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Author Topic: Drum channels Alignment  (Read 4225 times)

Brent Venter

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Drum channels Alignment
« on: August 20, 2014, 02:27:47 am »

Hi Guys

I'm not getting my head around getting accurate delay times to align drum channels to the overheads.

I can do this by recording the channels into a DAW and acquiring the data from there, however I was trying to do this via Impulse Response on the FFT.

Overhead into ref channel and snare into measurement channel with snare only played is what I tried however I'm not getting to a place to set the receive
delay properly and or getting a coherent impulse response. I did de-active all high-pass and EQ on the console.

Any ideas on a workflow to do it with FFT?

Regards,
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Mark McFarlane

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Re: Drum channels Alignment
« Reply #1 on: August 20, 2014, 05:01:11 am »

Hi Guys

I'm not getting my head around getting accurate delay times to align drum channels to the overheads.

I can do this by recording the channels into a DAW and acquiring the data from there, however I was trying to do this via Impulse Response on the FFT.

Overhead into ref channel and snare into measurement channel with snare only played is what I tried however I'm not getting to a place to set the receive
delay properly and or getting a coherent impulse response. I did de-active all high-pass and EQ on the console.

Any ideas on a workflow to do it with FFT?

Regards,

The way you have it set up you would need a negative delay.  The snare impulse is arriving before the overheads.
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Merlijn van Veen

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Drum channels Alignment
« Reply #2 on: August 20, 2014, 07:06:48 am »

The way you have it set up you would need a negative delay.  The snare impulse is arriving before the overheads.

+1

Overhead is late to the party, you need to measure by how much and apply it to the snare. So it'll make sense to use this signal as measurement and the snare as reference.

More important does it matter? The overhead to snare distance most likely exceeds the snare mic to snare by 3:1 or 10 dB and vice versa.

If both signals were added to mix proportionally loud, with respect to their designated function, the severity or ripple of the resultant comb filter(s) would be less than 6 dB.
« Last Edit: August 20, 2014, 07:09:10 am by Merlijn van Veen »
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Mark McFarlane

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Re: Drum channels Alignment
« Reply #3 on: August 20, 2014, 10:06:17 am »

...

More important does it matter? The overhead to snare distance most likely exceeds the snare mic to snare by 3:1 or 10 dB and vice versa....

Although the actual db difference will depend on the mic preamp gains, I'm still kind of from the 'does it matter' camp.  If I have multiple overheads live I do try to place them equidistant from the center of the snare, but you are likely going to add reverb t the snare anyway...

Is this a studio setup or live venue performance?   If it's live, if you can move your overheads closer to the main cymbals you are miking you can get the 3:1 or better that Merlin is talking about, but if you have them 'up high' and are picking up a lot of snare then alignment may make sense. I like to keep the overheads right on the cymbals for live gigs then I don't have to worry as much about snare bleed.

If your using the overheads as ambience, then that's a different story.
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Steve M Smith

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Re: Drum channels Alignment
« Reply #4 on: August 20, 2014, 10:11:16 am »

I'm still kind of from the 'does it matter' camp.

Me too.  It's not anything I have ever considered and I don't think it ever will be!


Steve.
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Tim McCulloch

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Re: Drum channels Alignment
« Reply #5 on: August 20, 2014, 12:33:35 pm »

Although the actual db difference will depend on the mic preamp gains, I'm still kind of from the 'does it matter' camp. 

This.

For recording I suppose you can fiddle about, Uncle Ernie, until you run out of patience or money.  Live?  Meh.  The bleed from the snare drum into the singer's vocal mic is a far, far bigger deal than aligning tom and snare mics to the overheads.
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Art Welter

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Re: Drum channels Alignment
« Reply #6 on: August 20, 2014, 09:04:52 pm »

This.

For recording I suppose you can fiddle about, Uncle Ernie, until you run out of patience or money.  Live?  Meh.  The bleed from the snare drum into the singer's vocal mic is a far, far bigger deal than aligning tom and snare mics to the overheads.
And since it seems most folks still seem to like to use dynamic mics on the snare, and condensers on the OH, their phase response wont align regardless of the time alignment, unless FIR filters are employed.
"Fiddle About, Fiddle About"...

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Ivan Beaver

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Re: Drum channels Alignment
« Reply #7 on: August 20, 2014, 09:21:55 pm »

Consider this:

Each of the overheads will be a different distance to each of the drums.  And each drum will be a different distance to every other drum.

