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Question for Cliff (or anyone that knows) about word clock sync through Axe II AES

Discussion in 'Axe-Fx II Discussion' started by wezx, Jan 12, 2012.

  1. wezx

    wezx
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    Cliff, is it possible to run out of my word clock (Black Lion Audio) into the AES "in" of the Axe II to sync the Axe with my MOTU HD192 which is also running off of the Black Lion word clock? I've never used a unit that didn't have a dedicated word clock "in" and I'm wondering if the Axe and MOTU being out of sync is causing the clicks and pops in the audio into my DAW?

    Thanks!
     
  2. cobbler

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    I think this is what I am experiencing as well. It seems to get worse the longer used. Could there be "drifting" between the external word clock and however the II does its internal sample rate clocking? Then again, I have no real clue what I am talking about here. :)
     
  3. Steck

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    and along the same lines, will the SPDIF in act as a master clock source or influence the samplerate of the AXE FX II?
     
  4. barhrecords

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    The AxeFx II sample rate is fixed at 48khz.

    Interesting thread though. I also run an external Apogee Big Ben clock for everything but the AxeFx II. But my normal way "in" is the AxeFx II analog outputs. I don't use the digital out except via USB and just for messing around with preset creation.

    Richard
     
  5. wynsmth

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    The way I understand it, unless all devices have a dedicated work clock input, the input device, in this case the Axe Fx, needs to be the master clock or they will drift or not sync up at all. I tried this with my TC G-Force & Eventide Eclipse. I wanted to run into the G-Force first & then to the Eclipse via spidif but have the Eclipse be the master clock because it has a much better clock but it was very unstable & not workable. It's like your sending the audio data downstream & wanting the clock to go upstream. If you using the Axe analog outs, it's not an issue at all. It only affects devices connected digitally.
     
  6. Ed DeGenaro

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    The pops and clicks are likely results of this. I know nothing about your external clock source. On my Motu 896 mk3 however I can set the AES/clock so that it runs the session at the sample rate I choose on the Motu, and then I sample rate convert the AES out of the Axe on the Motu. Which brings up the force resample at 44.1/48k tab. Not sure if that helps.
     
  7. cobbler

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    Ok then let me ask a really dumb question as I am so new to all this....

    Assuming you have your Axe II (fixed 48K on AES) connected to an audio interface which is set at 48k and your DAW project is set at 48k. Is it possible they can still drift because there in no clock?
     
  8. wynsmth

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    The Axe will be the master clock. All digital devices have an internal clock. Some have the word clock input & can be controlled by an external clock but there can only be 1 clock in the system no matter how many digital devices are connected.
     
  9. Steck

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    Not a dumb question at all.

    My understanding is that both SPDIF and AES are designed such that the clock can be recovered from the signal. Simply plugging an SPDIF output of one device into the SPDIF input of the next will work, *assuming* the downstream device either uses the clocking from the upstream device, or reads the data in and somehow resyncs it to the local clock. Distributing a seperate wordclock is the best way to ensure all the devices that are interconnected are in lock-step, but my experience is that in some cases it's not "mandatory".

    That's why we're hoping for Cliff (or someone in the know) to weigh in and share how the digital audio inputs of the AXE FX reconcile the internal clocking versus the external clocking of whatever is feeding those inputs.
     
  10. Ed DeGenaro

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    you will get pops and clicks because the clocks aren't locked.
     
  11. #11 cobbler, Jan 12, 2012
    Last edited: Jan 13, 2012
    cobbler

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    Gotcha. So I just changed the Interface which has options for (word, AES, Adat1, Adat2, internal) to AES and 48k and sure enough it went from no lock to synced. Alls good. And my DAW allows me to choose Axe II AES as the timng source. I had the interface set at Word and it was never really locking. How did I not see that before? Doooooooooooooooooooh. I must have changed it without realizing at one point.

    So basically, the Axe MUST be the master.

    Edit: For the sake of accuracy the above sentence was incorrect per Cliff. The II can be the slave by changing the INPUT source in the I/O menu. See his post below.

    Thanks so much guys.


    Sorry wezx... I didnt mean to hihack your thread but those pops were driving me nuts!
     
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  12. shasha

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    Yeah I went through this type of thing with my Ultra and a cheap soundcard a while back. What I was told by Cliff is that even though if devices are running at 48kHz that one will actually be running like 47875Hz and the other at 48357Hz internally which means that they are out of sync with each other. The Ultra did not have the ability to run as a slave so it had to be the master in a system and if the device you are plugging into doesn't like the clock it's going to pop and click. Now my cheap soundcard has been replaced with a midlevel one that I know works well as the master using my 11R. My AxeFXII gets here tomorrow and it's going to be interesting to see if the new soundcard works as a slave where the cheap one didn't even have it as an option.

    But to be honest I'm probably going to go analog anyway. I'm just not real fond of 48kHz for everything and the analog outputs of the Ultra were phenomenal. Rather than trying to force my setup to deal wiith clocks of several devices I want to use the soundcard as the only recording/monitoring device and see how it turns out. I mean staying in the digital realm is great on paper, but unless you are running everything via AES/EBU with a master word clock theres some luck involved.
     
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  13. Ed DeGenaro

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  14. wezx

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    I'm running a very well respected multiple out word clock from Black Lion Audio and it is the master. If the Axe must be the master then it wouldn't work for me. Daisy chaining word clock from unit to unit is not the best course of action...you always want to run all digital devices off the best word clock source...in my case it's the dedicated Black Lion word clock.

    After I posted this it occurred to me that I get the clicks and pops when THE AXE IS THE ONLY INTERFACE! So the clicks and pops are not from a word clock issue apparently?
     
  15. wezx

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    I guess I'm just wondering if I can get a BNC (out of the BLA word clock) to AES (digital in of the Axe) cable and have the Axe slave to the BLA word clock?

    I'm not seeing any BNC to AES word clock cables????
     
  16. barhrecords

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    I would think it's more than an adapter to go from BNC to AES. You would have to synthesize the AES protocol so the receiver would understand it?

    I use the Apogee Big Ben, it has AES clock out but I've never used it.

    Richard
     
  17. FractalAudio

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    The Axe-Fx II can be a slave. Set the Input Source to AES. It will derive its internal clock from the input stream. The input stream must be 48K. Note that SOMETHING must be the master in this case.
     
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  18. Ed DeGenaro

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    I think the ssue is that his master clock only outputs on word clock out not AES.
     
  19. Steck

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    Thanks, Cliff, good to get it from the source.
     
  20. wezx

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    Correct...however, there is an AES out on the MOTU Hd192...perhaps I can run out of that into the Axe AES in?
     

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