The SDR-3000 Reference CD Transport

The SDR-3000 Reference DC Transport is Spectral's first compact disc transport, completing the Spectral Digital Reference system begun with the SDR-2000 Digital Processor. The development program for the SDR components was initiated over ten years ago with the introduction of the Spectral SDR-1000 Reference Disc System, the industry's first truly high-end compact disc playback system. The innovative SDR-1000 was years ahead of its time, pioneering fundamental processing breakthroughs such as balanced decoding and conjugate correction filters.

More recently, the ambitious SDR-2000 Professional Processor has stunned the audio industry with its technical advances and resolving power. Sharing its uncompromising circuit architecture with the historic HDCD recording system by Pacific Microsonics, the Spectral SDR-2000 is widely considered to be the finest digital processor available as well as the acknowledged reference for High Definition Compatible Digital recordings.

The arrival of the SDR-3000 Reference CD Transport culminates the SDR program at Spectral and achieves the final integration of our high resolution digital technology. Supporting the challenge are new generation component technologies and state-of-the-art test systems to push forward the envelope of digital audio performance. Like other Spectral SDR components, no detail or expense has been spared in the SDR-3000 to achieve the status of a true digital reference.


Our commitment to advancing digital playback technology stems from our quest to develop ultimate performance audio systems. The component front-end plays an essential role in the sonic outcome of a fine music system. Achieving ultimate performance here, where the reconstruction of the recorded event begins, is a Spectral priority.
The vital role a transport plays cannot be overstated. All subsequent signal processing and amplification quality will be determined by the ultimate ability of the transport to recover the correct data from the disc, and deliver it without errors in timing. This is a major engineering challenge. Until now, data losses and introduction of timing errors (jitter) have plagued virtually all digital playback systems. The Spectral SDR-3000 Reference Transport is a quantum step forward in precision and quality, virtually eliminating jitter and resolution losses.


Conserving precious data resolution and eliminating timing errors must be the overriding priority in CD transport design. Ironically, there is little potential for achieving this in conventional disc transports due to fundamental economic choices. Data loss and timing errors are an inherent result of using mass-market drives and oscillator systems which are insufficiently precise. Even elaborate implementations will still exhibit compromises to disc rotational speed and radiate noise which generates jitter. In large part, these compromises explain the significant sonic differences evident among various CD transports.
To support the level of precision required in the SDR-3000 Transport, fundamental improvements in each basic transport section were pursued. To ensure ultimate data integrity, the state-of-the-art CD drive was sourced and modified to Spectral specifications. To eliminate time-based distortions, interactive communication between SDR-3000 and the digital decoder are accomplished by the Spectralink data system. This high performance interface includes optically isolated clocking lines to lock the SDR-3000 oscillator to the precision clock of the DAC. Sophisticated power supplies and instrumentation type enclosure design provide a precise foundation for transport performance. All the elements come together in a system which ensures absolute accuracy of signal recovery in the time domain: the basis for ultimate digital audio reproduction.

All digital interfaces on the SDR-3000 have been carefully optimized to deliver the finest performance the interface standards allow. For this reason, the SDR-3000 can perform superbly with a variety of digital processors and interface cables. In addition to standard format direct digital outputs such as SPDIF coax and AES/EBU balanced, the SDR-3000 Transport supports Spectralink, which integrates data and clock communication between transport and processor. The unique Spectralink data interface cable (optional) incorporates both high-speed balanced data transmission and precision clock lines. This nine conductor system features flexible cable construction with instrumentation grade connectors and machined pin terminations. Internal construction combines advanced dielectrics and sophisticated shielding for exceptional data precision. The Spectralink cable also incorporates automatic programming to actuate the specialized Spectralink function in the SDR-3000 and isolate the other outputs.


