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Dual Mono DAC AK4490/AK4497
Dual Mono DAC AK4490/AK4497
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Old 29th July 2016, 06:56 AM   #101
mtoc is offline mtoc
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Quote:
Originally Posted by Baka View Post
You need two AK4497 for that board.
lord, that's one 4497, the other chip is 4118.....
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Old 29th July 2016, 07:37 AM   #102
Baka is offline Baka  Montenegro
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Originally Posted by mtoc View Post
lord, that's one 4497, the other chip is 4118.....
Nope. Look at the picture carefully.
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Old 10th August 2016, 06:51 PM   #103
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Originally Posted by themystical View Post
Not many people building this DAC so I thought I would share my experience. I have separate super regulated power supplies for the Analogue 5V and the analogue 3.3V. Separating out the Digital 3.3V was not a huge subjective difference in SQ. However running the Analogue voltage at 6.8V was miles better. More clarity and density to the sound.
which kind of mods to the board have to be done to allow the usage of 7V?

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Originally Posted by themystical View Post
In terms of op amps I have tried various including LM49990, LM47910, AD4489 etc The cleanest sounding is LM4990.
you should try the OPA1688 in there...

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Originally Posted by themystical View Post
I would say that this chip is equal to or better than the Sabre ES9018Dual Mono DAC AK4490/AK4497
definitely way better, IMHO.

(at least for what I can tell from the implementations of the two that I have heard so far).

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Originally Posted by Green77 View Post
Just finished a DIYINHK ak4490 board. With a standard 7812/7912 psu for op and a lm317 for 3.3v. On the 5v in i'm use a low noise psu set to 6.8v.
I use the xmos USB card from DIYINHK too.
Everything works, but the sound is really bright.
Anyone have the same problem with this pcb?
I have a simple "full-DIYINHK" setup (also with their low-noise PSU boards for everything). No brightness whatsoever.

BTW: the DIYINHK board does not provide a "decoupling" resistor on the OpAmp output... thus you must add a good ~100 Ohm resistor in series with the analog output!

That will make any OpAmp happier and will provide great SQ improvement.

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Originally Posted by themystical View Post
In dual mono form this is one of the best sounding DACs I have heard.
is there a description of your setup somewhere? Or, could you describe how you have done that?

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Originally Posted by Green77 View Post
Well, i did use 6.8v where it say 5v.
Wait! Have you modified the board to separate the different supply? Without doing that, you can NOT apply more than 5V there!
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Old 13th August 2016, 09:49 AM   #104
themystical is offline themystical  United Kingdom
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Quote:
Originally Posted by UnixMan View Post
which kind of mods to the board have to be done to allow the usage of 7V?

No mods required. Simply connect 7V instead of 5V


you should try the OPA1688 in there...

These are not available from the usual suppliers in the UK but I notice that they are very cheap and seem to have really good specs for a headphone driver op amp. Perhaps somebody could send me a couple?Dual Mono DAC AK4490/AK4497



BTW: the DIYINHK board does not provide a "decoupling" resistor on the OpAmp output... thus you must add a good ~100 Ohm resistor in series


is there a description of your setup somewhere? Or, could you describe how you have done that?

Please see this thread - no mods required to the DIYinHK boards.
Dual Mono wiring for a Vout DAC

https://r.tapatalk.com/shareLink?url...6&share_type=t


!





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Old 13th August 2016, 11:21 AM   #105
UnixMan is offline UnixMan  Italy
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Originally Posted by themystical View Post
No mods required. Simply connect 7V instead of 5V
There's something strange... this is the answer I've got directly from DIYINHK customer service:

3. please notes the max voltage of AVDD is 5V, maximum VDDL/R is 7V, you will need to cut trace on our PCB if you want 7V to VDDL/R.

Supplying 7V to the +5V input of an unmodified DIYINHK board will provide 7V also to the AVDD line... doing so will likely damage your DAC chip.

Quote:
Originally Posted by themystical View Post
These are not available from the usual suppliers in the UK
you can get 'em e.g. from Mouser UK: http://www.mouser.co.uk/ or even order directly from TI.