There is no way to get every mic aligned to every other mic.  One mic to another-sure.  But you will be using more than 2 mics-at physically different locations-so every distance is different.

The best bet for a good drum sound is to tune the drums and have the kit working as a single unit.  That makes more of a difference than any mic or delay could possibly do.
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Josh Millward

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Re: Drum channels Alignment
« Reply #8 on: August 21, 2014, 09:44:26 am »

The best bet for a good drum sound is to tune the drums and have the kit working as a single unit.  That makes more of a difference than any mic or delay could possibly do.

Exactly.

Last night I was mixing a band who shall remain nameless and the drum kit sounded like a pile of poo.

The toms each had different timbre, different decay, different resonance... one of the rack toms sounded like it had a pillow stuffed inside! It sure made me appreciate the other times when I work with other drummers who pay more attention to the tone and tuning of their drum kit. The difference is amazing. 
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Tim Weaver

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Re: Drum channels Alignment
« Reply #9 on: August 21, 2014, 04:15:11 pm »

I do it with a tape measure
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Jay Barracato

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Re: Drum channels Alignment
« Reply #10 on: August 21, 2014, 04:43:34 pm »

Considering the 3:1 rule and the fact that a 6db or more difference in levels when combining signals makes it a neglible difference, I  usually don't worry about it.

Makes me wonder just how hot people run their overhead(s).

You actually get more interference between two overheads then you do with overhead/snare or overhead/tom interactions so I just use one. Before I would add a second overhead I would add a close under mic on the ride.

Sent from my DROID RAZR HD using Tapatalk

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Luke Geis

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Re: Drum channels Alignment
« Reply #11 on: August 21, 2014, 07:18:23 pm »

I usually only worry about time as it applies to the main PA. As mentioned there is nothing that can really be done to time align the mics to each other, but you can make it so that the signal from the mics is time aligned to the PA...... This is still a bit over the top in my opinion. I have done it before and it takes a while to get the entire kit and backline to line up. Although it is cool that it sounds as if all the instruments are the source of the sound, the amount of work required doesn't always add up to better. The depth and immersion of sound is really cool, but it closes the drums into a more mono like signal and then the guitars and bass have to be placed specifically ( in the stereo field ) to really make things hold together and line up. Then as soon as you move to another position in the room it all changes.........

In short, yes it makes sense to do it and can make for a really cool sound with clarity and depth, but it takes a bit of time to nail it in and it's not the same for everyone in the audience. The incidence of time between the mic and the PA is a constant, but the distance from the listener to the PA and the instrument is not. The only way it would truly work is if you ran a single speaker, mono system.

Also keep in mind with a stereo system you will always have one side of the PA out of alignment with the mic. The only way you could truly pull it off with a stereo rig would be to double all the tracks and pan them hard each direction. Then add in what you need from each track ( to place it in the stereo mix ) after time aligning each channel to it's respective speaker. And even after all that you still wouldn't have addressed the time difference between the listener, PA and instrument.
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Brent Venter

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Re: Drum channels Alignment
« Reply #12 on: August 22, 2014, 01:59:53 am »

Thanks for all the feedback guys.

My OP was submitted in the measurement forum because I am not getting a stable Impulse response and wanted to get some insight where there could be an issue to get IR with a volatile signal...this is an experiment for me and I believe this is how I grow my own knowledge irrelevant of subjectivity.

Thanks Tim for your method, this is how I started experimenting.
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Doug Fowler

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Re: Drum channels Alignment
« Reply #13 on: August 22, 2014, 07:47:12 am »

Thanks for all the feedback guys.

My OP was submitted in the measurement forum because I am not getting a stable Impulse response and wanted to get some insight where there could be an issue to get IR with a volatile signal...this is an experiment for me and I believe this is how I grow my own knowledge irrelevant of subjectivity.

Thanks Tim for your method, this is how I started experimenting.

If you must do it, try using either the delay finder or phase.  You can put a small speaker on the snare head, run some noise through it, and align it that way.  There is sufficient HF in the measurement for the delay finder to yield a proper value. You can tweak it with phase after that.

If you must :-)
« Last Edit: August 22, 2014, 07:49:21 am by Doug Fowler »
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Re: Drum channels Alignment
« Reply #13 on: August 22, 2014, 07:47:12 am »


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