ad1896 slave or master output?

[Lovan]

Hello everybody

I'm designing a DAC using AD1896 but I'm wondering if I should slave the output or use use it as a master with an output of 256*fs?

I will use a 24.576MHz clock and a PCM1794.

Any thoughts?

Thanks

 

[Nerull]

Neither, lol. Don't use it. I've learned the long, hard lesson in designing a DAC and that's not a step in the right direction. Many threads discuss this.

Of course you can always try it out anyway, but most people here will not like that idea (including me).

~Tom

 

[ezkcdude]

Neither, lol. Don't use it. I've learned the long, hard lesson in designing a DAC and that's not a step in the right direction. Many threads discuss this.

Of course you can always try it out anyway, but most people here will not like that idea (including me).

~Tom

Which part don't you like?

 

[Lovan]

Well since I'm doing a more general dac which needs to decode 44.1KHz ,48KHz, 96KHz...

...Or do I?
Since I'm using a CS8414 as a reciever, could I use MCK(256*fs) out from it to the PCM1794? Never thought about that...
I don't have to specify wordlength for PCM1794 do I?
That would be quite nice

Edit: damn spellingproblems

 

[Nerull]

My post is in reference to the AD1896. I was designing a DAC and many people told me that it was not a good choice at all.

As bocka said here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=66675&highlight=AD1896
The best ASRC is no ASRC.
And here:
http://www.diyaudio.com/forums/showthread.php?postid=528341#post528341

Instead of the actual filtering of jitter, you should probably try to eliminate it at the source (this is diy after all, so you can do it! ) ; kinda like going for the hive instead of killing the individual bees.

I guess if you really wanted to, you could. Personally though, I wouldn't use it and opt for stopping jitter and gaining sound quality through a different way. I2S...a new clock...modding the crap out of a cd player...making your own cd player...I guess this is half the fun though! You learn a lot along the way.

Good luck though!

~Tom

 

[ezkcdude]

I guess if you really wanted to, you could. Personally though, I wouldn't use it and opt for stopping jitter and gaining sound quality through a different way. I2S...a new clock...modding the crap out of a cd player...making your own cd player...I guess this is half the fun though! You learn a lot along the way.

Good luck though!

~Tom [/B]

Don't believe everything you read. Some people pray to the NOS gods, so they don't believe in ASRC, period. Personally, I believe that the virtually universally-shared negative opinions of brickwall digital filters at the DAC have rubbed off on ASRC, which is almost guilty by association. These two types of filters are not the same. Furthermore, as if I needed to explain myself further, not everyone can mod their CD players, and not everyone even has a CD player anymore. I use only a SqueezeBox and SPDIF out, so another solution is needed to reduce jitter. There are many people who DO believe in ASRC, so it's really a matter of choosing who to listen to, and your own ears, of course.

 

[gmarsh]

The PCM1794 only operates as an I2S slave.

I ran into an issue some time ago with the AD1896 chip - the application had to process audio at 96KHz with a DSP that could only handle slave mode input, and the box had to accept a 192KHz sample rate input.

The AD1896 can only accept sample frequencies up to MCLK/138, so if you're using the 24.576MHz as the MCLK into the AD1896 for a 96KHz master output then your maximum input sample rate is 178KHz. And if you clock the AD1896 at its maximum MCLK of 30MHz, its 256Fs master output will be 117KHz. I needed 96KHz.

My solution involved clocking the AD1896 at 29MHz with its own oscillator and putting it in output slave mode, and using the local 24.576MHz clock feeding a 74VHC393 counter to generate the 96KHz SCK/LRCLK I2S signals for both the ASRC and DSP.

So overall... if a 178KHz input sample rate limitation isn't a problem, using a 24.576MHz clock will work fine. If you need 192KHz input capability, you'll need to either use your DAC at 110KHz instead of 96 or go with the two-oscillator-and-counter system I just mentioned.

And as far as the ASRC-versus-no-ASRC argument goes, this topic has already been beaten to death in a number of threads, just search those. I'd personally go with the ASRC, but that's just my opinion after looking at a CS8416's recovered 256Fs clock on a spectrum analyzer.

 

[ezkcdude]

Gmarsh, what do you think about using CS8416/AD1896/PCM1794 with an external 24.576 crystal driving the clocks on the AD1896 and 1794? This is what I have in mind for a DAC. Also, I only plan to upsample everything to 96 kHz, as I have no 192 kHz source (nor do I plan to get one).

 

[gmarsh]

Gmarsh, what do you think about using CS8416/AD1896/PCM1794 with an external 24.576 crystal driving the clocks on the AD1896 and 1794? This is what I have in mind for a DAC. Also, I only plan to upsample everything to 96 kHz, as I have no 192 kHz source (nor do I plan to get one).

Sounds good to me.

I've got a CS8416/AD1896/PCM1792 headphone DAC here in front of me which is almost identical, and I'm pleased with it. Though I'm using a 29.4912MHz crystal, yielding a 115.2KHz sample frequency between ASRC/DAC and allowing 192KHz digital input.

 

[Lovan]

I am in a similar situation to ezkcdude. I only have a SPDIF signal(from either the PC directly spdif out or by pcm2902 spdif out)

gmarsch:
Yes the pcm1794 can only be a slave but I thought of using the clock with a divider. Thus the question if the ASRC gives a better clock than deriving av clock from the oscillator with a divider?
I also would limit myself to using only 96KHz since the implementation is a lot easier.
Maybe you could share some pictures or ideas from your project?

ezkcdude:
I'm building almost the same thing as you but with a cs8414(and a pcm2902). Maybe you could drop me a mail and we could share some thoughts?
Especially the IV-stage needs some thoughts on my side.

