dB pad
accommodates loud sources, and phantom power and polarity are switchable on each
channel. The line input has a separate ±20dB gain control, and the FET-based
instrument input — something no other SSL console can offer — provides a very high
impedance to suit electric guitars and the like.

The EQ section is, again, derived from the K-series console's four-band equaliser,
including a separate variable high-pass filter. The top and bottom bands are shelving
types, independently switchable to a bell shape, while the two middle bands are fully
parametric. The EQ section also features switchable characteristics corresponding to the
original E-series and G-series designs. The default mode provides the E-series response,
featuring standard 6dB/octave filter slopes, while the G-series mode provides steeper
slopes with an inverted gain region immediately before the turnover frequency. For
example, dialling in a high-frequency boost to give 'air' also results in a modest level dip
over the frequency region below the turnover frequency — a combination that often
works very well and certainly gives a different flavour to more conventional EQ

Located in the centre of the EQ panel section are three buttons which switch the
entire EQ section in or out, switch the insert point in and out (with separate
balanced TRS sockets for send and return), and reorder the signal path so that
the insert point is before or after the equaliser.

Cues & Auxes

The AWS900 has flexible aux and cue-send facilities, derived once again from
the SL9000K consoles. Each channel can access one of two stereo cue busses,
with level and pan control and pre- or post-fade selection. The send is turned on
and off by pressing the level knob. There are also two aux send controls —
labelled FX1 and FX2 — each being post-fade and switchable between two effect
busses, giving up to four aux-buss outputs in total. Again, each send is turned on and off
by pressing the level knob.

All these cue and aux sends can also be switched into an EFX mode, in which the
relevant send output is isolated from its normal buss and routed instead to the Track
Buss routing matrix (of which more in a moment) in place of the normal channel output
signal (the Cue signal is routed in mono when switched to the EFX mode). Obviously,
only one send control per channel can access this EFX mode at a time, but the idea —
borrowed from the SL9000 console — is to allow a lot of flexibility in signal routing
and output destinations while using a small control set. As an example, you could hook
up the eight Track Bus outputs to eight headphone amplifiers, and thus use the system
to generate an additional eight separate mono headphone feeds. Equally, you could use
the Track outputs to feed additional effects processors, extending the number of effect

The channel's Direct output socket normally carries a post-fade signal, although it can
be switched pre-fade using a button at the top of the sends section of the channel strip.
However, if the EFX mode is activated on any of the Cue or FX sends, the
corresponding signal is routed to the channel direct output instead. This whole EFX
scheme may appear a little complicated at first sight, but it allows for some extremely
versatile signal routing possibilities.

The last of the channel strip's analogue controls is the main stereo routing section,
which provides a pan pot and buttons to access the independent stereo Record and Mix
busses. The Record buss is intended to feed the DAW while overdubbing, with the Mix
buss allowing simultaneous and independent audition of the complete mix — another
example of the flexibility of the desk's design.

Meters & Routing Options

The meterbridge above the main channel strips carries a pair of bar-graph meters and
indicators for each channel, along with various routing buttons. The console's eight
Track Busses can be selected individually and are normally fed with a post-fade channel
signal. However, additional buttons allow pairs of Track Busses to be fed with a post-
pan (stereo) signal, or with a mono pre-fade signal. If the EFX mode is active, then the
Track Busses are fed from the appropriate Cue/FX control as previously described.

The bar-graph meters show either the analogue channel signal or the corresponding
DAW channel, depending on the mode of the desk. Normally, only the left meter is
active, but when a stereo DAW channel is being controlled, both left and right channels
are displayed. Above the meters are a pair of tally lights which illuminate when the
relevant DAW track is armed to record, or is currently being addressed by the plug-in

Four more buttons here allow one of the two assignable dynamics processors located in
the master section of the console to be inserted in the channel, with options to insert the
dynamics pre-EQ (after the channel input) or post-EQ (at the channel output).
Combined with the insert point routing facility incorporated within the EQ section,
these switches enable the channel signal path through the EQ, insert, and dynamics
blocks to be configured in six different ways.

Channel Fader & Rotary Encoder

The remaining portion of the channel strip comprises an encoder knob, the motorised
fader, two four-character electronic scribble strips, and separate Solo and Cut buttons
for the analogue channel and DAW channel. There is also a Select button to access the
appropriate DAW channels for track arming, plug-in editing, and so on.

