I have a simple 4 bar 808 sample loaded into T2 of the Octatrack on a flex machine.
I press play on the Octatrack and record the Octatrack playing the same 808 loop for about ten minutes.
When I take that ten minute recorded sample of the 808 and load it into the Octatrack into T3 on a static machine and play it as a one shot I would expect it to stay in time with the same flex sample on T2.
However it doesn’t. Straight away you can hear flanging and as the static sample plays it gets more and more out of time with the flex sample until about ten minutes later it’s now 36ms behind the flex sample.
Settings for the static machine are loop off, slice off, len off, rate pitch, TSTR off. No effects are on any sample.
CF card is the one that came with the Octatrack MKII: ScanDisk Ultra 16GB 50MB/s
Is this known / documented behaviour? A bug with the Octatrack or just a general inability to play a long sample off the CF card correctly maybe?
On what device are you recording the ten minute sample?
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Into Logic on a MacBook Pro using a Burl B2 Bomber ADC.
When the ten minute 808 file recorded from the Octatrack is played back from Logic it stays in time perfectly with the Octatrack (using an SND ACME-4 to sync Logic and the Octatrack).
But when that same ten minute file is loaded into the Octatrack, the Octatrack plays it back slightly slower than it has been recorded.
Did you record 48hz? Should be 44.1
The file is 44.1kHz 16bit.
Well Im no expert, but there’s your answer. Clock discrepancy between Logic and Octatrack.
I dont use Logic, or a computer (anymore). But ive been using OT for 7 years, and Ableton for about 15.
Ableton has a crappy clock. Dunno about Logic.
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Is the Octatrack running as MIDI slave, or unsynced?
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I don’t believe it is clock discrepancy between Logic and Octatrack as I am not actually sending any MIDI clock out of Logic to anything.
Octatrack is running unsynced when playing the 808 flex sample and also when playing the 808 flex and 808 static samples.
When testing with Logic I ran the Octatrack as MIDI slave to the SND ACME-4.
What you’re experiencing is known as clock drift, in this case the audio clock.
Two separate audio clocks will always drift apart no matter what you do.
There is no way to sync the actual audio clock of the Octatrack to anything, since it has no wordclock input like your converter.
There are only two ways to get what you want:
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Digital.
If you keep things in one box for both playback and recording, what you record will match the playback audio clock. So either everything in Logic, or everything in the Octatrack.
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Having a sample accurate midi clock output from Logic.
If you have a MultiClock, or an Expert Sleepers audio to midi solution. This will allow you to sync at least the midi clock to the octatrack to the audio clock from logic.
This will probably still cause some slight phasing with the same material, but it won’t drift apart.
To get a perfect loop, only digital will do since a perfect loop at a certain sample rate & tempo has to have an exact amount of samples.
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The SND ACME-4 is the sample accurate midi clock in this situation, and it works as I can perfectly match the Octatrack to the ten minute 808 recording when that recording is played from Logic alongside the flex machine 808 from the Octatrack (with the usual expected phasing effect).
It’s just the long static file that drifts when played from the CF card. I’ve discovered that if I actually measure how long it drifts out (in this case 36ms after 10 minutes when the Octatrack is playing at 117bpm) I can up the speed of the sample by 36ms (a 0.006% percent change) and it’ll play in time of the CF card.
If this was consistant then maybe Elektron could fix that, I haven’t done a lot of long static sample playing on the Octatrack yet though so am not sure if it varies due to BPM etc.
I guess that is the slight discrepancy you get because of midi, but 36ms is a bit more than I would expect with an audio to midi solution. That’s a lot of clock drift over 10 minutes.
The fact that the audio clocks are not synced makes that a single clock tick for Logic is still a bit longer or shorter than it is for the Octatrack.
But playing it back on Octatrack’s own clock without midi sync shouldn’t cause drift.
10 minutes of audio at 44.1/16 should be the same amount of samples for both Logic and OT.
What happens if you render 10 minutes of kicks from Logic itself? Does it still drift?
Hmm, tough to say what could be the problem here - did you try a new project - sometimes this will eliminate bugs/problems.
Octanube extrodanaire chiming I’m here but… do you have time stretch on?
Have you checked the OT audio editor BPM and bar length?
You didn’t use your sample-accurate clock when you recorded the loop into Logic. When you play back in the OT, you’re hearing Logic’s difference from the OT audio clock.
Consider re-recording whilst clocking the OT’s playback from Logic as you did in your other experiment where you play the long sample back in Logic.
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