Timeline Micro Lynx + Pro Tools HD9 - Progressive Drift Without ACG Card

[Paulpaulpaul]

Hi everyone,


I’m hoping someone with Timeline Micro Lynx experience can help.


I’m currently trying to synchronise a Tascam 488 with Pro Tools HD9 using a Timeline Micro Lynx.


Here’s my current setup:

• Track 8 of the 488 is striped with LTC.
• Tascam 488 Sync Out → RDR1 on the Micro Lynx.
• MIDI Out from the Micro Lynx → MIDI In on my Focusrite Saffire Pro 40.
• On the Micro Lynx keyboard I press and hold GRP, then select A first, followed by TCG.
• In Pro Tools I put the transport Online.

When I press Play on the 488, Pro Tools chases perfectly and starts playing in sync, so that side of things appears to be working correctly.


However, if I record the same section of tape into Pro Tools twice, the two recordings gradually drift apart rather than lining up accurately. The drift is approximately 25 ms over a 34-second recording, and it increases progressively rather than remaining as a constant offset.


I’ve discovered that my Micro Lynx does not have the optional ACG card installed (SETUP → ACG reports “ACG not available”).


From what I’ve read, I suspect the ACG generates a tape-resolved word clock, allowing Pro Tools to lock its audio clock to the tape machine rather than relying on its own internal clock. If that’s correct, it could explain the drift I’m seeing, but I’m not certain.


So I have a few questions:

• Has anyone successfully run a Micro Lynx with Pro Tools without an ACG card?
• Does my theory sound plausible, or am I looking in the wrong place?
• If the ACG is required, are ACG-1 or ACG-2 cards still obtainable anywhere?
• Is there a modern alternative that performs the same function, or is the ACG unique?

I’d really appreciate hearing from anyone who’s used a Micro Lynx in this sort of setup.


Many thanks!

 

[sweetbeats]

The ACG board is not necessary.

What is “LTC”?

And you do not need anything nearly as complex as the Micro Lynx with your setup, since the 488 needs to be master. It is not capable of operating as the slave device in in the sync array. All you need is a simple device like a JL Cooper PPS box…anything that converts SMPTE timecode to MTC, and then you connect the MIDI out of that to your computer MIDI interface and set PT to sync to incoming MTC. The Micro Lynx can do that too, it’s just a way more powerful synchronizer than what you need, capable of synchronizing up to three tape machines and a DAW (or any manner of MIDI devices) and being able to set any of those as master…and can also serve as an entire digital system master using the AGC card. But you don’t need any of that. You just need a SMPTE to MTC converter box. Does that help?

 

[Paulpaulpaul]

The ACG board is not necessary.

What is “LTC”?

And you do not need anything nearly as complex as the Micro Lynx with your setup, since the 488 needs to be master. It is not capable of operating as the slave device in in the sync array. All you need is a simple device like a JL Cooper PPS box…anything that converts SMPTE timecode to MTC, and then you connect the MIDI out of that to your computer MIDI interface and set PT to sync to incoming MTC. The Micro Lynx can do that too, it’s just a way more powerful synchronizer than what you need, capable of synchronizing up to three tape machines and a DAW (or any manner of MIDI devices) and being able to set any of those as master…and can also serve as an entire digital system master using the AGC card. But you don’t need any of that. You just need a SMPTE to MTC converter box. Does that help?

Hi Sweetbeats,


Thanks so much for your message.


Sorry, you’ll have to bear with me as I’m still trying to get my head around all this! I thought LTC was the name for the timecode ?


My goal is to stripe SMPTE/LTC onto track 8 of the 488, record audio on the remaining 7 tracks, then transfer those 7 tracks into Pro Tools. I then want to play those tracks back from Pro Tools while recording another 7 tracks onto the 488, transfer those, and repeat the process so I can effectively have unlimited tracks.


I’m using a Timeline Micro Lynx to read the SMPTE/LTC from the 488 and convert it to MTC, which is sent via MIDI to my Focusrite Pro 40. Pro Tools HD9 is set to chase the incoming MTC, and it starts playback correctly when I press Play on the 488.


The problem is that when I transfer the same section of tape twice, the recordings don’t line up perfectly. They drift progressively by which makes me think something isn’t staying locked.


Does that sound like a setup issue, or is there something else you think I should be checking?

Thanks so much for the help btw.

Cheers
Paul.

 

[sweetbeats]

I’ve never heard of “LTC” except as an acronym for “long-term care”. But I may just not be aware. I’ve always seen timecode simple abbreviated as “TC”, or with modifier for the particular type of timecode (like “MTC” for MIDI timecode, or “SMPTE TC”).

Anyway, I understand what you’re talking about.

Do you have the same frame rate set on the Micro Lynx and in PT? They have to be the same whether it is 24fps, 25fps, 29.97fps or 30fps, and you also have to be mindful as to whether or not it is drop-frame (DF) or non-drop-frame (NDF). So I’d start there if you are having trouble with progressive drift. The TC striped to the 488 is going to be whatever the frame rate is you have set in the Micro Lynx. But that needs to match what’s designated in PT, because if it’s different they will drift apart.

