Dual Mono DAC AK4490/AK4497

[cal1sto]

This thread is to initialize a new board and finished DAC based on a prototype build from base board from DIYINHK , idea behind is to get best quality and performance based on XMOS, AKM and NDK product.

My prototype based on AK4490 and XMOS isolated from diyinhk build my motivation to build first a dual mono AK4490 with ultra low noise supply and low jitter clock to reach the best performance of this nice and powerfull DAC chip interfaced with the XMOS Xcore-200 to have enought control and power (MIPS) to cover the need to reach the PCM 32bits 768khz and DSD 256 (native or DoP). Then an other board based on the new AK4497 when i get sample in February before mass production of this chip between April and May 2016 (seems to be officaly for summer 2016).

Some SPEC

For AK4490 32bit Stereo DAC:
S/N : 123db (in mono mode)
THD+N : -112db
PCM: up to 768khz
DSD: up to DSD256

For AK4497 32bit Stereo DAC
S/N : 131db (in mono mode)
THD+N : -116db
PCM: up to 768khz
DSD: up to DSD512

For oscillator part i select NDK but we will see if better solution could be proposed from our Diyer there.
I have already asked NDK for getting sample from the new Duculon product but first is this to expensive (arround 1600€ pcs) could be used only for public where a high end product for this type of over killed quality and price as no impact (DAC cost could be estimate arround 6K€)

Let go first to the first step the optimal choice in a reasonable price.

Before building a new PCB i will create with you the prototype by using DIYINHK product , we will proceed on some fine tuning and customization to get our target runing and be distributed or self builded.

After we will search a good way to build a nice litle PCB for and his boxed version.

Then one other PCB for the Premium last new AK4497 with his very good performance and quality.

This thread is to exchange experience and build a DAC together on a reasonable and performance way, and is not a commercial activities. I will give you the current state of my current experiences what is already done, what is currently in task list and what is to be planned.

When you have any question please ask me now on this thread before i begin any step to get it working (i tell you the current sound going out is amazing)

Enjoy to exchange your experience into this thread , thanks in advance all for your input

Cal1sto

 

[cal1sto]

List of Board we will work on :

AK4490 board from diyinhk with a 100uF electrolitic capacitor

- Customization will be to set 2 x 3.3V and 2 x 5V(or more max 7.2V) to split left and right operation.

XMOS Multichannel from diyinhk Xcore-200 (16 core, 2000Mips)

- Customization will be to provide twice the audio oscillator frequencies than the one on board to get the PCM 768khz and DSD256 over DoP, and customize the firmware for the customized HW (standard delivered one is not build for the AK4490 and is not able to manage the native DSD 256 or PCM 768khz).

- Also thinking to a solution to isolate this board to reduce any noise from any connected PC or media center and to have clean power on oscillator.

Power Supply
- The most important part before all other by any project is the DC power supply this should be with ultra low noise, enought current and isolated for all board part.

 

[manudrz]

Nice project. Do you plan to make "modulable" boards?
I don't need USB, just simple I2S inputs and SE outputs for my DSPiy... Yes, just six 24/96 little boards
Did you design an other DAC in the past ?

 

[cal1sto]

Nice project. Do you plan to make "modulable" boards?
I don't need USB, just simple I2S inputs and SE outputs for my DSPiy... Yes, just six 24/96 little boards
Did you design an other DAC in the past ?

Hi Manudrz,

This is my first DAC project, i design before a nice powerfull MOSFET (IRF) power amplifier with a passive preamp.
Yes i do everything "modulable" is i think the way for us to have any time the possibility to upgrade, control every part and build a stereo , 2.1, 5.1, 7.1 or more depending on need (i will go surely finaly for a stereo and 7.1 version).
The Xmos board (usb, S/pdif, coax) board is able to deliver 6 channels at 384khz, 8 channels at 192khz and up to 32 channels at 48khz, so to answer on your need only for the DAC boards this is able to deliver the 24bits 96khz you want to deliver over your DSPiy... (The DAC could 16,24,32 bits at up to 768khz) with I2S and I2C interface to have full control + H/W interface.

 

[UMarcus]

Nice, I'm also very interested in this project (especially AKA4497).

Would be I2S Input -> MonoMode Balanced Output possible ?

I'm general interested in minimized designs, especially in analog section, I just take a short look into the Datasheet.

Do you think the output couple 100µC are needed for Balanced Mono Out as used in the example ? I asking because i have alread a DC Couple C in my system.

About modular concept, maybe it would be also nice to have the possibility to use external power supplies / regulators.

Thanks,
regards
Marcus

 

[manudrz]

Nice, I'm also very interested in this project (especially AKA4497).

Would be I2S Input -> MonoMode Balanced Output possible ?

