Máy nghe nhạc AK240 Astell & Kern

The stainless steel finish AK240 Portable Hi-Fi Audio System from Astell&Kern is a media player and USB DAC that supports a wide variety of audio formats including WAV, FLAC, ACC, MP3, WMA, OGG, DSD, and more. It is equipped with a dual DAC Cirrus Logic CS4398 chip that allows for native DSD playback, meaning it does not need to convert DSD files to WAV prior to analog conversion.

 

 

The AK240 can be controlled via its 3.3-inch AMOLED touch screen and features a physical volume knob. The unit has 256GB of internal storage, and supports microSD cards up to 128GB, for a total of 384GB of potential storage. Thanks to its streaming capabilities, you are not limited to playback of songs you have on your device, as it can stream tracks from your Mac or PC connected to the same wireless network.

 

Closer to Original Sound

Besides providing a dual DAC setup to create better left and right channel separation with clearer sound quality, the AK240 also uses a balanced output and native DSD playback through the dual DAC setup.

 

 

Native DSD Support

DSD (Direct Stream Digital) is a digital audio file format originally developed for SACDs (Super Audio CD). Regular digital audio file formats such as PCM (Pulse Code Modulation) is separated into 65,000 (16-bit) to 16,700,000 (24-bit) of information on the Y axis, and 44,100 (44.1 kHz) to 192,000 (192 kHz) across the X axis for digital signals. DSD files have 1 bit (0s or 1s) for Y axis and is separated into 2,800,000 (2.8 MHz) to 5,600,000 (5.6 MHz) of information for X axis.

Compared to regular audio CDs with 16-bit/44.1 kHz PCM format, SACD's recording frequency goes up to 100 kHz and the dynamic range goes beyond 120 dB while maintaining sound clarity during the transmission.

 

In order to provide native DSD playback on the AK240, the player uses the Cirrus Logic CS4398 chip in the dual DAC setup with an added exclusive XMOS chip that will allow for Native DSD support.

 

Unbalanced vs. Balanced Output

The unbalanced method is the most commonly used basic method that consists of "left and right signals + ground line". This setup includes a ground line that blocks out external noises from the outside. However, since the ground line cannot block out all of the external noises completely, external noises can be mixed into the signals that are transmitted, which then result in changes to the sound. The longer the signals travel, the more external noises that will be mixed into the sound, which is why it is used within a short distance of 1 to 2 meters.

 

Unlike the unbalanced method, the balanced method has an additional cold signal to compliment the hot signal that reduces the external noises. The balanced method has a few advantages over the unbalanced method, the first is that the hot signal and the cold signal will remove the external noises received. The second advantage is increased output due to the 2 transmitted signals. Since the ground line cannot block out 100% of the external noises, noise will appear on both the hot and cold signals. The alignment of the 2 signals allows the noise to usually appear at similar points where they will eventually be removed as the signals are transmitted.

 

256GB of Storage

With 256GB of internal memory, about 2,500 MQS (24-bit/96kHz, 4 minute-long, 90MB) songs can be saved. With the addition of a 128GB microSD card, the AK240 can support up to a total memory capacity of 384GB.

 

MQS Streaming

To listen to your favorite music, you no longer have to turn on your computer, search for your music, wait for the songs to download, connect your player via USB cable, and then wait for the files to transfer to the player. Now with MQS Streaming, you can easily download or stream music directly from the AK240 by having the unit and your computer connected to the same network.

 

Over-The-Air Upgrade

With a Wi-Fi connection, you can receive instant notifications about new firmware updates and can update your unit whenever and wherever you are.

 

The Design

The design of the AK240 was derived from the combination of light and shadow. The front asymmetric look of the unit was designed from the shape of the shadow when light was shining on it. This shape strongly represents the Astell&Kern brand which expresses uniqueness and class while strongly protecting the volume knob as well.

There are 2 parts to the design of the volume knob on the AK240. First is the diamond-pattern design on the knob where it is gripped. Second is the fine hairline design at the end of the knob that shines to emphasize the design aesthetic of the AK240. The back of the unit is composed of real carbon fiber plates that blend with the overall AK240 design.

