How Can I Isolate Individual Drums From An Overhead Track?

Question

Me and my band were demoing some stuff at rehearsal the other day. For my style of mixing, I'd much prefer every drum close miked and as isolated as possible from everything, but this wasn't possible with the space and limitations we have. So we recorded the drums using just 2 mics (one just above the kick and one above the drummer's shoulder). Coming down to mix it, I want to try and replace the snare, kick and toms with samples, but obviously I can't just replace them from the track because it's picking up everything.

So how would you guys go about isolating each individual drum from the 2 tracks? I imagine I'll have to use an EQ and try and find a frequency specific to each drum, boost the hell out of it and use it as a trigger for some samples, but are there any better ways of doing this?

Thanks all!

Answer 1

Probably your best bet will be a gate with a sidechain or a gate plug-in with frequency/band settings. You definitely want to find a way to gate separately for each drum since you want no signal at times when you don't want the trigger to go off. You can set trigger sensitivity to eliminate quiet sounds, but you might want some of the dynamics going into the trigger and you'll get the easiest replacement by having a fully isolated track before you go into the trigger/replacement.

In case it's not obvious, you'll want to make a separate copy of your two channel drum tracks for each piece you want to isolate. Then start processing each copy separately until you can unmute them all and hear the kit pieces separated out.

• Kick might be the easiest because a low pass filter somewhere between 50 and 150 Hz before a gate should be good enough to mostly isolate it. You may get some floor tom coming through with a low pass and gate. If so, you'll probably have to manually mute/delete those regions that have floor tom. You're going to be doing some editing on these tracks so might as well warm up with an easy one.
• Snare will both be difficult and probably the most important one. The problem is that the body of the snare overlaps the toms and the snare rattle overlaps the cymbals. First thing I would do is go through and mute/delete all tom fills. Hopefully you mainly have toms played on fills and not as an integral part to many beats. In the latter case it's going to be a long night. Put a bypassed highpass filter and bypassed lowpass filter on the "snare" track, and then a gate. Start with the gate. Take the threshhold to the point where the gate is always closed and you have no sound. Dial back the threshold until the snare starts poking through. Usually the snare is really loud so this should be doable for the loudest hits. As you bring in the quieter snare hits you'll start to get kick hits and maybe some of the louder high hat and crash hits. At this point I would play with the time controls on the gate so I'm getting clean gate open and close on the loudest hits of the whole kit. Then I would bring the threshold down to where I'm getting 95%+ of the snare hits I want. Then start bringing the high pass up to eliminate kick hits coming through, and then bring low pass down to eliminate cymbals. You will probably reach a point where you are have eliminated most of the none snare hits but not all of them. You might have to manually mute or delete some section where there is just too much bleed. It's a pain but it's worth it for a clean, dymanic snare trigger track.
• For the toms, I would just edit around the tom fills unless there is a lot of tom work. If there is a lot of integral tom work, again, you're in for a long night. I would proceed like the snare work above, and look to find the note/tonal center of each tom. You might have more success with boosting a bandpass filter before the gate rather than playing with high and low pass filters. If the snare has a real "ping" to it, a narrow bandpass might isolate that better than high and low pass also.

It'll be a lot of work. But that's the story of good drum tracks, no matter how you get them. It's a lot of work but it's always worth it in the end.

Answer 2

Another idea to add (for future readers who want to put live humanized drums into their recordings but retain the ability to mix them optimally with their DAW), is to use drum triggers which make your acoustic kit record like an electronic one.

Obviously for the recording you have already made, Todd Wilcox suggestions are probably your best option (even if somewhat time intensive). But for future sessions, if you add electronic triggers to your drummer's snare, kick and tom, you will be able to manipulate those and convert them to samples in your workstation with far less work. You can also still use mics and create a custom blend of sampled hits and acoustic mic'd sounds to get a really unique and realistic sound in your finished demo.

I understand the technology in these type triggers is continually advancing and improving. Adding triggers to an acoustic set can not only be more economical than buying a decent electronic kit, but many drummers don't like the feel and responsiveness and the dynamics of the electronic kits.

But for recording drums, electronic kits or acoustic drum triggers can certainly make life easier for whomever is engineering and editing the tracks.

Just sayin .......

Answer 3

Do you have to replace the drums with samples? Can you get a decent mix from the drums as they are? The mic positioning you used is a common method for recording a well balanced kit with only two mics.

I realize that samples are common place, but as a drummer I wouldn't want the character and dynamics of my playing completely removed by replacing everything with samples. I do practice at home with an electronic Roland V-Drum kit and while it is great for low-volume practice, I feel the same way about the sound and feel of playing it vs a real kit. There just is no comparison! I would much rather hear even a mediocre recording of a real kit as it was actually played than pristine samples that sound fake.

I would give mixing the real drums a try before replacing them completely. Another option would be to mix samples underneath the real drums if you need to fatten or increase the volume of particular drums where normal EQ/compression isn't quite cutting it. Mix the samples in just enough to get what you need without overriding the original performance.

Answer 4

You could try nmfdemix, which is a simple commandline program that splits a signal into multiple frequency bands (free). I have successfully did exactly what you mentioned using this tool. If you search youtube for "nmfdemix" my tutorial is there for setup a demo (individual drum hit extraction is towards the end of it). It is all dependent on the quality of the source tracks, but it is the best I've found so far. Hope it helps.