Perhaps a little "cap/shield" on the output to do BAL/SE? Suitable for everyone and flexible, yes like many others designers do...

About modular concept, maybe it would be also nice to have the possibility to use external power supplies / regulators.

I think onboards regulators is better, wiring regarding. Mirand audio design is wonderful, but I only need half of his boards...

Could we imagine 3 little PCB:
One below with regs/PSU (too hot?)
One in the middle with AKM
One above with the output ?

I'm still dreaming of a tiny i2s mono board to SE, running the AK at 7V with good regs and AOP.
Just a few ideas, not my design

 

[manudrz]

The Xmos board (usb, S/pdif, coax) board is able to deliver 6 channels at 384khz, 8 channels at 192khz and up to 32 channels at 48khz, so to answer on your need only for the DAC boards this is able to deliver the 24bits 96khz you want to deliver over your DSPiy... (The DAC could 16,24,32 bits at up to 768khz) with I2S and I2C interface to have full control + H/W interface.

I don't even need USB in fact, just i2s to single ended

 

[UMarcus]

..
I'm still dreaming of a tiny i2s mono board to SE, running the AK at 7V with good regs and AOP.
Just a few ideas, not my design

+1 .. same for me as balanced variant (may by combine two of your dreams )

 

[Sangram]

The power supply routing on the DIYIHK AK4490 board leaves very,very much to be desired. That's what happens when you route a DAC using 2 layers and don't give priority to the power traces.

No idea about the 4497 boards, but I don't expect better.

There is not even space to fit your own LDOs.

Digital power needs to have extremely low impedance supplies very close to the chip, with HF bypassing at the pins. He's done the latter and not the former.

In addition when we asked for the schematic of the I/V stage he said it was same as datasheet but it's not. The value of whatever components we could make out was totally different, so he obviously has no idea about the board itself.

I would suggest a base board from someone who actually knows what he's selling, like sonnya on these forums. The price is much higher but at least you know that it will be properly designed.

The only remedy for the other board is to use a piggy-back style layout with a power supply placed just below/above the DAC board, feeding power straight to the required pads with very short (<10mm) traces. If you examine the chip layout, it was made to have separate regulators for each side of the chip with very short distance to chip. All 4 sides have power pins and respective grounds.

 

[manudrz]

The power supply routing on the DIYIHK AK4490 board leaves very,very much to be desired. That's what happens when you route a DAC using 2 layers and don't give priority to the power traces.

The only remedy for the other board is to use a piggy-back style layout with a power supply placed just below/above the DAC board, feeding power straight to the required pads with very short (<10mm) traces. If you examine the chip layout, it was made to have separate regulators for each side of the chip with very short distance to chip. All 4 sides have power pins and respective grounds.

+1, I think DIYINHK's board is a very poor base to mod with, but it's a cheap first step, I understand that. On ebay you can find other cheap designs around 27€...
Perhaps we could dreaming ask Sonnya to make a basic board with only the strict necessary ?

 

[cal1sto]

Nice, I'm also very interested in this project (especially AKA4497).

Would be I2S Input -> MonoMode Balanced Output possible ?

I'm general interested in minimized designs, especially in analog section, I just take a short look into the Datasheet.

Do you think the output couple 100µC are needed for Balanced Mono Out as used in the example ? I asking because i have alread a DC Couple C in my system.

About modular concept, maybe it would be also nice to have the possibility to use external power supplies / regulators.

Thanks,
regards
Marcus

One final target of this thread is to have one dual AK4497 DAC board (mono mode) to get the S/N of arround 130db, with balanced/unbalanced output to cover all our need.

The 100uF specified into my last post for the AK4490 is to custom the diyinhk board to split all power supply on left and right side of the chip (digital and analog side), this is specialy for the analog 5V where the FB1 and a trace will be cut (to split fully both analog supply).
For the AK4497 example see the attached AKM AK4497 shemas like on the AK4490 there is not output capacitor of 100uF, please share with us what you see or mean, thanks, the dac board as one or 3 LPF per Channels see the mono shemas from AKM for the AK4497 (AK4490 is more or less same).
I think one LPF is more than enought for the line out.

All the power supply will be provided as module with isolated short wire (interference protected).

But near the modular board i want to propose also one single board with all functionality into one litle compact board for the Dual AK4497 / XMOS and the Ultra low noise LDO.

Regards

 

[cal1sto]

Perhaps a little "cap/shield" on the output to do BAL/SE? Suitable for everyone and flexible, yes like many others designers do...



I think onboards regulators is better, wiring regarding. Mirand audio design is wonderful, but I only need half of his boards...

Could we imagine 3 little PCB:
One below with regs/PSU (too hot?)
One in the middle with AKM
One above with the output ?

