1541 clock frequency

Bernhard · 20th April 2004, 10:35 PM

Hi,

does the clock frequency have to be the weird 11.2896 MHz ?

Why is it the same for os and non os ?

Does the quality of the clock depend from the cristal quality ?

Bernhard

TDA1540 · 20th April 2004, 10:42 PM

The 1541 does not use 11,289MHz.

The 7210 and 7220 do.

guido · 20th April 2004, 11:21 PM

BCK:

non os (output 7210/7310)

44.1 kHz samplefreq * 32 bits/sample * 2 left/right = 2.8224 MHz.

4 x os: (output 7220)

4 * 44.1 *1000 * 16 (!) * 2 = 5.6448 MHz.

The 7220 needs the double freq for some reason (probably to control the in/out latches it needs more flanks), so thats
11.2896.

Jocko Homo · 21st April 2004, 06:37 AM

Philips uses 256 * Fs, or 11.2896 MHz.

Yeah, the oscillator is in the filter, which is a bad idea form the jitter point of view. But you either feed it 2.8224 or 11.2896 MHz.......regardless of where the actual oscillator is.

The crystal is not as important as the supply feeding the oscillator circuit, and the oscillator itself. Once you have all those porblems addressed, you can start looking into better crystals...which will be expensive and diminishing returns.

Jocko

Bernhard · 21st April 2004, 06:49 AM

Ok, it's not going with another frequency, in any case the crystal has to be 11,2896 ?

Jocko Homo · 21st April 2004, 06:59 AM

Yes.

Digital filters/DACs/SPDIF RXs/etc. work on:

192 * Fs
256 * Fs
384 * Fs
512 * Fs

The middle two bring the most common.

Now..........if you have a BB DF1704, and feed it 384 * Fs, it outputs 192 * Fs. But (o/s) CDPs use those two frequencies.

SACD......DVD...etc.......don't even ask. It is not so simple.

So.........be glad CDPs use only 2 "weird" frequencies.

Jocko

RR · 21st April 2004, 09:57 PM

Quote:

Originally posted by guido
BCK:

The 7220 needs the double freq for some reason (probably to control the in/out latches it needs more flanks), so thats
11.2896.

Yes, I2S use to be 32 bits per channel in each word. Then it can acommodates data with more than 16 bits resolution. I think that this is standard but I'm not really sure.

Roberto

RR · 21st April 2004, 09:59 PM

Quote:

Originally posted by RR

I2S use to be 32 bits per channel in each word.

Ooops, I meant 32 clock pulses.

guido · 21st April 2004, 11:17 PM

Quote:

Originally posted by RR

Yes, I2S use to be 32 bits per channel in each word. Then it can acommodates data with more than 16 bits resolution. I think that this is standard but I'm not really sure.

Roberto

No I2S can be any wordlenght!

7210: 32 (16 bits not used)
7220: 16
cd-pro output: 24 (think i read that somewhere).

20th April 2004, 10:35 PM	#1
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	1541 clock frequency Hi, does the clock frequency have to be the weird 11.2896 MHz ? Why is it the same for os and non os ? Does the quality of the clock depend from the cristal quality ? Bernhard

20th April 2004, 11:21 PM	#3
guido diyAudio Member Join Date: Mar 2002 Location: diepe zuiden	BCK: non os (output 7210/7310) 44.1 kHz samplefreq * 32 bits/sample * 2 left/right = 2.8224 MHz. 4 x os: (output 7220) 4 * 44.1 1000 16 (!) * 2 = 5.6448 MHz. The 7220 needs the double freq for some reason (probably to control the in/out latches it needs more flanks), so thats 11.2896. __________________ GuidoB

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20th April 2004, 10:42 PM	#2
TDA1540 diyAudio Member Join Date: Feb 2004 Location: Ehv	The 1541 does not use 11,289MHz. The 7210 and 7220 do.

21st April 2004, 06:37 AM	#4
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	Philips uses 256 * Fs, or 11.2896 MHz. Yeah, the oscillator is in the filter, which is a bad idea form the jitter point of view. But you either feed it 2.8224 or 11.2896 MHz.......regardless of where the actual oscillator is. The crystal is not as important as the supply feeding the oscillator circuit, and the oscillator itself. Once you have all those porblems addressed, you can start looking into better crystals...which will be expensive and diminishing returns. Jocko

21st April 2004, 06:49 AM	#5
Bernhard diyAudio Member Join Date: Apr 2002 Location: Munich	Ok, it's not going with another frequency, in any case the crystal has to be 11,2896 ?

21st April 2004, 06:59 AM	#6
Jocko Homo Banned Join Date: Feb 2002 Location: As far from the NOSsers as possible	Yes. Digital filters/DACs/SPDIF RXs/etc. work on: 192 * Fs 256 * Fs 384 * Fs 512 * Fs The middle two bring the most common. Now..........if you have a BB DF1704, and feed it 384 * Fs, it outputs 192 * Fs. But (o/s) CDPs use those two frequencies. SACD......DVD...etc.......don't even ask. It is not so simple. So.........be glad CDPs use only 2 "weird" frequencies. Jocko

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