SPL Director DAC / Preamp with VOLTAiR Tech (Red)

Description

The Director combines two units in one: a reference-class
preamplifier with six inputs (2x analog and 4x digital) and both balanced and
unbalanced outputs as well as a reference-class DA converter for PCM up to 384
kHz and up to Double Rate DSD (DSD128).

 

• 120V
  rail preamplifier with integrated DA converter

• Four
  digital inputs: USB, AES/EBU, coaxial, optical

• DAC:
  up to 384 kHz (PCM) and DSD 2 (Double Rate DSD, DSD128)

• Win
  driver; Apple class compliant

• Two
  analog inputs (2x RCA)

• Balanced
  and unbalanced outputs (XLR, RCA) 

• Analog
  volume control with motorized ALPS R K27 “Big Blue”
  potentiometer; remote controllable (learns any IR remote control)

• Remote
  controllable source selection (learns any IR remote control)

• Avago
  dot matrix display shows selected input and sample rate frequency for
  digital inputs

• Frequency
  range (analog): 4 Hz to 300 kHz (-3 dB)

• THD: 0,0008 %
  (analog),  0,0004 % (digital)

• Dynamic
  range: 137,6 dB (analog), 120,8 dB (digital)

• AMP
  CTR connection to Performer power amplifier for coupled on/off
  switching 

• Windows®
  driver, Apple class compliant

• Stand-By/power
  on switch

• Linear
  power supply with toroidal transformer

• Made
  in Germany

 

The technical basis of all Professional Fidelity
units is our proprietory 120 V Rail Technology, which we also call VOLTAiR
technology. The name makes reference to the unequalled high voltage of 120 V
(+/-60 V DC) and the huge dynamic range of over 140 dB that goes with it.

The name ‘Director’ describes its function pretty well. It
is the heard of the stereo system to which all components are being connected:
sources, amplifier, active speakers, headphone amps, phono preamplifier etc. It
determines what, with what and how loud we hear.

Preamplifier

Director is a full-fledged stereo preamplifier
with an extraordinary DA converter. There is provision for connecting up to six
stereo sources – two in the analog domain offering RCA connectors for e.g.
phono preamplifier like the Phonos and four in the digital domain
with USB, AES, Coaxial and Optical connectors.

At the output side a power amplifier or active loudspeakers
can be connected balanced (XLR) and unbalanced (RCA). We recommend the Performer
s800 as power amplifier in order to maintain a 120V Rail audio chain
from the DAC to the speakers for best audio performance.

Volume

Volume is controlled strictly in the analog domain
– for good reason. Commonly volume is regulated in the digital domain as
part of a chip’s functionality. Apart from being inexpensive the down side is
that the playback at lower volume than unity gain (0dB) is compromized due to a
shrinking bit resolution. And as you never listen with the preamp turned up
fully clockwise you always hear at a lower bit resolutions with diminished
audio fidelity. It makes not a lot of sense to listen to high res audio then,
does it? As this is not acceptable we opted for an analog solution that gives
you infinite resolution at all listening levels. We use a motorized ALPS RK27
“Big Blue” potentiometer with excellent feeling and channel matching.
Being motorized Volume can be remotely controlled.

A great feature is a small DIP switch at the bottom of the
Director. DIP switches number 3 and 4 allow to decouple the volume control and
to deliver a unity gain output at the XLR or the RCA output or both. You can
connect a headphone amplifier like the Phonitor e and have individual
volume control for the headphones. Another application is that connection of a
digital recorder.

Source

On the front of the Director is a toggle switch for the
selection of the input source. Toggle to the left to select the previous source
and toggle to the right to select the next source. The selection is shown in
the dot matrix display: IN 1 and IN 2 for the analog inputs and USB, AES, COAX
and OPTI for the digital inputs. The detected sample rate of the selected
digital input is displayed after about 2sec. (e.g. U384 = USB input, 384kHz
sampling rate). The input source can also be remotely controlled.

Remote Control

Volume as well as input selection can be remotely controlled
using any existing infra-red (IR) remote control. The cool part is that the
Director learns your remote! Take, for example, the remote control of the CD
player. Out of the many buttons there are maybe four you hardly use if at all
and that do not directly trigger a function on the CD player. Alternatively you
can use the Apple remote control which is small, slick and offers just the
buttons you need. Assign Volume Up / Volume Down to two buttons and Next Input
/ Previous Input to two other buttons and let the Director learn them. The
procedures are described in the manual.

DA converter (DAC)

The Director is equipped with the
best Digital-to-analog converter (DAC) we ever made. It sports four
digital stereo inputs (USB, AES, Coaxial and Optical) and supports
PCM audio as well as DSD audio playback.

