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Pure DSD done right
Introducing DirectStream Junior (DSJ), a world class DAC based on the architecture of the Stereophile and Absolute Sounds Product Of The Year, DirectStream.
DSJ uses the same FPGA architecture and customized code as PS Audios DirectStream DAC, and it is designed and built by the exact same team. The idea behind the DSJ was to offer near-identical performance at a fraction of the cost. How was this accomplished? Lower cost chassis and user interface.
DSJ, like DirectStream, is hand-written, discrete, perfection based conversion that uncovers all the missing information hiding in your digital audio media for all these years. CDs, downloads, high-resolution PCM or DSD based media are expertly upsampled in the DSJ to ten times DSD rate and output as pure analog directly into your amplifier or preamplifier. Classic PCM-based DACS, including many of todays DACS that can also process DSD, tend to cover up some of the subtle musical details buried deep within digital audio music; a problem inherent in their architecture. DSJ solves this problem by employing a pure DSD single-bit approach for both PCM as well as DSD media. This means that your entire library of music can finally reveal all the music and subtle low level details buried deep within its core and now, at a more affordable price than its progenitor, DirectStream.
Imagine going to a recording studio and listening to a master tape of any recording made. This is the experience DSJ affords its owners who enjoy a renewed sense of enjoyment and discovery when listening to everything in their library: CDs, downloads, DSD.
The start of the 30-year war
In 1981, music was reproduced exclusively on analog-based turntables and tape decks with limited dynamic range. Despite the very listenable music coming through those grooves, the audio world wanted more: greater dynamic range, lower noise, extended frequency response. No wonder that when, in 1982, Sony and Philips announced they had achieved Perfect Sound Forever, music lovers around the world waited in eager anticipation of analogs promise finally fulfilled. Unfortunately those early CDs sounded less musical than analog. In some cases, much worse. The launch of the PCM-based Compact Disc would set in motion a 30-year war amongst Audiophiles, decimate the analog format, cover up subtle musical details for decades and turn the music and audio industries upside downand not necessarily in a good way. There had to be a better way to fulfill the promise of analogs century of dominance for sounding like music and PCM would not be it. That answer is DSD.
The poor results of the first CDs might not have been a problem if Sony and Philips had waited another decade, passing over the classic PCM delivery system in favor of PDM (DSD). The problem is the PCM decoding process itself: whether a classic ladder-DAC or more modern multi-bit Sigma-Delta type, most PCM playback processors mask some of the subtle cues in music. Fortunately musics details have been more faithfully recorded than we ever suspected, but the cover-up of those recorded details has been with us for more than 30 years. Happily, the missing musical information is still buried deep within our audio librarieswaiting to be revealed. In order to extract everything hidden in PCM recordings, a completely new processing method is needed.
Pure DSD is the answer
Put DSD into DSJ, you get DSD. Put PCM (how CDs are recorded) into DSJ, you get DSD. DSJ converts all digital inputs, including PCM, to pure 1-bit DSD, in an elegantly-simple path. In the process, the PCM feed becomes more linear, less edgy, and never-before-heard musical details are released from all digital audio recordings. Millions of CDs and high-resolution downloads worldwide will gain new life, and be saved from obsolescence.
A better format
DSD is a high sample rate single-bit format while PCM is a lower sample rate many-bit format. DSD sample rates are 64 times higher than those used to create CDs and the output of a DSD stream can be placed through a simple filter to produce pure analog ready to feed your audio system. PCM, on the other hand, can produce great sounding music but to do so requires a very complex and technically daunting conversion process to produce something you can play on your system. Sometimes the simplest path is the best sounding one. DSD is a far more analog-like encoding and decoding process than classic PCM. In fact, most modern A/D converters (used to make the recordings) are Sigma Delta based already and that movement is growing. There are millions of PCM based recordings that will be in our libraries for years to come, but with the introduction of DSJ, you no longer need listen to them with a PCM based processor.
Converting PCM to DSD
Converting PCM to DSD can be an easy exercise using any number of computer software programs. Converting PCM to DSD properly, and in such a way as to reveal missing details in the music, is a serious technical challenge. To handle this properly DSJ utilizes 66-bit fixed-point FIR filters, eliminates headroom issues common to PCM, flattens noise response in the 20-100kHz region, uses coefficients optimized for best sound rather than faster processing speed and optimizes hardware-specific operations not possible in software. Unlike other processors available today, DSJ unifies all inputs (PCM or DSD) at 10x DSD, then uses a true single-bit double-rate DSD core engine. True DSD core engines (compared to the standard multibit Sigma-Delta converters followed by random lower quality multibit converters) offer advantages in simplicity, linearity, and in analog-like overload characteristics that avoid PCMs hard clipping potential and a PCM processors propensity to mask subtle details.
