Issues with ADAT Recording

Discussion in 'Microphones (live or studio)' started by Josh Jones, Sep 28, 2017.

  1. Josh Jones

    Josh Jones Active Member

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    Hi everyone!

    I am currently having an issue when multi track recording a worship band at my church, I have a the sound desk that goes into my 8 channel pre amp and the pre amp connects into my 8 channel interface via ADAT, which then connects into my laptop through USB.

    The problem is, is that when I have all 16 channels active and armed in my DAW, the ADAT 8 inputs go crazy, peaking all at the same time, moving up and down on the DB meter in my DAW, and when it is time to track the set, the audio files with those ADAT inputs are super crazy and on the play back its all just noise and static. (picture for reference).

    I'm not sure if it's the sync issue, both the preamp and the interface have word clock syncing so I'm not sure if I should be using those as well as the ADAT, I have tried both at the same though and still ended up with the same result. I am also not sure if it has something to do with my DAW settings, my hardware interface application (Focusrite Control), the way the settings are set on the back of the mic preamp or if it's even just hooked up backwards.

    I also have the hardware hooked up from the BBE Sound mixing board through a TRS snake from the Inserts (1/4" Jack), having them only on the first click in, so I receive the audio coming out of the inserts and sending them through the snake into recording devices.

    Recording on just my interface with only the 8 channels and not hooking up the other pre amp works perfectly fine, it's only when I try to connect my pre amp with the ADAT is when I have issues with the ADAT 8 channels

    Everything that I am running:
    • Focusrite Scarlett 18i20 Interface
    • Behringer ADA 8200 Microphone Pre amp
    • BBE MP24M digital mixing board
    • Macbook Pro 2016 16gb ram, quad core, 2.7Ghz
    • Studio One Professional 3.5.1
    • Focusrite Control
    • TRS Snake running from the Mixing board into the inputs of the pre amp and interface
    Thanks!
    Josh
     

    Attached Files:

  2. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    That sounds like a master/slave clocking issue. When you have multiple devices connected digitally, one needs to be the master and all the others need to be slaves. If the ADA is connected only by its output to the Scarlett, then the ADA has to be the master. I don't know that gear personally, but there may be a Focusrite driver setting to make the Scarlett slave to its ADAT input. If you use the word clock connection then the Scarlett must be the master as its word clock is out only. The ADA has a switch to set the master/slave function of its word clock connection, which in this case would be set to slave. It's probably also possible to slave the ADA to the Scarlett using a second ADAT connection from the Scarlett output to the ADA input, and setting the ADA's switch accordingly.
     
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  3. Boswell

    Boswell Moderator Distinguished Member

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    I think you may have a mixture of two issues here.

    The first is the clocking, which Boulder has covered.

    The second is the use of a TRS cable for the pickoff from the insert jacks on the mixer. The line inputs of a digitizing pre-amp such as the ADA8200 capture the difference in signal between the rig and tip connections on the TRS cable plugs. If you use a TRS loom and do the horrible trick of a half-insertion into the mixer insert jacks in order not to break the signal path to the mixer's master section, the very best you can achieve is a connection to the tip of the plug, with the ring contact left floating. This means that the difference signal is undefined, as there is no ring contact, and, in general, the ADA8200 pre-amp will capture noise and other rubbish. The Scarlett may be more accommodating in this regard.

    The connections you should be using for this task are the balanced analogue outputs, available on three 25-pin D-connectors on the BBE MP24M mixer's rear panel. These D-connectors are configured with standard Tascam pinout, and you can buy a pair of 8-channel D-type to TRS plug looms to this standard that will take the balanced output signals into your interface and the ADA8200.

    Get the clocking sorted and stop using the insert jacks as outputs and there's a very good chance that your problems will magically disappear.
     
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  4. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    I agree that the "first click" method of tapping from inserts is fraught with risk, but it "should" work. There should be no signal on the ring, so the tip should provide adequate signal.

    Ideally, build a snake using TRS on the insert end with the tip and ring connected (to complete the send-return path), and TS on the other end. Then you can insert the plug all the way to make a more reliable connection.
     
  5. paulears

    paulears Well-Known Member

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    Have you set the sync source to be the ADAT input? Any other source for the sync will make the ADAT's output disintegrate. Work checking you'r not using a clock from somewhere else.
     
  6. Davedog

    Davedog Distinguished Member

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    In all my time with ADAT I have found that any device running ADAT needs to be the master clock.
     
  7. nsureit

    nsureit Active Member

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    I'm late to this thread. What sample rate do you have set on each device? I'm wondering if the last device in your digital chain requires a hardware termination?
     
  8. bouldersound

    bouldersound Real guitars are for old people. Well-Known Member

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    Well, if you're using ADAT to connect devices you have at least two, and they can't both be master.
     
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  9. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    Like Boulder said, there can only be one master.

