Tales of VELVET SOUND

A history of surpassing limitations

TECHNOLOGY

Audio quality is affected by a variety of different factors, and certain performance indicators demonstrate that a high level of quality has been achieved.

These performance indicators are not the entire story - many other factors also have a major impact on audio quality.

Based on the knowledge and experience gained in over 30 years of audio product development, VELVET SOUND's approach to audio technology is to treat both measured performance and the less easily quantifiable aspects of the listening experience as essential.

Technology with Perfect Accuracy

Perfect live sound, 
made possible by perfect numerical accuracy

Is your listening experience faithful to the original?
An authentic listening experience must be free of added noise and distortion.
VELVET SOUND continuously improves performance and creates new technology in order to eliminate those distractions, revealing a world of real live sound.

Low-noise technology:

Reconstructing low-level signals with clarity

Technology with perfect accuracy

In order to achieve noise characteristics as close as possible to the theoretical limit, AKM closely examined optimal architectural choices even if it meant deviating from existing technology.  The result is the AK4499, AKM's first current-output DAC.

The AK4499 audio DAC has achieved the industry's best SNR at 140 dB, improving noise performance by 6 dB as compared to conventional products.

AKM has developed a new low-noise technology by combining analog circuit control technology with the conventional approach of voltage-output DACs.

AKM's new LSI process approaches the improvement of noise performance from the very beginning, at the manufacturing stage.

The resulting outstanding low noise performance makes it possible to accurately re-create low-level signals with perfect clarity, allowing for a wider range of audio expression.

The ability to clearly re-create low-level signals from a high-resolution 32-bit source is a unique feature made possible by AKM's low-noise characteristics.

* Mono mode

AK4499
Reproduction of signals as quiet as -155dBFS – one 50 millionth of full scale.

Low-distortion technology

A more faithful re-creation

Technology with perfect accuracy

The AK4499 has achieved an industry-best performance of -124dB THD+N.  This is an 8dB improvement over conventional products.

VELVET SOUND's low-distortion analog circuit technology has led to the development of many products that feature the industry's best low-distortion characteristics.

The AK4499 current-output DAC features newly-developed low-distortion technology.

The non-linear aspects of the elements used in semiconductor circuits are generally understood to degrade an audio system's distortion characteristics.

Even if the circuit technology eliminate those non-linearities, unnecessary charge emissions from the device make it difficult to eliminate distortion completely.  VELVET SOUND technology excels at suppressing distortion due to these emissions.

The AK4499's new low-distortion technology (patent pending) delivers the industry's best level of ultra-low distortion for high-end DACs.

This outstandingly low distortion makes it possible to reproduce signals in a way that is completely faithful to the original sound, to an unprecedented degree.

AK4499

Undesired components reduced to -124dB - a ratio of 1:1,500,000
A faithful re-creation of the original
Spectrum at 1kHz, 0dBFS input

Components other than the fundamental wave are suppressed.
THD + N (total harmonics other than the fundamental wave + noise integral value) -124 dB in the 20 kHz band is achieved.

Artifact-free technology:

More natural sound

Technology with perfect accuracy

The AK5578 / AK5572 achieve the world's smallest intermodulation distortion characteristic of 116 dB, in addition to a wide dynamic range of 121 dB (single-channel mode) to 130 dB (channel sum mode).

A music signal is comprised of multiple frequency components.  The generation of spurious tones due to the interaction of these components is suppressed by VELVET SOUND's low-distortion technology.

This leads to a high spurious-free dynamic range (SFDR), enabling more natural sound reproduction.

AK5572
Spectrum at 800Hz, 1kHz dual tone input
Intermodulation components such as 200Hz, 600Hz, and 1.2kHz are suppressed, and intermodulation distortion of -116dB is achieved.

Technology with a Single Purpose

A faithful re-creation of the original experience,
beyond any numerical representation.

There is sound beyond sound.  The sound beyond what our ears can hear is critical to the experience.
The experience is more important than the measurement.
AKM's years of experimentation have yielded a multitude of techniques to create sound that resonates, emotionally.
VELVET SOUND addresses every aspect of sound, building a world of authentic sonic experience.

OSRD Technology:

More expressive audio

Technology with a Single Purpose

Low out-of-band noise

AKM's OSRD (Over Sampling Ratio Doubler) has a signal bandwidth of approximately 200 kHz, which is 10 times the audible range (~ 20 kHz).