Pure 100% single bit DSD based D to A Converter
Most of todays sophisticated DACs are IC based instruments using off-the-shelf-chips that are Multi-bit Sigma Delta based designs. While these are relatively simple to design and produce, they dont often give the best results sonically. Because they are one-chip systems compromises are made in their architecture that are not found in DSJs custom based architecture. DSJ takes both PCM and DSD, upsamples the data and converts to single-bit DSD and then outputs pure music regardless of input format for the data. The results of this design can be heard in increased musical information presented to the listener at every opportunity.
Passive/active output stage
Most modern DACs use some form of active tube or solid state output stage to amplify, filter and drive the DACs output. DSJ takes a different approach: passive filtering with high-speed, high current analog buffering. In one of the simplest, elegant and musically correct executions of an output stage, high speed class A video amplifiers are used as the final switch for the single-bit, double DSD output of DSJ. When you listen to DirectStream you never are accosted by added bright, hard glare in the music as happens with many op-amp based designs. Instead, clean, pure music flows from DSJ directly to your preamplifier or power amplifier.
Resolution perfect volume and balance controls
Designer Smith perfected a 100% bit-perfect volume and balance control thats built into DSJ, enabling users to control the output level when feeding directly into a power amplifier or preamplifier. That the volume control is completely bit-perfect means there is no loss of resolution for any volume setting, a feature unique amongst the majority of DACS in the world today. The ability to eliminate the preamplifier in the system without any resolution loss is a major benefit to DSJs outstanding musical performance.
Simple, direct signal path with only one master clock
Typical high-end DAC designs use more than one master clock. There are often separate clocks for USB, Audio and others, causing challenges for system designers trying to synchronize the clocks. DirectStream obviates the problem by basing the entire design on one master clock of extraordinary high quality. Used is a low phase noise, low jitter clock designed for DSJ by Crystek. Using this advanced approach the need for synchronization is eliminated, jitter levels are reduced and music is delivered with a clarity rarely heard.
High immunity to jitter from sources
Sources have always had a major impact on sound quality with DACS. Transports, computers, CD players, cables all make a significant impact on performance into a typical DAC. This problem has been significantly reduced with DSJ. Now, for perhaps the first time, sources of just about any quality and jitter level sound nearly identical. For example, you can take a cheap $30 DVD or CD players digital output, connect with DSJ and have sound quality unthinkable for such a poor source. Performance levels no longer are as dependent on the quality of source or connections; certainly not to the degree they have been in the past. Yes, cables and sources still make a difference, but with DSJ that difference is significantly reduced.
Asynchronous high speed USB and Network access
DSJ can match up to either a computer or a home network. If a network connection is desired, DSJ comes equipped with our latest network card, Bridge II. Connect to a NAS or computer with ease, and control your music with an iPad, iPhone, or Android device. You can also connect directly to your computer via USB. USB communication, if handled properly, can have every sound quality advantage of a dedicated CD transport or Network Bridge. DSJ provides a fully synchronous 24 bit 192kHz path for USB based audio, supporting up to 32 bit 192kHz, and single as well as double rate DSD. Using a good quality USB cable between DSJ and your computer, like a quiet MAC Mini, provides an instant media server that can be controlled through any number of handheld devices like an iPod, iPhone or Android using a 3d party controller program. Your music can be managed by iTunes, Bit Perfect, Pure Music or Ammara for ease of use.
A handy feature on DSJ is the polarity (phase) control. This remote control option allows users to select normal or inverted polarity for every input and for every performance. Sources and music have no standard for absolute polarity, a fact easily demonstrated by switching polarities on the as the music plays. Many Audiophiles mark their discs in polarity and out of polarity and are very careful to select the proper polarity before playing each disc. Some CD players and sources themselves invert polarity so that a disc you believe is inverted actually is correct played on a specific device and incorrect on yet another. To fix this problem you can assign each input on DSJ to switch to the proper polarity when you activate that input, through the menu system. Activating this control is the same thing as reversing the loudspeaker connections of both loudspeakers (+ to -) at either the amplifier or speakers. All live acoustic music is in absolute polarity but some recordings may accidentally be made inverted and should sound more realistic when you correct their phase with the switch.
Play directly into your power amplifier or preamplifier
DSJ offers the ability to play directly into either your preamplifier or power amplifier through either its balanced or single ended outputs. You can select the optimum gain setting through DSJs setup menu, or from the remote control, to match your amplifier and loudspeakers sensitivity. If you choose to go through a preamplifier, its easy to set DSJ at maximum level (or any level you wish) to match the preamps gain. DSJs unique zero-loss volume control maintains full resolution bit-perfect performance at any volume setting from the lowest to the highest levels.
