DIGITAL IN

Forums Forums Qu Forums Qu feature suggestions DIGITAL IN

This topic contains 18 replies, has 7 voices, and was last updated by Profile photo of Buie Buie 6 years ago.

Viewing 15 posts - 1 through 15 (of 19 total)
  • Author
    Posts
  • #45297
    Profile photo of SONIX
    SONIX
    Participant

    Ordering a QU32 which is exactly what I’ve been looking for for ages – EXCEPT it is such a shame it doesn’t have a digital input! AES, SP/DIF, ADAT… Anything would be welcome!

    #45299
    Profile photo of mervaka
    mervaka
    Participant

    Maybe you should order a GLD?

    #45301
    Profile photo of Andreas
    Andreas
    Moderator

    Digital inputs would require the whole desk to synchronize to some external wordclock which adds complexity to the internal clocking domains thus increasing hardware cost. I could imagine this was one of the first features dropped when designing the Qu series…
    Indeed, if digital inputs (and wordclock sync) is required, the Qu isn’t yours…

    #45303
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    It has digital in, kind of.

    USB B is digital in 😉

    #45304
    Profile photo of Andreas
    Andreas
    Moderator

    sure, but this synchronizes the connected PC/MAC to the wordclock of the Qu (from the samplerate the Qu sends out)…

    #45306
    Profile photo of MikeShand
    MikeShand
    Participant

    Maybe you should order a GLD?

    Err… What digital in on a GLD? Do you mean via an additional I/O module?

    #45307
    Profile photo of mervaka
    mervaka
    Participant

    Yes, ADAT via MMO. Maybe I’m mistaken on functionality?

    #45308
    Profile photo of mervaka
    mervaka
    Participant

    Sorry, I should remind myself what MMO stands for. Output only! Doh. But a Dante card should still provide digital input, surely?

    #45309
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    Hmm, I’ve just sold the PC that this could have worked with, so I can’t test this…

    PC with USB-B connection to QU, ADAT card acting as the clock master to an I/O device…

    PC then passes audio from one to the other – I have *NO* idea if this would work…
    Of course it might end up with horrify latency, and of course re sampling if the I/O isn’t already at 48kHz…

    It is plausibly possible, but I’m not sure I’d want to run it live! (Or rather, I am sure I wouldn’t want to run it live without a lot of testing)

    #45310
    Profile photo of Andreas
    Andreas
    Moderator

    Ok, some technote from my side, sorry… 😉
    For proper digital connections between audio gear a global clock reference needs to be established. I’m not talking about everything switched to the same sampling rate (which is a prerequisite) but for sample clock on all units running in sync.
    Even with everything set to 48kHz, for example, any oscillator still has some tolerance (~100ppm). So one unit may run with 48.000,1 Hz, the next one with 47.999,8Hz.
    Word Clock in/out is the magical word here. Even if word clock could be extracted from ADAT or S/PDIF streams, it is far more reliable and provides less clock jitter (turns into noise when converted to analog) to run a separate BNC cable for the word clock.
    There is exactly one Word Clock Master providing the reference and one or more slaves synchronizing their (internal) clock generators to that word clock (using PLL/DLL/VCXO or similar technology).

    With everything running in the same word clock domain no resampling is required at all. If the units are not synced, resampling is required (on a sub-sample basis) or you’ll hear a click from time to time.

    Bob’s scenario may work, if the ADAT card is able to synchronize to the clock reference from the Qu (via USB), but this would require some generic API within the OS which is aware of clock domains at all. Nothing a PC will do, maybe CoreAudio on Mac, not sure. ASIO is not an option, since you only can use one ASIO driver per application, for the same reason (not synchronizable).

    I’d probably prefer an analog connection… 😉

    #45311
    Profile photo of [XAP]Bob
    [XAP]Bob
    Participant

    I would too, the PC I just sold could certainly master the ADAT connection (though I usually slaved it) – passing the word clock around in software would be ‘fun’

    #45315
    Profile photo of
    Anonymous

    Price point!
    The QU is fabulous!
    He should probably buy a mixer that one can build on.
    http://www.allen-heath.com/ahproducts/firewire-interface/
    Word Clock input and output BNC connectors
    4 x ADAT Input and 4x ADAT Output ports

    And never sell your old equipment until you are absolutely sure you will never want to use it again… hind sight!

    my 2 cents worth

    #45316
    Profile photo of Andreas
    Andreas
    Moderator

    Hmm, the GS-R is an analog desk and this interface is “just” a bunch of DACs and ADCs (sourced from FireWire resp. ADAT). Of course a similar interface could be used to convert from ADAT etc. to analog and then connect to the Qu, but that’s probably not an acceptable path for the initial request…

    #45318
    Profile photo of mervaka
    mervaka
    Participant

    A question to the OP: what is the use case in mind for the digital inputs? To a DAW etc, or to digital rack equipment? Ie, is a stereo or multichannel link required?

    #45320
    Profile photo of Andreas
    Andreas
    Moderator

    Had a similar question in mind but didn’t dare to ask… 😉
    I guess this is more a studio question where the Qu replaces a regular audio interface which likely provides ADAT or S/PDIF inputs and connects to some vintage gear like MD-Recorder or a stack of ADATs or specialized units like the Eleven Rack.
    If the DAW does not support multiple concurrent audio interfaces and is connected to the Qu, there’s no chance to receive audio from those sources digitally.

    If this is worth bothering is another point, though…

Viewing 15 posts - 1 through 15 (of 19 total)

You must be logged in to reply to this topic.