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Simaudio Technical Education Updated: November 2, 2009

MOON CD Player Technologies

32-bit Processing

The digital-to-analog conversion process uses bits of digital information to produce an analog waveform, represented as a sine wave (in this example only a part of a sine wave is shown) to produce a music signal. When more digital information is made available, the result is a more accurate and detailed music signal. A higher bit-depth (or a higher resolution) yields smaller, finer and more accurate steps in the reconstruction of this sine wave (grey) as seen in the animated figure below. A 32-bit (blue) data stream contains significantly more information than a 24-bit (green) or 16-bit (red) data stream.

The advantage of using this 32-bit process to reconstruct a 16-bit digital signal (i.e. Redbook CD) is simple; This process interpolates the digital information more accurately by calculating the finer steps with 32-bit resolution that were lost during the analog-to-digital 16-bit mastering process. The result is, after the D-to-A conversion, a more realistic waveform that is incredibly analog sounding; Each musical note's harmonic decay is restored more accurately than with a 16-bit or 24-bit process, creating a uniquely life-like sound that was previously inaccessible from digital audio until now. In the past, the poor restoration of harmonic decay was a major contributor in what gave digital audio that cold, uninvolving and analytical feeling.

As a general rule, increased processing power is directly proportional to resolution: For each additional bit of resolution,the number of availble levels will double, as shown in the following table:

	Bit Depth	Steps
	16	65,536
	20	1,048,576
	24	16,777,216
	32	4,294,967,206

To summarize, the higher the resolution of the data, the smaller the steps will be. This results in more detail as each individual step covers a smaller section of the waveform. More detail in the digital domain leads to a much more analog signal signal at the end of the conversion process.

Another major benefit of this 32-bit process is smaller data truncation errors. These errors result from the extensive mathematical calculations performed during upsampling & sampling rate conversion, prior to the D-to-A process. These truncation errors - shown in the above figure, occur when the data sample rises outside (or above) the grey curve - will be signifcantly smaller as bit-depth increases due to finer and more accurate calculations. As well, because of the sheer processing power that's readily available at 32-bits, the errors will not impede the circuit's ability to accurately recreate the music waveform.

When digital meets analog ... you will have to suspend disbelief that you're actually listening to a digital music source.

Delta and M-Quattro Suspensions (Simaudio Ltd. Proprietary Technology)

These suspensions acts as a decoupling device between the drive and the CD player's chassis. It is accomplished through the use of a special gel based transport mount that provides for exceptionally accurate mechanical grounding. The main objective is to dampen the vibrations resulting from both the transport mechanism and the disc's rotation, keeping in mind that the majority of CD's aren't perfectly centered when they are manufactured. The result is virtually total immunity from all external vibrations. Furthermore, this allows the player to better handle errors on the disc, such as gaps in the data, much more efficiently.

Ambient and spatial cues in your recordings will
come to life as you never heard them before.

Alpha Clocking System (Simaudio Ltd. Proprietary Technology)

Featuring PLL syncronization, this clocking system achieves extremely accurate phasing and much better than average recovery of information from the compact disc. As well, digital clock-signal integrity is dramatically improved. The result is extremely low jitter in the order of less than 10 picoseconds RMS which means the elimination of digital fatigue in the high-frequency region, and therefore a more analog-like, yet very realistic sonic signature.

The significant differences, with respect to jitter, between a digital clock signal from the MOON Alpha Clocking system and a typical digital clock signal can be seen in the figures below:

When the width of the digital impulses (A, B, C, D, E, F) are identical, then the phasing between the impulses (1, 2, 3, 4, 5) will all have same width, resulting in extremely low phase errors.

When the width of the digital impulses (A, B, C, D, E, F) are not equal, then the phasing between the impulses (1, 2, 3, 4, 5) will vary noticeably in width, resulting in significant phase errors.

High-frequencies never sounded so natural ... cymbals so life-like that you'll want to reach out and touch them ... a genuinely non-fatiguing sound without even a hint of digital grain.

Digital Audio Signal Processing (Simaudio Ltd. Proprietary Technology)
with M-AJiC

Traditional digital audio signal processing circuits suffer from timing variations. This is commonly referred to as jitter. The more jitter present in the digital domain, the more harmonic distortion will exist in the converted analog signal. Clearly, minimizing the amount of jitter is one of the objectives of a quality digital audio circuit. Jitter results from a variety of sources: Unstable or noisy power supplies, inferior CD transports and most significantly, the multiple clocking systems used in digital audio circuits:

MOON Asynchronous Jitter Control (M-AJiC) reduces the amount of jitter to a level so low, that until recently it was considered a pipe dream. This achievement is the result of a carefully implemented “Sample Rate Conversion” (SRC) circuit, which uses our own Alpha Clocking System only at its final stage (all previous stages work asynchronously). As well, the entire digital audio signal processing circuit is driven by a very precisely regulated power supply and uses a single clocking system which eliminates synchronization issues common to multiple clocking systems:

In the above example, the M-AJiC circuit produces a jitter-free, 24-bit/176.4kHz high-resolution digital audio signal for digital filtering, oversampling and digital-to-analog conversion. Once converted from digital, you have an audio signal that’s free of any jitter induced distortion prior to analog signal filtering.

Natural and lifelike music so accurate that you will feel
the presence of musicians in your own space.

Digital Audio Signal Processing (Simaudio Ltd. Proprietary Technology)
with M-AJiC32

Building on the MOON Asynchronous Jitter Control (M-AJiC) circuit released in the MOON CD3.3 disc player, we have developed an even more advanced version of this jitter reduction system called M-AJiC32. Operating in 32-bit mode and initially launched in the revolutionary MOON 750D DAC/Transport, this circuit virually eliminates jitter, reducing it to an unprecedented 1 pico second:

M-AJiC32 is based on ESS Technologies SABRE³² ES9018S circuit with 32-bit Hyperstream^TM. The only point where clocking occurs - using our own Alpha Clocking System - is at the very end of the digital audio stream during the final phase of Digital-to-Analog conversion. This, along with both the Sample Rate Conversion circuit and the "Time Domain Jitter Eliminator" reduce jitter to 1 pico second.

There are numerous benefits to asynchronous circuits:

Completely independant of jitter from all previous stages
Higher processing speed
Better tolerance to voltage fluctuations
Improved immunity to noise
The circuit's speed adapts to conditions of the input signal
Less source electromagnetic interference (EMI); Synchronous circuits generate a great deal of EMI in the frequency band of their clocking frequency and its related harmonics; Asynchronous circuits generate EMI patterns that are much more evenly spread across the entire frequency spectrum resulting in lower distortion.

Another significant feature is a total of 16 Digital-to-Analog converters (DAC's) in the M-AJiC32 circuit; The left and right channels each use 8 DAC's in a differential topology. For each channel, the outputs of 4 DAC's are summed to create the positive signal and the outputs of the other 4 DAC's are summed to create the inverted signal. Since a DAC's output is in current, the output of 4 DAC's can easily be summed together to yield much better results when compared to using 1 DAC per channel.

The reason for this is because there are unique imperfections for each individual DAC. However, they become diluted within the current of the other DACs. As well, there are imperfections common to all the DACs in a circuit. These common imperfections are cancelled out because of the differential topology used in the M-AJiC32 circuit; Ultmately, since all these imperfections are eliminated, better measurements are produced in terms of lower noise and lower distortion which translates into far superior sonic performance.