This diagram shows another way to get 8x linear interpolation with NOS DACs. All timing is derived from a synchronous counter clocked either by a local oscillator or S/PDIF. The oscillator also exports a clock to slave the CDP.
CLK0-3 are quadrature clocks. WS0-7 are 8-phase strobes. Everything else should be obvious. The circuit can be implemented with as few as 14 logic ICs (74xx type), 8 stereo DACs, a S/PDIF receiver, and transceivers to slave the CDP.
Use the local oscillator in conjunction with a slaved CDP. Use the S/PDIF clock source with non-slaved CDPs. Or, use the local oscillator with a non-slaved CDP if you prefer the sound of missing/duplicated samples, as do users of the DDDAC. If you like the sound of jitter, add a USB receiver but be sure to aschronously reclock BCLK for maximum the effect. The choice is yours.
CLK0-3 are quadrature clocks. WS0-7 are 8-phase strobes. Everything else should be obvious. The circuit can be implemented with as few as 14 logic ICs (74xx type), 8 stereo DACs, a S/PDIF receiver, and transceivers to slave the CDP.
Use the local oscillator in conjunction with a slaved CDP. Use the S/PDIF clock source with non-slaved CDPs. Or, use the local oscillator with a non-slaved CDP if you prefer the sound of missing/duplicated samples, as do users of the DDDAC. If you like the sound of jitter, add a USB receiver but be sure to aschronously reclock BCLK for maximum the effect. The choice is yours.
Re: Re: Re: 8xNOSDAC
Ulas is not listening to music, he spends his time reading datasheets, so no need to ask him.
DDDAC users collectively think this dac sounds great (read my site, don't believe me, just read what others say ....) So if reproduced music sound great, even when you loos or duplicate a few samples, who cares? Ulas does, but he is not listening to music, so his opinion is only of technical value. He is mostly right, but missing the point what makes really a difference in musical experience.
If every one prefer blond, Ulas will tell you, for good reasons I guess, that brown is better for practical reasons, but who wants that ?
doede
Ulas said:
Ulas is not listening to music, he spends his time reading datasheets, so no need to ask him.
DDDAC users collectively think this dac sounds great (read my site, don't believe me, just read what others say ....) So if reproduced music sound great, even when you loos or duplicate a few samples, who cares? Ulas does, but he is not listening to music, so his opinion is only of technical value. He is mostly right, but missing the point what makes really a difference in musical experience.
If every one prefer blond, Ulas will tell you, for good reasons I guess, that brown is better for practical reasons, but who wants that ?
doede
Common practice is to run the CS8412 in master mode. That way all clocks are synchronous with the clock derived from the SPDIF datastream.
The DDDAC runs the CS8412 in slave mode. In that mode one is required to generate FSYNC/WS/LRCLK and BCLK/SCLK. These are then used to clock data out of the CS8412. In the pro arena these clocks would be derived from a VCXO locked to a common reference as would the CDP so there would synchronicity across the board. Alternatively one can derive the clocks from an XO and in turn run the CDP off a feed from the same XO. Again there is synchronicity across the board.
Now DDDAC opts for neither of the above options, sticking solely with the XO. Needless to say any frequency other than that for which the XO was chosen is out. Even when the frequencies match one has to hope that the phase discrepancy between the incoming SPDIF datastream and the onboard XO are not enough to overwhelm any buffering the CS8412 may provide otherwise there will be dropped or repeated samples.
The DDDAC runs the CS8412 in slave mode. In that mode one is required to generate FSYNC/WS/LRCLK and BCLK/SCLK. These are then used to clock data out of the CS8412. In the pro arena these clocks would be derived from a VCXO locked to a common reference as would the CDP so there would synchronicity across the board. Alternatively one can derive the clocks from an XO and in turn run the CDP off a feed from the same XO. Again there is synchronicity across the board.
Now DDDAC opts for neither of the above options, sticking solely with the XO. Needless to say any frequency other than that for which the XO was chosen is out. Even when the frequencies match one has to hope that the phase discrepancy between the incoming SPDIF datastream and the onboard XO are not enough to overwhelm any buffering the CS8412 may provide otherwise there will be dropped or repeated samples.
poobah said:That is nuts... if I understand you correctly.
It would seem to me that dropping or repeating samples would be the most horrible form of jitter.
This is nuttier than the linear oversampling thread.
Seems par for the course to me. People play 24 bit DVD's through the TDA1543 and proclaim the greatest sound ever. Yet truncating the last 8 bits cannot possibly do anything for the sound.
poobah said:
No, nothing's nuttier than that.
I've been studying duplicate samples for some time now. I started a thread on the subject here some time ago but no one was interested. Clockmongers dominate this forum so the only discussion allowed is clock jitter. You are the first person I've encountered who recognized that duplicate or repeated samples are a form of jitter. I commend you.
