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Word Clock suggestions - 4k / 192khz Workflow in a large Orchestral Facility
Old 7th July 2020
  #1
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Word Clock suggestions - 4k / 192khz Workflow in a large Orchestral Facility

Please suggest the best Master word clock, that goes up to 192Khz, has 4k Video black burst and sufficient star-distribution via BNC / XLR.

It need not be one unit, it can be a combination to achieve the top.

The usage is to have a Master clock in a large (mostly digital) Orchestral recording facility, that can well distribute WC in all formats to several devices. 4k video recording/streaming and 4k video playback from Protools will also need to be considered.

Thank you.
Old 8th July 2020
  #2
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https://rosendahl-studiotechnik.com/nanosyncs.html

For the record, "black burst" is baseband video, not 4K. But that doesn't matter as all video gear will take black burst.

HD tri level sync hasn't totally caught on.
Old 8th July 2020
  #3
Gear Maniac
 
Mr P's Avatar
 

If it is a genuinely large facility, you will need distribution amps rather than simply a high output master clock. Brew is correct that your 4k video stuff will still sync off black burst just fine, unless it is IP video gear in which case it may need a PTPv2 master (and your getting into much more complicated territory).

Since you are talking facility wide synchronization, what other requirements do you have? Does it need to sync to GPS? Do you need timecode? Do you need NTP for server synchronization or PTP for dante/aes67? On the video side do you only need black burst or do you require Trilevel as well? Test patterns? Redundancy? Remote management?

We use Telestream (Tektronix) SPG8000a's with a change over unit and DAs. It is good, but without knowing the answers to the above questions its hard to know if its appropriate or overkill; it ain't a cheap solution - but if you answer yes to most of the above, it or something equivalent is what you are after... Never mind this unit wont do 192K. But worth thinking about which other requirements you may have for your sync generator.
Old 8th July 2020
  #4
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Quote:
Originally Posted by Mr P View Post
If it is a genuinely large facility, you will need distribution amps rather than simply a high output master clock. Brew is correct that your 4k video stuff will still sync off black burst just fine, unless it is IP video gear in which case it may need a PTPv2 master (and your getting into much more complicated territory).

Since you are talking facility wide synchronization, what other requirements do you have? Does it need to sync to GPS? Do you need timecode? Do you need NTP for server synchronization or PTP for dante/aes67? On the video side do you only need black burst or do you require Trilevel as well? Test patterns? Redundancy? Remote management?

We use Telestream (Tektronix) SPG8000a's with a change over unit and DAs. It is good, but without knowing the answers to the above questions its hard to know if its appropriate or overkill; it ain't a cheap solution - but if you answer yes to most of the above, it or something equivalent is what you are after... Never mind this unit wont do 192K. But worth thinking about which other requirements you may have for your sync generator.
Dear Mr.P,

Yes, it is genuinely a large facility. Yes, absolutely agree that the distribution has to be rock solid as well.

Yes, GPS sync would be needed, and yes to Timecode as well. Yes we need NTP for server Synchronization and PTP for Dante as well. Trilevel sync for Video will be needed, as its a remote operable multicam facility, that needs to synched and live-casted. Test patters, Redundancy and remote management are not key requirements.

Thank you for your detailed questions.
Old 8th July 2020
  #5
Gear Maniac
 
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There is probably enough yes's there that looking at the sync generators aimed at the broadcast market is worthwhile. However 192Khz isn't really a thing in broadcast, so that may become the sticky part of the problem. Apart from the Tektronix unit, Evertz, Ross and Trilogy all do sync generators that I would expect to do most or all of this.

With regards to the Dante stuff I think you have three options
(a) find a sync generator that does PTP that can be the master clock for your Dante network. This will be much easier if all your dante devices are modern and AES67 (PTPv2) compatible.
(b) use a secondary dedicated dante master clock that slaves off the main sync generator. Like the Studio Tech 5401.
(c) Use a primary piece of your production gear as dante master clock, again slaved of word clock or black burst.

The facility I look after does (b). I would avoid (c) for practical reasons personally.

As far as distribution, look at the modular broadcast frames. These will be reliable and scale easily. Evertz, Ross, GV are good options. You should be able to find options that have cards for black burst, tri-level, word clock and LTC easily.
Old 8th July 2020
  #6
Lives for gear
Echoing some bits I'm sure: your facility sounds sufficiently sophisticated enough that you need a professional broadcast master clock (GPS). Those won't do >48k because that's not a thing in broadcast.