 

[Paulpaulpaul]

I’ve never heard of “LTC” except as an acronym for “long-term care”. But I may just not be aware. I’ve always seen timecode simple abbreviated as “TC”, or with modifier for the particular type of timecode (like “MTC” for MIDI timecode, or “SMPTE TC”).

Anyway, I understand what you’re talking about.

Do you have the same frame rate set on the Micro Lynx and in PT? They have to be the same whether it is 24fps, 25fps, 29.97fps or 30fps, and you also have to be mindful as to whether or not it is drop-frame (DF) or non-drop-frame (NDF). So I’d start there if you are having trouble with progressive drift. The TC striped to the 488 is going to be whatever the frame rate is you have set in the Micro Lynx. But that needs to match what’s designated in PT, because if it’s different they will drift apart.

Ha ye I’m sure you’re right about LTC, my mistake.


I checked the frame rates as you suggested. The 488 was striped with a 30 fps wav of timecode from pro tools . My Pro Tools session is also set to 30 fps, and I changed the Micro Lynx from 29.97 Hz/30 to 30 Hz/30 before repeating the test.


Pro Tools was online and chased the incoming MTC correctly when I pressed Play on the 488.


I repeated the transfer and compared the same points from two separate transfers. The offsets I measured were:

• 1:25.202 vs 1:25.209 (7 ms)
• 1:47.899 vs 1:47.907 (8 ms)
• 2:05.570 vs 2:05.574 (4 ms)

These don’t appear to show a steadily increasing drift like I initially thought, although there is still a small variation between transfers.


Does this look like normal timing variation for a 488 running as the master, or would you expect repeated transfers to line up exactly?

I should have probably done a full length song to compare rather than just 30 seconds or so, but will test that next.

Thanks again for all the help.

 

[sweetbeats]

Don’t confuse fps (frames per second, a rate gradient associated with timecode) with Hz. Yes, fps is technically a frequency measurement (events over time), but fps here references the timecode we are talking about, and using the more general “Hz” frequency measurement could confuse with audio or sampling frequency. So, okay. You are using 30fps.

And I’m not exactly sure how to address the rest of your last post because I’m a little confused about what you are doing and what your offsets reference or how you are experiencing those, which may very well be on me.

First of all, just to confirm, you are striping the 488 with SMPTE timecode on track 8 (with dbx defeated on track 8), right? And that timecode reference is synced as master to the MTC reference in PT (and the Micro Lynx is converting the SMPTE timecode on the 488 to MTC), right? I just want to make sure…you said you striped the 488 with a “30fps wav” of timecode from PT…you shouldn’t be striping from an audio file…you should be recording the timecode or “striping” the timecode directly from a timecode generator, and maybe PT can do that…but it has to be SMPTE, which is an audio format timecode suitable for recording on an analog recorder. MTC is digital timecode, and just suffice it to say you won’t get MTC striped to an analog recorder, especially a cassette multitrack, to effectively reproduce in order to sync with one or more systems. So does PT generate SMPTE timecode, and if so am I correct you connected the timecode generator function of PT to an audio output on your interface and recorded that to track 8 of the entire cassette you are using? And dbx is off on track 8 and you recorded it at about -10 on the level meter?

And then with all that, help me understand what is happening…are you creating an audio event on the 488 while PT is chase-locked, then transferring that to PT, then moving to a different section of the the same cassette, entering the offset in PT so the beginning of the project in PT is aligned with the new position on tape, overdubbing new material on the 488 while PT is chase-locked to the 48, and then transferring the new material to new tracks in PT? That’s the normal process…building the project in the DAW while preserving all the native analog tracks in the analog recorder, and keeping everything sync’ed in the DAW while it’s being built. And with that are you saying you are having trouble with the start of the different blocks in PT being perfectly aligned? That is “offset”. Or are you saying they start together, but then there is a time differential at the end of the block? That is called “drift”. Are you experiencing offset, or drift?

 

[bouldersoundguy]

As far as I know, LTC is SMPTE linear time code for analog tape, as distinguished from SMPTE VITC, vertical interval time code, used in analog video systems (imprinted in the space above video fields normally not visible).

If I'm not mistaken, Vegas Pro can read and sync to LTC right from the audio input.

 

[sweetbeats]

As far as I know, LTC is SMPTE linear time code for analog tape, as distinguished from SMPTE VITC, vertical interval time code, used in analog video systems (imprinted in the space above video fields normally not visible).

If I'm not mistaken, Vegas Pro can read and sync to LTC right from the audio input.

Oh very cool. Thanks for clearing that up and for the education! So, to the OP, you are correct and LTC, if that’s how it’s designated in PT, is the correct format for what you are doing.

 

[jpmorris]

Yeah, LTC is Linear Timecode. I don't know if that abbreviation is specific to TimeLine Lynxes or more general.