New Flagship DAC the AK4499EX to Debut at the IPS / HIGH END® Munich2022 Show

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#24
Hi all ... Looks interesting indeed :emoticon: .. I just wonder how (exactly) the output circuitry works ... Might any of you have found a more detailed description of what the OPIN** pins do ... ? I.e. what "comes out of them"?

And I reckon that the SQ will depend also on the AK4191 - will it e.g. be better than HQPlayer in terms of processing the incoming data?

Yet basically really interesting ...

Cheers,

Jesper
 
#26
OPIN pins are supposed to be input pins from the external opamp based I/V converters.. in practice the opamp feedback loop is closed through this pin.

Then, in theory, AK4191 has the same direct DSD path like the previous AK chips, so external DSP could be used
 
#27
Hi both ... & thanks for your feedbacks 😉

@HpW: Well, I reckon this could be interesting, however, I am not a programmer so it probably would be some challenge. Also, my impression is that HQPlayer really is very well made sound-wise so is it likely that the AK4191/AK4499EX could do better than this? In any case will be interesting to see - in due time ...

@Joseph K: Looking at the datasheet for the AK4499, the OPIN pins appear to be an output pin and not an input pin ... ?? I think this would make sense as they connect to high impedance input pins on the opamps. And assuming that the OPIN//opamp impedance is 1 Mohm then the 180p capacitors would only give an appr. 880 Hz cut-off frequency for what is transferred through these capacitors. I think the OPIN pins need be outputs ...

My consideration really is if the AK4499EX could somehow be made with a passive I/V setup?

Then, in theory, AK4191 has the same direct DSD path like the previous AK chips, so external DSP could be used
Click to expand...

Hmmm ... I am not quite clear on the terminology of DSD "native" & "direct" but the AK4191 has filters for DSD - and as far as I can see the AK4499EX does not have a direct DSD path .. Or might I have missed something ... ?

Cheers, Jesper
 
#30
Joseph K said:
that "dsd filter 2" sounds quite a 'formality', given that it then goes directly to the output interface, there is no modulator included..
Click to expand...
Just guessing: it could be a FIR low-pass filter of which the coefficients are chosen such that the output signal always fits in seven bits. There is no need for a sigma-delta modulator then. The filter will filter off sharp edges/far ultrasonic quantization noise and make the DAC much less sensitive to far-off phase noise/jitter than if the DSD were just passed on unfiltered.
 
#31
MarcelvdG said:
Just guessing: it could be a FIR low-pass filter of which the coefficients are chosen such that the output signal always fits in seven bits. There is no need for a sigma-delta modulator then. The filter will filter off sharp edges/far ultrasonic quantization noise and make the DAC much less sensitive to far-off phase noise/jitter than if the DSD were just passed on unfiltered.
Click to expand...
Who have heard AK4499EX vs. AK4499EQ in a listening test - and what kind of audible differences are to note ?
This question rises up in my head after reading this:
https://www.audiosciencereview.com/forum/index.php?threads/akm-is-dead.38857/
 
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