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Clock drift/sync problem in multi endpoint Roon system - with Sonic Orbiter SE


happybob
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I have a drift/sync problem in a multiroom Roon system and may have some insight on a workaround or solution but still have questions. I have a 3 Roon endpoint system. I was experiencing drift on one of the endpoints (a Soncic Orbiter SE) but then resolved the problem and the solution had nothing to do with the network but rather to make sure all DACs were asynchronous USB or directly connected to the server. But I still want to be able to use another Sonic Orbiter on another system that doesn't have a USB DAC (only toslink input).

 

Problem: Roon endpoint drifting in playback timing - i.e. getting out of sync relative to other Roon endpoints (2 of my endpoints are USB and HDMI connected directly to my MacBook Air server running Roon, the 3rd and problem endpoint was a Sonic Orbiter SE connected via Toslink to an iFi Retro 50 DAC.)

 

Solution: to switch to direct USB connection from the SOSE endpoint to the iFi Retro 50 DAC (instead of toslink connection between the same Sonic Orbiter endpoint and same iFi Retro 50 DAC). So the only variable changed was how I connected the endpoint "computer" to the actual DAC. I replicated this same problem/solution with an iFi iDSD micro DAC also.

 

Question: does the system use the DAC clocks as reference or some overall system clock or each Roon endpoint's "computer" clock? Thanks for any clarity!

 

My theory: a bit long below, but given for reference. I would like to use toslink endpoints in the future and am not sure how to do this reliably. Thanks for any further clarifications. Here's more on my theory on the resolution which aligns with what others have written in earlier posts:

 

I’ve been pondering this drift issue and realized that the level of accuracy in cheap clocks is pretty low (and the Sonic Orbiter (SOSE) for sure has a cheap clock, possibly not even a crystal oscillator, maybe just RLC - not sure). But even modestly highend crystal (or Rubidium) oscillators are far far more accurate. There are 86,400 seconds in a day. So every hour is 3600 seconds, so if my oscillator in the SOSE is 100ppm accurate (assumption), then after one hour of listening, I’d be out of sync by 1 part in 10000 of 3600 seconds - or ~1/3 of a second. This seems about what’s happening. But then I have the sense that the crystal oscillator in the iFi Retro 50 is probably a lot better than this - probably accurate to 1ppm - again an assumption but I’m guessing it may even be better than that. That means that after one hour of listening I’d be out of synch by 3 msec or perhaps much less (barely audible). I’m of course making and educated guess about the accuracy of the iFi Retro clock, but given that it has an Asynchronous USB DAC and if I connect via USB (instead of toslink which is synchronous to what’s being sent by the SOSE which gets its info from the network and then has to reclock that out via toslink), then the iFi becomes the clock reference and is likely good enough.

 

Here's the post on the Roon forum for reference: https://community.roonlabs.com/t/grouped-playback-exhibiting-clock-drift/15407/4

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I have a drift/sync problem in a multiroom Roon system and may have some insight on a workaround or solution but still have questions. I have a 3 Roon endpoint system. I was experiencing drift on one of the endpoints (a Soncic Orbiter SE) but then resolved the problem and the solution had nothing to do with the network but rather to make sure all DACs were asynchronous USB or directly connected to the server. But I still want to be able to use another Sonic Orbiter on another system that doesn't have a USB DAC (only toslink input).

 

Problem: Roon endpoint drifting in playback timing - i.e. getting out of sync relative to other Roon endpoints (2 of my endpoints are USB and HDMI connected directly to my MacBook Air server running Roon, the 3rd and problem endpoint was a Sonic Orbiter SE connected via Toslink to an iFi Retro 50 DAC.)

 

Solution: to switch to direct USB connection from the SOSE endpoint to the iFi Retro 50 DAC (instead of toslink connection between the same Sonic Orbiter endpoint and same iFi Retro 50 DAC). So the only variable changed was how I connected the endpoint "computer" to the actual DAC. I replicated this same problem/solution with an iFi iDSD micro DAC also.

 

Question: does the system use the DAC clocks as reference or some overall system clock or each Roon endpoint's "computer" clock? Thanks for any clarity!

 

My theory: a bit long below, but given for reference. I would like to use toslink endpoints in the future and am not sure how to do this reliably. Thanks for any further clarifications. Here's more on my theory on the resolution which aligns with what others have written in earlier posts:

 

I’ve been pondering this drift issue and realized that the level of accuracy in cheap clocks is pretty low (and the Sonic Orbiter (SOSE) for sure has a cheap clock, possibly not even a crystal oscillator, maybe just RLC - not sure). But even modestly highend crystal (or Rubidium) oscillators are far far more accurate. There are 86,400 seconds in a day. So every hour is 3600 seconds, so if my oscillator in the SOSE is 100ppm accurate (assumption), then after one hour of listening, I’d be out of sync by 1 part in 10000 of 3600 seconds - or ~1/3 of a second. This seems about what’s happening. But then I have the sense that the crystal oscillator in the iFi Retro 50 is probably a lot better than this - probably accurate to 1ppm - again an assumption but I’m guessing it may even be better than that. That means that after one hour of listening I’d be out of synch by 3 msec or perhaps much less (barely audible). I’m of course making and educated guess about the accuracy of the iFi Retro clock, but given that it has an Asynchronous USB DAC and if I connect via USB (instead of toslink which is synchronous to what’s being sent by the SOSE which gets its info from the network and then has to reclock that out via toslink), then the iFi becomes the clock reference and is likely good enough.

