Touch vs. Transporter digital output (again)

[Phil Leigh]

Interesting, I've never found a DAC that can completely eliminate jitter and I've tried a few, including a Bel Canto DAC2 (that supposedly reclocked) and my existing Meridian 568.2 that uses some clever FIFO. On both DACs, different quality digital sources sounded different, implying that neither was fully successful in eliminating jitter.

Not necessarily. Just because a DAC sounds different does not necessarily mean jitter is involved... every DAC has a slightly different filtering circuit after the DAC and a slightly different analogue output stage and so will have a signature sound of its own.

DAC's are no different to any other source component - they all have their own "take" on what the output should sound like.

[cliveb]

Not necessarily. Just because a DAC sounds different does not necessarily mean jitter is involved... every DAC has a slightly different filtering circuit after the DAC and a slightly different analogue output stage and so will have a signature sound of its own.

DAC's are no different to any other source component - they all have their own "take" on what the output should sound like.

Phil, I think you've misunderstood what Mr_Sukebe is saying. He is saying that he hears differences in output *from the same DAC* when using different SPDIF sources. So he's not comparing one DAC to another.

That said, I remain unconvinced that jitter is the cause of these differences. Too many people say that there are only two things that can possibly distinguish digital sources: the bits they deliver, and the jitter. Not so - there are two another possible sources of difference that I can think of:
a). The EMI radiated by the devices which can affect the operation of other nearby analogue circuitry.
b). Grounding topology which may allow noise to transfer between the ground planes of devices. On unbalanced devices, the ground plane becomes part of the signal (in that the actual signal is in fact the difference between the "signal" and ground). Therefore if there is any noise on the ground plane it gets interpreted as signal. (*Perfect* shunting of the ground plane to earth is of course impossible).

[Phil Leigh]

Phil, I think you've misunderstood what Mr_Sukebe is saying. He is saying that he hears differences in output *from the same DAC* when using different SPDIF sources. So he's not comparing one DAC to another.

That said, I remain unconvinced that jitter is the cause of these differences. Too many people say that there are only two things that can possibly distinguish digital sources: the bits they deliver, and the jitter. Not so - there are two another possible sources of difference that I can think of:
a). The EMI radiated by the devices which can affect the operation of other nearby analogue circuitry.
b). Grounding topology which may allow noise to transfer between the ground planes of devices. On unbalanced devices, the ground plane becomes part of the signal (in that the actual signal is in fact the difference between the "signal" and ground). Therefore if there is any noise on the ground plane it gets interpreted as signal. (*Perfect* shunting of the ground plane to earth is of course impossible).

erm yes...you are right, I misread it. Sorry Mr Sukube.

I think your item B is of great interest, plus contamination of the mains from RFI.


I've been playing with my RFI sniffer. Some interesting results so far, but it's too early to form any definite conclusions.

I'm in the processs of switching to shielded mains cables... (I already had them on half my equipment).

One thing - the amount of RFI from the mains lead of my (LCD) TV in standby is worrying...

[mswlogo]

Phil, I think you've misunderstood what Mr_Sukebe is saying. He is saying that he hears differences in output *from the same DAC* when using different SPDIF sources. So he's not comparing one DAC to another.

That said, I remain unconvinced that jitter is the cause of these differences. Too many people say that there are only two things that can possibly distinguish digital sources: the bits they deliver, and the jitter. Not so - there are two another possible sources of difference that I can think of:
a). The EMI radiated by the devices which can affect the operation of other nearby analogue circuitry.
b). Grounding topology which may allow noise to transfer between the ground planes of devices. On unbalanced devices, the ground plane becomes part of the signal (in that the actual signal is in fact the difference between the "signal" and ground). Therefore if there is any noise on the ground plane it gets interpreted as signal. (*Perfect* shunting of the ground plane to earth is of course impossible).

You points on A and B are correct. But you'd have to have one really F'd up setup for those to occur (and have cables significantly change it). I have tons of Meridian boxes and never found a digital cable to make any difference.

I've done similar experiments that I posted and recorded the signal right at the digital tape output of 861 to assure data was perfect from rip to processor.

[cliveb]

You points on A and B are correct. But you'd have to have one really F'd up setup for those to occur (and have cables significantly change it). I have tons of Meridian boxes and never found a digital cable to make any difference.

Meridian gear is top-notch stuff, so if it happens to be very immune to noise on the ground plane and deals with incoming jitter well, that would be no surprise. Some of the "boutique audiophile" gear that people say demonstrate differences in digital cables is probably not so well engineered.

But to put things in context: I personally have never heard any significant differences between digital transports or cables. Any differences that I think I may have detected were most likely imagined, because they were sighted comparisons.

[Themis]

Better yet. Why don't you read the actualy thread I explained myself in rather than read it here out of context.

http://forums.slimdevices.com/showthread.php?t=79245

I replied to this thread with a LINK to that because someone asked if I had posted information about some testing further up in this thread.

So, if I read properly, you assume there are two types of jitter : peak-to-peak and clock drift jitter.
Then, you come to the conclusion that, as clock drift cannot be affected by the cable and the peak-to-peak is not affected in the measures, then the cable makes no difference.

Yes, but : how do you interpret what Nugent says ? : http://www.positive-feedback.com/Issue43/jitter.htm