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#1
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P. 22 of the HD User guide has an excellent diagram showing how to set up loop sync with an Hd3 system. However, it doesn't show how to set up an external master clock.
System: 1. HD core, 2 HD accel cards (HD3) 2. Black Lion Audio MK3 for master clock using canare word click cable 3. Two 96ioanalog, two 192io all analog 96io connected to HD core and daisy chained to other 96 io, 192io connected to accel card and then daisy chained to 192io Do I send external word clock to each interface or only one? Do I then loop sync all interfaces as shown on p 22 |
#2
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Avid does not make it easy to externally clock all the hardware the way it should be done. Ideally, you would run to the external in on each interface so there’s only one phase lock loop between the master clock and each interface clock. You can do this, but the interfaces do not consistently maintain being set to their individual clock ins. Opening sessions, changing sample rates, etc will eventually cause an interface to revert so you’ll constantly need to check the hardware setup and look at the external clock indicators on the interfaces to be sure their all set correctly. To make this work you just select each interface in the hardware setup and set it to sync to its’ own word clock input.
It would be easier to only clock the first interface from the BLA and rely on loop sync to handle the rest. Here’s a possible solution if you only ever use 44.1 and 48K sampling rates. Loop clock is base clock. Base clock is always either 44.1 or 48K even when running at HD sampling rates. I once set up a system where the BigBen went to the word input on the first interface, and then the loop sync input on the second interface with all the other loop cables properly in place. This made for a single PLL in each clock connection, the clock cables were properly terminated, and only the first interface had to be set to sync to word clock in. On the other hand, if you want to be working at 96K, this won’t work for you. Sent from my iPhone using Tapatalk
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James Cadwallader Mac Studio, 64GB RAM, 1 TB SSD, Glyph 2TB USB3 HDD, OWC drive dock, Mac OS Monterey 12.6.8 Pro Tools Ultimate 2023.9, HD Native, Focusrite Red 8Pre Presonus Faderport, Pro Tools | Control |
#3
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Avid could fix this issue if they just made clocking part of the system setup instead of putting this in session setup. That and making their warning message of not having valid clocking alert for all interfaces and not just the first one (gives people a false-sense of security when they don't get that error message but it only checks the first interface)
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Pro Tools Ult 2024.10.2, HDX 2, MTRX/SPQ, SyncHD, DNxiQ, RME BBF Pro + MADIface Pro • S1 x 2, Fire Max11 x 2, Dock, iPad Air5 • Mac Mini 14,12, 12 core, macOS 14.7.2 • RAM 32GB, SSD 4TB, GPU 19 core • QNAP TVS-872XT 148TB TB3 Last edited by BScout; 01-02-2025 at 05:41 PM. |
#4
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As per the HD User Guide, I have connected the above for Loop Sync using 75 ohm BNC coax cable.
Currently, I have high quality word clock cable going OUT from your BLA MK3 to each device (scenario 1) QUESTION: Is this Scenario 1 the proper configuration, or do I daisy chain all of the devices from ONE BNC OUT from the BLA MK3, terminating on the last device? This second scenario 2 seems counter-intuitive since the BLA MK3 has 6 ports, enough for all of my devices, and one would think each device receiving a word clock from the external master clock directly, rather than being passed through a daisy chain, would intuitively seem to give a better signal. Last edited by maximumimpactmedia; 12-03-2024 at 02:15 PM. |
#5
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Why are you worrying about any of this? Can you hear any difference with the claimed better word clock?
Be careful over-worrying about fancy "word clock" cables here and paying too much for cables, any 75 ohm video/digital cable with BNC connectors should be fine. I have my own biases for high-spec Belden cable here, largely for flexibility and make sure they are using 75 ohm BNC connectors but they are not expensive cables made by Blue Jean. If you wanted to improve sonics, replacing some or all the 96 IOs or even 192 IOs with HD I/O might be more effective. |
#6
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#7
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Thank you all for your interest and assistance.
This legacy system is one that we can afford. We are a 501c3 nonprofit. Since today is Giving Tuesday, perhaps you would consider donating the equipment that you speak of including a PT subscription. Amongst others, we train autistic students to be audio engineers. Otherwise, I am looking for advice about the system that we HAVE. |
#8
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If money is tight I would not have purchased the Black Lion Audio MK3 for master clock and Canare cables and just run this with Loop sync. Avid did a pretty good job with loop sync to make it easy to use and even with a 96 IO it delivers pretty good low jitter clocking performance. All this worry about external master clocks is likely a distraction for your students and users. To make best use of what you have I would pull open a drawer throw this stuff all in there and don't worry about it every again, or maybe just sell that on EBay for a few hundred dollars. That is where it would live if this was my system and somebody had given that to me. If you need clock distribution outside of the loop sync environment that that may be a very different story.
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#9
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You either do loop sync or your do external clock. You do not do both and you do not hook both sets of cables up.
Pro Tools has a hard time with that. If both cable sets are hooked up, Pro Tools will default to loop sync. I've already stated what you should be doing for external clock. And Darryl is right, if you are a nonprofit, sell the BLA clock. It wasn't a good purchase and gets you nothing (and makes things more complicated.) And all 75 ohm cables for word clock are the same if they use 75 ohm terminators. There's nothing special about word clock. It's a square wave analogue pulse. The device being clocked just needs to know when it gets a peak value of that wave. It doesn't get better with more expensive cables. Only time I put master wordclocks into use is if I have multiple Pro Tools systems to keep in sync (pretty standard in post-production to have 3 Pro Tools systems) or I have external digital hardware that needs to be integrated (since those don't use loop sync)
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Pro Tools Ult 2024.10.2, HDX 2, MTRX/SPQ, SyncHD, DNxiQ, RME BBF Pro + MADIface Pro • S1 x 2, Fire Max11 x 2, Dock, iPad Air5 • Mac Mini 14,12, 12 core, macOS 14.7.2 • RAM 32GB, SSD 4TB, GPU 19 core • QNAP TVS-872XT 148TB TB3 |
#10
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QUOTE: "Only time I put master wordclocks into use is if I have multiple Pro Tools systems to keep in sync (pretty standard in post-production to have 3 Pro Tools systems)"
How do you set up multiple independent systems to have one master clock, when the interfaces in each system need to be loop synced? We have our current TDM system; and am building another HDX PCIe-based system as you suggested. I am assuming that the interfaces in this HDX-based system also need to be loop synced. Last edited by maximumimpactmedia; 12-19-2024 at 05:59 AM. |
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