which kind of mods to the board have to be done to allow the usage of 7V?
you should try the OPA1688 in there...
definitely way better, IMHO.
(at least for what I can tell from the implementations of the two that I have heard so far).
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.
is there a description of your setup somewhere? Or, could you describe how you have done that?
Wait! Have you modified the board to separate the different supply? Without doing that, you can NOT apply more than 5V there!
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?[emoji846]
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?ur...share_tid=291672&share_fid=10716&share_type=t
!
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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.
you can get 'em e.g. from Mouser UK: http://www.mouser.co.uk/ or even order directly from TI.
UnixMan said:
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).
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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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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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.[emoji846]
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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?
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?Is there anything I'm overlooking?
Whether the DAC operates in mono mode is set via registers using I2C. If mono mode is selected (and channel specified), I don't think it matters if I2S signals are going to both inputs or not. The DAC will still only operate on one channel.
Is that a correct understanding? Do you still get the increased THD specs if you have signal going to both inputs? Not sure if that affects noise or not.
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Oh, I see.
You're right, of course. So you are using some external MCU to control it? Which one?As above. I converted mine from 5.0V to 7.04V with no issues (except better sound). the only thing to check is the V of your decoupling caps.
@themystical, IIRC you had a noise/click issue with your setup in dual mono. Did you fix this?
Oh, I see.
Arduino Uno
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could you provide some more details? (maybe it have been already described in previous posts / somewhere else?) the code is available?
Thank you.
BTW: after checking the caps (default ones, no problems... all >=10V), I have changed +5V to +7V. Indeed, it does work.
could you provide some more details? (maybe it have been already described in previous posts / somewhere else?) the code is available?
Thank you.
BTW: after checking the caps (default ones, no problems... all >=10V), I have changed +5V to +7V. Indeed, it does work.
The Arduino Uno is very simply connected to the I2c, no fancy display or anything. There is no code available in the public domain as far as I know. I simply write the required value for each register using very basic commands. See the Hifiduino site if you want to learn about writing your own code.
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There are volume control registers in the chip but I personally have not implemented volume control in the code that I use.
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Yes. The DIYINHK Xmos interface -with their dedicated firmware for the ak4490/4495 - does support "lossless" volume control (controlled via USB computer interface). It works also for DSD.
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