Thank you for your replies

PS:
Am I right in that CS8414 is limited to 96KHz output?
DS

 

[peranders]

PS:Am I right in that CS8414 is limited to 96KHz output?
DS

Hint: Always read the datasheets carefully especially those kinds of IC's. Try to understand (hard sometimes) the relevant facts and when you don't seek information elsewhere also. Beware of errors in the datasheets and check for updates and errata notes.

I remember when I designed my CS8412/CS4328 DAC. The CS8412 datasheet had a couple of errors in the datasheet... which I did notice after a while, comparing real life function.

 

[gmarsh]

Igmarsch:
Yes the pcm1794 can only be a slave but I thought of using the clock with a divider. Thus the question if the ASRC gives a better clock than deriving av clock from the oscillator with a divider?
I also would limit myself to using only 96KHz since the implementation is a lot easier.
Maybe you could share some pictures or ideas from your project?

My headphone DAC project - schematics, eagle files and other bits are posted later in the thread.

As for master versus slave mode causing jitter differences or other things... *shrug*

 

[Lovan]

PA:
Yes I see that I was lazy. I remember the cs8416 datasheet saying it supports 192KHz. I did see it now. Thanks anyway.

gmarsch

Thanks. I will look into your design

 

[audio3000]

Hi Gmarsh,

I am working on my DAC project which uses CS8416 as the receiver. But I have been having problem to control it using i2c bus without error. I can change the configuration and make it run right after RST. But it will not respond with an "ACK" if I keep sending i2c packet to it. RSTing it will fix the problem until it fails to "ACK" again. It only takes about one to two second to make it fail. I checked all the timing using scope and they looks reasonable to me. I am running less than 60KHz i2c clock.

Just wonder if you have experienced the same/similar problem.

Thanks, A3K

 

[gmarsh]

Hi Gmarsh,

I am working on my DAC project which uses CS8416 as the receiver. But I have been having problem to control it using i2c bus without error. I can change the configuration and make it run right after RST. But it will not respond with an "ACK" if I keep sending i2c packet to it. RSTing it will fix the problem until it fails to "ACK" again. It only takes about one to two second to make it fail. I checked all the timing using scope and they looks reasonable to me. I am running less than 60KHz i2c clock.

Just wonder if you have experienced the same/similar problem.

Thanks, A3K

Never experienced that; I've found the CS8416 to be more or less bulletproof.

Do you have a schematic for your design? Also, are you "bit-banging" I2C from a micro or are you using a TWI peripheral on a microcontroller? And finally, do you have I2C pullups?

 

[duddface]

CS8416 -> AD1896 -> PCM1792

Hello,

I am developing my DAC interface that would play CD format music from my PC that has a SPDI/F output. I have a few very basic questions about the implementation.

The DAC would support 24/96 format and had chosen the CS 8416 SPDIF receiver. It will be Tranny isolated(Pulse Xformer). I did not want to use the recovered clock from CS 8416 and hence to ASRC it I am using the SRC4192. My DAC would be the PCM1792.

(1) What I don't understand is the serial interface of the CS8416(SDA/CDOUT, SCL/CCLK) and PCM1792(MDO_SDA,MC_SCL). Do I need to hook these control pins up and slave it to a Micro controller based I2C bus master?? Or, can I just leave those pins unconnected ? What I really am trying to understand is what is this control interface for? We have serial audio out from CS8416 that is available in I2S format( serial audio Word clock OLRCK, serial audio Bit clock OSCLK,serial audio data output SDOUT ) that can be directly fed in to the SRC 4190 (BCKI, LRCKI and SDIN) for reclocking and finally in to PCM 1792 (Data,LRCK,BCK) directly. So what is the need for this control bus?

(2) For generating resets for the SRC4190 on power on reset can I use a simple POR circuit in case I don't have to use a Micro based I2C Bus master.


As you can guess from my questions i am a total noob in DIY Audio and would appreciate your help.

Thanks,
Ananth

 

[duddface]

Well,

I have decided to use the CS8416 in Hardware mode and PCM1794 instead of PCM1792.So no messing around with I2C bus and I am more than relieved. This should make my task a little easier. Routing in Eagle should be interesting. I am off to making the schematic symbols.

Please disregard my earlier rants.

 

[ezkcdude]

Well,

I have decided to use the CS8416 in Hardware mode and PCM1794 instead of PCM1792.So no messing around with I2C bus and I am more than relieved. This should make my task a little easier. Routing in Eagle should be interesting. I am off to making the schematic symbols.

Please disregard my earlier rants.

Your welcome?

 

[bongoman]

I'm planning on doing a CS8416 to CS8421 (ASRC) to PCM1798 using a 24.576MHz master clock.

I've been trying to get a prototype together on breadboard with an exisiting working CS8414/TDA1543 DAC by adding the CS8421 into the I2S.

No matter what settings I try on the ASRC (including passthrough and internal oscillator), I am unable to get any sound out of it.

Maybe I'm doing something really stupid here, but because I'm not using a controller I just just hold the RESET pin high, will this work?

...maybe I should start a new thread on this.

 

[duddface]

Hi EZKCDUDE,
This DAC that i am building is inspired by Peufeu's extremist DAC. I really liked his re clocking scheme and other attentions to detail. But I am following your implementation of the CS8416(Hardware mode) to SRC4190 and PCM1794. Best of both worlds you see!.