KMS-30 tape sync - only as tight as the original master?

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Pope Jewish
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KMS-30 tape sync - only as tight as the original master?

Post by Pope Jewish » Mon Mar 04, 2013 6:38 pm

I want to use the Korg KMS-30 with an audio sync signal (FSK on a track in my DAW) master that will then generate MIDI clock and DIN sync, essentially as a "Poor Man's Innerclock" device. Here's what I don't understand - the KMS can only stripe that sync signal when it's driven by another device in the first place, since it doesn't have any onboard tempo or transport controls.

Is, then, that FSK signal only as accurate as the original device driving it, or is it somehow buffered or otherwise regulated to be more accurate? I'm trying to figure out if I need to select my tightest clock source in the first place (and which that would be, between multiple devices) or if the KMS buffers it somehow.

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Re: KMS-30 tape sync - only as tight as the original master?

Post by Sir Ruff » Mon Mar 04, 2013 10:31 pm

Pope Jewish wrote:I want to use the Korg KMS-30 with an audio sync signal (FSK on a track in my DAW) master that will then generate MIDI clock and DIN sync, essentially as a "Poor Man's Innerclock" device. Here's what I don't understand - the KMS can only stripe that sync signal when it's driven by another device in the first place, since it doesn't have any onboard tempo or transport controls.

Is, then, that FSK signal only as accurate as the original device driving it, or is it somehow buffered or otherwise regulated to be more accurate? I'm trying to figure out if I need to select my tightest clock source in the first place (and which that would be, between multiple devices) or if the KMS buffers it somehow.
The simplest solution to me would be to send midi clock out from your DAW, and then just lock everything else to that. The MKS has another 2x midi outs that can be used in conjunction with the midi in, along with DIN sync out. I would avoid tape sync entirely if you can.
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Re: KMS-30 tape sync - only as tight as the original master?

Post by Pope Jewish » Mon Mar 04, 2013 11:26 pm

Why? Shouldn't the tape sync be tighter than DAW clock?

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Re: KMS-30 tape sync - only as tight as the original master?

Post by Sir Ruff » Tue Mar 05, 2013 3:31 am

Pope Jewish wrote:Why? Shouldn't the tape sync be tighter than DAW clock?
I can't say for sure that one is tighter than the other, but I really imagine there being a significant difference, especially since you're only sending clock (rather than actual midi notes). FSK requires that lock-in period which isn't necessary with midi. You can always test your midi clock's accuracy by recording to audio and then seeing if there's any drift.
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Re: KMS-30 tape sync - only as tight as the original master?

Post by Steve Jones » Tue Mar 05, 2013 10:30 am

Pope Jewish wrote:Why? Shouldn't the tape sync be tighter than DAW clock?
No.
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Re: KMS-30 tape sync - only as tight as the original master?

Post by Pope Jewish » Tue Mar 05, 2013 7:45 pm

Steve Jones wrote:
Pope Jewish wrote:Why? Shouldn't the tape sync be tighter than DAW clock?
No.
Why?

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Re: KMS-30 tape sync - only as tight as the original master?

Post by Steve Jones » Tue Mar 05, 2013 10:27 pm

If you are not syncing to actual tape, but instead recording sync pulses from a machine to your DAW and then treating a track of your DAW as a tape sync track to play back into the KMS-30 then you are just accumulating errors at each stage. Timecode was recorded to tape so that the tape machine could provide a master clock to other machines that would have a time reference to the material on the tape and be portable between machines, but the important thing about tape was the the speed was never perfect, so by using a timecode track the sequencer would slow down or speed up with the tape and thus stay in synch with the audio on the tape.

DAW's do not have speed variations or wow & flutter. If you want to use pulses from your DAW rather than MIDI clock then it would be best to write sample-accurate pulses into a track rather than recording them from an old sync box. I doubt that replaying recorded pulses from an old sync box back from a DAW track would be anywhere near as accurate as locking to the DAW's MIDI clock.
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Re: KMS-30 tape sync - only as tight as the original master?

Post by Pope Jewish » Wed Mar 06, 2013 6:44 pm

But then why is Innerclock Devices a thing? Isn't it established that DAW clock is Jittery Joe?

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Re: KMS-30 tape sync - only as tight as the original master?

Post by Steve Jones » Wed Mar 06, 2013 10:18 pm

Now, DAW sync is fine. It is sample accurate when used with the Innerclock device.
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Re: KMS-30 tape sync - only as tight as the original master?

Post by waveterm » Wed Mar 13, 2013 10:35 pm

Pope Jewish wrote:But then why is Innerclock Devices a thing? Isn't it established that DAW clock is Jittery Joe?
Steve Jones wrote:Now, DAW sync is fine. It is sample accurate when used with the Innerclock device.
Actually, this is not true. DAW sync ( Midiclock ) is dependent on several things, the actual DAW software, the protocol that transfers the code from the DAW software and the Midi-interface and finally the Midi-interface CPU. Considering the many different combinations that exists you can never expect it to be perfect.

The Innerclock Sync-Gen is a software/hardware unit that uses the samplerate of the DAW to generate its various clockoutputs. This means they are "sample-locked" with no jitter. Something which cannot be said about DAW´s own Midiclock.

What happens inside the Sync-Gen box is that it takes audiopulses at high rate ( from the Innerclock VST through your audiointerface ) and converts them to Midiclock, Dinsync and clockpulses, with Zero Latency.

You will never ever get that stable sync using other methods.

As for the original question, Recording the KMS-30 FSK will give you any more precise sync than the Master will output. Let´s say that you´re using a drummachine like the ALesis SR-16 as your masterclock going into the KMS and the from the KMS FSK to DAW. If the SR-16 drifts in tempo or jitters, this will be recorded to the DAW. Upon playback, the KMS will convert the drifting FSK and convert it back into Midiclock. The SR-16 will then sync to its own drifting/jittering clock.

Now, if the SR-16 is bad at being a slave, matters will be even worse. It will drift/jitter more. See ? No good.

Best option for perfect sync is to stay inside the box.

Next best is Innerclock Sync-Gen II Pro.

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