• Registered: 2013-01-30
  • Posts: 3

Topic: Digital noise with two FF400 (syncing correctly)

Hello,

I'm having a very specific problem I hope you can help me with.
The set-up is the following:
2 FF400, synced correctly over ADAT with WordClock as the clock. (same firmware)
They are connected to 2 MBP, a Behringer patchbay and active speakers.

When connecting without the patchbay, no problem for years, with the patchbay however, a clear digital noise appears.
The patchbay operates correctly when used with other sources.
The noise comes from both interfaces - I've tried unplugging PSU's etc to no avail.
However, removing the Wordclock cable instantly removes the noise.

Another indicator that some digital loop must be going on is that when the Wordclock cable is connected, when I switch programs (cmd+tab) on the master computer, the noise in the slave changes frequency!

Any help would be greatly appreciated, many thanks,

Isjtar

  • From: Germany
  • Registered: 2007-04-10
  • Posts: 9,751

Re: Digital noise with two FF400 (syncing correctly)

Please provide more details. What kind of patchbay is this exactly? Where does the noise occur, also on e.g. the FFs' phones outputs?

Regards
Daniel Fuchs
RME

Regards
Daniel Fuchs
RME

RME Support's Website

  • vinark
  • DAW Mastermind
  • Offline
  • Registered: 2009-06-05
  • Posts: 2,759

Re: Digital noise with two FF400 (syncing correctly)

If I read it correctly, why don´t you just get rid of the WC cable and sync through adat? There is no jitter disadvantage when using adat.

Vincent, Amsterdam
https://soundcloud.com/thesecretworld
BFpro fs, 2X HDSP9652 ADI-8AE, 2X HDSP9632
  • Registered: 2013-01-30
  • Posts: 3

Re: Digital noise with two FF400 (syncing correctly)

OK. So the mystery continues:
The patchbay is a Behringer PX2000, all connections are set to "Open". We have two and they both have the same problem. These are passive devices.
We've removed one FF400 for troubleshooting, no more WordClock.
The noise is always present.
It becomes much stronger when we disconnect firewire or PSU.
It also comes out of the phones output, but not when connecting headphones (bypassing patchbay and speakers)
When we go from the FF400 straight to the speakers there's no noise.

When we put the second FF400 back in, without WordClock, this one does not make noise.

We've now switched the computers, so that the first connects to the second interface and vice versa and this seems to be the key. It is only the combination of 1 computer and the patchbay that makes the noise. Removing peripherals and power cord from the computer always makes a difference, but the noise is ever present.

The problematic computer is:
Mac OSX 10.6.8
Model Name:    MacBook Pro
  Model Identifier:    MacBookPro8,1
  Processor Name:    Intel Core i5
  Processor Speed:    2,3 GHz
  Number of Processors:    1
  Total Number of Cores:    2
  L2 Cache (per Core):    256 KB
  L3 Cache:    3 MB
  Memory:    4 GB
  Boot ROM Version:    MBP81.0047.B27
  SMC Version (system):    1.68f98

The FF400's are running 3.12, v1.7

thanks!

5 Reply by vinark (edited by vinark 2013-01-31 12:18:20)

  • vinark
  • DAW Mastermind
  • Offline
  • Registered: 2009-06-05
  • Posts: 2,759

Re: Digital noise with two FF400 (syncing correctly)

AFAICT this is noise on the conmen ground caused by the PSU of the laptop, the noise is the switching of the power needed by the cpu. It is a very common problem in both lap- and desktops and very hard to cure, involving all kinds of ground lifting, making sure cards don´t touch the chassis, in desktops and special cabling.
If you can get this setup working by switching units and using adat for clocking, I would go that way, as trying to find a permanent cure can be both frustrating and/or impossible.

Vincent, Amsterdam
https://soundcloud.com/thesecretworld
BFpro fs, 2X HDSP9652 ADI-8AE, 2X HDSP9632
  • Registered: 2013-01-30
  • Posts: 3

Re: Digital noise with two FF400 (syncing correctly)

yes it does seem to point to PSU noise, though in the past when unplugging that would be gone, not now.
I also switched an external screen from a VGA to DVI connection, which also helps, it's all very random.
The problem is I will need all devices all the time in my set-up.