768kHz/32Bit AK4490EQ DAC, I2S/DSD input

AK4490EQ is a new generation Premium 32-bit 2ch DAC with new technologies, achieving industry’s leading level low distortion characteristics and wide dynamic range. The AK4490 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 AK4490 has five types of 32-bit digital filters, realizing simple and flexible sound tuning in wide range of applications. The AK4490 accepts up to 768kHz PCM data and 11.2MHz DSD data.

This item includes PCB with all SMT component soldered, thru-hole component are not soldered.

*The XMOS PCB in the kit is flashed with our AK4490/4495 customized bit perfect lossless I2C DSD and PCM volume control firmware, it send software command and switch AK4490/4495 between DSD and PCM playback. We are the first (since last year 2014) and still the only one (as of today 2015) 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 one year. Please notes AK4490/4495 can only playback PCM when running in the default non software control mode.

Zero pop/click noise is achieved when switching DSD/PCM mode or shuffling through DSD song file in either DoP/Native DSD mode(tested in foobar) with our new 768K XMOS PCB flashed with our fine tuned ak449x customized firmware.

Features:

1) 768KHz/32Bit AK4490 DAC Chip (industry’s leading level low distortion characteristics and wide dynamic range.)

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

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

4) 0.1% Low noise thin film resistor and C0G Capacitor sourced from Digikey USA (10x higher price than those thick film resistor from China)

5) 2200uF panasonc Low ESR capacitor at VREFH/L pin for super bass response and highest performance at 20Hz range frequency.

6) 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 AK4490 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 AK4490 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) Compact size 60mm x 60mm

Additional user guide when used with XMOS PCB flashed with our AK4490/4495 customized bit perfect lossless I2C DSD and PCM volume control firmware:

1) Install jumper on AK4490 PCB PSN 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 and the volume control is done in the DAC chip. 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 AK4490 is used with isolated XMOS PCB:

1) To avoid click noise occurs during replug of USB cable, remove FB1 and uses external 5v supply to CN3. Please notes reversed polarity or over voltage can damage the xmos chip immediately.

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

*According to the AK4490 official datasheet page 44 notes 6 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 AK4495/AK4490 as well as all the other DAC chip requires this feature.

*For normal user, the newer AK4490 should be a better choice than AK4495. AK4490 has better THD+N, lower cost and officially support upto 11.2Mhz DSD. AK4495SEQ is the first 768k DAC chip from AKM and it can be used as a reference for advanced user. Both can playback DSD512 file in our lab test condition.