does AES/EBU help if i implement reclock?

[Guido Tent]

I think it's not ony a problem of the chip but also from the incoming SPDIF signal. But as the SPDIF receiver is only able to attenuate jitter above its cutoff frequency of about 30 kHz (I think so, but I've got no datasheet here at home). jitter below 30 kHz is directly fet through the receiver.

On the other side the jitter also changes when switching between the two different phase detectors in the CS8416. This shows that the CS8416 has an influence on the jitter performance. If I'd knew this before I'd better use the AKM SPDIF receiver...

It is about 20kHz. So everything you put in, you get out, included data related jitter, that is why you measure 5ns (what BW by the way ?).

therefor:
- The SPDIF jitter should be as low as possible from the beginning
- A cascaded PLL should take care of the rest. It should be slow.

best

 

[stolbovoy]

>>Is it on the format specs? If some of ADCs have 20kHz LPF - it is design feature, IMHO.
No, the filter must be there as a part of an overall circuit.

I did not question need of LPF, I just stated that cut off frequency can be anything in 20.0-22.05 range. Anyway it is offtopic.

The transient behavior of the switch produces a multitude of various harmonics. When you look at the spectral content of the image, you will see those harmonics extending pretty much everywhere. The anti-imaging LP filter works to reduce that unwanted spectra. Naturally that filter needs space to work.

Instead of zero-order-hold we have a different function. Ideal zero-order-hold has pretty wide spectra of harmonics anyway.
In case this behavior adds some additional nonlinearity, it will manifest itself in 0-22.05 band anyway. I don’t expect significant performance decrease because of it.

My point was that a few kHz available, as in the case of non-oversampling DAC, is simply not enough to attenuate the unwanted spectra to the tune of 16-bit precision or about 96 dB. Well, actually a little less if you account for the zero-order hold.

Typical NOS DAC doesn’t have dedicated LPF in analog path.

>Original "data" is a sound of cymbal, flute, etc. It is not band limited.
>And if you cut part of the original spectra - you just added an error equal to
>negative inversed A/D LPF frequency response applied to this original signal
>which is not band limited.

Again, this is not so. The data is band-limited by the A/D converter circuitry. In fact the anti-aliasing filter is the very device the limits the frequency content of the data. I agree that the cymbal, or whatever the tone may be, might extend past the 20 kHz. Naturally we don’t care, - we can’t hear it anyway, unless you are 16 and sitting in the lotus position…Damn, I can’t hear anything past 17 kHz!

I thought about sound prior to mike as original "data". Again, I don’t argue that ADC should have LPF with cutoff frequency <= Fs/2. I argue only with taking data stream after ADC as the reference.

As one friend of mine said “I can’t near tones past 18êÍz, but I can hear absence of them”. Personally I clearly prefer 24/96 to 16/44.1 and probably mostly not because 16 vs 24 part.

Its ok, I get confused by all this terminology just as well. Anyway, as I pointed out above, you cannot get away from anti-imaging requirement on the D/A side. It is just not possible to recover the signal that the sound engineer heard during the recording process without it.

Don’t recover signal, recover sound.

Personally, I’m not NOS admirer, although I listened to Audio Note DACs and found their sound pretty attractive.

 

[bocka]

when stating 1 mV, what BW are you refering to ?

About 10Hz for the second PLL. The BW for the VCXO is much higher indeed (some 10kHz typical), so noise figures above the cutoff frequency (where ever they induced) results in higher jitter.

So everything you put in, you get out, included data related jitter, that is why you measure 5ns

Yes, it's my transport (a not so cheap Perreaux CDP1 and a low cost Mustek DVD Player both SPDIF coax), another transport (Denon MD-Player TOSLINK) showed much lower jitter.

 

[jwb]

There are twisted pair cables designed for data transmission, that would work well if the proper connector was used. But sourcing them will be a problem

That's an odd claim. The whole planet is overrun with a perfectly suitable cable: category 5 (5e, 6) unshielded twisted pair wire with modular plugs. Operates perfectly well at 350MHz with suitable cross-talk and reflection properties even at 100 meters. Pennies per foot.

 

[Jocko Homo]

Yes, of course it works. But you should know that jitter affects sound more than it affects data.

The cables that I am refering to were designed for harsher environments. All we had back then, but they were rugged, and worked. And I would bet better than the CAT5 cable used everywhere now.

Also............we used lots of pre-equalisation on twisted pairs back then. Not sure what the FCC would have to say about that without a lot of screening. The cables we used did have such measures.

Jocko