I'm still dreaming of a tiny i2s mono board to SE, running the AK at 7V with good regs and AOP.
Just a few ideas, not my design

By the amplifier i build, i take as priority to split and protect the Power supply component from the operational board part , to protect any impact generated by the PSU itself (HF, Temp., magnet...) with a dedicated shielded place into the case, then all power wire enought dimensioned (short as possible, equal in length for same operation type, section size, material) and shielded.

Regards

 

[UMarcus]

One final target of this thread is to have one dual AK4497 DAC board (mono mode) to get the S/N of arround 130db, with balanced/unbalanced output to cover all our need.

..
All the power supply will be provided as module with isolated short wire (interference protected).
..

That's great !

...
For the AK4497 example see the attached AKM AK4497 shemas like on the AK4490 there is not output capacitor of 100uF, please share with us what you see or mean, thanks, the dac board as one or 3 LPF per Channels see the mono shemas from AKM for the AK4497 (AK4490 is more or less same).

Please find the attached shema with marked capacitors.

 

[cal1sto]

The power supply routing on the DIYIHK AK4490 board leaves very,very much to be desired. That's what happens when you route a DAC using 2 layers and don't give priority to the power traces.

No idea about the 4497 boards, but I don't expect better.

There is not even space to fit your own LDOs.

Digital power needs to have extremely low impedance supplies very close to the chip, with HF bypassing at the pins. He's done the latter and not the former.

In addition when we asked for the schematic of the I/V stage he said it was same as datasheet but it's not. The value of whatever components we could make out was totally different, so he obviously has no idea about the board itself.

I would suggest a base board from someone who actually knows what he's selling, like sonnya on these forums. The price is much higher but at least you know that it will be properly designed.

The only remedy for the other board is to use a piggy-back style layout with a power supply placed just below/above the DAC board, feeding power straight to the required pads with very short (<10mm) traces. If you examine the chip layout, it was made to have separate regulators for each side of the chip with very short distance to chip. All 4 sides have power pins and respective grounds.

I agree with you on some point like the low impedance need on the digital side (but with the two 3.3v for each side of the board with a short wire of 50mm i don't measure any impact during operation) , this board is a diy board and we are lucky to have it 2 Layer with enought reported pin to custom it and to be able to cut trace . Target is to use them as study base to build a dual mono board where we could have the power line part already splitted and well placed on board (without need to desolder part and cutting trace to have what should be delivered at the begin, i agree fully with you)
I will take a look on Sonnya board to understand what you mean, thanks.

Regards

 

[Sangram]

Good Luck with your project I had recommended the DIYINHK board to a friend who purchased it as the price is fantastic, but after working with it once I figured it has some issues in terms of execution.

And money would not have solved that, just proper board design technique. That is what you pay the extra money for and is a gap that HK/China manufacturers yet need to cover. They will catch up, but they're not there today.

 

[marce]

To get the best signal and power integrity a minimum of a 4 layer board would be required..... How much difference this would make is impossible to tell without careful measurements..... But for anything digital these days (and for many many years) I would never go below 4 layers, cost is not that much more than 2, benefits are many, if for no other reason than you can control the digital signals return paths...

 

[cal1sto]

That's great !



Please find the attached shema with marked capacitors.

Ok, you mean the high pass filter and DC decoupling from the analog output of the DAC before the LPF part. When you already have a high pass filter in your next board connected to the lpf out (and the opamp is matching this way of operation ) you could modify the shemas on your need, but anyway filtering before getting signal amplifyed (gain) by the LPF is better, so this doesn't (with low esr) affect a lot the analog signal.

Regards,

 

[cal1sto]

Good Luck with your project I had recommended the DIYINHK board to a friend who purchased it as the price is fantastic, but after working with it once I figured it has some issues in terms of execution.

And money would not have solved that, just proper board design technique. That is what you pay the extra money for and is a gap that HK/China manufacturers yet need to cover. They will catch up, but they're not there today.

That is why the first part i did with this board is to split the power supply 2 X 3.3v and 2 X 5V (or 7V) , this split is done by providing and by moding the board , desoldering component , soldering one and cutting trace to physically split correctly the board power. Without this i could imagine bad supply with merged power on this board could have some operational issue

Regards,
Marc

 

[cal1sto]

To get the best signal and power integrity a minimum of a 4 layer board would be required..... How much difference this would make is impossible to tell without careful measurements..... But for anything digital these days (and for many many years) I would never go below 4 layers, cost is not that much more than 2, benefits are many, if for no other reason than you can control the digital signals return paths...

I agree fully the minimum of 4 Layer give the best of layering the trace for best signal and power integrity , thanks for your precision We will go this way ^^^^

Thanks

 

[manudrz]

An other base to mod with ? AK4490 - I2S over USB Audio