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Topic: OT: Converting from Analog to Digital

  1. #1

    OT: Converting from Analog to Digital

    Hi all,

    I was looking for some direction in converting my analog connections to digital ones. All this MADI, coax, lightpipe, ADAT, word clock, synchronization, s/mux, and SPDIF stuff is a bit overwhelming. So I was hoping some folks could point me in the right direction.

    I have 3 sample/soft synth playing comps that I would like to digitally connect to my DAW. Multi channel connections would be preferred (so I guess I kinda ruling out spdif here - plus I\'ve had bad experiences with spdif in the past). Also, I would like to things in 24/96. Any comments would be appreciated.

    Thanks in advance...

  2. #2

    Re: OT: Converting from Analog to Digital

    Some ideas:

    - spdif or AES3 - 2 channels, goes up to 24/96
    - ADAT - 8 channels, 24, 44.1/48 or
    4 channels, 24/96 (Not supported in every adat device)

    Other formats - TDIF, RBUS, mLan, etc...

    Very important - SYNC. All sound card must be in sync. I sugest having the DAW as your master clock, which means that you must have wordclock between them all, or having spdif/aes/adat outs (from DAW) to soundcard inputs (other pc\'s) to transport sync...


  3. #3

    Re: OT: Converting from Analog to Digital

    Get something with 8 in/8 out analog with an ADAT digital back end on it. The Tango24 from Frontier Designs I own, and use, and love it, and it has wordclock sync as well, but I\'m syncing to ADAT right now. Just make sure whatever you do get, it has wordclock sync. If you continue to grow, you\'re going to eventually need wordclock... or you might get lucky and get sync on ADAT lines, depending on the devices involved. Just sucks if you realize after you get everything together you get pops and clicks from lack of good sync, and the only way to fix it is to go wordclock.

    In a lot of ways, analog is so much easier though, even if it does suffer signal loss.


  4. #4

    Re: OT: Converting from Analog to Digital

    Thanks for the replies guys. What\'s the difference between adat sync and word clock sync? Do these things require additional cabling (I see some cards with word clock connectors and some without)? Sounds like sync on adat lines might be the least complicated - is this word clock or something different?

  5. #5

    Re: OT: Converting from Analog to Digital

    There is word clock, ADAT internal sync (using the ADAT connector), and ADAT sync (9 pin D connectors).

    Word clock is one way signal that only transmit sync information. ADAT internal sync is the sync information that ADAT connections can transmit (they also transmit digital audio). ADAT sync, that uses 9 pin D connector is more about time code information, to use several multitrack recorder together (you don\'t need this).

    Between word clock (external cable with BNC connector)and ADAT internal sync (the same cable that transports the audio), you can choose.

    At the moment i would probably go to ADAT, but i would buy soundcards with word clock....

    Not simple, right? [img]images/icons/wink.gif[/img] [img]images/icons/confused.gif[/img] [img]images/icons/tongue.gif[/img]

  6. #6

    Re: OT: Converting from Analog to Digital

    Yes, it is quite confusing. And after my bad experience with all those pops and clicks using spdif, I\'m still not 100% certian this will out.

  7. #7

    Re: OT: Converting from Analog to Digital

    It doesn\'t have to be confusing. The following is mostly cut and paste, with a couple of edits for your situation:

    The principle is simple: any time you transfer digital audio from one device to another, the receiving device has to reference the same clock as the sending device. If you have three sending devices feeding one receiving device, as you have, all four have to reference the same clock.

    The clock can be embedded in the digital audio datastream, which works if you only have have two devices (meaning that you won\'t get clicks and pops; it may not be the best sounding way to do it). Or the clock can be distributed to all the devices from one master, independently of the audio runs. That requires a clock distribution box or a clock generator with (in your case) at least four outputs.

    You could use the DAW as the master and get a clock distribution box like the $300 FriendChip one, but the Lucid GenX-6 is probably a better solution (it costs somewhere around the same price and generates good clock). Or you could go for the Apogee Big Ben - $1500 and worth every penny, according to a friend of mine whose opinion I trust.

    I didn’t think so.

    A S/PDIF or AES/EBU line with clock only (\"digital black\") is just as good if not better than a BNC word clock line (because you can send it a greater distance - 20’ is about the max recommended for WC). I don\'t know what problems you were having, but there\'s nothing inherent in the S/PDIF format that doesn\'t work beautifully; I’ve been feeding it to my Tascam PCI-822 card from a MOTU Digital Timepiece (which is also clocking other toys in other clock formats) since last April without the slightest problem.

    However, other than the $800 Aardvark Sync DA (distribution only, no clock), I don’t know of anything with multiple S/PDIF or AES/EBU outs. The Lucid box is probably the one to get, and you want sound cards with a word clock *input*. DevonB said that, but for instance the Tascam/Frontier PCI-822 only has WC *out* - no help here.

    Clocking to ADAT lightpipe isn\'t ideal even if you do get by without clicks and pops, because you\'re probably going to have much worse jitter than any of the other formats (due to light refraction), especially over longer runs. But if you run a separate clock line, sending audio down the lightpipe is fine. Alesis didn’t send clock down the lightpipe when they stacked ADATs, by the way - they used ADAT 9-pin (which also carries control and location information, but you don’t care about that). At least two devices that use lightpipe (the Mackie HDs) don’t even offer clocking to lightpipe as an option. It’s just not the best way to go.

    TDIF is very similar to AES/EBU, but it’s a different bi-directional 8-track format. S/MUX is a way of sending sending four 96k streams down a single lightpipe (instead of eight channels at 44.1/48k). MLan is a Yamaha format for sending everything down a Firewire cable. It’s been pregnant for at least 12 years, and unless things have changed, it’s not suitable for your application due to the latency.

    Finally, clocking is a subtle thing. If getting rid of clicks and pops is a hard bite in the noo-noos, minimizing jitter is touching your hair with a feather. Supposedly jitter only affects converters (so it’s possible to hear it while monitoring and still end up with a perfectly good transfer if you write the incoming data to a file - i.e. record it), but I’ve seen - heard, really - proof that this isn’t 100% true.


  8. #8

    Re: OT: Converting from Analog to Digital

    The exception to the above is when you get a DAW that can re-clock each digital input, i.e. change its sample rate. Pro Tools HD can do that, for example, but I don\'t think this applies to your situation. I\'m just mentioning it in case someone like Kip reads this and corrects me!

  9. #9

    Re: OT: Converting from Analog to Digital

    Wow, thanks for the great info Nick! You cleared up a lot of things for me. I would have never know about the clock distribution device. So does the Lucid device just generate a continuous clock that keeps all the other devices in sync? Thanks again...

  10. #10

    Re: OT: Converting from Analog to Digital

    Yes, that\'s exactly what it does. But it only does word clock and Digidesign Superclock - no S/DIF - so your cards have to accept WC.


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