 

Duralumin

Even though the body of AK240 is just one piece, it goes through 12 stages of production until it is complete. The initial 6 stages involve the original materials being prepared, and the next 6 stages involve putting together all of those original parts.

 

10-Band 0.5 dB-Step EQ Setting

Accurate EQ setting is available on the AK240 by doubling the bands (from 5 to 10 bands) and halving the dB steps (from 1 dB to 0.5 dB) available. One can also create and save customized preset EQ settings to fit various music genres.

 

Full Touch Screen

Compared to the AK120, the 3.31 inch AMOLED display on the AK240 is about 82% bigger to provide more information at a glance. With the bigger display, the full touch screen is designed to be easy to navigate, especially for smartphone users.

The playback and volume control buttons have also been upgraded on the AK240. Music tracks with long titles, such as a classical music, are displayed on 2 lines for better navigation. Due to the speedy file scanning functionality, a separate dB scanning function is no longer needed and file search is available for access to music.

 

USB DAC

The AK240 supports native DSD USB DAC function (DoP method). Through the USB connection, the AK240 can be used as a USB DAC that supports Native DSD playback. The combination of the exclusive DSD chip and the dual DAC in the AK240 improves the playback from most computer sound cards and is able to create a sense of space and deeper sound while listening to your music.

 

Leather Case

The included case is made with minerva leather, using full vegetable tanning to bring out the special characteristic of leather while creating a natural tanned look. This leather material has a lot of oil in it that will allow the leather to shine the more it is used.

 

 

Astell & Kern AK240 Specs

 

Display	3.31" (84 mm) WVGA (480 x 800) AMOLED touchscreen
Supported Audio Formats	WAV, FLAC, WMA, MP3, OGG, APE (Normal, High, Fast), AAC, ALAC, AIFF, DFF, DSF
Sample Rate	FLAC, WAV, ALAC, AIFF : 8 kHz to 192 kHz (8/16/24-bits per sample) DSD Native : DSD 64 (1-bit, 2.8 MHz), Stereo / DSD 128 (1-bit,5.6 MHz)
Output Level	Unbalanced: 2.1 Vrms (Condition No Load) Balanced: 2.3 Vrms (Condition No Load)
DAC	Cirrus Logic CS4398 x2 (Dual DAC)
Decoding	Support up to 24-bit/192 kHz bit to bit decoding, DSD 64/128
Input	USB Micro-B input (for charging & data transfer, PC & Mac) Connection Mode : MTP (Media Device)
Output	1x 1/8" (3.5 mm) headphone output 1x 1/8" (3.5 mm) optical output 1x 0.13" (2.5 mm) balanced output (4 pole)
Wi-Fi	802.11 b/g/n (2.4 GHz)
Bluetooth	Version 4.0
Frequency Response	20 Hz to 20 kHz, ±0.023 dB, balanced and unbalanced 10 Hz to 70 kHz, ±0.3 dB, balanced and unbalanced
Signal to Noise Ratio	116 dB @ 1 kHz, unbalanced 117 dB @ 1 kHz, balanced
Crosstalk	130 dB @ 1 kHz, unbalanced 135 dB @ 1 kHz, balanced
THD + N	0.0007% @ 1 kHz, unbalanced 0.0005% @ 1 kHz, balanced
SMPTE	IMD SMPTE: 0.0004% 800 Hz 10 kHz (4:1), unbalanced 0.0003% 800 Hz 10 kHz (4:1), balanced
Output Impedance	Balanced 2.5 mm: 1 Ω Headphones: 2 Ω
Jitter	50 ps, typical
Battery	Capacity: 3.250 mAh, 3.7 V Li-Polymer battery
Memory	Built-In Memory: 256 GB (NAND) External: microSD, maximum 128 GB
Supported Operating System	Windows: XP, 7, 8 (32/64-bit) Mac: OS X 10.7 and later
Dimensions (WxHxD)	2.59 x 4.21 x 0.68" (66.0 x 107.0 x 17.5 mm)
Weight	6.5 oz (185 g)

Packaging Info

Package Weight	2 lb
Box Dimensions (LxWxH)	7.4 x 5.4 x 4.1"

 

Source: bhphotovideo