Sound Philosophy

Sound Philosophy
Real Live Sound

An accurate, "reproduction of the original", is the VELVET SOUND philosophy.
AKM duplicates all sound elements contained in the, "original source".
AKM provides an active space just like a live performance.

The History of AKM's D/A Converters
Since 1989,

AKM released a delta-sigma D/A converter (DAC) in 1989.  An advanced multi-bit DAC based on bi-directional DWA, (Data Weighted Average), technology was developed as the first generation premium audio DAC.  In 1998 the 2nd generation premium DAC, and the first 32-bit DAC was released in 2007. 
A new generation architecture, the VELVET SOUND brand was launched in 2014.  The 3rd generation premium DAC, VERITA AK4490 was released which achieved an industry best voltage output performance of -112dB THD+N and 120dB S/N characteristic using enhanced low-distortion technology.  Four multi-channel products have now been added to the premium DAC AK445X series. In addition, with best sound quality and characteristics, the new flagship AK4497 was released in 2016.  Seven 32-bit products in total are available in the premium DAC lineup.
The AK4497 supports next generation high-resolution sources up to the 22.4MHz DSD format realizing 128dB SN and -116dB THD+N with AKM's original LSI manufacturing process for high quality sound.  
AKM products have been widely adopted by well-established companies from high-end to consumer uses around the world because of advanced solutions we provide with many years' experience.

AKM DAC ヒストリー

Sound Philosophy
Real Live Sound

The sensitivity of the human ear can discern fine sound that exceeds the measurement limit by general audio instruments. Focusing on this point, AKM has developed a high-resolution 32-bit product group and has been providing audio device to achieve a higher resolution. This new generation of device has reconstructed the architecture to express beyond the human ear "sounds feel", and striving to be more to the "true sound". To "represent all without exhaustively" is VELVET SOUND philosophy. Powerful space that can not be felt only in live but sound that touches the instrument; we are pursuing this "amount of information and strength" in order to get a feel without leaving the original content.

In pursuit of the music to the device
AKM sound boards

In AKM, engineers offer a high-quality sound board to allow assessment of the reproduced sound in the finished state, close to the component level. In particular, the evaluation board of D/A converter (DAC), digital input and power supply are supplied from the outside, allowing the user to simulate their system. In order to incorporate the ultimate theme of AKM "music" and "rich sensibility", AKM has paid great attention to materials and construction of the board along with carefully selecting supporting components and board layout. These boards are the results of several versions that were reworked over and over to optimize the sonic performance.

Dedicated listening room for sound validation
Evaluation Environment

At AKM, there is a listening room setup with industry leading components so we can truly evaluate our latest audio devices sonic qualities. This allows AKM to fully evaluate our audio devices beyond the traditional audio test equipment used on the bench. AKMs audio Meister is repeating sound quality evaluation of the test chips and feeding the results directly back to the circuit designers. This direct relationship and feedback is constantly advancing AKMs audio technology always pursuing better sound quality. This listening room is also utilized to evaluate various digital formats to allow AKM to optimize our devices for every digital audio standard in the industry.


Design concepts to pursue and achieve
the, "intensity", and the, "amount of information".

the architecture of new generation audio devices.
Velvet Sound's philosophy is a combination of
measured performance and human listening tests,
because ears will always exceed any test measurement.

"Large Amount of Information and Sound Strength"
Design Concepts to Achieve

As the basic concept to represent all of the elements of sound, such as components of the fundamental wave and harmonics, sound pressure, changes in the time domain, the presence of small signal components, the difference between treble and bass of attenuation, etc., AKM has built a new VELVET SOUND architecture.

Amount of information:
Delicate Sound Reproduction thorough Noise Optimization

VELVET SOUND architecture has enabled the expression of elusive sounds by enabling a highly noise-tolerant design.  Verifying and identifying the noise mixing paths from every angle is particularly critical to reducing noise sources required for operation of digital and switching circuits.  Furthermore, not only the signal path line itself, but the internal reference signal and clock that determines the time information are separated through layout isolation to thoroughly eliminate influence by noise.  System noise beyond the audible range also reduces more than 40dB compared with the conventional products simplifying the external circuit design.