    If you have 2 units, the best way is to sync via the adat signal. Either the interface OR the preamp unit can be master.
    If you have 3 or more units to sync, you must use world clock (with the specialised cables). The last unit should have a terminaison.
    In my setup, I've got a Mitek AD96 as the master clock. My clock chain is AD 96, UA 4-710, RME Fireface800 and it works like a charm ;)
     
  10. Boswell

    Boswell Moderator Distinguished Member

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    Hi Marco (@pcrecord), I didn't know you had a Mytek AD96, so I hope that you could answer a question about it. Mytek's specification for analogue input level says only that it is +4dBu nominal, but I cannot find any headroom or 0dBFS figures for the unit. They provide internal adjustable trims to set different nominal levels, but these should not affect the number of dB headroom. Do you have any information as to what the maximum input level is?

    Sorry to go off topic for a moment.
     
  11. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    Here is what the manual says :

    upload_2017-11-2_15-37-9.png
    Dynamic Range: 120dB A-weighted, 117dB
    Total THD+Noise: -105dB (<0.0005%)

    Other than that, your guess is good as mine... What would it take to test the unit to establish a true info ?
     
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  12. Boswell

    Boswell Moderator Distinguished Member

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    OK, Marco, thanks. That extract tells me what I wanted to know: 15dB headroom above the nominal level of +4dBu. This gives a full-scale figure of +19dBu at standard calibration. I hadn't realised it was as low as that, and it would need attenuators in some applications.

    I passed over the opportunity to buy a Mytek ADC at a good price a little while back, and I'm half regretting it now.
     
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  13. Davedog

    Davedog Distinguished Member

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    This I know. Sorry if it sounded like I didn't. What I meant to say was if you have a chain of devices that must be sync'd together and they have to clocked as one, I (personally) have found that the first device running ADAT protocol should be the master clock. Perhaps this is different for some. But for my experience having WHATEVER ADAT device you choose to use, not two or three or four ADAT devices (just to be f*rkin clear)....ONE should be the clock.

    I clocked all of my studio through my HD24 as the master clock. Including all sorts of stuff.

    Is that better now?
     
  14. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    My 2 LA-610 are very happy on it ! ;)
     
  15. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    I think we've been teasing you a bit there, hey ! ;)

    It is known that some units have better clock capacity. You'd want your strongest clock as master clock and slave other units. I chose the AD96 as master after reading about it's clock.
    Unfortunatly some preamp units don't have ADAT inputs but output only with no wordclock input. In that case there is no choice but putting them as master.
    The HD24 is built like a tank.. I have no doubt, it's clock would be good...
     
  16. Boswell

    Boswell Moderator Distinguished Member

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    I've done a bit more digging, and eventually found that the LA-610 output has a maximum level of +23dBu. While this is 4dB over the FS level of the Mytek AD96 when set to standard gain, using the Mytek's variable input control can easily accommodate this. I assume this is what you do to avoid "overs" and triggering the limiting functions on the Mytek.

    I had got rather hung up on the Mytek's standard input settings, jumpered to by-pass the input level control. Winding the control all the way up gives you a gain that's appropriate for -10dBV inputs, but I've still not been able to find what the maximum level of input could be used with the control set to minimum.

    Probably time I stopped diverting this thread. Thanks for your help, Marco. Back to the scheduled programme...
     
  17. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    Yes ! It's at 75% all the time. High enough so I don't push the preamp too much and get noise and not hot enough to get clipping but still have some mojo.
    Of course the compressor of the LA are of great help to keep things from getting out of hand..

    Control set to minimum is mute.. I need to test this when I get to the studio but I wonder why it's important to you.
    Unless you want to overdrive a preamp and still get decent levels ?
     
  18. Boswell

    Boswell Moderator Distinguished Member

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    It's simply that on the few occasions when I'm called on to specify or design studio installations, having uncalibrated variable knobs on back-end gear is not regarded as consistent with repeatable operation. It's acceptable on pre-amps, as they have to be able to operate with microphones of varying sensitivities, but even there, having switched gains like those on the DAV BG1s is great for repeatability. To date, as it happens, I have never included Mytek in my choice converter list, but if I were to, I would probably specify 6dB or even 12dB attenuators installed ahead of the jumpered fixed level, thus by-passing the variable control.

    I think that Mytek have an understanding of this need by providing the internal jumpers to set fixed input levels, but then they have their maximum level of +19dBuFS, which is on the low side. I know that they sell their ADCs and DACs both professionally and to the domestic hi-fi market, so a variable input control that can cope with -10dBV levels is a necessary feature.

    That was really the basis of my interest in your comments on the Mytek.
     
  19. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

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    I get you Bos...
    Repeatable operation is critical for many. The sad part about the AD96 is that the level Knob is continuous instead of stepped which isn't helping.
    So having it to maximum and using attenuators makes alot of sens.
     
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