Clocking issues with LTC as master

[williamsongs]

Hi folks, first time post so please be gentle...

I have the following happening:
DAW = Cubase SX slaved to LTC on a Fostex Model 80 1/4"
Digidesign USD is the SMPTE to MTC unit, sending word clock to:
MOTU 828 MKII as well as a DIGIMAX FS

all good...

The problem is this:
The DIGIMAX DAC out is there specifically to provide more outs from any DAW via lightpipe, which it does well. I have it set up to run outs to the reel to reel.

all good...

Until trying to run the DAC outs to the tape machine while the DAW is slaved to the tape machine. Then what the DAC outs of the DIGIMAX send is unclocked noise to the tape machine. When the setup is still slaved to the USD (you can start/stop/run from the front panel to check sync) this does not happen, the tape machine receives clean, clocked signal from the DAC outs, so even though I did swap ADAT cables around, it obviously isn't the cables it would seem.

So it is only when I actually need the DAW slaved to the SMPTE on the rolling tape, that the DAC outs of the DIGIMAX garble it. In the other scenario, "faking" SMPTE sync by using the SMPTE generator as the source, it doesn't fuck up.

Any ideas? I've been reading and searching 24 hours now, this is probably the only place anyone will know what I'm talking about.

Sorry, that's a lot of fancy typin' hopefully someone has an idea. Thanks....



Oops, I neglected to mention... I ran this exact setup through its paces when I first get the DIGIMAX and this same scenario worked without these issues, so although I'm reluctant to accept it, I'm starting to fear that the Presonus unit is going south already in some way. It's almost one year old.

[Roc Mixwell]

Hi folks, first time post so please be gentle...

I have the following happening:
DAW = Cubase SX slaved to LTC on a Fostex Model 80 1/4"
Digidesign USD is the SMPTE to MTC unit, sending word clock to:
MOTU 828 MKII as well as a DIGIMAX FS

all good...

The problem is this:
The DIGIMAX DAC out is there specifically to provide more outs from any DAW via lightpipe, which it does well. I have it set up to run outs to the reel to reel.

all good...

Until trying to run the DAC outs to the tape machine while the DAW is slaved to the tape machine. Then what the DAC outs of the DIGIMAX send is unclocked noise to the tape machine. When the setup is still slaved to the USD (you can start/stop/run from the front panel to check sync) this does not happen, the tape machine receives clean, clocked signal from the DAC outs, so even though I did swap ADAT cables around, it obviously isn't the cables it would seem.

So it is only when I actually need the DAW slaved to the SMPTE on the rolling tape, that the DAC outs of the DIGIMAX garble it. In the other scenario, "faking" SMPTE sync by using the SMPTE generator as the source, it doesn't fuck up.

Any ideas? I've been reading and searching 24 hours now, this is probably the only place anyone will know what I'm talking about.

Sorry, that's a lot of fancy typin' hopefully someone has an idea. Thanks....



Oops, I neglected to mention... I ran this exact setup through its paces when I first get the DIGIMAX and this same scenario worked without these issues, so although I'm reluctant to accept it, I'm starting to fear that the Presonus unit is going south already in some way. It's almost one year old.

Have you tried using a Track with a SMPTE strip feeding the deck? I would try that to see if you can generate stable lock between the decks. I guess its kind of hard to understand your problem without being in the room with you, experiencing what is really going on.

[williamsongs]

Hi folks, first time post so please be gentle...

I have the following happening:
DAW = Cubase SX slaved to LTC on a Fostex Model 80 1/4"
Digidesign USD is the SMPTE to MTC unit, sending word clock to:
MOTU 828 MKII as well as a DIGIMAX FS

all good...

The problem is this:
The DIGIMAX DAC out is there specifically to provide more outs from any DAW via lightpipe, which it does well. I have it set up to run outs to the reel to reel.

all good...

Until trying to run the DAC outs to the tape machine while the DAW is slaved to the tape machine. Then what the DAC outs of the DIGIMAX send is unclocked noise to the tape machine. When the setup is still slaved to the USD (you can start/stop/run from the front panel to check sync) this does not happen, the tape machine receives clean, clocked signal from the DAC outs, so even though I did swap ADAT cables around, it obviously isn't the cables it would seem.

So it is only when I actually need the DAW slaved to the SMPTE on the rolling tape, that the DAC outs of the DIGIMAX garble it. In the other scenario, "faking" SMPTE sync by using the SMPTE generator as the source, it doesn't fuck up.

Any ideas? I've been reading and searching 24 hours now, this is probably the only place anyone will know what I'm talking about.

Sorry, that's a lot of fancy typin' hopefully someone has an idea. Thanks....



Oops, I neglected to mention... I ran this exact setup through its paces when I first get the DIGIMAX and this same scenario worked without these issues, so although I'm reluctant to accept it, I'm starting to fear that the Presonus unit is going south already in some way. It's almost one year old.

Have you tried using a Track with a SMPTE strip feeding the deck? I would try that to see if you can generate stable lock between the decks. I guess its kind of hard to understand your problem without being in the room with you, experiencing what is really going on.

Thanks for giving this some thought. To be clear, there is only one deck in play here. It's a straightforward DAW slaved to SMPTE on track 8 of a Fostex reel to reel. Not two tape decks, I got over doing that a long time ago!!

I think what I have discovered is that the Digimax FS has a hypersensitive wordclock in and will not work with any fluctuations such as might be introduced by slaving to a tape deck. When running the SMPTE sync unit in a "regenerate" mode where the sample clock master is still the LTC from the tape, but the Positional reference is set to "interenal" (which I assume is just a regenerate function) then we avoid this problem totally.

Just like in my test scenarios, in this case the rig seems to behave well when fed references from the USD sync unit's internal crystal oscillator rather than slaving directly to the SMPTE code on the tape. Live and learn.

Now in that mode the DAW is not directly slaved to the rolling SMPTE code and thus wide fluctuations from the tape will appear more obviously againsts any DAW tracked sounds, but I think it should be good enough for what we are doing with it (drums on tape, all else on DAW)

Thanks again for giving it some thought.