Help with latency settings for recording external gear

So I'm recording some drums and synths from my outboard gear. I'm using Midi Clock sent from Logic to my drum machine to synch playback. When I record, the first drum hit is slightly cut off (see image below of the 2nd drum hit which doesn't line up with the grid... I'm illustrating this with the 2nd hit so you can see just how much of the drum hit is cut off).

This causes an issue when I try to loop the region (obviously, I hear a pop). I know I can add a very short fade to the beginning of the region, but I'm curious if there is a way to prevent this altogether. Should I be using low latency mode? Should I set the buffer size as low as possible? I've been reading through the forums and the user manual, but all of the explanations seem to fly over my pea-sized brain.

I'm new to this whole recording with outboard gear thing, and I'm hoping it's a simple issue of choosing the right settings. Any help?

So tweaked some settings and I'm seeing some results that are raising even more questions:

I found a setting for "Delay Transmission" in the Project Synchronization settings menu. I set this to a 10 tick delay so logic would delay the clock message to the drum machine and hopefully not cut off the first drum hit. Settings below:

Project Synchronization Settings

I did a few recordings and, in general, it helped. MOST of the time the first drum kick is not cut off, but I'm seeing some inconsistent results. Check out the screenshot below of two separate recordings, both made with the same settings.

2 Recordings, Different Results

I'm guessing this inconsistency was always there (and not caused by the delay transmission setting), and I'm just noticing it now as I'm doing multiple back-to-back test recordings. Maybe some sort of jitter that comes with using analog gear?

I'll continue to test different parameters/settings, but I'm curious if anybody else has dealt with this situation and could provide tips/best-practices.

.R

Ok, after some more tests. I'm not so sure the issue is with latency.

Check out the image below which illustrates the first drum hit, and drum hits 2, 3, and 4 (simple 4/4 kick pattern). The vertical green line represents the playhead at positions 1, 1.2, 1.3, and 1.4 respectively.

If you follow along for each take, you can see that the drum hit starts earlier than expected at times and later than expected at other times on each take. These takes were recorded by sending MIDI Clock to my drum machine to start playback (Jomox Xbase999 responds to MIDI Clock only, so I can't use MTC or anything else like that).

Next test is to take logic out of the equation completely and record some sequences triggered from the Jomox internal sequencer. Per other users who are using the same make/model of drum machine, it should have a fairly solid clock, so I would expect any jitter to be must smaller.

Seems like it's some sort of analog jitter? Is it normal to have such extreme drift with analog gear? From what I understand, MIDI Clock is less accurate than other methods of synchronization, but is it THAT inaccurate?

analog drum jitter?

What your seeing there is the result of jitter, but that jitter is all digital.

I really recommend you get Macprovideo's "Logic Latency Toolbox" tutorial by Tom Rice (LPH member "nosebagger"). He goes into the details of probably all you'll ever need to know about latency and how to properly set things up for the tightest sync with external MIDI instruments.

http://www.macprovideo.com/tutorial/logic9207

From what I understand, MIDI Clock is less accurate than other methods of synchronization, but is it THAT inaccurate?

Worst case scenario, if the jitter is not tolerable for you, you can always get your audio dead on using Flex.

J.

Reporting back in.

A MASSIVE thank you to Jordi. Probably the best purchase I made all year. I followed his instructions to set up an external midi instrument and routed the inputs from my soundcard directly to an aux, then used a bus to record the audio to an audio track. Now I just need to follow his steps to account for some latency and I should be set.

Seriously... that guy does some black magic voodoo with Logic that just blew my mind.

.R

Reporting back in:

I watched through the entire "Logic Latency Toolbox" tutorial by Tom Rice twice, and applied some of the techniques he mentioned to fix my latency issues. Great tutorial that helped me sort out the following issues:

1) How to test my audio device to make sure it is reporting the correct roundtrip latency, and how to compensate if it is wrong

2) How to adjust the midi latency of each external instrument, such that all of my external instruments are in synch with each other

3) How to adjust the overall midi recording offset such that my external instruments are in synch with Logics grid

Now I'm 85-90% happy with my setup. However, there is one issue left that I still need help with: Jitter

Let's say that I have midi notes programmed in Logic, and sent to my external instrument. The external instrument plays the sounds and I record them back into logic. In this case, I understand that two notes sent at the same time from Logic (e.g., a Kick and a Snare) could arrive at the drum machine at least 1ms apart, due to the serial nature of MIDI. Throw a whole bunch of other MIDI events in the mix at the same time and the recording will have a lot of Jitter. (and indeed, this is what I experience when I record this way)

However, let's say I have a drum pattern programmed in my external drum machine, and I simply want to trigger a start event when I press record in logic (via MIDI Clock). In this case, I would expect there to be much less jitter as the note triggers are programmed directly in the drum machines step sequencer. Unfortunately, I'm getting a very similar amount of jitter when recording this way.

@Jordi, you mentioned that my issue was digital jitter. Would this still be the case when triggering patterns in my external drum machines step sequencer?

However, let's say I have a drum pattern programmed in my external drum machine, and I simply want to trigger a start event when I press record in logic (via MIDI Clock). In this case, I would expect there to be much less jitter as the note triggers are programmed directly in the drum machines step sequencer. Unfortunately, I'm getting a very similar amount of jitter when recording this way.

 

@Jordi, you mentioned that my issue was digital jitter. Would this still be the case when triggering patterns in my external drum machines step sequencer?

Hello, razzzzz.

If your drum machine is synced to Logic's clock, you will still experience jitter even if the patterns were programmed in the drum machine. You see, when sending MIDI Clock from Logic, you're not merely telling the machine "start playing now", you're telling it "start playing now and follow me".

I don't think the drum machine would ignore the timing clocks and just listen to the Start message while set to sync to an external clock (in case of trying an experiment of sending the Start command only).

Like I said before, if you can't live with the amount of jitter you're getting, using Flex Time in Slicing mode would be a nice solution.

J.