Pursuing the, "feeling of sound"
Sound beyond the audible range

Human's audible frequency range is believed from 20Hz to 20kHz, but AKM's next generation products cover up to a 200kHz signal range, enabling the expression of, "feeling sound", beyond the audible range.

Powerfulness: "Signal Stream as the first priority"
Luxury design with sufficient margin

Special designs technics for sound quality are applied to each blocks for achieving balanced, smooth and powerful signal flow. In addition to L/R perfectly symmetrical layout, more than 5x trace width is used for signal line compared existing products, supplying rich current to analog signal output blocks. To achieve low impedance, two analog power supply pins and two signal reference pins are assigned for each channel, allowing the system to utilize thick PCB trace pattern giving low impedance sources.

VELVET SOUND Core Technology

Core Technology
Technologies representing the, "sound feeling",
exceeds the numbers.

the core technology of AKM's new generation audio devices.
This technology features low-distortion technology,
OSRD technology, and, IRD filter,
which translates, sounds into emotions.

Technologies representing the "sound feeling"
exceeds the numbers

In addition to our 25 years of accumulation of experience and know-how of audio device development, an "evolved ΔΣ modulator", "evolved switched capacitor filter" and this development of new VELVET SOUND technology have achieved the "sound feeling" beyond the audible range.

Ultra-low distortion
Low distortion technology (patent pending)

New high-end DAC VERITA AK4490 has adopted a newly developed low-distortion technology, improving the distortion level for conventional products more than 6dB achieving ultra-low distortion levels of S/(N+D) = 112dB, industry best for a DAC of 120dB class.

Ultra low out-of-band noise
OSRD technology (patent pending)

OSRD (Over Sampling Ratio Doubler) is a new technology that doubles the effective OSR without speeding up the internal operation. In general, although it is possible to achieve high performance and low out-of band noise by increasing the OSR, there is a disadvantage that the power consumption increases due to high speed operation. OSRD is the technology breaks through the trade-off of the OSR and the power consumption allowing to double the OSR without an increase in power consumption. New generation DACs have adopted this technology achieving ultra low out-of-band noise.

Sound Colors
IRD filter

IRDF (Impulse Response Designed Filter) is a technology to control the transient response of the signal. The 32-bit product group is equipped with a high-resolution internal calculation circuit that has been extended to 36-bit, reproducing a more natural and more attentive signal waveform.


Key Features
Fully compatible with, "Hi-Res", sound sources
up to 768k PCM and 11.2M DSD.

a key feature of AKM's new generation audio devices
which are equipped with specs and performance
for the, Hi-Res, digital audio era.

"Ultimate analog, natural sound"
Fully supporting of high-resolution audio source

AKM's next generation D/A converter adopts 32-bit resolution and supports digital playback up to 768kHz PCM and 11.2MHz DSD to realize an, "ultimate analog, natural sound". AKM leads the field by fully supporting high-resolution audio sources.

Controls the transient response of the signal
Sound Color Digital Filter (SCDF)

Focusing on the waveform in the time domain, the built-in 32-bit 8x digital filter controls the transient response of the signal.  In PCM mode, 5 types of digital filters, (6 types with the AK4497EQ), allow music playback in a variety of sound settings by switching the filter type.

Sound Color Digital Filter

Premium D/A Converters

Product Portfolio

Product Portfolio -Premium DACs -

* Bubble Size = "Sound Quality"

Premium DACs

AKM's 3rd generation stereo DAC, the new flagship, "VERITA", AK4497EQ achieves 128dB S/N in summer 2016 as a higher performing solution of the VERITA AK4490.  The AK4490 was adopted by many audio products since it was launched in 2014.
Four multi-channel products have been added to the premium DAC AK445X series.  In total, seven products are available in the next-generation 32-bit premium DAC lineup.
An extensive lineup will cover a wide range of applications, from high-end to mid-range audio systems.