768kHz/32Bit AK4497EQ DAC, I2S/DSD input

The AK4497 is a new generation Premium 32-bit 2ch DAC with VELVET SOUNDTM technology, achieving industry's leading level low distortion characteristics and wide dynamic range. The AK4497 integrates a newly developed switched capacitor filter "OSR Doubler", making it capable of supporting wide range signals and achieving low out-of-band noise while realizing low power consumption. Moreover, the AK4497 has six types of 32-bit digital filters, realizing simple and flexible sound tuning in wide range of applications. The AK4497 accepts up to 768kHz PCM data and 22.4MHz DSD data.

This item includes PCB with SMT component soldered(includes NO AK4497 DAC chip option), thru-hole component are not soldered.

*AK4497 DAC Chip is currently available from AKM authorized dealer Digikey at USD52.53
http://www.digikey.com/product-detail/en/akm-semiconductor-inc/AK4497EQ/974-1142-1-ND/6235385

AKM Corporation local sales contact is available at the official website URL:
http://www.akm.com/akm/en/product/datasheet1/?partno=AK4497EQ

The most distinctive features of this USB DSD DAC is our customize xmos firmware for bit-perfect lossless I2C DSD and PCM volume control. Most people may not notice many so called "bit-perfect" device on the market is bit-perfect ONLY when you play at FULL volume. If the volume is not set to maximum in the computer, the audio data is ruined/scaled/altered before sending to the DAC chip and the result is signal to noise ratio seriously affected.
Related paper on this important feature:
http://www.esstech.com/PDF/digital-vs-analog-volume-control.pdf

Compare on the audio data flow path:
General device on the market: "Partial" Bit-perfect only at full volume
Computer -> USB -> XMOS/CMxxxx/AMxxxxx -> I2S(audio data scaled/altered if not at full volume) -> DAC Chip (es9018/cs4398/pcm1794 etc.)

This USB DSD DAC: Always Bit-perfect lossless at any volume
Computer -> USB -> XMOS -> I2S(audio data bit perfect at any volume)+IIC volume control -> DAC Chip (es9018/cs4398/pcm1794 etc.)

After many hours of work on customize the xmos firmware on this USB DSD DAC, audiophiles can move the volume control bar up and down freely in the computer volume mixer panel and still enjoy bit perfect audio. DSD audio as well as PCM audio can also be bit perfect volume control easily from the computer. Please notes there are many so called bit-perfect device can play DSD BUT you must set the computer master volume control to full volume.

*The XMOS PCB in the kit is flashed with our AK4490/4495/4497 customized bit perfect lossless I2C DSD and PCM volume control firmware, it send software command and switch AK4490/4495/4497 between DSD and PCM playback. We are the first (since last year 2014) and still the only one (as of today 2016) in the major market can achieve DSD volume control from the PC os mixer bit perfectly. We are proud to ahead of the major market for at less two year. Please notes AK4490/4495/4497 can only playback PCM when running in the default non software control mode.

Features:

1) 768KHz/32Bit AK4497 DAC Chip (industry’s leading level low distortion characteristics and wide dynamic range.)

2) Bit perfect lossless I2C volume control firmware for DSD and PCM when used with the bundled XMOS PCB.(we are proud to be the first one and still the only one in the market can include this important feature since two year ago!) Without this important feature, the audio data send to DAC chip is ruined if the user is not playback at full volume from the computer operation system.

3) Solid ground plane with careful split of digital and analog portion(a must for highest fidelity audio)

4) No Via in active circuit (via inductance always create jitter problem)

5) 0.1% Low noise thin film resistor and C0G Capacitor sourced from Digikey USA (10x higher price than those thick film resistor from China)

6) 2200uF panasonc Low ESR capacitor at VREFH/L pin for super bass response and highest performance at 20Hz range frequency.

7) Gold plate I2S input connector and four GND return path dedicated for each I2S signal(lowest contact resistance and highest signal quality)

User guide:

1)The AK4497 PCB can work immediately with only I2S signal and power supply connected, one 3.3V (>300mA), one 5.0V (>100mA) and one +-12V (>100mA) regulated power supply in the default parallel operation mode.

