Topic: 4 channel board feed & aud matrix slightly out of sync..

[ellaguru]

hello all..
  ran an r4 4 channel recording last night.  i was way in the back of the venue therefore the board channels are slightly out of sync with the aud channels.  i totally understand why but ill be damned if i can find the formula for how much time needs to be shifted in my DAW mixing of the gig..id wager i was no more than 60ft. from the stage

chris

[Gordon]

no formula needed.  just do it by eyes & hears.  once it's lined up in one spot the whole thing is lined up b/c they are on the same clock.  I do mine in the montage in wavelab.  just zoom in and you should only have to move the aud over a tad to line them up.

[DLay]

there probably is a way to figure out how much delay compensation is needed based on the distance away of the far back source but like Gordon said, theres no need for that whatsoever. it should only be milliseconds off. if youre able to zoom in all the way to 'sample level' then you should be able to 'nudge' the off waveform in the smallest increment possible, which is a sample. just like nudging video frame by frame to make it sync.

[Patrick]

I usually look for a snare hit or a guitar scratch...something percussive with a heavy transient.  This makes it super easy to nudge the AUD source back (or vice versa) to line them up perfectly.  Zoom in and see if you can match the phase of the two sources as well, which is usually easy to do if you have a sound with a sharp attack to analyze.

Most importantly, listen after you make these edits and let that be the final decision   

[danlynch]

I used to think there was a formula, but it really depends upon the venue.  Sometime I ask the sound guy how much delay he applied, but there are some sound guys who don't even know what I'm talking about.  I've done consecutive bands in the same venue (with their own sound guys) and have the delay be off from one band to the next by 10 milliseconds.
So, the advice above ends up being correct, do it by eye and ear.  I usually pick out the first spike (usually drum beat) zoom in the max and determine its exact time, and then align accordingly with the second source.  With the R-44, you don't have to worry about things like drift, so its really relatively easy.

[page]

I agree with others, I take a (preferably isolated) snare/percussion hit.

I've found that there is a spot between perfectly lined up, and a delay of up to 20 samples (so roughly 1 millisecond) that lends itself to a nice mix. The vast majority of my stuff I line it up, but some times I find that I get a more pleasant result when I delay the audience pull by about 10 samples or so. Depends on the content of the individual tracks. If they are balanced already, then I line them up, if one is bass heavy and not much top end and the other is really bright, I'll try the delay and if it doesn't work in a couple of spots (say, 15ms, 10ms, and 5ms) then I line it up.

[ghellquist]

There are two different delays.

First is speed of sound in air. This goes at about 1millisecond per foot. So 60 feet would be 60milliseconds. Use this as a starting point, then align the wave forms in your program, aim for a snare hit or something else very prominent seen in both recordings.

Second delay is what goes on in the PA. Most professional mixers today are digital. They add a small delay when the sound passes through, in the order of a few milliseconds. In larger venues you delay the sound from the "back" speakers compared to the "front". Depending on where you stand in the room this might make a difference. It might also be that the soundboard guy gave you a delayed signal.

// Gunnar

[morst]

I agree that it is best done by eye/ear in a wave editor, but you can definitely approximate it by calculating with the speed of sound. Of course, the speed of sound varies from 1126 f/s at sea level, depending on environmental factors, so it may actually vary over the course of a single show, even with one clock.

Another factor is that PA systems are frequently time-aligned so that the house speakers are delayed. Imagine the wavefront from a kick drum. Well, it's got to travel from back at the drums up to the PA before the sound system needs to reinforce it! So there's often that delay added. Additionally, the tweeters' compression drivers are not always lined up with the woofers' or mids', so there can be additional micro-delay used there.

So yeah. Eye & ear works good.

[Brennan]

I think the others have it pegged, but really it's just like beatmatching when DJ'ing. All you're trying to do is match up a clear snare hit, or bass kick, or something obvious. It SHOULD then all be in sync when you get the one perfect (zoooom in).

If it's then still out of sync, personally I would pull open Ableton Live and 'warp' it to match. They should be almost identical though, unless one was recorded to say a tape deck which you said it wasn't.

[Patrick]

If it's then still out of sync, personally I would pull open Ableton Live and 'warp' it to match. They should be almost identical though, unless one was recorded to say a tape deck which you said it wasn't.

Show was recorded on an R4 = all channels were recorded with the same clock so warping is not applicable here.  The amount of delay in your SBD channel is going to be consistent throughout the whole show unless the mics were moved mid show 

[runonce]

In Audacity, you want the "Time Shift" tool. That will allow you to adjust each trackset relative to the other.

Also - as others have mentioned, a percussion hit is good place to start...

But IMO, the most telling sound is the inner-bell area of the cymbal. When that sounds "right"  - you're on.

[ellaguru]

thanks for all the tips...i was having a bit of trouble sliding the out of sync aud channels, so i just deleted a small part at the start...2670 samples to be exact and whammo the mix is spot on..

chris

[page]

But IMO, the most telling sound is the inner-bell area of the cymbal. When that sounds "right"  - you're on.

I can see that. I've played with mine a number of times and my best mixes generally exhibit this trait as well.

[ellaguru]

But IMO, the most telling sound is the inner-bell area of the cymbal. When that sounds "right"  - you're on.

I can see that. I've played with mine a number of times and my best mixes generally exhibit this trait as well.

well..if the drummer of the band im mixing actually had cymbals it wouldve made sense...

[gratefulphish]

thanks for all the tips...i was having a bit of trouble sliding the out of sync aud channels, so i just deleted a small part at the start...2670 samples to be exact and whammo the mix is spot on..

chris

This is where Audacity makes things very easy.  As someone noted, it has a time shift tool, which allows you to just slide the SBD (or AUD) tracks one way or the other, until they are lined up.  I zoom in, then use the "Selection Tool" which puts a line across the tracks, and if you hit "Shift" and the Down Arrow, the line will cross all four tracks, making lining things up at a specific point very easy.