World Premiere Design
with VOLTAiR technology

We have been looking at many DAC designs and we have always
wondered why all the innovations happen on the digital side. Almost no
innovation is to be found on the analog part for the DAC. Maybe that is because
most designers have a background in digital engineering and as a result they
apply only standard ‘cook book’ designs on the analog side. We, having a little
background in analog, find cook book design out dated and boring. We believed
we can do that part much better and –simply put– revolutionize the design of
DACs. Here is how:

The output of a DAC chip is either a voltage or current
(as in our design) that represents the value presented on their digital inputs.
This output is to be converted to voltage (in case of a current output) and
filtered with a low pass filter. These two stages are typically designed with
the same reference voltage of the DAC chip at e.g. 5V. Think about this: the
first stage that the analog waveform is exposed to has a headroom limited to
5V. Now imagine this to be 120V! This is what we have done in the Director. The
current to voltage conversion as well as the low pass filter are both running
on a 120V rail – our VOLTAiR technology. The incredible headroom and the
enormous power lets the analog wavefront come to life and evolve without
limitations. And that is audible. Very much so.

AES input

AES (or more precise 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 can carry two coded PCM
audio channels of up to 192kHz sampling rate. The standard is defined
under IEC 60958 Type I. Type I connections use balanced, 3-conductor,
110-ohm twisted pair cabling with XLR connectors.

Coaxial (SPDIF) input

The consumer grade variant of AES is SPDIF (Sony/Philips
Digital Interface). Worldwide it is the most commonly used method for digitally
interconnecting audio equipment – typically the digital output of a CD
player. The connector is labelled “Coaxial”. Like AES it
can carry two coded PCM audio channels up to 192kHz sampling rate. The
standard is defined under IEC 60958 Type II. Type II connections use
single-ended, 2-conductor, 75-ohm coaxial cable with RCA connectors.

Optical (TOSLINK)
input

Type II Optical connections use optical fiber with F05
connectors, which are more commonly known by their Toshiba brand name, TOSLINK.
Type II Optical connections are also used in consumer audio and are also called
“Optical”. Like AES and Coaxial it supports sample rates up to 192kHz
for two coded PCM audio channels.

USB input

The most interesting input is the USB port for connection
with a computer. The Director supports both audio formats PCM and DSD audio.
For PCM audio sample rates are supported up to 384kHz and for
DSD audio sampling is supported up to DSD2 (double-rate DSD) also known as
DSD128 (128 times the CD sampling rate of 44.1kHz).

When connected to a PC the Windows driver must be installed
to playback audio files with a higher resolution than 44.1kHz or 48kHz. In a
Mac environment the install of a driver is not needed. Apple natively supports
USB class 2 with sample rates up to 384kHz.

DSD over USB

SACD or BluRay players typically do not put out the DSD
stream for copy protection reasons. This means that an existing SACD/BluRay
player can only be connected to the analog inputs of the Director. To
playback (non-encrypted) DSD files from a computer can only be handled over
USB. Specific software players like 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 defined several formats for
the more common PCM approach to digital audio, but did not define a format for
DSD. In 2012, representatives from many companies and others developed a
standard commonly known as “DSD over PCM”, or
“DoP” to represent and detect DSD audio within the PCM frames
defined in the USB specification.

PCM & DSD

Pulse-code modulation (PCM) is a method of encoding sampled
analog signals generally used for uncompressed audio. It is the standard form
of digital audio in computers, Compact Discs, digital telephony and other
digital audio applications.

Direct-Stream Digital (DSD) is the trademark name used by
Sony and Philips. They developed DSD for SACD (Super Audio CD) which should
have become the designated successor of the CD (that was also designed by these
two companies).

Since PCM and DSD are digital formats, there are other ways
to play back high-resolution music. The highest possible resolutions are
available on download portals like HD Tracks, Qobuz, HIGHRESAUDIO, primephonic,
HDMusicStore, Bleep, Cybele, Gimell, HD-Klassik, 7 Digital etc.

DSD differs fundamentally from conventional PCM. While in a
PCM stream, the amplitude of the analog signal is sampled regularly at uniform
intervals, and each sample is quantized to the nearest value within a range of
digital steps, DSD stores a sequence of single-bit values before applying
a “decimation” process that converts the signal to a PCM signal.

A PCM stream has two basic properties that determine the
stream’s fidelity to the original analog signal: the sampling rate, which is
the number of times per second that samples are taken; and the bit depth, which
determines the number of possible digital values that can be used to represent
each sample. In the Director PCM audio is supported up to sample
rates of 384kHz (8 times 48kHz) and bit resolutions of up to 24 Bit.

