Using SYNC HD with Two HD Omni systems.

[davidhermiston]

Trying to run/lock two systems with HD Omni units, and a SYNC HD for a dual mix setup, rather than Satellite. Can't find much info on locking two systems together with the sync hd.

The main system connected to the SYNC HD is an HDx system. Serial cable is connected, Pro Tools recognizes the Sync HD with the OMNI, Loop sync is patched from the Sync HD > OMNI 1 > OMNI 2> Back to SYNC HD. All seems good?

The second system is HD Native with an HD OMNI. On this second system with the (HD OMNI 2). I can only see Internal/wordclock as an option for clocking. No sign that Loop sync is working, or that it can somehow recognize the SYNC HD...

I'm hoping someone might have some insight in order to save me a few more hours of troubleshooting.

[LukeHoward]

Originally Posted by davidhermiston

Trying to run/lock two systems with HD Omni units, and a SYNC HD for a dual mix setup, rather than Satellite. Can't find much info on locking two systems together with the sync hd.

The main system connected to the SYNC HD is an HDx system. Serial cable is connected, Pro Tools recognizes the Sync HD with the OMNI, Loop sync is patched from the Sync HD > OMNI 1 > OMNI 2> Back to SYNC HD. All seems good?

The second system is HD Native with an HD OMNI. On this second system with the (HD OMNI 2). I can only see Internal/wordclock as an option for clocking. No sign that Loop sync is working, or that it can somehow recognize the SYNC HD...

I'm hoping someone might have some insight in order to save me a few more hours of troubleshooting.

I may be completely off base here but: I don't think Pro Tools recognises Loop Sync across systems, I think you'll need to feed ordinary WC out of the Sync I/O (or the first Omni) into the second Omni. Also if you're not doing video there's probably no value in the Sync HD.

[davidhermiston]

It does feel strange loop syncing two systems, but this is the info I was supplied with from the store I'm renting the Sync HD from. Are most people running dual mixes just using Satellite? Or perhaps in those situations each system has a sync IO and they lock the secondary system via LTC...

[LukeHoward]

Originally Posted by davidhermiston

It does feel strange loop syncing two systems, but this is the info I was supplied with from the store I'm renting the Sync HD from. Are most people running dual mixes just using Satellite? Or perhaps in those situations each system has a sync IO and they lock the secondary system via LTC...

If you want the systems to start at exactly the same place, and not drift, both systems need to be both synchronised (same position) and syntonised (same frequency). If you only do the latter, even in a Satellite Link configuration, the offset will change from one playback to the next. Here is the text from the Satellite Link guide:

All Pro Tools systems in a Satellite Link network must be resolved to a common video reference, or “house sync,” using a SYNC peripheral.

i.e. you need two SYNC HDs and a video reference generator. I don't believe it's possible to skip the video reference generator even in an audio only workflow.

It should be simpler in 2020 – it's possible to carry both position and frequency over IP or Ethernet using PTP (see SMPTE 2059, AES67, AVB/TSN, etc). This may take a generational change though, technology-wise, to make it into Pro Tools.

[LukeHoward]

One more thing: Loop Sync isn't really going to work because both systems will think they are the loop master.

If you're OK with a variable offset each time you hit play (in a Satellite Link configuration), then you can just send word clock from one Omni to the other and potentially do away with the Sync HDs (I can't remember off-hand if it's a hard requirement to have at least one).

I hope I haven't confused you further. It's worth reading both the Satellite Link and SYNC HD manuals carefully.

[Hugh-H]

Hello davidhermiston,

To hopefully add clarity and not further confuse -

Loop Sync does not carry positional information, clocking only, despite it's name. In reality it's a wc signal. It can only provide "sync", i.e. speed clock information, between devices on one system (I'll leave out that you can feed loop sync into a wc input which would break the "loop" part). So on your non-SyncHD system you can't select loop sync because one of it's devices must be master.

Clock speed sync - send wc from one system to the other and set up appropriately. They will be speed locked.

Positional lock - that depends on how accurate you need it to be. If you need the two machines to be very accurately locked all the time you'll need another Sync peripheral plus your wc signal between them. Satellite requires another Sync peripheral. However we regularly use tc over network on the Mac and it works well. Lock variations are typically under 1ms if the two systems are digitally speed locked (wc) which may be adequate depending on your program material. If it is accurate enough you set it up in Audio Midi Setup on both machines, then in PT with one as master and the other as slave, and can even use MMC if you want but it's not necessary.

Good luck,
Hugh

[JFreak]

More specifically, Loop Sync is 1x WC signal that is adjusted every time the signal gets back to the Loop Master, reducing jitter. There are white papers and technical documents that explain it in more detail if you are interested, but the point is the WC stays stable even if you have multiple interfaces.

[davidhermiston]

Thanks for all the info. It's much appreciated. I did read through the SYNC HD manual. I'll go through and read the Satellite too. I think there is a lot of confusion out there among resellers. One of the larger businesses in the area doesn't stock sync Hd units anymore since there is very little demand.

Ideally I would like to keep the systems as close as possible. The last few years we would compile the mix into one session, from two. Then Printmaster. Now they would like to print in a dual mix configuration. I have the digital out from the secondary system printing a stem in the main mix system. This isn't ideal since destructive punches will create a click since it's not locked well enough. Perhaps this isn't even possible with two sync units running.

I'll study everyone's notes and see what I can do! Thanks again.

[LukeHoward]

Originally Posted by davidhermiston

Ideally I would like to keep the systems as close as possible. The last few years we would compile the mix into one session, from two. Then Printmaster. Now they would like to print in a dual mix configuration. I have the digital out from the secondary system printing a stem in the main mix system. This isn't ideal since destructive punches will create a click since it's not locked well enough. Perhaps this isn't even possible with two sync units running.

If the systems are locked with word clock (or loop sync), they won’t drift, however they may not start at precisely the same time, even with positional information delivered over Satellite or LTC/MTC. You need a Sync HD on each system in order to synchronise the frame edge (when the LTC turns over) with the word clock edge.