Quantcast
Possibly ADAT Sync issue - Gearspace.com
The No.1 Website for Pro Audio
Possibly ADAT Sync issue
Old 9th March 2014
  #1
Here for the gear
 
Milner84's Avatar
 
🎧 5 years
Possibly ADAT Sync issue

Hi guys, gonna be honest and say I'm not certain this is in the right place but here goes...

Set up:

Mid 2010 27" iMac, upgraded to i7 with 12GB ram
M-Audio Profire Lightbridge
4 x Behringer ADA8000
Allen & Heath Saber 32/16 recording console with patchbay

A couple weeks ago while I was away on holiday something weird seems to have happened to my set up. While I was away the AD/DA's were switched off but I'd left my Mac running so the interface itself was still being powered by Firewire and I dont think I switched it off.

Anyway, upon my return I'm getting some very strange noises which I can only assume as related to a syncing issue over the ADAT connection.

Now I feel I have adequately proved to myself that this is not a software or driver issue as these issues occur without the Firewire cable being connected to the interface so it would be in complete stand alone operation. So I went through a number of steps to try and confirm where the issue might lie, here are my results, I just wanted to check with you guys to see if anyone has any alternative ideas or if I am getting something wrong here:

Step 1: Interface powered by external power supply, not connected to Mac, all AD/DA's switched on and not connected to interface via optical cables

In this situation, as you would expect there is no audible sound whatsoever.

Step 2: Connect digital out optical cable from interface to digital in of AD/DA

At this point I am presented with this sound, irrelevant it would seem to which of the 4 digital outputs I use on the interface or which AD/DA I connect it to.



After about 10 minutes this goes away and on AD/DA 1, 2 and 3 is replaced by the following hum:



Now at the time I took these recordings earlier today, AD/DA 3 took a little longer to resolve the "sync" sound than the other 2 and went through a period of making a similar sound as follows:



Now when the original sync sound had subsided, AD/DA 4 was no making a humming sound whatsoever. To try to establish whether this was an issue with the interface outputs or the AD/DA's themselves I then proceeded to try connecting the AD/DA's to different outputs of the interface and found that the hum followed AD/DA's 1-3 and AD/DA 4 remained in a stable condition. Another that might be worth noting is that when I recorded these sounds into pro tools, obviously with the interface connected over Firewire, there is a significant DC offset occurring as per the following screenshot:

http://i860.photobucket.com/albums/a...ps859e17cb.png

From further troubleshooting I can confirm that the hum that is present is removed by disconnecting the optical cable between the AD/DA and the interface, however I dont know enough about the technology to deduce if that means it is the AD/DA not communicating properly or the interface outputting something nasty, however it it were the interface you would expect it to occur on all 4 units on the same digital output port, however that is not the case as AD/DA does not hum on any connection. However they all experience the same issue with initial connection which would still point to the interface unless all 4 of them have encountered an identical problem at the exact same time!

In addition to this I am also having an issue with the input stage. At current, I can only activate 8 inputs via 1 ADAT cable and only from AD/DA 4. Again this is connected to any port. Within the Profire control software I can activate the 4 ADAT ins and outs individually. I can activate any of the inputs with nothing plugged in, and plugging AD/DA 4 into any of the ports while active causes no problems an records ok.

However, if I plug any of AD/DA's 1-3 into an active input I am met with a sold click every 10ish seconds and all outputs sound as if they are being run through some heavy digital distortion, which I can provide a sound clip of if people are interested but thought there might be enough information here.

Now, based on the fact that one AD/DA seems to react within normal operating expectation post the point of there being issues on switch on this would possibly point to the fact that 3/4 AD/DA's have some kind of issue. This seems odd for them all to fail at the same time but even more odd that there is another issue that all 4 of them share. However it also makes no sense for this to be an issue with the interface due to the fact that one AD/DA works within expected parameters. None of this really makes all that much sense to me but logic dictates that at least one of the issues must lie with the AD/DA's. Now as luck would have it they are still covered by a Thomann 3 year warranty so this is really just to check my findings before I contact them and see if I can get them replaced.

Sorry this is so long but I thought it best to include all information that I could thing of to make sure it was detailed, as I say, not sure this is a newbie question as such but I'm tearing my hair out here!

Last edited by Milner84; 9th March 2014 at 01:04 PM.. Reason: Soundcloud link issue
Old 10th March 2014
  #2
Lives for gear
 
1 Review written
🎧 15 years
How are you clocking these devices? What is the master, and are you using discrete clock or through ADAT?

To test ADAT IO, just loop the out back into itself.

You need to set one master, and then set the rest to slave to external clock, and make sure you've selected a valid clock source.
Old 11th March 2014
  #3
Here for the gear
 
Milner84's Avatar
 
🎧 5 years
Cheers Brew,

The Profire Lightbridge is the master clock source over ADAT and all AD/DA's are set to be slave over ADAT.

On your advice I have just performed a quick test. I first activated ADAT input 1 on the Lightbridge to get the clicks and the digital distortion on playback.

