Kick drum splat/overload sound

[stormymondays]

I'd like to gather some "collective intelligence" about this problem that I encounter a bit too frequently for my taste.

Many times a kick drum recording will have a few hits that are over-the-top, and the sound turns to a splatty high frequency "pop" with loss of low end.

Is this something of a "known problem" with kick drum recording?

The thing is, I haven't been able to figure out whether it's the drum itself, the mic, or the pre! Or the performance itself, plus a combination of all factors.

I also had this happen on a completely different drum, studio, pre and mic. So it's not specific to my studio setup.

I always set levels conservatively and I've had this happen with an M88 (with its own foam pop filter as recommended) and an ATM-25.

At first I thought it was the saturation quality of the API-style preamp I use, a Warm Audio TB-12. I substituted the OpAmp for one made by Louder Than Liftoff and the problem got better but didn't get away. I added a shure inline preamp (plus the pre is padded too). Another small improvement but not a fix.

I also experimented with the kick drum (20" Yamaha Recording Custom) mic position: completely inside the hole, completely outside, etc. There's some crazy stuff happening at a very specific point where the sound level gets way hotter, so there might be something there too.

Little by little I got it to a point where the problem had probably been fixed by a combination of everything.

Enter young drummer that plays very aggressively... SPLAT TIME! Added inline pad, changed to a Neve style preamp, finally put a Sontronics DM-1B instead of the ATM-25 and the problem was more or less fixed.

Is this a familiar story to any of you? Am I overloading the mic itself, maybe it runs out of excursion and that's the splat and loss of low end?

Sorry this turned out a bit longer than I thought...

[Wonks]

I'm not sure why (as I read it from your description) you'd use an inline preamp and then pad it down? Or did you mean an inline pad?

Where is the mic signal hitting on the preamp meter when you record? The meter itself will be working on an short period average value, so won't show the very peaks of the signal like a digital peak meter does. So the transient peaks could be going well over the levels indicated.

But any clipping of the preamp should show up on the captured waveform.

It may be the ATM25 mic can't take the high SPL. There's no maximum figure on the AT website for the mic (or its successor the ATM250), but it is designed for drums and high SPLs so should take high SPL without any problems. If the mic's SPL is exceeded, the diaphragm will simply hit the back of the capsule and stop, which could be a cause of the 'splat' sound (which according to Shure talking in general about dynamics and high SPLs won't damage the capsule).

Any inline attenuator is not going to affect the sound from the capsule itself, it will just lower the signal level to the preamp.

The Sontronics is specified up to 155dB, which may be the reason you don't get the 'splat' with that.

Have you tried the ATM25 on the snare just to to see if you get a similar 'splat' sound? IME a really hard snare hit will be much louder than a kick drum so is more likely to cause a dynamic to max out and the sound won't be affected by any possible interactions between the inner and outer skins and the resonant head sound hole like a bass drum. If you get a 'splat' sound as well, try increasing the snare hit volume and maybe compare to another dynamic like an SM57 as to when the 'splat' starts to occur.

But it may well come down to the sound of the bass drum itself and the interaction of the beater with the heads and the hole.

[The Red Bladder]

Neve preamp - good! Set the gain low, so that the peak is well below 0dB and pre has loads of headroom. That way the smoothing cap in the pre cannot run out of puff.

ATM-25 - not good. I have never tried (or even heard of) the Sontronics DM-1B. Try an Audix D6, slightly off-centre inside the drum. It is my go-to kick mic. Clear all the rubbish such as pillows and a dead cat, etc. out of the kick and remove the resonance skin completely and replace it with an empty hoop. Cover the empty drum with a heavy duvet.

Overheads - AKG C414 B-ULS or C414 XLS.

Nothing else, unless there is heavy use of toms. A few really good mics is always going to give you better results than a huge range of cheap nonsense. Or as Bruce Swedien told me "Good mics are the sound engineer's secret weapons!"

He also told me how he records drums and that method (above) is based on his description, though there was no D6 when he was still recording.

[stormymondays]

Sorry, I meant inline pad, not pre! (too late to edit the topic). Thanks for the thoughtful responses, this forum is really great!

Levels are quite low all the way, the signal is coming into the interface at -20dBFS, maybe peaking at -10dBFS. I will peak at the waveforms of the splatty sounds.

Good idea about trying the ATM 25 on snare, will do that. However, I still think it's something to do with the low frequency content. I might also try the snare mic (Beyerdynamic M201) on the kick.

I've never tried the Audix. This also gives me an idea, I also have a Beta 91A which I can throw inside the kick and hear what happens inside when it's splatting.

For reference, I use a Vanguard v44s stereo mic on overheads (love it), M201 on snare (love it), ATM-230 clip-on on toms, just in case they are needed.

Also, I had the M88 fail due to over-excursion even though I used the foam. So there might be something about my kick drum too...

Again, thanks for the replies!

[Hugh Robjohns]

Its very easy to overload the impedance converter circuitry in a capacitor (or electret) mic placed in/near a kick drum. You'll need a mic with a peak SPL capability of 140dB or more. Some can do that with a pad switched in.... but using an in-line pad is shutting the stable door after the horse has bolted — you're just turning a clipped signal down.

There's a reason most people stick with dynamic mics for kick drums.

[Wonks]

The ATM25 is a hypercardioid dynamic, as is the M88. Only the Sontronics is a capacitor, and that has a 155dB SPL capacity (using its 15dB pad), so 140dB SPL without the pad.

[Hugh Robjohns]

Whoops. I thought the atm25 was a dual element mic. Confused it with the atm250.

Dynamics can 'bottom out' but it's unusual, especially in mics designed for use in kick drums.

Which leaves overload of the mic pre as a possibility. If it's the front-end that's struggling using the pad and/or an in line-attenuator should help. If it's the output that can't cope with the transients back off the gain and increase the headroom.

But it is also possible that the drum sounds like that....

[Sam Inglis]

Nothing wrong with the ATR-25 in my experience. My money's on the mic preamp overloading. Meters often don't reflect the very fast transients that drums can generate, so you can get clipping even when red lights aren't visible.

[stormymondays]

Thank you all - I've seen the light! Actually, the lack of lights on many preamps!

I think it's 95% preamp clipping and I can't believe that after many years of faithful SOS reading I fell for this.

I'm always very careful of input levels but I never realised that a preamp could run out of headroom, clip the signal and spit it out at a "sensible" level when metered at the interface.

There's probably a bit of the drum changing sound at that point and generating the extra volume. And maybe the mic is stressed too? Not sure.

I would have thought that the -15dB of the pad would fix that but maybe I need to come down to -25dB at the mic and take it from there. Or change the preamp. Or get the drummer to not do that!

[resistorman]

I'm sure Plugin Alliance has a De-Splat plugin

[Wonks]

I'm always very careful of input levels but I never realised that a preamp could run out of headroom, clip the signal and spit it out at a "sensible" level when metered at the interface.

Driving a preamp into the clipping zone (or transformers into saturation) is how you get the 'character' from it. There will be some headroom in the preamp with the signal around the nominal 0dB level, but not a huge amount. Otherwise if all preamps had nice flat characteristics with tons of headroom, there would be no point in splashing out on esoteric hardware to plug your mic into!

[stormymondays]

Yes, I'm guilty of trying to juice as much character from the preamps as possible. It just never occurred to me that with a very fast transient, the pre clipping could be acting as a limiter. Somehow I was expecting it to clip both the pre AND the converters. Lesson learned!

I will still report back with my findings as soon as I get a chance to do some "science experiments" at the studio.

Thanks again, I love this forum and the expertise of its contributors. I should visit more!