Digital Audio Denmark
ADDA 2408
For anybody with a significant investment in digital recording and/or mixing, the first items of equipment to come under scrutiny in the
quest for sonic transparency are the convertors employed. JON THORNTON is blown away by this top-end Dane.
HE ADDA 2408 from Digital
Audio Denmark is one of a
number of recent, and not-sorecent, entrants to the higher end of 8channel A-D and D-A convertors.
What makes DAD’s effort distinctive is
the flexibility on offer as a result of its
modular processing arrangements.
To understand the significance of this,
it’s worth starting at the back panel of the
unit, where a ‘bare’ unit would exhibit 8 XLR connectors
for analogue inputs (mic or line), a further pair of XLRs
for analogue or digital stereo output, and BNC and XLR
sockets for video, wordclock or AES11 sync inputs
together with a wordclock output. In among all of this are
eight blanking panels that can be filled with a variety of
additional I-O options. These include TDIF, AES or ADAT
lightpipe cards giving 8 channels of digital I-O. A Pro Tools
card allows direct ‘host’ connection to a Pro Tools Mix 24
system (Tools sees the device as an 888/24 interface –
albeit only working at sample rates up to 48kHz) and
there are also cards giving 4 or 8 channels of D-A
conversion. Multiple options can be simultaneously
installed, and their inputs and outputs selected from the
front panel.
The review unit shipped with a Pro Tools interface, an
8-channel AES card, a TDIF card, and a card that offers
individually addressable optical, SPDIF and AES digital
I-Os. If this wasn’t enough, the ADDA 2408 comes as
standard with eight high quality mic preamps built in.
With such a plethora of options and I-O possibilities,
I was expecting this unit to be confusing to operate,
but once you grasp a couple of fundamental user
interface principles it’s actually very straightforward.
Each pair of the eight possible inputs has a selector
switch that toggles through the available inputs
skipping over any uninstalled options. Selecting a pair
of digital inputs from an I-O card that supports multiple
pairs (for example, the Pro Tools interface, TDIF or 8channel AES options) will select the logical channel
association. In other words, setting the ADDA 2408’s
input channels 5 and 6 to TDIF will assign channels 5
and 6 of the T-DIF port to those channels.
Selecting an analogue source – and the three choices
here are line level and mic level with or without
phantom power – brings into play the data entry knob
on each of the unit’s eight channels. With a
microphone input selected, gain is adjusted in 0.5dB
steps (although you aren’t aware of it, the unit steps
through analogue gain increments of 3dB, interspersed
with digital gain steps of 0.5dB). Each input channel
has an associated peak-reading meter, and each pair of
channels has a small LCD display – which at this stage
shows the amount of mic gain added.
Moving further along brings you to ten buttons that
perform global or system level functions. In among
selecting sample rate, sync reference and dither options
is a button that, when pressed repeatedly, toggles
through a number of options for each
input channel that can be set using
the relevant data entry knob,
regardless of the type of input
selected. These options are a
switchable high pass filter (80Hz),
phase reverse and a variable delay of up to 100ms on
each channel. Each of these parameters can be viewed
or altered for each of the eight channels by pressing and
holding dedicated ‘short-cut’ buttons located along the
top of the unit.
Each of the eight input sources are passed directly to
the logical digital outputs of all multiple channel I-Os
that are fitted. Analogue inputs are sampled at the
unit’s current sample rate, and dithered to the selected
bit depth. Digital inputs operating at a different sample
rate to the unit’s current sampling rate are
automatically detected and sample rate converted, and
sent to all digital outputs in the same manner.
This means that a single interface unit, with the
appropriate options installed, could preamplify,
phantom power and convert a pair of microphone
signals, do the same for a pair of line level analogue
signals, sample rate and format convert a pair of
ADAT, and a pair of TDIF signals – all at the same time.
The only significant caveat to this is that the
multichannel I-O options can only operate at one
unified sample frequency for input and output. As an
example, if your TDIF input is being presented to the
unit at a different sample rate to that selected on the
front panel, the signal will be sample rate converted
but not sent to any multiple output that is not
operating at the ‘system’ sample rate.
The flexibility of this unit doesn’t end there – as it also
features a clever 8:2 monitor mixer. This can be fed from
the selected analogue or digital sources on each channel,
or directly from the inputs of any of the installed cards.
Level and pan can be set for each of the eight monitor
channels using the same user interface described above,
and the output of the mixer can be user-selected to
appear on the output XLRs as an analogue signal or as
one AES pair. If an AES output is selected, this signal
can be cascaded into multiple ADDA 2408s by feeding
it into the AES11 sync input of additional units. The
monitor output can be listened to via headphones.
So, an impressively flexible unit, but how does it
sound? With the price tag (UK£3999 inc. VAT)
commanded by this device, you would expect it to
sound special – and it doesn’t disappoint. The mic
preamps are quiet, open and transparent – and the
quality of analogue to digital conversion is exceptional
– particularly when really looking at that problematic
low end. Sample rate conversion is also refreshingly
free of any perceptible audio artefacts, which was a
relief as the review unit got me out of a sample rate
hole almost immediately after it arrived.
Despite initial impressions, the user interface is well
designed and works very well indeed. DAD has
sensibly included warning indicators for carrier
present, digital sync alarms, and digital overload
conditions when using the monitor mixer.
In summary, it’s hard to find anything to dislike
about the unit. ■
Terrific convertors; intuitive (after a
while) user interface; flexible options
and assignment.
Not a ‘cheap’ option; some users may
not require all the flexibility on offer.
DAD’s 2402 is a 2-channel converter that
supports sample rates from 32kHz to
96kHz in 24-bit. A variety of connectors
are available for easy interfacing to
professional and consumer
environments. It has a peak programme
meter and dither and is full duplex.
Tel: +45 72 203555
UK, Systems Workshop +44 1691 658550
March 2003
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