What's the best way to get rid of tom ring (a ringing noise after the tom is hit) picked up by the tom mics on a recording of a drum kit? I did my best to cure the problem at source, but now some is on the recording.
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Technical Editor Hugh Robjohns replies: Obviously, it is essential to control excessive ringing from toms, snares, kick drums and whatever else is in your studio using damping before you start to record anything — it is extremely hard to fix what are inherently mechanical problems picked up on a recording using EQ, compression and other kinds of processing later on. It's also important to remember to check the sound of individual drums throughout the session to make sure nothing has changed.
As to the best approach in this situation, if the majority of your drum sound is based on the signals from the overhead mics, with the individual close mics simply adding impact and definition rather than the core sound, then you need to check the overheads by themselves to see how obvious and unacceptable the ringing is there. If the overall sound from the overheads is acceptable, then you can concentrate on treating the signal from the close mics so that the attack of the hit is preserved but the ringing decay is eliminated.
You can accomplish this using a gate or, at a stretch, the Strip Silence function found in nearly all DAW software, set with a higher threshold than normal. For preference however, I would use expanders on the close mics to chase down the ringing and subjectively tighten everything up. An expander is essentially a compressor in reverse — it decreases the level of low-level signals and increases the level of high-level signals, thus increasing the dynamic range of the signal. The SPL Transient Designer is a very good tool for this kind of job, too.
If the overheads are mainly delivering the sound of the cymbals, with the bulk of the drum sound coming from the close mics, then the situation is more tricky, as simply cutting off the toms' decay will sound obvious and unnatural. First, high-pass filter the overheads to remove as much of the drums (as opposed to the cymbals) as possible. Next, you are in for a lot of difficult work tidying up the individual drum sounds.
Assuming you have each drum on a separate track on your computer DAW or multitracker, you can manually edit each hit to replicate the action of an expander in reducing the level of the ringing, but with the manual precision that such treatment really needs.
Begin by editing the section between the start of each drum decay and the next drum hit, and reduce the level by 12dB or so (experiment with the degree of attenuation until you achieve the desired effect).
At the first edit point, straight after the drum hit, you'll need to set a crossfade time and shape that makes it sound like the drum is well damped, but has a natural-sounding decay curve. On the second edit point immediately prior to the next drum hit, you'll want a very short crossfade — possibly even a butt join if the spill isn't too bad.
With a little care and a lot of patience you should be able to fix it, and you certainly won't forget to check the sound of the kit before you start recording next time!