Hear more than you ever imagined from CDs
DSJ converts everything to DSD, even PCM before delivering the music to your system. This approach, coupled with careful design, low jitter and a simple and direct signal path has the benefit of uncovering details buried in the music you may not have realized are even there. CDs come alive with subtle details that were never apparent with your older DAC; details you never knew even existed. CDs sound more like high resolution audio than you imagined, closing the gap between higher resolution PCM and DSD copies. No longer do you need to consider replacing your CD library because once you hear whats truly on your discs, you may not need to upgrade to a higher resolution copy at all. Yes, it is that obvious and significant.
DirectStream is the culmination of one mans quest for perfection, coupled with one companys search for the same. Principal designer Ted Smith put more than seven years of work into designing what turned out to be one of the most highly acclaimed Digital To Analog Converters yet made.
DirectStream doesnt fit into every budget and, following its launch, an intense design effort was formed to explore how a lower cost version of the units FPGA based architecture could be realized.
The first steps in Js design process involved reducing the manufacturing costs of the PerfectWave chassis. DirectStreams PerfectWave chassis is assembled from a combination of castings, extrusions, machined parts, laser cut plates, and finished with a hand painted and polished piano black top cover. Add a touch screen to the many machined chassis parts, and the design groups first decisions were fairly straightforward. DirectStreams touch screen was replaced by a lower cost OLED display and haptic feedback volume control. Instead of multiple piece assemblies, Js chassis is constructed out of aluminum extrusions that are less complicated to assemble. Instead of a hand-painted and polished HDF top cover, as found on DirectStream, J sports a beautiful gloss black Plexiglas cover that looks nearly identical to DirectStreams, mounted to a metal substrate.
Our core design requirement was to employ the identical engine of DirectStream into J. Both DirectStream and J are based on the same Spartan 6 FPGA (Field Programmable Gate Array) and the same basic operating system developed over many years by designer Smith. Where the two differ is in the PCB, power supply and output stages. DirectStream uses multiple printed circuit boards: a separate digital, analog and Bridge/power supply board, where J has everything on one PCB. DirectStream has several power transformers and multiple regulators, J relies on one power transformer and the same number of voltage regulators. The output stage of DirectStream incorporates high-speed, high-current analog video amplifiers driving a specially designed audio output transformer, while J uses similar, passively filtered amplifiers driving the output directly, without an audio output transformer.
Two years of work with PS Engineering, hundreds of hours in the listening room by designer Smith, PS Audio CEO Paul McGowan, and Arnie Nudell (founder of Infinity Loudspeakers), coupled with many more hours of tweaking, tuning and care, resulted in DSJ exceeding our best expectations.
DSJ is one of the finest audio instrument in the world today. That it includes a built-in Bridge II and is far more affordable than its progenitor, DirectStream, turns out to be a source of pride for the entire engineering team.
Unit Weight 18 lbs [8.1 kg]
Unit Dimensions 14” x 17” x 2.75” [ 36cm x 43cm x 6.98cm]
Shipping Weight 27 lbs [12.25 kg]
Shipping Dimensions 20.5”x 24” x 10” [52cm x 61cm x 25cm]
Input PowerModel specific 100VAC, 120VAC, or 230VAC 50 or 60HzPower Consumption30W
Digtial audio inputs
I²S, Coax, XLR Balanced, TOSLINK, USB, Ethernet
I²S,S/PDIF, and USB -- 44.1kHz to 352.8kHz 16bit, 24bit, DSD 64, DSD 128
TOSLINK – 44.1kHz to 96kHz 16bit, 24bit
Analog Audio Output
Connector RCA/XLR Unbalanced /Balanced (X2)
Output level, low 1.41 Vrms(+5BV)/3.15
Output level high, maximum 2.81 Vrms (+8dBV)/5.3 Vrms (+12dBV)
Output Impedance 100Ω/200Ω
Frequency Response 20-20KHz +/- 0.25dB
THD+N @ 1KHz (full scale)<0.03%
Output Stage Active high current, high speed analog amps producing double rate DSD.
PCM or DSD
Sample rate (PCM) 44.1kHz, 48.0kHz, 88.2kHz, 96.0kHz, 176.4kHz, 192kHz, 352.8kHz
Word length (PCM)16b, 18b, 20b, 24b
Data rate (DSD)Standard (2.8MHz) or Double (5.6MHz) DoP on all inputs as well as raw DSD on I²S
inputsInput jitter reduction Effectively 100%, residual immeasurable. No input PLLs, FLLs.
Input Processing 170MHz
Signal Processing 50MHz
Synchronous Upsampling, all inputs28.224MHz
Digital Processing S/N ration>146 dB
Digital Volume Control Zero loss of precision
Analog Conversion method Delta Sigma (DSD) Single-bit double rate
I²S Digital Input
Format PCM or DSD. DoP on all inputs as well as raw DSD on I²S inputs
USB Digital Input
Connector USB “B” Type
Format PCM or DoP v1.1 (DSD over PCM)
Transfer mode Asynchronous