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24 channel digital recording solution

Discussion in 'Recording' started by EvilOverlord, Jun 12, 2006.

  1. EvilOverlord

    EvilOverlord Guest


    Looking for some advice,

    Need to record from 24 XLR inputs onto seperate tracks.
    Needs to be moveable (to be used at concert gigs).

    What's the best route to go down? Are their dedicated units that don't cost the earth for this? Or would a multi channel input to PC be better? The bandwidth requirements are going to be huge, so I'm not sure a PC could cope.

    Oh and it'll need to cope with over an hour of recording.

    Are there units I can hire first to see if it's worthwhile?

    Thanks for your time. :)
  2. Kev

    Kev Well-Known Member

    one of the hard drive recorders perhaps

    Alesis ADAT HD24XR 24-Track Digital Hard Disk Recorder

    24-Track Hard Disk Recorder with Removable 18G HD
    (Dead Link Removed)

    very cool if the file types or the HD itself loads straight into you Editor Computer

    I use a computer but only want 16
    The compouter does give me monitoring and viewing while recording
    I can also run a quick backup or even simple mix at the end of the night while packing up.
  3. RemyRAD

    RemyRAD Well-Known Member

    My question to the Eviloverlord is, will your microphones be shared with a PA system i.e. will you need to "split microphones"? This would certainly be a most important factor.

    The recorder that Kev suggests is a marvelous machine. I use the standard non-XR machine. That saves you about $700 US if you don't think you need the required Extra Resolution?

    Generally if splits are required there are numerous choices you do have to make. Do you want the microphones to be plugged directly into a passive transformer isolated splitter? Or do you want an active amplified splitter? Do you want your microphone preamplifiers to also be fed to the PA system and to your recording? Is it just a recording where no splitter is required for a PA system? Is the electrical circuit you're plugging into the same as the electrical circuit for the PA system? Will ground loops be introduced? Are you dealing with phantom power issues between your preamplifiers and the PA systems? Who's feeding the phantom is another big issue. Sometimes feeding phantom from 2 different sources can actually cancel the phantom power and/or cause other problems.

    Being able to answer the above questions will better point you in the proper direction for the system you need to assemble for your purposes.

    Pick a card, any card. Or would you rather roll the dice?
    Ms. Remy Ann David
  4. Boswell

    Boswell Moderator Distinguished Member

    I don't advise splitting the microphone XLR signals unless there is really no alternative. I also would not advise going the PC route for that number of channels.

    You presumably have a mixer that you use for your live sound with at least 24 channels, or there is one at the venues you use. The easiest thing to do is to get an Alesis HD24 and connect its inputs to the channel outputs on the mixer. Make sure these are set to pre-eq and pre-fader. If your mixer does not have channel outs but does have inserts, use a specially-wired loom that has TRS jacks at the mixer end with tip wired to ring, and TS jacks at the HD24 end.

    If you have a digital mixer, connect the mixer ADAT outs to the three ADAT ins of the HD24 using optical cables.

    Using a mixer (analog or digital) and an HD24 like this is a guaranteed route. Many of us live sound engineers use it week in, week out. If I know I'm using the venue's sound gear, I sometimes take the train to a live recording gig with just an HD24 in a suitcase with a bunch of cable looms.

    You won't need to hire a multitrack recorder just to see if it works. Whether it's worthwhile is another question...
  5. zemlin

    zemlin Well-Known Member

    While I'm not going to say that recording direct to PC is the BEST route, it's what I do and have done for several years without problems.

    I use a MOTU 24i - the predecessor to the MOTU 24i/o which is fed with balanced 1/4" inputs. I often do FOH and multitrack recording at the same time, and for that I use an A&H Mixwizard 16:2DX which has direct outs on every channel. It works well.

    I did 24 track test recordings on my first DAW - a PIII 750. It did fine recording 24 tracks - today's faster CPUs and disks make it even easier.
  6. EvilOverlord

    EvilOverlord Guest

    First I must say that my knowledge is patchy, I've done some gig work, but it's mostly a solid grounding in physics coupled with experience. Some of what's been said has lost me.

    Indeed they are shared. The desks we have used in gigs have had direct outs so we've been able to take a clean copy of the sound to a recording desk for mixdown to stereo. The results have been, haphazard. This has always seemed a better option that trying to split everything.

    What's the difference? I've looked on the Alesis site and it doesn't make it very clear, does the XR allow 96kHz sampling? If so I won't bother with that, seems totally over the top to me.

    What the heck is that?

    Wouldn't avoiding using splitters be for the best considing this kind of thing?

    Well having done the calculations it only amounts to about 2.5 MB/sec, but the PC isn't designed for realtime, so unless the input has some magically large buffer I'm inclined to agree.

    You've lost me there, what are inserts? We will have this problem as some venues don't have desks with direct outs. That wiring sounds like a bit of a hack, shouldn't you have a DI box to go from balanced to un-balanced?

    Sounds good, I often have to go with what I can carry :-/

    I've been doing alot of ambient recording using a pair of oktava mk-12s or a stereo mix into an m-audio microtrack, but for the larger gigs I need to be able to mix it properly, especially for CD production.

    While I like the PC idea, as they are generally more flexible and cheaper, what is there to stop the audio being dropped? Is there any particular software you have to use for this? It does have lots of flashy lights :) How is it interface? Do you need a seperate PCI card for it? Or is it firewire or some such thing? Having a quick look at prices it seems more expensive. Though I've found a 2nd hand MOTU 24i that's not badly priced.

    Thanks for all the feedback :)
  7. Boswell

    Boswell Moderator Distinguished Member

    You answered one part of this earlier when you said most of the desks have direct channel outs. In contrast, a channel insert is a 3-pole jack (TRS) that breaks the circuit between the output of the pre-amp and the feed to the mixing buses. It's designed for adding effects units and compressers into a channel. The TRS jack has the unbalanced output from the channel on the tip and the unbalanced return on the ring. You can often use the insert jack as a channel out, but plugging in a normal jack-jack lead gets you your output but breaks the circuit to the rest of the mixer. Hence the need for wiring the tip to the ring to maintain the circuit. You can buy these special jack leads from Hosa and others. So the output from the desk is unbalanced, but the HD24 input is balanced. That's fine as long as you use mono (TS) jacks at the HD24 end, as they just ground the -in.

    I think you will find that if you record the individual tracks and mix them down in peace and quietness later, the results will be vastly better than trying to guess at a stereo mix on the fly.
  8. zemlin

    zemlin Well-Known Member

    The MOTU 24i and family interface through a PCI card. I have had good results recording with VEGAS and Samplitude. I have setup test recordings where I sent a simple click track at 60 BPM to as many tracks as I can wire up. Then I setup to record all 24 tracks. I let it record for a few hours and then check the data. I look at the data down at the individual sample level at a number of places in the recording. If all the clicks line up sample for sample, I know nothing's been dropped.

    It took a bit of system tuning to get things working reliable enough for live recording, but I have not had a hosed recording yet. I don't plug anything in without running it through a UPS, so I know I have reliable power. I don't have any crap on the computer that I don't need.

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