An Auto button near the top of the fader is used to activate the various console and
DAW automation modes, with adjacent red and green LEDs to show the current read
and write status. The electronic scribble strips are used to show DAW track or channel
names, the assigned encoder control function, DAW I/O allocations, fader and
automation trim levels, and various other useful things,
depending on the console mode.

The default mode is for the fader to control the
analogue channel level, while the rotary encoder
controls the corresponding DAW channel's virtual
fader. However, a Master Flip control in the master
section swaps these controls, allowing a monitor mix to
be built up on the faders while the console channel
'record' levels are set on the rotary encoders — the
latter then being akin to the small fader on a traditional in-line console.

It probably won't come as a surprise to learn that audio is not routed through the fader or
encoder. Instead, both generate high-resolution control signals that are routed either to
the DAW or to the channel MDAC (Multiplying D-A Converter) which essentially uses
switched resistors to provide the required degree of signal attenuation. The MDAC
technology was adopted because it provides better sonic performance than traditional
VCAs for the console signal path.
The fader and rotary-encoder data is transmitted to the DAW as a pair of Continuous
Controller messages, allowing excellent 14-bit resolution, and every button sends
separate control messages to indicate when it is both pressed and released. Clearly, this
means there is a lot of data passing between console and DAW, but there is no
perceptible control or tally-light lag at all. Everything works exactly as you would
expect it to, as one perfectly integrated system with no difference in response between
using a control to address a console signal path or a DAW channel.

Master Section

The master section of the console occupies the right-hand side and cannot be relocated
to the centre of the desk, but this is not a problem, since the entire console can be
reached easily from a central position, and hence there is no need to leave the
monitoring sweet spot while working. The master section incorporates all the traditional
analogue console facilities: main fader, buss compressor, FX and Cue send masters,
monitoring controls, and so on. But there is also a full set of transport controls (with
auto-locator), a comprehensive array of dedicated DAW control keys, and a colour TFT
screen, of which more in a moment.

Above the display screen is a panel section which includes a line-up oscillator providing
one of six selectable tone frequencies or pink noise (with both preset and variable level
options), routable to the Track, Record, and Mix busses. There is also a built-in talkback
mic with separate output-level controls for Slate, Foldback, and Direct output, plus an
input-level control for the studio Listen mic, which is processed with SSL's infamous
Listen Mic Compressor. An external talkback mic can be used instead of the internal
mic, if required. A quartet of LEDs indicate the presence of the critical power-supply

To the right of the screen is a section devoted to the four stereo returns and the two
foldback outputs. The stereo returns are usefully equipped with Width, Balance, and
Level controls, in addition to separate left and right cuts, AFL, and independent routing
to the Record and Mix busses. There are also facilities to send these return signals to the
two Foldback outputs, with an independent Studio level control, making it easy to set up
reverb in the headphones when recording vocal takes.

Each foldback output is provided with Level control, cut and AFL facilities, and six
source-selection buttons, allowing contributions from the two stereo Cue busses, the
Record and Mix busses, the four stereo returns, and the control-room monitor outputs
— all of which makes it easy to arrange zero-latency headphone monitoring for
performers. The engineer's headphone outputs can be fed with the control-room stereo
monitoring signal or either of the foldback signals.

Assignable Dynamics Processors

Above and to the right of the TFT display are the dynamics facilities: a pair of mono
multi-function processors and the stereo buss compressor. The two mono units can be
linked for stereo operation and allocated to any pair of input channels (using the
appropriate buttons in each channel's routing section) or to the Record or Mix busses
using a clever matrix arrangement.

The mono dynamics processors provide both compressor and expander/gate facilities,
sharing a common gain-reduction element. The compressor section follows SSL's usual
practice of providing variable Ratio, Threshold, and Release controls with fully
automatic gain make-up.