But that's not really an issue because you can just sync your 192k audio gear from a Dante device that will take a simple black burst.

I'm a little skeptical that a facility this large would be all 192k though... I'd like to see that!

Nm I see Mr P very thoroughly addressed all this!
Old 10th July 2020
  #7
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Quote:
Originally Posted by Mr P View Post
There is probably enough yes's there that looking at the sync generators aimed at the broadcast market is worthwhile. However 192Khz isn't really a thing in broadcast, so that may become the sticky part of the problem. Apart from the Tektronix unit, Evertz, Ross and Trilogy all do sync generators that I would expect to do most or all of this.

With regards to the Dante stuff I think you have three options
(a) find a sync generator that does PTP that can be the master clock for your Dante network. This will be much easier if all your dante devices are modern and AES67 (PTPv2) compatible.
(b) use a secondary dedicated dante master clock that slaves off the main sync generator. Like the Studio Tech 5401.
(c) Use a primary piece of your production gear as dante master clock, again slaved of word clock or black burst.

The facility I look after does (b). I would avoid (c) for practical reasons personally.

As far as distribution, look at the modular broadcast frames. These will be reliable and scale easily. Evertz, Ross, GV are good options. You should be able to find options that have cards for black burst, tri-level, word clock and LTC easily.

Quote:
Originally Posted by brew View Post
Echoing some bits I'm sure: your facility sounds sufficiently sophisticated enough that you need a professional broadcast master clock (GPS). Those won't do >48k because that's not a thing in broadcast.

But that's not really an issue because you can just sync your 192k audio gear from a Dante device that will take a simple black burst.

I'm a little skeptical that a facility this large would be all 192k though... I'd like to see that!

Nm I see Mr P very thoroughly addressed all this!
Thank you Mr.P - very clear answers there, and I am now almost sorted. Have written to Evertz and the others to come up with a solution with my requirements. Also the Studio Tech Model 5401 is not 192k, I'm choosing the Sonifex AVN-GMCS-ISO for my secondary Dante Master. Yes, I will verify that all my Dante devices are AES67 capable.

Brew - This facility will not always be 192k, but it will be on occasion, and I want to be capable for such times.
Old 10th July 2020
  #8
Gear Maniac
 
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Hi,

A couple of things:

Most of those SPGs I suggested have PTPv2 clocks. This definitely includes the Tektronix, Evertz and Trilogy units. If you're going to run dante stuff that can natively sync to PTPv2 in AES67 mode, then I don't think you will require the Sonifex unit. Which, the sonifex, doesn't appear to have redundant network connections, which will be an issue if you are planning to have redundant dante networks.

With regards to the ST M 5401, it may not do 192, but other dante devices that can wont care, they will still be able to slave off it. You can have multiple sample rates operating on one dante network all following the same master clock. However you cannot patch between devices at different sample rates. The only functionality you would lose would be access to the 5401 oscillators.
Old 16th July 2020
  #9
Gear Maniac
 

Just to jump in, Dante and AES67 can both derive media (sample) clocks at various sample rates from a single PTP clock. (As can AVB, although the relationship between the media and PTP clocks is a little more complicated.)

Your biggest issue will probably be qualifying that all the gear can run at 192K. Setting up a test bed before committing to purchasing anything would be a wise idea.

As mentioned above, Dante uses PTPv1, whereas AES67 and SMPTE 2110 use PTPv2; most dedicated clocks support the latter protocol (it's hard to find a PTPv1 implementation around at all now). So for maximum choice in dedicated clocks, you will need at least one Dante device to be running in AES67 mode, which should allow it to run as a boundary clock between the two versions of the PTP protocol. That is orthogonal to getting Dante devices to run at 192K in AES67 mode, though: Dante in AES67 mode is, at the time of writing, limited to 48K with a packet time of 1ms and latency of 2ms. (Shorter packet times are permitted with Dante Domain Manager.)

Last edited by lukehatpadl; 16th July 2020 at 11:12 AM..
Old 16th July 2020
  #10
Gear Maniac
 

One other thing, if you do want to avoid AoIP and stick to MADI/AES3/etc, then you can feed most Pro Tools interfaces base word clock (44.1K or 48K) as long as you send it to the Loop Sync rather than Word Clock input. (For the MTRX, there's only one input but the behaviour is selectable in software.)

So if you have a house clock that is fixed at 48K you can still run sessions at high sample rates. Irrespective of AoIP, the MTRX is the Swiss army knife of interfaces and ideal for this sort of deployment.
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