| Discussion: sync |
funkman
Captain
Posts: 315
|       | 3:05 pm on Dec. 12, 2009 |
| I use a RS7000 as a midi sequencer with my aw4416, works perfectly as if it was one machine! even though it works I just wanted to make sure how! I can use MTC and just press play on the AW4416 and the sequencer is slaving. What I want to make clear to myself is how does the transport controls sync? Is there MMC messages such as start/stop being sent down the MTC cable? The reason for my sudden curiosity is I was wondering how practical syncing up an adat machine is. I know you have to get a sync converter to change the MTC to the adat sync, but what about transport controls? Then there is the Y56K lightpipe connector, I've heard someone say they had sync problems with this connector -something about word clock only passing one way and the adat running fast. This sounds to me like the frame rate wasn't matched, but I wonder if anyone else has tried it. Of course the better adats were only 20 bit word length as well.... I could use the analogue connections though - as long as it's synced and the transport slaves. This has all come about because I have a friend with some old adat masters. The machines seem quite cheap these days (ebay!) so I was wondering on the possibilities of keeping one after we transfer his masters to give me 8 more tracks - I can't afford a second AW4416 at the moment :)
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buckdharma
Captain
Posts: 813
|  | 3:34 am on Dec. 13, 2009 |
no mmc through mtc.
your midi sequencer starts when it detects incoming mtc, that's all. mtc is pure clocking in a way that gives a position in a song. the start /stop instructions are not coded in the mtc signal, the slave device is programmed to react in a certain way when it detects the mtc signal (you may probably set it to not react when it detects time code)sync through adat connector is something else, it's only audio clock sync. there's no "frame rate" in an audio clock.
the adat signal is self clocking, it means that it is coded in a way that allows to extract timing from the data. not all digital audio formats allow this, it's a matter of the physical waveform that codes the data (electrical for coax s/pdif, optical for adat), no clocking code is added.
such a clocking code would use several bits for every position, when what is needed is a real time bit per bit sync.
audio clock sync is permanent as long as devices are connected and "on". when no useful audio is transmitted, there's 'digital black' (silence) instead. that keeps the clocks synced. the device that extracts audio clock from adat sees a continuous bit stream and so cannot in anyway way extract start/stop or position data, because there are not any ones. it just counts the duration of a bit cell. the adat norm doesnt force an adat device builder to implement the possibility of extracting the clock from the signal.
waves giving always less functionality for more money, they didnt take the time and effort to implement clock extraction in the 56k. adat = mere permanent audio clock sync (if extraction isimplemented)
mtc = hh:mm:ss:ff sync (location in the song, sent only when playing)
mmc = remote control(start / stop /wind / rewind / rec ready / rec )
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buckdharma
Captain
Posts: 814
| | 3:39 am on Dec. 13, 2009 |
if i were you, i wouldnt bother with a tape machine. heads get worn, need to ble cleaned very often, not every vhs tape will work, time to rewind, location problems, drop outs caused by tape being damaged etc.
i'd rather look for a DtD machine, like an old fostex 8 tracks. a lot less mechanichal problems and probably as cheap.
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funkman
Captain
Posts: 316
| | 5:23 am on Dec. 13, 2009 |
| thanks buck. I want the adat machine to recover old recordings made in the 90's. I was just looking at any problems I might encounter. What happens after the transfer was a second thought - to keep or sell on. Maintenance is not such a worry - I used to service video machines and have often cleaned heads for friends with DA88 machines. I have transfered from an adat machine in the past using the waves adat connector, but I had no MTC. Word clock was no problem though, I'm sure I used the clock in the adat connector through the waves board. I know someone on this site had problems with the waves passing word clock, but I'm not sure it's a fact it doesn't do this. The poster mentioned that the adat was running fast which often means the wrong frame rate has been set. I don't think adat machines have a seperate word clock connector so it has to be through the light pipe. So if I wanted to do this I would need a sync converter to convert the MTC to adat sync, word clock through the adat lightpipe via the waves board if poss (I think it is) or switch to analogue ins. The recordings had an MPC sampler running with the adat so the sync is a must have, I can live with the analogue audio if I have to. That part I think I understand and can handle. What worries me is the transport. Now I know (thanks for that) the RS7000 is set to just respond to MTC and play and stop whenever the MTC changes or stops, I can't see the adat doing this. So I assume I will need to connect MMC somehow to the adat. That's the bit I'm worried about as I don't think adat machines even have a midi socket. I would probably need the adat remote control which also handles things like sync conversion. So, MTC ok, word clock if poss or use analogue but transport sync?? MMC?? Unless the adat CAN do like my RS7000 and just follow the changing MTC. It's a lot more complicated than the AW4416 manual suggests - page 67 - 70 :) I think your right, it's not the way to expand the AW4416, however it will be nice to be able to remix those old recordings. The adat machines are going cheap these days as of course they are redundant, and I think a lot of people may do like me - buy one to transfer old masters and then sell on. The cheap price is what made me think of doing this now, but of course nothing's that simple! (except my RS7000). For expanding my set up I think I will try and get a second AW4416 or maybe a AW2816 would be just as good as a second unit. Thanks again.
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buckdharma
Captain
Posts: 815
| | 6:16 am on Dec. 13, 2009 |
the adat remote control translates mtc to adat sync.
adat is 48k only, no 44.1.
keep in mind that if you need to produce a music cd in the end, you'll need to recalculate sampling frequency on a computer, or mixdown to an external 2TK through analog.
by the way : changing sampling fequency is producing a whole new waveform, so leave yourself a little headroom, because higher peaks may occur during calculation. a perfectly clean 48 k recording may clip when converted to 44.1 (if close to 0FS)what i remember is that the guy who couldnt audio sync the waves card asked somenone at waves that confirmed clocking was not implemented. but that's hearsay. you can pass audio through adat with unsynced clocks, it will lead to clicks and glitches, but audio will pass. my computer adat card and the AW are connected trough adat and sometimes, i forget to sync the clocks and it works fine for a moment, both machines being masters. clicks and glitches happen only after a while when clocks have significantly shifted.
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funkman
Captain
Posts: 317
| | 7:09 am on Dec. 13, 2009 |
| thanks buck. The XT can do 44.1 as long as the tape was formatted at 44.1 khz. This is the unit I would buy (£70ish). Don't know at what sample rate the old recordings were done, so will keep in mind what you say when setting the stereo master levels if I have to convert sample rates. still pretty sure I set the word clock off the the y56k input though - can't confirm as I was using a hired adat. Will post what I find here, although not much will be done till the new year. hope you have a good xmas
cheers
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funkman
Captain
Posts: 318
| | 10:17 am on Dec. 13, 2009 |
just found out by reading manual of adat, MMC is provided by the timecode interface, so that's one issue resolved any way.
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Dennis
Captain
Posts: 144
| | 2:56 pm on Dec. 13, 2009 |
you may be able to use a brc for all the control issues. i used to control an o2r from the brc(automix etc.) they have midi outputs im just not sure about the mmc issue.
dennis
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funkman
Captain
Posts: 319
| | 5:01 pm on Dec. 13, 2009 |
| thanks dennis, I think your right - thing is the remote control costs more than the adat these days :) - thats why I will try for a cheaper unit such as a JL Cooper one first. when I do try this out, and these things are always fun to do when they work, I hope those tapes are ok - just realised they haven't been played for 15 years! I'm getting old:(
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buckdharma
Captain
Posts: 818
| | 3:08 pm on Dec. 14, 2009 |
15 years ??! ouch ! that's a lot for a digital tape.
keep us informed, please, i'm interested about that.
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