 

Here's the post on the Roon forum for reference: https://community.roonlabs.com/t/grouped-playback-exhibiting-clock-drift/15407/4

 

The USB output is not affected by the on board oscillator when you use an asynchronous DAC. The on board optical output or even an adaptive USB DAC would be affected by the on board oscillator. Most computers use a single clock to produce the on board i2s, SPDIF, and/or analog outputs. Ideally, you would have two oscillator with specific rates for audio. The Cubox we use for the Sonicorbiter SE is no different than most computers and only has one oscillator. The issue here is probably not the quality of the oscillator used, but rather the rate of the oscillator itself. Depending on the content played the speed of playback might be slightly faster or slightly slower and overtime you could get a deviation from other devices. If Roon Server and Roon Ready play a role in all this will have to be explained by them.

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The USB output is not affected by the on board oscillator when you use an asynchronous DAC. The on board optical output or even an adaptive USB DAC would be affected by the on board oscillator. Most computers use a single clock to produce the on board i2s, SPDIF, and/or analog outputs. Ideally, you would have two oscillator with specific rates for audio. The Cubox we use for the Sonicorbiter SE is no different than most computers and only has one oscillator. The issue here is probably not the quality of the oscillator used, but rather the rate of the oscillator itself. Depending on the content played the speed of playback might be slightly faster or slightly slower and overtime you could get a deviation from other devices. If Roon Server and Roon Ready play a role in all this will have to be explained by them.

 

Thanks, - this is sort of what I had determined. And I think this means unfortunately that I can't use a Sonic Orbiter for my next planned endpoint since it will only be able to connect via toslink and not USB (since the endpoint doesn't have USB DAC input at all). I could I guess get a MicroRendu and then use a USB to optical output, but that's a lot of expense and overkill and may not even work since the actual DAC would still not be Asynchronous.

 

Additionally, I was considering a SonicTransporter i5 as my Roon server, but that also would require an optical connection even to some of the existing (and new additional) endpoints I use that are now connected directly to my MacBook pro Roon server via HDMI.

 

I'm sensing that to make this multi-endpoint Roon system work, I either need Asynchronous USB DACs or to connect directly to the Roon server. Anything else (short of fancy external clock approaches) is not likely to work it appears.

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Thanks, - this is sort of what I had determined. And I think this means unfortunately that I can't use a Sonic Orbiter for my next planned endpoint since it will only be able to connect via toslink and not USB (since the endpoint doesn't have USB DAC input at all). I could I guess get a MicroRendu and then use a USB to optical output, but that's a lot of expense and overkill and may not even work since the actual DAC would still not be Asynchronous.

For something a bit cheaper, you might consider a SOSE followed by an async USB>S/PDIF converter with an independent clock. That's what I have on one of my systems (but I haven't checked for drift because each zone has a single endpoint...).

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For something a bit cheaper, you might consider a SOSE followed by an async USB>S/PDIF converter with an independent clock. That's what I have on one of my systems (but I haven't checked for drift because each zone has a single endpoint...).

 

Yes, that could work - though it seems to be getting harder and harder to find affordable USB to toslink converters. Here are two that I've found that did exist but are no longer for sale:

 

Peachtree: X1 24/192 USB to SPDIF Converter | Peachtree Audio

 

NuForce: Nuforce U192S USB to S/PDIF Converter | Hifi Pig

 

It seems most units now available have built in DACs which I don't need or want, or they're cheaper low performance units limited to 96K and/or not asynchronous. Dang...

 

I'd appreciate any recommendations!

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Yes, that could work - though it seems to be getting harder and harder to find affordable USB to toslink converters. Here are two that I've found that did exist but are no longer for sale:

 

Peachtree: X1 24/192 USB to SPDIF Converter | Peachtree Audio

 

NuForce: Nuforce U192S USB to S/PDIF Converter | Hifi Pig

 

It seems most units now available have built in DACs which I don't need or want, or they're cheaper low performance units limited to 96K and/or not asynchronous. Dang...

 

I'd appreciate any recommendations!

 

Does your DAC have any other inputs?

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Does your DAC have any other inputs?

 

Sort of, but no USB DAC inputs, just toslink, sometimes spdif coax, Ethernet/wifi and HDMI and analog inputs. I have several potential Roon endpoint destinations with this same issue. It really does appear that a simple key is the async input to keep the Roon system from drifting timewise between the various endpoints. If the time bases in the destination endpoint computers were very good then a non-syncrhonous connection via optical would be fine. But at a likely typical 100ppm accuracy, they just drift too noticeably.

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