We’ve watched the No.39 CD Processor sales continue as strongly as ever, with the rather poor CD playback performance offered by the majority of the DVD machines on the market. Our customers have been asking us if we would ever consider taking the No.39 to that "S" designation found on several of our Mark Levinson separates, allowing even higher performance in a one box CD playback solution.

We have completed design of an update for the No.39 that delivers a remarkable improvement in sonic performance over our original design. The "S" version is based on the original, updatable chassis. It features a complete re-design of the No.39’s DAC/analog output module. Borrowing heavily from the design of the No.32 Reference Preamplifier and upcoming Audio Processor portion of the No.40 Media Console, the No.390S incorporates our latest advances in D-to-A converter design, output buffer and volume control technologies, all implemented on a four-layer Arlon® 25N circuit board. We’ve decided to take the No.39 to an entirely new level of performance and provide an upgrade path for our No.39 owners in the process.

No.390S as CD Transport

The first task performed by the No.390S is that of a high performance digital transport. The characteristics of an outstanding CD transport are simple to define: it must recover the correct data from the disc and deliver it to the digital processor with exacting precision. As simple as this sounds, in reality achieving it has been extremely difficult-as evidenced by the significant sonic differences among various transports.

Recovering the correct data is not difficult. Modern CD transports include powerful error correction systems, making uncorrectable errors quite rare. Even badly scratched discs can often be played without difficulty.

Since compact discs operate with a 44.1 kHz sampling rate, there should be exactly 44,100 error-free samples transmitted each second. Moreover, each such piece of musical information should exist for exactly 1/44,100th of a second before being replaced by the next piece. Inconsistencies in this respect account for most of the sonic variations heard between transports, and are referred to as jitter.

Digital audio depends on the proper signal being reconstructed at precisely the right time. An early (or late) digital sample distorts the audio waveform, causing it to sound harsh and unnatural. One of the greatest challenges in digital audio is delivering these samples with adequate precision. Without achieving precision measured in picoseconds (trillionths of a second), the full potential of the system cannot be realized.

Traditional transport designs seek to retrieve the digital audio information from the disc itself at exactly the correct rate. A “clock” mounted on the laser pickup mechanism determines the “tempo” at which the musical information is recovered. If a discrepancy exists between the tempo of this clock and the flow of digital information, the transport’s motor attempts to adjust its speed.

Unfortunately, the performance of this important clock is limited by cost and by its environment. Typically, a 1000 part-per-million oscillator is used in an extremely noisy electrical environment, adjacent to the motor that spins the disc and to other circuitry. The resulting electrical noise introduces timing errors in the oscillator. Mechanical limitations such as friction, vibration, and inertia introduce additional inaccuracies of their own.

Subsequent handling of the digital audio signal within traditional transport designs cannot improve upon this “jittery” signal. To the contrary, the various stages of signal processing between the laser pickup and the final output can only contribute additional jitter of their own.

A New Generation

The Mark Levinson No.39 CD Processor, the predecessor to the new No.390S, went beyond conventional digital audio playback technology by employing a proprietary, Closed-Loop Jitter-Reduction (CLJR) system. Simply put, the No.39 separated the recovery of the digital data from the task of maintaining a consistent, jitter-free output. This separation allowed each task to be performed more accurately. The No.390S continues with this design approach.

As in the No.37 CD Transport, the No.390S derives its reference frequency from a custom made, temperature-compensated crystal oscillator that acts as a “clock” with better than five part-per-million accuracy (a two-hundredfold improvement over the standard oscillator). This oscillator is removed from the noisy environment of the laser mechanism and placed on a quiet, independent digital circuit board. With its own dedicated power supply and electrical isolation, this clock provides a far more stable reference frequency than in any traditional design. Significantly, the all-important reference clock is located in the most critical area of the design, adjacent to the digital processor section and the digital outputs-where it belongs.

Each bit of the digital audio signal is stored momentarily just prior to its transmission to the digital processor. The reference clock determines the precise moment when each bit is released from this memory buffer. This purely electronic process virtually eliminates transport-related jitter, whether of mechanical or electrical origin. Of course, another bit must be ready to be loaded into the buffer as the current bit leaves on its way to the processor. For this reason, the same crystal oscillator that controls flow of information out of the memory buffer also directs the digital servo that sets the rate at which data flows into the buffer.

By placing the all-important reference clock in the final stage of the transport section, and slaving the mechanical subassemblies to it rather than the other way around, the signal presented to the digital processor section of the No.390S is uncontaminated by electrically- or mechanically-induced jitter. The sonic advantages of this design are immediately apparent in the stunning clarity, warmth and dynamic contrasts exhibited by the No.390S.

Sonic Summary

The No.390S successfully builds on the strengths of the popular No.39 CD Processor. The name change is intended to convey the level of sonic improvement that you can expect. It doesn’t sound like a better No.39 – it sounds like a completely new and significantly better product.

Many of the improvements have resulted in a further reduction in noise. Low-level musical details that were previously masked are now revealed. High frequency clarity and extension are improved. Low frequency detail is improved. Imaging and spatial information are substantially improved, with a greater sense of depth and width. There is an almost holographic, wrap around quality to the presentation.

All of this musical information was obviously always present on the CDs. Once again, significant sonic improvements were attained by better implementation of an existing technology. We encourage you to compare the new No.390S to other digital products, including separate D/A converters and SACD players. We are confident that you will agree with us that the No.390S is an outstanding value. < Click for more details >