How to handle "Source out of range" clocking issues

[snafu]

Sorry for spamming the forum lately with my questions. I try - once again - to wrap my head around word clock, and I need to make sure, whether I have technical issues here or even damaged gear.

So, I tried to connect to a Motu 2408 in stand-alone mode via ADAT connection. I made sure, the ADAT OUT of the DM3200 is connected to the ADAT IN of the Motu (it's connected to Bank C).

Unfortunately that didn't work. I tried to put signals through to the outputs of the DM, but there was nothing but strange pumping pink noise sounds.

So, I decided to connect the DM's ADAT IN with the ADAT OUT of the Motu.
On the front panel of the Motu I chose ADAT Bank C, and under CLOCK DIG with a sample rate of 44.1k*.

Currently my DM is set to 44.1k with it's clock set to INTERNAL. On the project page under CLOCK I tried to select ADAT.

It did sign the checkbox as checked, but I constantly got a warning "clock source out of range", and after a few seconds - bam - the clock was there again. And this went back and forth for a while, until I decided to set my clock back to internal.

Now, I am not sure what to do: could the Motu be broken? The DM? The cable?

Oh, about the cable: one might assume, the ADAT cable is broken. OK. But I can also connect a TDIF cable to my DM. If the Motu is switched to SOURCE = analog, I can get signals into the DM! (There is no direct analog connection to the DM, so this is send via TDIF for sure!). There is no BNC cable connected. The same is true for ADAT.

But if I want to route a signal from the DM and out of the Motu - I get strange pumping pink noise sound.
Under the assumption, my BNC is OK, it seems like the Motu can't handle the word clock signal from the DM. It could mean,that both cables (ADAT and BNC) could be broken. Not impossible, but somewhat unlikely. The switch on the backside of the DM should be in position Out (unaccessible area atm).

Any ideas? (a brief instruction about TDIF/ADAT connection would be very welcome! I've never needed that before...)



(* I switched through all available clock settings possible - there's just pink noise or nothing)

 

[skier]

Hey Snafu, sorry about the delayed response, we’ve been away for the last 10 days skiing in the Rockies and I disconnect from the net when on vacation.

As to your problem, I have no experience with the Motu 2408, but I have to believe you configure it the same as any other device. So let’s start with configuration to assure that’s correct, and we’ll look at the potential for bad connectors or bad cable only if we’re sure the configuration should work, yet doesn’t.

First, on the Clock tab of the Project screen, you need to select the sync method you want to use. I’m going to suggest the settings that should work, but you can choose what you want, though you may want to try my example first to get things going. On the aforementioned screen, select the DM as the master and use its internal clock, and your sample rate of 44.1k is fine.

Second, on the Motu, you likely can select ADAT or Word Clock. ADAT has the clocking embedded and can work well, but I prefer to use Word because I can use it with almost any device – not all support ADAT. Also, I feel that we get a cleaner clock signal when not embedding it with the audio, sometimes it feels like the audio is interfering with a clean clocking signal. You should also consider this with S/PDIF and/or AES/EBU signals.

For both devices, I’ll also usually set all the sample rates the same (Word, ADAT, etc., even though I'm only using one of those) so I can change clock source/slave if I feel sync is not good enough and want to try alternatives. While Word should be the best in my mind, some older equipment will sometimes work better with something else, and separately, that older gear is sometimes just not as "sync solid" as much of today’s gear.

As for sample rates, I hope not to start a flame war here, but I can’t hear the difference in audio using 44.1k, 48k, 88.2k, 96k, or any of the higher rates, and I haven’t yet found one person who claimed they could, who truly could, when I subjected them to a test. So I use the lower rates and save a ton of disk space as well as more available channels with lower CPU load. Others may chime in with their preferred settings, and I’ll respect them, but I’m offering the results of my own experience. Hey, if others can truly hear the difference, who am I to question it? I just can’t and don’t currently know anyone who can, or at least anyone who could prove it to me in an actual test.

Now, for bit depth, that’s a little different. Bit depth controls dynamic range and I always use 24bit – 16 just doesn’t give me enough and I can hear the difference once I’ve processed a signal several times. Fortunately, today’s plug-ins and even hardware will process audio at least at 24 bit, most go 32 bit or more. The price of using 24 bit tracks rather than 16 bit is 50% more disk space, but here, I can hear the difference as well as most others, so I’m willing to pay the price and will use the extra space.

In a post a year or two ago, I explained why using a good pre-amp as the master clock is often the best approach because it assures that your recorded signal is solid and captured with minimum jitter, but let’s first get things working before we worry about tweaking. Also, while the foregoing always applies when you have a simple setup, more complex setups requiring a central clocking source gets into compromises as you decide between daisy-chaining and an external clock – a topic for a different discussion

I hope this helps, please let us know how you make out.

 

[snafu]

Hey skier,

thank you very much, mate - I hope you enjoyed your vaccation
Actually I could solve my clocking issues - turns out that little black switch on the rear side of the DM has actually a real meaning

When I built my DM into my working desk, the rear was inaccessible - you have to untie a lot of screws to get the lid open, and actually get there. So before installing, I made sure - to the best of my abilities, and knowledge - that this tiny bastard was set into the right position. Turns out, it was not. Even worse: I got the answer already in my hands, asked some five years prior to this, but could not remember that thread.

Anyway: it just had to be switched to the far right. For reasons unknown to me, this position is labeled as the 75 Ohms internal termination at IN, whereas OUT should be off (?). Initialy I chose the second position, where - I thought - it was supposed to be Out with the In turned off. In fact - I do not need Clock In, but since I had to open the desk, I put in a second BNC, 'cause you never know...

SO, I'm all set right now - I have 32 outputs in total now...should I ever need them, which maybe a bit unlikely, but I'd rather have the options than to regret I didn't go for it while still possible. I hope, this was the last time, I had to open the lid of the desk, because my displays are located right on that lid, and it's a total grind to get them off from there.

Have a great weekend, and once more: thanks a lot!
snafu

 

[skier]

Glad you solved your problem!

The switch you mention handles a combination of functions. It can be used to output Word Clock, pass Word Clock thru from another source as it also receives that source as a slave, and if it is the last slave in the daisy chain, placing it on 75 ohms inserts a 75 ohm resistor as a terminator. The last device receiving Word Clock must provide such a terminator. This allows the DM to supply WC timing as the master, act as an intermediate slave receiving WC plus passing it along to the next device, or act as a slave at the end of the chain and supplying the terminator.

I hope this is clear; if not, let me know and I’ll try to provide a better explanation.