Tip for MASSIVE isolation

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hotmeal
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Tip for MASSIVE isolation

Post by hotmeal »

I'm using Drumagog on a recording for a metal band, where heavy tom hits were always bleeding through into the snare track, causing the snare to misfire. Setting the threshold to grab only the snare hits was impossible in this case and messing around with the frequency filters just took too much time. Then this idea came to me. It's very simple and works great. (Note: If you do this, you'll want to go for 100% replacement because the recorded sound that the mic picks up will be awful!!!)

First, cut off the bottom of a plastic soda bottle
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Then cut some acoustical foam to about the size of a mic (SM57 in this case)
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Roll it up, and stuff it in the bottle
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Keep the mic buried about halfway inside the foam
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Add some more acoustical foam around the bottleneck:
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Now, through the bottleneck opening you basically have a direct shot right into the mic and everything else is essentially blocked out. You could also wrap the outside of the bottle with a towel or anything you can think of if you want even more isolation. I placed this contraption under the snare, just as close to the bottom head as I could get without actually touching. (I'll also place one inside the kick, and one *inside* each tom, going in from underneath.) Legitimate snare hits are now coming in at around -4dB and *heavy* toms hits (I mean HEAVY, probably harder than any drummer would ever reasonably play) are leaking through into the snare mic at only -20 dB. With that much clearance, setting the threshold is pretty much a no-brainer. Again the recorded sound is awful, but who cares... replace with the drum library of your choice, hit it with some reverb, and in the end it sounds amazing.
zumbido
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Post by zumbido »

BRILLIANT!
jwnc
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Post by jwnc »

Great idea.. how good does this work with snare/ HH bleed?

Jason
hotmeal
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Post by hotmeal »

In my initial test, I couldn't get any cymbals to leak through enough to set off the snare. We're recording this weekend with this setup, so I'll post a follow up on Monday to let you know how it went in a real setting. I'm also wondering if maybe a funnel in the top would help direct the sound straight into the mic? Anyone have ideas for dense material that could be wrapped around the bottle itself (on the outside) to further block leakage through the side of the bottle?
hotmeal
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Post by hotmeal »

I've made another improvement to this: I added a funnel to the top and several layers of duct tape around the body. The funnel helps me to reject other sounds better, as does the extra tape by making the body of the container a little more dense.

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I have 5 of these, each containing an SM57.

I'm replacing drums on 5 tracks: kick, snare, and three toms.

I ran a more formal test tonight and here's the numbers. For each mic I did three passes:

1. I first hit the drum over and over again for about 2-3 minutes to set its input level. This is no different from how you'd normally set levels in any session.

2. I cleared the meters, and made a pass striking all the cymbals to see how much they bleed into the primary mic.

3. I cleared the meters again, and repeated but this time striking only drums (no cymbals).

Since I'm specifically testing for mic bleed, I made sure to strike the drums as hard as any drummer would when doing my "bleed passes." In fact for pass #3 above, I used two sticks at once to really nail it hard.

So here's the results:

Track 1 KICK
Direct mic: -3dB
Cym bleed (into this mic): -48dB
Other drum bleed (into this mic): -18dB

Track 2 SNARE
Direct mic: -1dB
Cym bleed (into this mic): -46dB
Other drum bleed (into this mic): -13dB

Track 3 TOM1
Direct mic: -2dB
Cym bleed (into this mic): -40dB
Other drum bleed (into this mic): -12dB

Track 4 TOM2
Direct mic: -3dB
Cym bleed (into this mic): -46dB
Other drum bleed (into this mic): -22dB

Track 5 TOM3
Direct mic: -4dB
Cym bleed (into this mic): -47dB
Other drum bleed (into this mic): -18dB

Those are pretty encouraging numbers! They tell me that cymbals have practically no bleed effect at all. I was surprised to see that the hi-hat bleed into the snare mic still registered this low, considering that it's the closest one to that mic. And the distance between any drum's primary mic and the other drums that bled into it was still huge.

So OK, time to record a quick demo. I sat down at the kit and started playing some repetative stuff with lots of fills going from snare through all the toms. Below is a screenshot of how the snare track looks for it. Snare hits are the white circles, and waaaaaaay down below is everything else that is bleeding in. As you can see, I have lots of room to raise the threshold if I want; but even where it is, the stuff that's bleeding in is in no danger of causing a false trigger.

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Without the isolation capsules this kind of thing was always problematic for me to work out. But with them, I seriously just turned on Drumagog, set my thresholds, and called it a day. Within 5 minutes the drums (problem tracks at that!) were replaced.

Another interesting thing that I noticed was that in a couple of places my inputs were too hot and I got some digital clipping on the original track. But again since I'm replacing at 100%, that apparently doesn't matter; the replacement sample I'm hearing back sounds crystal clear.

I'm still looking for ways to improve the isolation even more. We were originally going to use triggers on all these drums, but that has its own share of problems. If anyone can think of extra ways to add more isolation feel free to comment :) I guess the only thing I haven't mentioned was that each isolation capsule was placed up inside the drum (hiding up it in there makes a huge difference.) Snare drums sound a bit strange with no bottom head, but who cares when the final sound will be a complete replacement? :mrgreen:
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Post by Teri »

Cool!
Teri Grossheim
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Post by maskedman72 »

that is awesome! very innovative. i bet it looks funny with all those on stands around the kit.

what types of problems were you having with the triggers? what triggers were you using?

i am using the ddrum pros and they work great. (the music style i record is deathmetal and hardcore)
zumbido
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Post by zumbido »

I recently obtained the ddrum pro triggers. Thumbs up!
hotmeal
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Post by hotmeal »

Hey, glad so many people dug this thread. I came up with a better way though: tape some earbuds to each drum head. They'll work as a very cheap contact mic (I got enough for the whole kit for 3 dollars each at a local music store). Over the earbuds, tape one half of a clamshell hearing protector. The isolation is insane. Of course it sounds like popcorn but drumagog latches onto it with zero problems. I prefer this over triggers because if you rely on triggers entirely and the trigger misfires, you can't tell what happened (the mistake could have been the dummer, or it could have been the trigger.) With a mic though, even a crummy mic like this earbud method, you have the waveform of the original performance to reference your replacement against.

I'm still on the fence about whether or not 100% replacement feels real or not. Part of me still thinks it feels kind of wonky. But in the right songs it can really work great, and this method makes the replacement part a no-brainer.
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