It is possible to achieve lower out-of-band noise in the frequency band beyond the audible range by increasing the OSR, but this comes at a price, as power consumption increases due to higher-speed operation.

OSRD technology eliminates this trade-off by allowing OSR to be increased without raising power consumption.
VELVET SOUND DACs have adopted this technology, resulting in ultra-low out-of-band noise. (Patented in 2016)

AK4490
Plot of out-of-band noise at 1kHz, 0dBFS input
The noise floor up to about 200kHz is flat, enabling more broadband signal re-creation.

Layout technology:

Delicate and bold expression

Technology with a Single Purpose

VELVET SOUND's layout technology is built to honor the original signal content.

The noise resulting from the operation of switching digital circuits is reduced to the utmost degree.  All noise-mixing paths to the signal are eliminated.

Beyond just the audio content, the timing references are also thoroughly separated from noise sources, greatly improving noise rejection in the resulting audio signal.

VELVET SOUND devices use a fully symmetrical left-to-right layout.  Features such as channel-independent assignment of analog power supplies and signal reference terminals enable smooth and flexible signal flow.

This approach to layout and signal routing enables the most delicate and bold expression of sound possible today.

Sound color IRD filters:

More colorful sound

Technology with a Single Purpose

Everyone is aware of the importance of accurately conveying the signal waveform itself, but what about its transient response?

After much experimentation focused on the signal waveform, AKM has developed the IRD (Impulse Response-Designed) Filter, which allows the user to control the transient response of the signal.

DAC

In PCM mode, six types of digital filters enable music playback optimized for a variety of settings.

ADC & SRC

In PCM mode, four types of digital filters are available, enabling optimization for a variety of settings.

DAC: Sound Colors
ADC & SRC: Sound Colors

High resolution digital core:

Expression in even higher definition

Technology with a Single Purpose

The human ear can distinguish low-level differences in sound that may not appear in the measurement values of general audio instruments.

VELVET SOUND's 32-bit product line is equipped with a high-resolution digital core that has ben extended to 36-bits, enabling the re-creation of even the faintest sounds and a truly realistic high-resolution experience.

Dedicated listening room for sound validation

Technology with a Single Purpose

AKM’s listening room has been designed and filled with industry-leading components, allowing for the most thorough evaluation possible.

This allows AKM to fully assess the sonic qualities of our audio devices, beyond the traditional approach of using audio test equipment on a bench.

AKM’s Audio Meister evaluates new test chips for sound quality and feeds the results directly back to the circuit designers.
Designs are modified and test chips are sent back to the Audio Meister until he is satisfied with the results.

This listening room is also utilized to evaluate various digital formats in order to allow AKM to optimize our devices for every digital audio standard in the industry.

Audio Room

Hardware in pursuit of musicality:

AKM Evaluation Boards

Technology with a Single Purpose

AKM’s engineers provide high-quality evaluation boards to allow assessment of the reproduced audio content in a state that is very close to that of a finished product.

In the service of musicality and rich sensibility, AKM has paid great attention to the layout, materials, and construction of these boards, along with carefully-considered component selection.

AKM’s DAC evaluation boards expect digital audio sources and power supplies to be provided externally, allowing the user to more closely simulate their system.

AKD4499 Sound Board
AKD4490 Sound Board
AKD4493 Sound Board
AKD4497 Sound Board
AKD4499 Sound Board

LSI manufacturing process

Technology with a Single Purpose

AKM creates high-level audio quality, all the way from the LSI manufacturing technology stage.

AKM has its own dedicated LSI manufacturing site, and has consistently improved transistor noise characteristics, non-linearity of capacitors and resistors, manufacturing variation, etc. All of these enhancements lead to greatly increased audio quality.

AKM creates high-level audio quality from the LSI manufacturing technology stage.

About VELVET SOUND

VELVET SOUND is a sound philosophy and brand concept for AKM’s next-generation audio devices, featuring new chip architectures and core technologies.

The new circuitry found in VELVET SOUND devices is designed to maximize dynamics and ensure pure, unaltered audio data, prioritizing the accurate capture and reproduction of the source material in order to achieve high performance and rich musicality. These devices were designed specifically for the high-resolution digital audio era.

*VELVET SOUND Logo™, Audio 4 Pro™ and Audio 2 Go™ are trademarks of Asahi Kasei Electronics Corporation in Japan, Europe and the United States.

velvetsound.akm.com
by ASAHI KASEI MICRODEVICES