Re: [SlimDevices: Audiophiles] Timing Jitter question
A most succinct and balanced reply. The only thing I want to add is to point out that if your DAC has a clock out then you can slave the Transporter to it, which should reduce jitter to almost zero, although is probably not quite as low as the 'internal' Transporter system. Oh plus the standard health warning: WARNING: The audibility of jitter in the low picoseconds is disputed. Other factors may affect sound quality. This thread may self-destruct in ten seconds. -- adamslim Those are my principles, and if you don't like them... well, I have others SB+, EAR V20, Living Voice OBX-R2s plus some other stuff SB3, Charlize, Harbeth HL-P3ES adamslim's Profile: http://forums.slimdevices.com/member.php?userid=7355 View this thread: http://forums.slimdevices.com/showthread.php?t=47491 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Timing Jitter question
Hello- A Slim Devices salesperson suggested I post this question, in hopes someone who knows ( has time- apparently their engineers are quite busy) can answer for all to read. The question is: does the Slimserver, or other Slim hardware/software, have a feedback chain from the hardware (that puts out the S/PDIF) to the server (which sends the music stream to the hardware)? Normal USB-DACs don't- they run asynchronously, with a PLL to keep the output bitrate at a speed that matches the incoming packet rate, so that the buffer never over- or under-runs. This results in timing jitter, as the PLL servos the output frequency back forth to accommodate the not-very-precisely-timed computer packets. It would appear that the Slim system could get around this, since they have their own hardware software. Hence there would be no real need for re-clocking equipment between the Slim device and your DAC, since the real culprit in timing jitter is that asynchronous feed PLL follower, not the inherent jitter on the oscillator (which is usually extremely low). Can anyone tell me if the Slim system works this way? If it does, I'll be in line with my $$ right away. I am particularly interested in the equipment other than the Transporter, since I already have an excellent DAC really just want a jitter-free S/PDIF output for it. Thanks to any who can post the answer (especially if it's Sean Adams, who the salesperson says reads this forum knows the answers)- Neil PS: if the answer is yes, Slim has hardware-to-software feedback so that they need no PLL, then you should put this in your product info/advertising- for audiophiles, it is a huge deal. If I knew this to be true, I'd already have ordered one (maybe more) be telling my friends. -- lork lork's Profile: http://forums.slimdevices.com/member.php?userid=17438 View this thread: http://forums.slimdevices.com/showthread.php?t=47491 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Timing Jitter question
lork;300871 Wrote: Normal USB-DACs don't- they run asynchronously, with a PLL to keep the output bitrate at a speed that matches the incoming packet rate, so that the buffer never over- or under-runs. This results in timing jitter, as the PLL servos the output frequency back forth to accommodate the not-very-precisely-timed computer packets. I'm afraid you have this backwards. The whole idea of an asynchronous interface is that there is NO connection between the incoming data rate, and the outgoing. An asynchronous interface does not require a PLL, and if properly implemented, will not transmit jitter from the incoming stream to the outgoing. A SPDIF connection is synchronous, and requires a PLL to extract the clock from the data stream. This type of interface has the potential for noise and jitter in the incoming data stream to affect the PLL's output jitter. lork;300871 Wrote: It would appear that the Slim system could get around this, since they have their own hardware software. Hence there would be no real need for re-clocking equipment between the Slim device and your DAC, since the real culprit in timing jitter is that asynchronous feed PLL follower, not the inherent jitter on the oscillator (which is usually extremely low). The Slim system is totally asynchronous. The data arrives in packets over the ethernet, and is loaded into a memory buffer, and then clocked out by the main system clock (which is not a pll). When the buffer gets low, the hardware requests a new packet and thus ensures it never runs out. As such, the total jitter is the sum of the Crystal controlled clock, and the associated clock distribution (pcb traces, glue logic etc), which can be tightly controlled. While this holds true for the slims internal DAC, as soon as you go outboard, via the SPDIF interface, your external DAC must use it's clock recovery circuit and PLL to re-generate the clock. So the potential for increased jitter exists once again. Is a re-clocker required with an SB3? I'd say no, it's inherent jitter is very low, so unless your external DAC has a poorly designed clock recovery circuit, it shouldn't be necessary. The jitter from a transporter is even lower, but it's DAC is very good, so there's little reason to go outboard. Cheers, Dave -- DCtoDaylight DCtoDaylight's Profile: http://forums.slimdevices.com/member.php?userid=7284 View this thread: http://forums.slimdevices.com/showthread.php?t=47491 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Timing Jitter question
Right, what Dave said. -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=47491 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] Timing Jitter question
You are quite correct- I think the term I should have used was adaptive rather than asynchronous. Much appreciate both the very complete ( helpful) answer and also the lack of flaming over my ignorant/incorrect use of the term. Best- Neil -- lork lork's Profile: http://forums.slimdevices.com/member.php?userid=17438 View this thread: http://forums.slimdevices.com/showthread.php?t=47491 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
