Non oversampling 2xPCM1702 feed by I2S experiment results - Page 2

Jocko Homo · 25th March 2002, 10:36 PM

Ahem.......I believe you meant DF1702. TI no longer lists it. Looked the same, probably sounded the same.

Anyway.......all these newer filters have NO ultrasonic crap. Now look at the SAA7220.........UGH!

I suspect part of the reason is that it has a zero in the response to cancel out of the (3) poles in the analog section.

Jocko

rfbrw · 25th March 2002, 11:03 PM

Jocko,
Two things.
What dac did you use with the DF1704? The other
thing is your preference for digital filters. Is it based on the belief that if the numbers are right the sound must be right and if you dont it like the too bad. Or is it down to listening ?

ray

ps. DF1700 => SM5813

ergo · 26th March 2002, 06:53 AM

Here is the interface schematic I used for I2S conversion

Ergo

capslock · 26th March 2002, 08:22 AM

Hi Ergo,

I believe there is one cosmetic flaw: the L and R signals will not appear at the outputs at the same time. Rather, there will be a skew of 23 microseconds. I doubt that this is audible, it corresponding to one speaker being advanced by 7 mm, but if it does not hurt my purist ear, at least it hurts my purist eye...

Greetings,

Eric

tschrama · 26th March 2002, 08:34 AM

Hi Ergo....

I hope you can help me out a bit... I just got myself a couple of PCM1702 chips.. I really really want to get more into digital design and was aiming for a zero oversampling DAC with the PCM1702 .. I'm not aiming for High End performance (yet) ... now what do I need besides the PCM1702?

Could you explain a bit or maybe give me a link to a Digital Audio introduction?

Thanks for this great thread! It is very informative stuff for me...

greetings,
Thijs

Elso Kwak · 26th March 2002, 08:38 AM

Hi All,
The Analog Drevices Application 207 note takes care of that using a dual D-type flip-flop and a quad NAND gate.
The two stereo channels separation is accomplished by the so called "stopped clock" technique i.e. the bitclock is stopped during loading the data to the DAC of one channel (don't remember which one). Both channels are latched simultaneuously as they share the same LATCH. No timing difference between left and right channel.
Unfortunately the Application Note is no longer on the AD website but I can send the PDF file by email if in need.

tschrama · 26th March 2002, 09:00 AM

Hi Elso Kwak,

I would very much like to read that application note. Could you send one to me?

Greetings,

Thijs (t.schrama@lumc.nl)

Jocko Homo · 26th March 2002, 11:45 AM

rfbrw:

DF1700.........DF1702.......whatever. Getting too old to keep all these numbers in my head.

I used the DF1704 with the PCM1704.

My belief is based on listening (mine and others), and my spectrum analyzer.

Jocko

rfbrw · 26th March 2002, 06:49 PM

Jocko,
I am sort of in the middle with this o/s no o/s debate as I am still not sure. The thing is the non o/s camp are no less adamant that they are right. Whatever,my way out is finish off my dac with a digital filter (NPC5843) that can be switched in and out of circuit.

Re: AN207
AN 207 IS available on the ADI website at http://www.analog.com/library/applic...udio/AN207.pdf
Alas AN207 will not work with the PCM1702 or PCM63 as is.
ray.

Jocko Homo · 26th March 2002, 06:55 PM

No problem with being open-minded. I just can't see the point.

I personally don't like the sound of tubes, but I understand the appeal. I suspect the non-o/s crowd really doesn't like digital, which is fine. Then they should stick to vinyl and tubes, and we will all be happy.

See other posts today about slew-rate & op-amps in I/Vs. Might explain my adamant postion.

Jocko

26th March 2002, 08:22 AM	#14
capslock diyAudio Member Join Date: Feb 2002 Location: Germany	little flaw Hi Ergo, I believe there is one cosmetic flaw: the L and R signals will not appear at the outputs at the same time. Rather, there will be a skew of 23 microseconds. I doubt that this is audible, it corresponding to one speaker being advanced by 7 mm, but if it does not hurt my purist ear, at least it hurts my purist eye... Greetings, Eric

26th March 2002, 08:38 AM	#16
Elso Kwak Banned Join Date: Dec 2001 Location: Zamboanga, City of Flowers, Mindanao	I2S Philips format conversion to Sony/Burr-Brown Hi All, The Analog Drevices Application 207 note takes care of that using a dual D-type flip-flop and a quad NAND gate. The two stereo channels separation is accomplished by the so called "stopped clock" technique i.e. the bitclock is stopped during loading the data to the DAC of one channel (don't remember which one). Both channels are latched simultaneuously as they share the same LATCH. No timing difference between left and right channel. Unfortunately the Application Note is no longer on the AD website but I can send the PDF file by email if in need.

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25th March 2002, 10:36 PM	#11
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	Ahem.......I believe you meant DF1702. TI no longer lists it. Looked the same, probably sounded the same. Anyway.......all these newer filters have NO ultrasonic crap. Now look at the SAA7220.........UGH! I suspect part of the reason is that it has a zero in the response to cancel out of the (3) poles in the analog section. Jocko

25th March 2002, 11:03 PM	#12
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	Jocko, Two things. What dac did you use with the DF1704? The other thing is your preference for digital filters. Is it based on the belief that if the numbers are right the sound must be right and if you dont it like the too bad. Or is it down to listening ? ray ps. DF1700 => SM5813

26th March 2002, 08:34 AM	#15
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	Hi Ergo.... I hope you can help me out a bit... I just got myself a couple of PCM1702 chips.. I really really want to get more into digital design and was aiming for a zero oversampling DAC with the PCM1702 .. I'm not aiming for High End performance (yet) ... now what do I need besides the PCM1702? Could you explain a bit or maybe give me a link to a Digital Audio introduction? Thanks for this great thread! It is very informative stuff for me... greetings, Thijs

26th March 2002, 09:00 AM	#17
tschrama diyAudio Member Join Date: Jul 2001 Location: The Netherlands	Hi Elso Kwak, I would very much like to read that application note. Could you send one to me? Greetings, Thijs (t.schrama@lumc.nl)

26th March 2002, 11:45 AM	#18
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	rfbrw: DF1700.........DF1702.......whatever. Getting too old to keep all these numbers in my head. I used the DF1704 with the PCM1704. My belief is based on listening (mine and others), and my spectrum analyzer. Jocko

26th March 2002, 06:49 PM	#19
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	Jocko, I am sort of in the middle with this o/s no o/s debate as I am still not sure. The thing is the non o/s camp are no less adamant that they are right. Whatever,my way out is finish off my dac with a digital filter (NPC5843) that can be switched in and out of circuit. Re: AN207 AN 207 IS available on the ADI website at http://www.analog.com/library/applic...udio/AN207.pdf Alas AN207 will not work with the PCM1702 or PCM63 as is. ray.

26th March 2002, 06:55 PM	#20
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	No problem with being open-minded. I just can't see the point. I personally don't like the sound of tubes, but I understand the appeal. I suspect the non-o/s crowd really doesn't like digital, which is fine. Then they should stick to vinyl and tubes, and we will all be happy. See other posts today about slew-rate & op-amps in I/Vs. Might explain my adamant postion. Jocko

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