2)For Diyer requires more deeper customization or switch to DSD playback(software I2C command is needed), the latest veraion of AK4497 datasheet is available in the official AKM website.

3)The PCB is designed to be DIY friendly. Diyer can cut the trace and uses the socket labelled AVDD_R(5.0V) for the supply the right channel analog power supply individually. Remove FB1 and use DVDD(3.3V) for optional individual digial power supply.

4)The differential output directly from the DAC has labelled with preallocated 2.54mm spacing socket for diyer easily connecting to their favorite IV and LPF and bypass the default onboard one.

5) All dual opamp in single dip8 package IC can be used for this PCB output stage, such as OPA2134 AD8620 etc. One free opamp is included in the package and the model depends on stock.

6)If AK4497 PCB is used standalone in hardware control mode, (i.e. it is not used with our xmos pcb flashed with specific ak449x firmware or you do not have external MCU to send the software control command), PSN and ACKS must jump high or not sound. For software control mode, i.e. connect to the bundled xmos pcb which is flashed with specific ak449x firmware, PSN and ACKS must jump low.

Additional user guide for running the AK4497 PCB in software control mode(i.e. used with XMOS PCB flashed with our AK4497 customized bit perfect lossless I2C volume control firmware):

1) Install jumper on AK4497 PCB PSN and ACKS socket and SET it to LOW. The DAC will start to run in software control mode.

2) With our customized firmware, the audio data send to the DAC is always bit perfect / lossless and the volume control is done in the DAC chip by I2C. DSD volume control is available using the operating system mixer.

Without DAC specified firmware, the OS mixer will ruin the audio data if the volume is not set to full and DSD can only be playback at full volume.

Please notes the maxiumum sampling rate is limited by the XMOS PCB.

For advance user only, when AK4497 is used with isolated XMOS PCB:

1) To avoid click noise occurs during replug of USB cable, remove FB1 and uses external 3.3v supply to CN3. Please notes reversed polarity or over voltage can damage the xmos chip immediately.

SMT soldering guide(for no AK4497 dac pcb option):

1) The thick solder on AK4497 soldering pad is used for user easilier to install the smt IC and it should not be removed normally.
The normal procedure to install the smt IC:
a) Paint a thin layer of soldering flux on the top of the pad which already has thick solder(if needed, add a little more solder on the center pad with a solder iron can help the ic auto align more easily during the solder in liquid phase)
b) use a hot air gun ~340C to blow it from 3-5cm distance until the solder melt
c) apply soldering flux on the IC and place the IC on the pad. Do not blow it longer than 2min. the IC can be damaged. Flux is essential for the the solder to become wet and help the IC auto align (due to surface tension of the solder in liquid phase)
d) while the solder melt, the IC should auto align to it's position(due to surface tension from the liquid stage of the solder) If it is still misaligned, user can use a tweezer to move the ic to it's position while the solder is still in the liquid stage. The finish quality of this method will be as good as a computer motherboard.

Specification:

1) I2S Input (MCLK, LRCK, BCK, DATA, GND)

2) Output level: 2V RMS

3) Resolution/Sampling Rate: Up to 32bit/768KHz

4) Supply: Regulated 3.3V, 5V, +-12V

5) Compact size 70mm x 70mm

*According to the AK4497 official datasheet page 66 notes 5 and our test, click noise occurs during power on/off, external mute circuit may be needed if click noise adversely affect system performance.

*Our latest D1X headphone amplifier includes power on delay and instant off output relay. It can mute the power on/off click noise of AK4497/4495/AK4490 as well as all the other DAC chip requires this feature.

*For normal user, AK4490 has higher c/p over AK4495/97. All can playback PCM768k and DSD512 file in our lab test condition. With our latest specific xmos firmware test condition, ak4490/95 do not have pcm/dsd switching click noise but ak4497 still have a little.

*All SMT components on the PCB is assembled by pick an place machine in one step, the outcome is professional. AK4497 is soldered one by one manually afterward when order is received, no cleaning need soldering flux is used, some flux may remain on the PCB, it will not affect the PCB performance and usage.

PCB without DAC chip option has plently of stock, user are welcome to order as many as they like. PCB with DAC chip option has limited stock, maximum one per buyer. Please contact us if you want to buy more than one, thanks.