One conspicuous area of compromise among high-end audio CD transports is the choice of the compact disc drive itself. Most high-end transports rely on standard CD drives developed for mass-market automobile and CD ROM applications. Although inexpensive, these drives were never designed for the performance and durability requirements of truly high-end audio. Plastic construction and optics are an undeniable compromise in today's finest compact disc components.
Spectral engineers evaluated many premium drives and found virtually all to be compromised by the imperatives of mid-fi cost constraints. A cooperative effort between TEAC and Spectral has resulted in a custom version of their finest hand built Esoteric drive, made exclusively for the SDR-3000.
Unlike most available CD drives, the Spectral/Esoteric drive is developed exclusively for high-end audio applications. Based on the low production Esoteric P2s drive, the Spectral/Esoteric reflects a marriage of state-of-the-art mechanical and opto-electrical performance. Vibration-Free Rigid Disc Clamping (VRDS) allows the convenience of front disc loading without the attendant performance compromise. (Most other front loading drives use magnetic disc clamping, and the magnetic puck seldom centers itself exactly, inducing mechanical vibration). The VRDS clamping system offers full vibration damping of the sensitive compact disc while eliminating the inconvenience of additional disc weights and stabilizers commonly required with top-loading transports.
The VRDS system is a new generation design built to exacting standards for Spectral. No other drive that we have evaluated offers the data precision and mechanical quality achieved here. Superiority of the Spectral/Esoteric drive starts with its full size die-cast zinc/bronze disc turntable and stabilizer clamp which keeps disc and laser pickup in their precise relative positions. Servo correction need only deal with tracking the variable disc rotation speed because of the superb inertial damping and stability of the turntable which employs a double-layer construction of machined brass and aluminum. The overhead turntable's heavy design and high precision clamp greatly reduce undesirable vibration while its massive bearing and 6 mm spindle ensure excellent rotational stability and long life.
The superstructure of the drive is cast from non-resonant zinc-alloy including a massive 1 Kg base unit and vibration resistant bridge assembly for the precision motor and bearing of the disc turntable. A floating suspension system with sophisticated resonance damping completes the state-of-the-art mechanicals.
The disc loading system also sets high standards for precision and durability. Its non-resonant loader tray rides on twin polished stainless steel linear bearing rods for positive disc control and long life. This polished bearing loading mechanism is distinctly superior to the weak plastic bearings found in conventional CD drives.


Massive construction alone does not address the multiple dimensions of resonance and vibration management required in a digital transport. The enclosure design of the SDR-3000 is an essential element of distortion control, and, as a result, signal integrity.
Multiple shield construction compartmentalizes sensitive transport sections and limits noise coupling. Mechanical and harmonic disturbance is eliminated through a critical series of laminated sections and damping elements. Radius corner, welded aluminum chassis design detunes resonant frequencies which can impact clocking and program signals. The essential requirements for chassis rigidity and optimum vibration control are carefully balanced in the SDR-3000.


The SDR-3000 has a sophisticated array of four power supplies to individually support each section of the transport: CD drive and loader, servo circuitry, display and control system, and the Spectralink oscillator system. Extensive design detailing ensures that the elaborate SDR-3000 power supply system isolates the ultra-quiet transport electronics from the vagaries of all types of line-borne distortion and noise as well as eliminating all emissions from the transport which could affect other sensitive system components.

Engineering refinement in the SDR-3000 Transport extends to the quality of the user interface as well. The SDR-3000 front panel is a model of understated elegance and useability, in the Spectral tradition, with a hand polished satin front panel and machined acrylic construction. Large alphanumeric displays monitor the CD drive and playback functions, allowing visual confirmation of remote operations.
Refinement is also reflected in the convenience and precision of the 3000R remote control. The 3000R duplicates the SDR-3000 front panel controls and offers full input keypad and repeat functions. All metal construction of fully machined aluminum alloy components and premium powder coat finishing ensures rugged durability. The instrumentation grade momentary switching used on the SDR-3000 front panel is also employed on the 3000R remote for positive actuation and for long life operation. Two infrared transmitter diodes maximize signal power for extended operating range.
The SDR-3000 Reference Transport joins that select group of reference components which most completely define our design philosophy and represent our finest efforts. The SDR-3000 completes the Spectral Digital Reference system, representing the coming age of digital audio as the musical medium of choice.

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