Quote:
Originally Posted by UnixMan
BTW: the DIYINHK board does not provide a "decoupling" resistor on the OpAmp output... thus you must add a good ~100 Ohm resistor in series
Quote:
Originally Posted by themystical View Post
is there a description of your setup somewhere? Or, could you describe how you have done that?
just add the resistor in series with the analog outputs, wherever you see fit... (also right on the board output connectors, or just before them). They must be outside of the OpAmp NFB loop, but before any cable connection. Their purpose is to "shield" the OpAmp output (and its NFB loop) from capacitive loads (such as cables).

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Originally Posted by themystical View Post
Please see this thread - no mods required to the DIYinHK boards.
Dual Mono wiring for a Vout DAC

https://r.tapatalk.com/shareLink?url...6&share_type=t
Thank you. That's for what regards the analog out... which is the easy part. But what about the digital in?

How have you connected the USB interface to the two DAC boards I2S inputs to get dual-mono operation?
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Last edited by UnixMan; 13th August 2016 at 11:24 AM.
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Old 13th August 2016, 01:18 PM   #106
jdlayman is offline jdlayman
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Originally Posted by UnixMan View Post
There's something strange... this is the answer I've got directly from DIYINHK customer service:

3. please notes the max voltage of AVDD is 5V, maximum VDDL/R is 7V, you will need to cut trace on our PCB if you want 7V to VDDL/R.

Supplying 7V to the +5V input of an unmodified DIYINHK board will provide 7V also to the AVDD line... doing so will likely damage your DAC chip.


Disclaimer: I don't have one of these boards yet, but looking at a picture of the board from hifiduino, I don't see any trace connecting AVDD and VREF. I see a connection between AVDD and DVDD as well as VREFR+L and VDDR+L. Am I missing something or is it possible the DIYINHK support team got the pins confused in their response?


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Old 13th August 2016, 02:59 PM   #107
UnixMan is offline UnixMan  Italy
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Originally Posted by jdlayman View Post
Disclaimer: I don't have one of these boards yet, but looking at a picture of the board from hifiduino, I don't see any trace connecting AVDD and VREF. I see a connection between AVDD and DVDD as well as VREFR+L and VDDR+L. Am I missing something or is it possible the DIYINHK support team got the pins confused in their response?
mmmh, I'll have to check the board (will also ask them again), but likely you're right: looking at the Ak4490 data-sheet, the AVDD supply voltage allowed range is 3.0V to 3.6V... thus it should be connected to the 3.3V supply line, not to the +5V... (unless it is connected to it through some divider, but that sounds unlikely).
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Old 13th August 2016, 03:16 PM   #108
themystical is offline themystical  United Kingdom
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Originally Posted by UnixMan View Post
mmmh, I'll have to check the board (will also ask them again), but likely you're right: looking at the Ak4490 data-sheet, the AVDD supply voltage allowed range is 3.0V to 3.6V... thus it should be connected to the 3.3V supply line, not to the +5V... (unless it is connected to it through some divider, but that sounds unlikely).


DiyinHK is privy to the same data sheet as you and I and I looked at the Datasheet and the board quite carefully before I upped the voltage to 6.8V.Dual Mono DAC AK4490/AK4497


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Old 13th August 2016, 04:03 PM   #109
themystical is offline themystical  United Kingdom
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Also the i2s signals are simply paralleled to the two mono boards. Some people would argue that you need 10-30 Ohm resistors in series with each connection but I don't use any.


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Old 13th August 2016, 05:03 PM   #110
UnixMan is offline UnixMan  Italy
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Originally Posted by themystical View Post
Also the i2s signals are simply paralleled to the two mono boards.
well, but then each DAC/board will still be processing both (different) audio channels. That's not "dual mono"... this way you're just using two DACs in parallel.

To get real "dual-mono" - that is, to use both channels of one chip/board for one audio channel (say, R) and the other board for the other channel (say, L) - you would need to act on the I2S signal so to send only "L" samples to (both channels of) one board and only "R" samples to (both channels of) the other.

Am I wrong? Click the image to open in full size. Is there anything I'm overlooking?
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