By default the side-chain is RMS-sensing with a soft-knee transition, but the Peak
button switches the response to peak-sensing and hard-knee, which is generally more
appropriate for transient-rich signals. The attack time is normally programme dependent
(varying between 3ms and 30ms), but a Fast Attack button fixes the attack time at 3ms
if necessary.
A column of yellow and red LEDs shows the
compressor's gain reduction, while an adjacent column
of green LEDs shows the gain reduction applied by the
gate section. The gate has four rotary controls —
Range, Threshold, Release, and Hold — plus another
Fast Attack button and an Exp switch to change the
mode to a 1:2 expander instead of a hard gate. The gate
can be triggered by an external key signal (input via a
                                                          Underneath each channel's
rear-panel connector and shared by both dynamics
                                                          multi-function meter are a
                                                          matrix of routing buttons,
                                                          below which are the switches
The stereo buss compressor is derived from the G-
                                                          which are used to assign the
series quad compressor, and uses the same dual-VCA
                                                          two mono dynamics sections
feed-forward topology. It can be switched into either
                                                          for individual channel
the Record or Mix busses (but not both at the same
time), and is equipped with a full set of controls:
                                                          Underneath each channel's
Threshold, Ratio, Attack, Release, and Make Up Gain,
                                                          multi-function meter are a
plus a bypass switch and a traditional white-on-black
                                                          matrix of routing buttons,
moving-coil gain-reduction meter.
                                                          below which are the switches
                                                          which are used to assign the
The main buss matrix allows any of six separate
                                                          two mono dynamics sections
functions to be introduced into either the Record or
                                                          for individual channel
Mix busses. Both stereo busses have their own
balanced insert points which can be switched in or out
                                                          Underneath each channel's
using this matrix, and unusually the insert return can
                                                          multi-function meter are a
either replace or be summed with the main buss signal
                                                          matrix of routing buttons,
— a facility that allows an external mixer output to be
                                                          below which are the switches
combined with the main busses, or for the Record buss
                                                          which are used to assign the
output to be summed back into the Mix buss, for
                                                          two mono dynamics sections
                                                          for individual channel
The two dynamics processors and/or the buss
                                                          Underneath each channel's
compressor can also be inserted using the matrix, and
                                                          multi-function meter are a
the master stereo fader can be assigned to control either
                                                          matrix of routing buttons,
buss. By default the master fader operates with unity
                                                          below which are the switches
gain at the top of its travel (which makes fade-ins and
                                                          which are used to assign the
fade-outs a lot easier), but an additional 10dB of gain
                                                          two mono dynamics sections
can be introduced if required, so that it works like the
                                                          for individual channel
channel faders, with gain in hand.
                                                          Underneath each channel's
In the top right-hand corner of the master section are
                                                          multi-function meter are a
rotary level controls and associated AFL buttons for the
                                                          matrix of routing buttons,
eight Track Busses, and a section concerned with the
                                                          below which are the switches
master outputs for the two stereo Cue busses and four
                                                          which are used to assign the
mono FX busses. The level controls all have centre
                                                          two mono dynamics sections
detents which correspond to unity gain, with an
                                                          for individual channel
additional 10dB of gain available if required. Each
output has its own AFL button, and a set of bar-graph
meters above these controls shows the output levels for the Cue, FX, and Foldback

The monitoring section is surprisingly well equipped, with comprehensive facilities to
drive two sets of 5.1 monitors and two sets of stereo monitors, complete with automatic
downmix to stereo or mono. There's also individual-speaker level calibration, bass
management, and encode/decode processor inserts. Further clever facilities make it easy
to integrate a visiting engineer's preferred front monitors while retaining the 'house' rear

External monitor inputs are provided for four 5.1
sources and a further four stereo sources — all of
which can be mixed together and/or routed to the main
monitors, studio foldback, or headphones. The first six
Track Busses are also available to the surround
monitoring (to accommodate a 5.1 stem) and there is
even a dedicated 5.1 output facility to feed a multi-
channel metering system like DK Audio's MSD range.

The monitoring facilities are further enhanced with an
elaborate solo system, again derived from the SL9000K      The Solid State Logic web site
console. Destructive in-place solo, stereo AFL, and        already has an extensive
mono PFL modes are all available, with a separate PFL      library of FAQs and detailed
output to feed a dedicated PFL speaker if required.        tutorials, and there are even
There is also a useful in-front solo mode, which is        things like track sheets to
essentially stereo AFL, but with a user-configurable       download.
level of the entire mix added back in, allowing the        The Solid State Logic web site
soloed channels to be heard more clearly, but in           already has an extensive
context.                                                   library of FAQs and detailed
                                                           tutorials, and there are even
The master volume control has an associated numeric        things like track sheets to
display to show the relative level either of the entire    download.
selected monitoring system, or of individual channels
in calibration mode, or of the current dim levels when configuring the Solo modes. A
bank of six buttons is used to assign the volume knob to adjust the default levels of
various monitoring signals including the AFL, PFL, and solo-in-place feeds. Three large
white buttons switch the monitoring between the alternate 5.1 system, and the two
stereo 'mini' systems. Additional arrays of buttons serve to mute or solo the individual
monitoring speakers; select 5.1, 5-into-2 downmix, or mono modes; and select the
monitoring source, with an option to mix the selections together if required. Its all very
intuitive and flexible, and just what you would expect of a thoroughbred console from
the SSL stable.

