SPL Mercury Stereo Mastering DAC Digital to Analog Converter (Red)

Description

Mercury Mastering DA converter

Mercury is the first Mastering DA converter in 120V rail
technology.

Mercury is a stereo digital to analog converter that
fulfills the highest demands both technologically and tonally.

A total of seven digital inputs, two AES/EBU, two SPDIF, two
TOSLINK as well as USB can be connected to Mercury. AES input 2 also supports Dual-Wire
(DW) mode.

Each digital sources has its dedicated and illuminated
switch for instant selection and fast comparison.

DAC with DLP120

We looked at many converter designs and asked why
innovations are almost exclusively on the digital side and very rarely on the
analog side. Maybe it’s because most of the developers have their background in
digital technology and therefore develop analog technology more like a
‘cookbook’.

We have 30 years of experience in analog technology and
consider ‘cookbook’ designs rather boring, inefficient and in need of
improvement.

The output of the DAC-IC (AK4490) is an analog signal that
must be filtered with a low-pass filter. This analog circuit is typically
operated with the same voltage as the DAC-IC – for example 5V. Imagine that the
first stage that finds the analog signal has a dynamic range and
signal-to-noise ratio limited by this voltage. What a bottleneck.

The Mercury uses our 120V technology instead of the standard
technology. And this twice in the newly developed DLP120 module. DLP stands for
“Dual Low Pass”. These are two separate analog filters in 120V
technology. Depending on the type of digital signal, the analog signal passes
through the PCM or DSD filter and can freely unfold into a huge dynamic range.
This is audibly better.

Velvet Sound® DA Converter

The DA converter (DAC) in the Mercury is the AK4490-Velvet
Sound® converter chip from AKM.

It offers a bit depth of 32 bits and a maximum sampling rate
of 768kHz for PCM digital signals and DSD4 or DSD256 for direct-stream digital
signals.

AES & DW

AES (or more precisely AES3 or AES/EBU) is a standard for
the exchange of digital audio signals between professional audio devices. AES3
was jointly developed by the Audio Engineering Society (AES) and the European
Broadcasting Union (EBU).

An AES signal transports two encoded PCM audio channels at a
maximum sampling rate of 192 kHz.

The standard is defined under IEC 60958 Type I.

A special feature is the Dual-Wire mode (DW), where two AES
jacks are operated together to double the maximum sampling rate. The second AES
input therefore has two XLR jacks. Dual-Wire allows Mercury to be connected to
any digital AES/EBU source.

Balanced, 3-core, 110 Ohm “twisted pair” cables
with XLR plugs are used for connection.

Coaxial

The consumer version of AES is S/P-DIF (Sony/Philips Digital
Interface). It is the most common method for connecting digital audio devices
worldwide. Typically, the digital output of a CD player is connected here.

The jacks are labeled “Coaxial” and carry two
encoded PCM audio channels with sampling rates up to 192kHz.

This standard is defined under IEC 60958 Type II.

Unbalanced, 2-wire 75-Ohm coaxial cables with RCA connectors
are used for connection.

Optical

The two ‘Type II Optical’ connectors use optical fibre with
an F05 connector better known by the Toshiba brand name TOSLINK.

These jacks are labeled “Optical” on Mercury.

Just like the coaxial S/P-DIF inputs, these inputs support
sampling rates up to 192kHz for encoded PCM audio.

Our tip: You should attach importance to the quality of the
optical fiber. With inexpensive plastic optical fibers, transmissions with
fourfold sampling rates (176.4kHz/192kHz) can be subject to errors. In this case
a real fibre optic cable should be chosen.

USB

The USB port, for connecting a computer, converts PCM and
DSD audio formats.

Sample rates up to 768kHz are supported for PCM audio. For
DSD audio up to DSD4 (quad-rate DSD or DSD256).

No special driver is required for an Apple Mac, as Apple
natively supports USB class 2 up to a sampling rate of 768kHz.

To use Mercury to its full extent on a Windows PC, the SPL
Mercury driver should be installed. With this driver, higher sampling rates
than 44.1kHz and 48kHz can be output on a Windows PC.

DSD via USB

A playback of (unencrypted) DSD data from the computer can
only be done via USB.

Specific software players such as Audirvana Plus (Mac),
Channel D Pure Music (Mac), J River Media Center (Mac/PC), Signalyst (PC),
Foobar2000 (PC), JPlay (PC) support DSD playback.

The USB Audio 2.0 specification defines different formats
for handling PCM audio signals, but it does not define the handling of the DSD
format. In 2012, representatives of many companies and institutions have
developed a standard known as “DSD over PCM” or “DoP”. This
will represent and detect DSD audio in the PCM frames of the USB specification.

SACD or BluRay players usually do not output the DSD stream
for copy protection reasons. This means that such a player can only be
connected to one analog input, e.g. on the SPL DMC Mastering Console.

PCM & DSD

Pulse Code Modulation (PCM) is a method of encoding sampled
audio signals that is commonly used for uncompressed audio. It is the standard
format for digital audio in computers, on compact discs, in digital telephony
and other digital audio applications.

Direct-Stream Digital (DSD) is a trademark of Sony and
Philips. Both developed DSD for SACD (Super Audio CD), which was to become the
designated successor to the CD (which was also developed by the two companies).

Since PCM and DSD are digital formats, there are other ways
of playback. The highest resolutions for music are now available from download
portals such as HD Tracks, Qobuz, HIGHRESAUDIO, primephonic, HDMusicStore,
Bleep, Cybele, Gimell, HD-Klassik, 7 Digital etc.

DSD is fundamentally different from conventional PCM. While
in a PCM stream the amplitude of an analog signal is sampled regularly at equal
intervals and each sample thus obtained is quantized to the closest value
within the digital stages, a DSD stream stores a sequence of 1-bit values before
a “decimation” process converts the signal into a PCM signal.

Volume Control

On the analog side, Mercury offers a regular stereo output,
which can be calibrated to all common reference levels, as well as another
stereo output with continuously adjustable output level. Thus Mercury can also
be used as a state-of-the-art monitor controller.

The volume control for the variable output of the Mercury is
completely analog. In most other designs the volume control is done digitally
as part of the converter chip functionality. A disadvantage of digital volume
control is that the original bit resolution is only available at 0dB (maximum
value).

As volume control we use the ALPS RK27 “Big Blue”
potentiometer which provides a nice, sensitive feeling and excellent channel
synchronisation. So not only the auditory, but also the haptic experience is on
the highest level when adjusting the volume.

0dBfs Reference Level

Holding the Sync button down for more than two seconds will
cause Mercury to change from Sync to 0dBfs display. In this mode it is possible
to define the analog level of a full scale digital signal (0dBfs = 0dB full
scale).

Mercury supports all currently used reference
levels starting with 0dBfs = 14dBu. Followed by 15, 16, 17, 18, 20, 22 and
finally 24dBu.