Hey
I´m not sure if a couple of dropped/repeated samples per second is an issue, but to my mind, it certainly can´t be worse than the jitter from the spdif of a cheap CDP (like mine).
I will certainly experiment and find out by myself.
That being said, I believe Peufeu (Pierre) did investigate this in his "extremist dac" (there´s a webpage). I recall him saying that when he unplugged the clock feed to the soundcard (which implies dropped/repeated samples), he could hear no difference.
I´m not sure if a couple of dropped/repeated samples per second is an issue, but to my mind, it certainly can´t be worse than the jitter from the spdif of a cheap CDP (like mine).
I will certainly experiment and find out by myself.
That being said, I believe Peufeu (Pierre) did investigate this in his "extremist dac" (there´s a webpage). I recall him saying that when he unplugged the clock feed to the soundcard (which implies dropped/repeated samples), he could hear no difference.
Alexandre said:
Good, I think determining something for your self is preferable to taking the word of some unknown person with a web page. Exactly how are you going to determine how many duplicate or dropped samples you will be hearing or not hearing? It could be that the clocks in your source and DAC are, for all practical purposes, identical, in which case there would be no duplicate or dropped samples to hear or not hear.
Wow!
I do ADC & DAC stuff some of the time for my living. I don't listen to motors and batteries though. I don't know all the chips and the jargon for audio. This is just nuts...
I thought the speaker cable guys were crazy...
This is a real example of a little bit of knowledge being a dangerous thing.
I cannot believe that someone would tamper with the FIFO memory, and the disc speed, and let a CDP run free, and then asynchronously re-clock, and let 2 oscillators fight for the truth.
Nuts... just plain nuts...
Maybe... if these same people would play with their computer, instead of CDPs, they wouldn't (couldn't) post this madness...
I do ADC & DAC stuff some of the time for my living. I don't listen to motors and batteries though. I don't know all the chips and the jargon for audio. This is just nuts...
I thought the speaker cable guys were crazy...
This is a real example of a little bit of knowledge being a dangerous thing.
I cannot believe that someone would tamper with the FIFO memory, and the disc speed, and let a CDP run free, and then asynchronously re-clock, and let 2 oscillators fight for the truth.
Nuts... just plain nuts...
Maybe... if these same people would play with their computer, instead of CDPs, they wouldn't (couldn't) post this madness...
some people find it nuts to build amplifiers with parts from 1930, having distortion figures way above 1% etc etc, where there are great opamps available, showing much better results on datasheets. I used them all and I like tubes more. Some like opamps better. Some like fish, some steak..... what is better ?
This is the old discussion between, what makes technically sense and what does appeal to to one listening to music.
The ones who followed the development of the DDDAC a bit, know, that the first version (I had big doubt as well on the asynchrone reclocking, as I DO know the technical stuff behind...) had an option to switch between slave and master mode. 2 years usage of the first model, showed by experience, that 99% of the users preferred the slave/reclocking, even if purely technological it is the strangest thing to do (I am not "religious" about this or something, so no point to admit this is just the case)
That is why I keep hammering
on the fact, that not all what is technically the most sensible or obvious thing to do, is leading to the most joy ( note please, I did NOT write best results 
)
But as always in this typical discussion, we will probably never come to a conclusion, so lets drop it a bit and let every one decide for himelf what he likes best.
Doede
PS: I like Red too
This is the old discussion between, what makes technically sense and what does appeal to to one listening to music.
The ones who followed the development of the DDDAC a bit, know, that the first version (I had big doubt as well on the asynchrone reclocking, as I DO know the technical stuff behind...) had an option to switch between slave and master mode. 2 years usage of the first model, showed by experience, that 99% of the users preferred the slave/reclocking, even if purely technological it is the strangest thing to do (I am not "religious" about this or something, so no point to admit this is just the case)
That is why I keep hammering
on the fact, that not all what is technically the most sensible or obvious thing to do, is leading to the most joy ( note please, I did NOT write best results )But as always in this typical discussion, we will probably never come to a conclusion, so lets drop it a bit and let every one decide for himelf what he likes best.
Doede
PS: I like Red too
According to my analysis software, my DDDAC style DAC drops/ repeats a sample roughly every two seconds. I don't believe anyone can hear one bad sample in circa 88,000.
As Doede says, it is simple to swap between the S/PDIF clock and the local clock. The local clock sounds so much more transparent that it's obvious that even if there is an audible loss in quality via dropped samples, the gains far outweigh it. Try it for yourself and doubt no more.
As Doede says, it is simple to swap between the S/PDIF clock and the local clock. The local clock sounds so much more transparent that it's obvious that even if there is an audible loss in quality via dropped samples, the gains far outweigh it. Try it for yourself and doubt no more.
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