In DSD audio the fidelity is determined by the rate of the
1-bit stream. The Director supports up to double-rate DSD also known as DSD2 or
DSD128. Single-rate DSD is the typical SACD/BluRay resolution and it is
referred to as DSD1 or DSD64 because the sample rate is 64 times that of CD
(44.1kHz) namely 2.8224 MHz. DSD2 samples at 5.6448 MHz, twice the
SACD/BluRay rate. This is also referred to as DSD128 because the sample rate is
128 times that of CD.

The long-term average of a DSD signal is proportional to the
original signal. DSD uses noise shaping techniques to push quantization noise
up to inaudible ultrasonic frequencies. In theory, it only requires a
lowpass filter to reconstruct the original analog waveform. In reality it is a
little more complex. A one-bit signal cannot be dithered properly: most modern
sigma-delta converters (like the DAC in the Director) are multi-bit.

Because it has been extremely difficult to carry out DSP
operations (for example performing EQ, balance, compression) in a one-bit
environment, and because of the prevalence of solely PCM studio equipment such
as Pro Tools, Nuendo, Cubase, Logic, the vast majority of SACDs and DSD
downloads—especially rock and contemporary music, which rely on multitrack
techniques—are in fact mixed in PCM (or mixed analog and recorded in PCM) and
then converted to DSD in mastering. It is kind of rare to find or identify a recording
being multi-tracked and mixed in the analog domain. Merging Technologies has
invented the DXD format with which theoretically a production can be recorded,
mixed and mastered entirely in the DSD domain.

Professional Fidelity
• Pro-Fi-Serie

Phonitor x is part of our Pro-Fi series of products.
Pro-Fi stands for Professional Fidelity and it expresses that these products
have their roots in professional studio technology being optimized for
high-fidelity music playback.

SPL stands for simple elegance and uncompromised
quality. Therefore we renounce over-dimensioned housing milled out of a
solid block and other mostly price-driving attributes of many high-end
products. Our background is come from professional studio technology, where
inner values and audio performance count the most.

Mastering studios give your records and CDs the final
tough – with SPL 120V technology. And because the Phonitor x is built
with the same technology it belongs to best headphone amplifiers on the
planet. With its extraordinary specifications and enormous headroom Phonos
plays back audio in the most relaxed and uncompromised fashion. Ear fatigue is
reduced by far and hearing session stay delightful for a long.

VOLTAiR-Technologie

VOLTAiR technology is what we also call the 120V rail
technology to express the unequalled high voltage, which is four times as high
as usual. The performance characteristics are unique and they have just such
effect on the listening experience.

The 120V electronics operate quasi ‘idle’ even at highest
audio levels and impulse peaks. They never operate on the limit and therefore
never get stressed. The music presents itself with a serenity that you feel
pleasant when listening.

The Sound

120V Rail Technology is our reference
technology developed and manufactured to run on an operating voltage of
120 volts, which corresponds to twice that of discrete operational amplifiers
and four-times that of semiconductor operational amplifiers.

120V Rail Technology reaches outstanding technical and
sonic performances. Technically especially in terms of dynamic range and
headroom and sonically especially in reproducing the finest details and
delivering a totally relaxed sounding audio experience. Music sounds absolutely
natural and hearing fatigue is drastically reduced.

Even the best audio measuring equipment arrives at the
boundaries. In same situations we ended up just measuring the Audio Precision
Cascade 2 measuring device and we cannot say how good the 120V Rail Technology
actually performs.

Comparisons

The direct relation between operating level and maximum
level is fundamental for the classification: the higher the operating level,
the higher the maximum level a circuit can handle. And since virtually all
essential acoustic and musical parameters depend on this relation, a higher
operating voltage also has a positive impact on the dynamic range, distortion
limit and signal-to-noise ratio.

Do bear in mind that dB scales do not represent linear but
rather exponential increases. A 3dB increase corresponds to doubling the
acoustic power, +6dB correspond to twice the sound pressure level, and +10dB
correspond to twice the perceived loudness.

When it comes to volume, the 120V Rail Technology exhibits a
performance, in regard to maximum level and dynamic range, that is twice that
of common components and circuits given that its values are approximately 10dB
higher.

THD measurements of the 120V op-amp show a difference of
more than 3dB compared to the OPA134 at 36V — in terms of sound pressure level,
that corresponds to an improvement of more than 50%.

The operating level most commonly used for audio equipment
is 30 volts.