Snare tracks go out of sync? WhaWhaWhat?

[HerbertGroover]

Hi everybody! I ran into a problem this weekend that I simply cannot figure out and I'm hoping someone can help shed some light on it.

My environment is: MacBook Pro running Mavericks, Logic 9, two pretty old Presonus Firepods daisy chained together, recording approximately 14 tracks simultaneously via firewire.

This weekend I was recording a band practice, drums (7 mics), keys (direct), bass (direct), guitar amp (miced). I've been experimenting with getting a better snare drum sound, so I have two mics on the snare, one above and one below (both are sm57s). Sounds much better than my old setup, so I'm psyched about that.

Here's the weird thing- Halfway through a song, the two microphones get out of sync, kinda. For the first part of the song, they are in sync- by which I mean the same snare hit sounds on both channels at the same time, as one would expect. Then, at some point, one of the channels gets a few millisecond delay, right in the middle of a take. There is no outboard signal chain, both mics are run directly into the Firepods. I cannot figure this one out for the life of me.

I've posted a short sample of where it happens here:

(Okay, apparently I can't post a URL because I'm not 10 posts in, but if you look up the track "SnareWeirdness" by herbertgroover on SoundCloud you should be able to hear it)

...this is a bounce of the two snare tracks solo'ed together. Things are fine at first, but at the 10 second mark, there's a drum fill that after coming out of it, one mic sounds a bit delayed. The effect is fairly obvious. There are no effects active in Logic that could cause this, and if there were, it would effect it the entire time (there's no automation, etc, I've checked repeatedly, I'm really only working with the raw tracks).

The ONLY thing i can think of is that the snare mics are plugged into different fire pods (remember, I'm daisy chaining them here), and some glitch happened where they got out of sync after that interface-melting drum fill (har har)? Any thoughts anyone? I'm mystified.

Thanks!

/kurt

 

[miroslav]

I would say it IS some sort of timing issue between the two pods. Don't know how many channels you have on one pod, but have all the drums on one rather than across two.
That said.....if the pods are drifting apart, it will do the same thing with other instruments.
There has to be a common sync between the two pods....check your manual for how you set that. They should both be getting their clock from the same source (most likey your computer), and set to the same sampling frequency.

Also, watch th bottom snare mic....its polarity is 180 degrees opposite the top mic....make sure you invert the bottom mic track when combining.

 

[HerbertGroover]

Thanks for the reply! Yeah, the more I think about it, it would definitely seem like a FirePod issue. I'll try moving that channel to the pod where the rest of the drums are and I'll check the clock sync. Its just so weird that it happened in the middle of a recording like that. Never seen that before (or just never noticed it). Also thanks for the tip regarding inverting the bottom snare track. I've always heard of phase, but have never really, REALLY understood it. Time to hit the books and finally figure it out.

Thanks!