Dual Mono DAC AK4490/AK4497

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felipeunix

Member
Joined 2013
androa76 said:
You have some mods that can be done. -+12v lines. No FR!! Cap. Replace with Kz 47-100uf. Near ak4490 unsolder one FR and replace it in 3.3v digital position. Gold capacitor must go near AK so on both VA L.R should be same FG cap. At dig supply is better black Fr than Fine gold. You have used just half of regulator for 3.3v position. Install another 3.3v reg and supply separately VDIG and VAN 3.3v supply. Desolder ferrite choke. Because dig line is very noisy on scope and noise goes into analog supply line.Use low esr cap 47-100uf on VD 3.3V as i described earlier...FR or os-con
Instal 100uh choke between Tps7a4700 and dac on +5v. That should relaxed sharp sound...
Replace opamp. enough for beginning.
Yes you could instal xmos dirrectly on dac with no wires.
Move xmos away from transformer to another side. And dac also. Move -+12v reg to another side near transformer.
Click to expand...

Please , can I explain why it is usually used only 10uF near the 3.3v and 5v terminals? Higher values ​​simply makes no difference or cause any inconvenience?
 
T

themystical

Member
Joined 2006
hcbonfim said:
Hi,
Could i use de DACR+ DACR- and DACL+ DACL- on AK4490EQ DAC board (red one) from Diyinhk to feed the balanced inputs (XLR) of my integrated amplifier ? and bypass the OPAMP.
Best regards
Click to expand...



It will probably work to a fashion but you would be bypassing the LPF filter and Buffer stage which would probably not be right and possibly end up overloading the DAC. I would not recommend it.
If you want to use the raw DAC balanced outputs, I would suggest building a LPF Buffer stage recommended in the Datasheet.



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C

ChuckT

Member
Joined 2002
androa76 said:
You have some mods that can be done. -+12v lines. No FR!! Cap. Replace with Kz 47-100uf. Near ak4490 unsolder one FR and replace it in 3.3v digital position. Gold capacitor must go near AK so on both VA L.R should be same FG cap. At dig supply is better black Fr than Fine gold. You have used just half of regulator for 3.3v position. Install another 3.3v reg and supply separately VDIG and VAN 3.3v supply. Desolder ferrite choke. Because dig line is very noisy on scope and noise goes into analog supply line.Use low esr cap 47-100uf on VD 3.3V as i described earlier...FR or os-con
Instal 100uh choke between Tps7a4700 and dac on +5v. That should relaxed sharp sound...
Replace opamp. enough for beginning.
Yes you could instal xmos dirrectly on dac with no wires.
Move xmos away from transformer to another side. And dac also. Move -+12v reg to another side near transformer.
Click to expand...

Hi, I have a ak4495 dac and it sound surprising good.
So you you seems to recommend using the FG audio grade caps at the analog side VDD and VRef pins. Currently I have Panasonic FM 100uf at VDD and Rubycon ZL 1000uf at the Vref running at 7.1V (I know the caps is a bit of an over kill).
I have 100uf Nichicon KZ and Silmic at my disposal, but I think the Nichicon KZ legs is a bit too thick to fit.

The 3.3V is from a LT3042 with oscon decoupling to the digital while the 7.1v is from an LT1963A
 
B

boriss111

Member
Joined 2010
hcbonfim said:
For shure i pretend to use 4 film caps at outputs to block DC. One cap for each XLR line,
Click to expand...
That will not be sufficient as you need sone sort of low pass filter (LPF) to remove high frequency noise from your amplifiers input. Also in my experience with different DAC filters, removal of capacitors from the signal path has always yielded sound improvements.

I would definitely bypass the onboard filter as I suspect it has fairly low performance - only single 1uF capacitor on board looks like simple first order filter is implemented, that I am sure AKM wouldn't recommend (I remember for older 4399 it was recommended to use second order LPF with 3 opamps).

My preference is to use transformers, as they remove DC offset and HF noise at the same time. In my case the next stage has sufficient input impedance so I don't need any buffers after the transformer but you might. But this definitely is not a cheap route to take as good transformers are fairly expensive.

I have seen a buffer with a passive LPF designed by Joachim Gerhard here JG buffer - I2S over USB Audio, maybe it could work for you. I plan to try it at some point in the future.


Just my two cents.


Cheers,
Boris
 
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