I then disconnected the optical cables from the input and output ports for ADAT 1 and plugged another optical cable directly between the input and output ports and had no audible issues at all. I'm fairly sure that this shows that the introduction of the AD/DA into the system is what is causing the issues?

As a side note I did a little rewiring over the weekend to wire the 2 analogue outputs from the Lightbridge into an FX Return on the console so that I could have PT FX routed back to the desk without using up channels and also simply assign the general output of OSX to the same place for internet or music use. When I activated the ADAT input 1 with the AD/DA connected to it the output from analogue outputs was clean. It was only sound routed out through the ADAT system that was affected. I should also note, as I am not sure if I did, that despite the input of AD/DA 1 being activated the clicks and digital distortion are present no matter which output is being utilised at the time.
Old 11th March 2014
  #4
Lives for gear
 
1 Review written
🎧 15 years
Try changing who is the master. Try looping the ADA.
Old 11th March 2014
  #5
Here for the gear
 
Milner84's Avatar
 
🎧 5 years
Ok, looping the AD/DA made no difference to the situation at all. The AD/DA doesn't do anything and nor do any of the others.

Only problem I have is that I don't currently have any BNC cable to try using one of the AD/DA's as a master as looking at the manual it doesn't seem to imply that it can be the master over ADAT.

Having not configured an external clock before, I'm assuming that I set one AD/DA as the master, then the other 3 as slaves and the Lightbridge as a salve as well? then wire them up with T type connectors and terminate at the Lightbridge with a resistor?

Out of interest, based on the sounds that the set up is making and the information thus far do you have any theories? Does it sound like a sync issue or something else that I should be looking for? It seems strange that looping at either end is fine but only an issue when they are actually connected to each other..... Starting to remind me of a lot of past relationships!
Old 11th March 2014 | Show parent
  #6
Lives for gear
 
1 Review written
🎧 15 years
Quote:
Originally Posted by Milner84 ➑️
Ok, looping the AD/DA made no difference to the situation at all. The AD/DA doesn't do anything and nor do any of the others.
I think it does something, it converts analog inputs to ADAT and vice versa. So if you connect an analog source, and you loop the ADAT, you should hear the same source on the line out. That's how you test stuff with loopback.

Quote:
Only problem I have is that I don't currently have any BNC cable to try using one of the AD/DA's as a master as looking at the manual it doesn't seem to imply that it can be the master over ADAT.
Of course it will, just set the other device to external ADAT clock and leave the ADA as internal. Its on the manual page 4 and 5. Did you try looking at the back of it?? There's a switch labeled for exactly this. If that's not set correctly none of this will work.

Quote:
Having not configured an external clock before, I'm assuming that I set one AD/DA as the master, then the other 3 as slaves and the Lightbridge as a slave as well? then wire them up with T type connectors and terminate at the Lightbridge with a resistor?
Digital audio 101: One master, many slaves. Doesn't matter how you do it as long as you follow that rule. You can sync over wordlock or via any digital audio format like ADAT, and even mix them all up. ADAT sync should be enough but sometimes you never know until you try others. According to the manual the ADA is unterminated and would require a 75 ohm termination, but on runs under 6' it often doesn't matter.

Quote:
Out of interest, based on the sounds that the set up is making and the information thus far do you have any theories? Does it sound like a sync issue or something else that I should be looking for? It seems strange that looping at either end is fine but only an issue when they are actually connected to each other...
Didn't listen to the sounds. Doesn't seem strange at all, seems like a sync problem. Generally when troubleshooting it's not useful to have too many "theories," it's better to just try stuff out.
Old 11th March 2014 | Show parent
  #7
Here for the gear
 
Milner84's Avatar
 
🎧 5 years
The Lightbridge was configured to be the master clock source using its internal clock and all the ADA8000's are set to slave over ADAT and has been fully functional for a little over 2 years

I have tried telling the Lightbridge to use the sync source of ADAT 1 and setting ADA8000 to be the master at 48k. In this instance the Lightbridge never managed to sync to it. I have tried this with all 4 of the units and the Lightbridge fails to pick up a sync to any of them except over ADAT 4, which so happens to be the only one that seems to want to broadcast properly when recording.

In the instance where this is the clock source the same audible issues are present. So it seems that the other 3 AD/DA's are having some issues if they wont even operate as a master clock source.

In addition, setting AD/DA 1 to be a master clock source at 48k, plugging in a DI with a guitar attached and looping it back I experience the same issues as activating the inputs using it in a stand along capacity so I think this should be a clear enough indication of fault?
πŸ“ Reply

Similar Threads

Thread / Thread Starter Replies / Views Last Post
replies: 55 views: 30561
Avatar for IM WHO YOU THINK
IM WHO YOU THINK 13th October 2020
replies: 84 views: 68303
Avatar for Melodnb
Melodnb 2nd July 2012
replies: 2372 views: 403443
Avatar for TJ99
TJ99 2 days ago
replies: 1296 views: 178407
Avatar for heraldo_jones
heraldo_jones 1st February 2016
Topic:
Post Reply

Welcome to the Gearspace Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…

Forum Jump
Forum Jump