achri-d;253654 Wrote:
> Yes, when I used a dCS Delius as external clock to Transporter this
> works as well. Indeed, the 44.1 sounds speed up. I also tried to run 96
> like this. And then of course slows down. Notice, in this case I used
> the analogue outputs. If I turn
> off the clock the Transporter goes silent (in my system).
If that is the case then it means your transporter is definitely
recovering the 48KHz signal from the word clock input correctly.
A further test you could do would be to put the DAC into slave (normal
s/pdif clock) mode, and verify that it is able to play the s/pdif
signal coming from the Transporter while the Transporter is being fed
by the 48KHz external clock.
If this works, then you have now verified all of the following:
1. The external clock is generating an acceptable 48KHz word clock
2. Transporter's word clock input circuitry is able to electrically
receive this clock
3. Transporter's s/pdif output is indeed being derived from the word
clock input, and not it's internal clock.
4. All of Transporter's internal clcok paths are functioning
correctly (otherwise the DAC and/or s/pdif would not work).
5. The s/pdif connection (which is being used here only as a data
connection) is working correctly, and there is sufficient signal
integrity for the DAC's s/pdif receiver to be able to recover a data
stream from it.
This means the only possible explanation, given all the information at
hand, is that your DAC does not function when given a 48KHz word clock
input and a s/pdif signal synchronized to that clock. (A bizarre
configuration anyway, as I've noted).
> Well, I use a system where the dCS Paginini clock is used to syncronize
> the Transporter and a dCS Paganini DAC. The DAC receives S/PDIF data
> from the Transporter and does not need to decode the clock from the
> data - as is also the situation in master mode.
Yes I am aware that the clock is coming from the word clock input and
not the s/pdif. The point is that doing the former is definitely far
worse than using an internal oscillator directly, and probably even
worse than recovering the clock from s/pdif.
>
> 1) You may use a DAC in master mode to feed clock to the Transporter. I
> used to do this with a dCS Delius, and have tried the same with the dCS
> Paganini DAC.
>
And this also works at 48KHz, right?
>
> 2) Even better is to syncronize both the DAC and the Transporter to an
> external clock - if this clock is of higher precision than the one in
> the DAC.
>
No, this is where you are very wrong. I have already explained why from
a theoretical standpoint, but to put it another way, which do you expect
will have more jitter:
- A crystal oscillator running at 12.2880 MH, directly driving the DAC
Or
- A crystal oscillator running at 12.2880 MHz
- driving either a synchronous counter or a series of flip-flops, to
divide that signal down to 48 KHz
- then feeding this signal through some transmission circuit to a BNC
connector
- coupling that signal into a cable
- feeding it down the cable
- getting it into another connector at the other end of that cable
- driving that signal into a PLL circuit which multiplies the word
clock signal back up to 12.2880 Mhz
- feeding the output of that PLL into the DAC chip.
> Sorry, your statement is wrong - at least as I see this issue and as I
> understand your statement. I use a dCS Paganini clock that syncronizes
> a dCS Paganini DAC and the Transporter.
Well, one of us clearly is wrong. I have explained why I am right.
Could you point out the flaw in my reasoning?
Otherwise if you will not accept the theory, we would have to settle
the question empirically. That would require us to meet up in my lab
and you will need to bring all your equipment. :)
Also, again, have you contacted dcs? They have a technical paper about
jitter on their site so it is clear that someone there has an
understanding of these issues. I have no doubt that the author of that
paper would agree with me on this point. Their marketing person, on the
other hand, might tell you that you additionally need the external
$$$$$$$ clock in order to get the best sound.
>
> Yes, with a dCS Delius - 44.1 works but 48kHz does not work. The dCS
> Paganini works well at 44.1 but does not output 48 so this I can not
> try (that's why I have the Paganini clock - which outputs also 48).
Well, that is odd but given that the Transporter clearly is being
clocked by the 48KHz word clock (because the analog outputs are
working) it still points to an issue with the dcs.
>
> I have the user's manual of my dCS units and they explain the issue in
> details.
OK... so is there anything I'm missing? I looked on their web site and
they do not have the manuals posted for current products.
> Further, I have tried to contact the support at slimdevices - may be I
> did not succeed to post it properly(?) - and they haven't provided any
> technical answer yet.
They would just forward the question to me.
--
seanadams
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