DAW Control

As already mentioned, the multiple-HUI aspect of the desk enables the 24-channel
fader, mute, solo, encoder, and channel-selection controls to be assigned to operate the
desk's analogue path, the corresponding DAW channels, or both, in banks of eight. The
faders assigned to the DAW can be scrolled individually or in banks to access any
number of DAW tracks.

However, it is in the master section that the majority of DAW
facilities are to be found. The basic transport functions are
supplemented with auto-locate features, including Return To Zero,
End, Loop, Pre/Post-roll, Punch In/Out, and so on. There is also a
numeric keypad, a jog/shuttle wheel, and a set of navigation
cursor buttons. Particularly thoughtful additions are the Undo,
Save, Shift, Alt, Control, Option, Escape, and Enter buttons,
which allow access to all the context-sensitive alternate functions
which proliferate in every DAW's menu architecture. This renders
the keyboard all but redundant for normal operations.

The small colour TFT screen has a relatively low resolution, but
provides clear graphical and textual information relating to both the console automation
and the recall facilities, as well as various DAW functions including effects plug-ins.
The question many will ask is, can the display be output to an external screen, as on the
big SSL consoles? The answer is no; the display resolution is much too low, and there
really is no need because its wide viewing angle allows it to be seen clearly from
whichever end of the console you happen to be sitting.

The various menus and graphical displays are controlled using an array of soft keys and
four rotary encoders below the screen. The encoders (with a press switch action) and
associated soft keys are used mainly to control graphical plug-in parameters, while two
more buttons scroll forwards or backwards through any additional parameter options or
menu pages. Two rows of eight buttons below these access the various console and
DAW global options and commands, as shown with neat labels running across the
bottom of the screen. This arrangement is very clear and intuitive, although some
familiarity is required to manage these functions at speed.

Finally, to the right of the jog/shuttle wheel are an array of talkback buttons which fall
easily to hand, and there is even a button to switch on the studio's red light — how

On Session With The AWS900

The sonic and ergonomic pedigree of this console was immediately evident from the
outset. It is very easy to find your way around the channel strips, and the flexibility of
signal routing allows the desk to do far more complex things than you would have
thought possible. The mic preamps and EQ are classic Superanalogue designs and do
exactly what you need them to do.

The monitoring section is surprisingly comprehensive (and future-proof too with its 5.1
support), and all the tools are provided for easy communication with the talent. After
only a few minutes familiarisation I felt completely at home with the analogue aspects
of the console, and controlling the primary DAW functions — arming tracks, recording,
overdubbing, adjusting channels, tweaking plug-in settings — came just as easily.
Overall this desk is Intuitive, ergonomic, and professional.
However, there are a few aspects that restrict the ultimate flexibility of the console and
highlight the fact that it was conceived mainly as a tracking desk, before analogue
mixing again became more fashionable. The first clue is the absence of any groups or
VCAs, although you can link faders.

Perhaps a more obvious clue is the lack of dynamics on every channel — a pair of
assignable dynamics processors may well be sufficient when tracking, but a lot more are
usually required for mixdown. Of course, you could use DAW plug-ins, but that defeats
some of the advantages of an analogue mixdown. Fortunately, SSL have addressed this
issue by announcing the XRack range, the first unit of which will provide up to eight
dynamics processors (the same as those in the console) which can be patched into the
required channel insert points. The rack also incorporates Total Recall facilities which
integrate fully with the console's system.

The second element is the lack of surround panning facilities in the channels, making
surround mixdowns rather tricky. Again, there are various workarounds, but a lot of
reliance must inherently be placed on the DAW's facilities. Fortunately, again, the
monitoring section is sufficiently flexible to allow several 5:1 stems to be combined
from the internal Track Busses and external inputs.

Having said all that, these compromises are not likely to be particularly significant to
most users, and are easily outweighed by the numerous highlights of the console — a
Superanalogue mixer with 'big desk' sound, features, and flexibility, for a remarkably
modest UK price. You can really see where the money has been spent on this console,
and it constitutes a truly professional high-end console for the mid-market studio or post
house. Throw in the perfectly executed DAW interface and console integration and this
has to be my product of the year!

Published in SOS November 2005

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