In another of our monthly Google Hangouts with experienced and talented audio engineers Brad Pierce, Joseph Baffy and Joshua Wilson, we continued in our efforts to bridge the gap between what you are hearing as an engineer and how the room is causing that problem. The following video and transcript comes from one particular section where we addressed the issue “How To Remove Room Sound When Recording Drums”. If you would like to see the full hour and a half discussion you can see the video further down the page.
AD: Dennis from your side, as an acoustics engineer, how do you remove room sound for these guys? Are there starting dimensions people should start with if available?
Dennis: Well, everything that has been said so far in the discussion is about two main variables: pressure and reflections. Has anyone ever decoupled the mics from the floor?
Joseph: Yeah generally I decouple in the mic holder.
Dennis: How about the base?
Brad: You can apply a shock mount to the kick drum mic as well.
Joseph: You mean the base of the mic stand?
Dennis: Well, the base and the mic stand decoupling it from the surface area that it is sitting on. Has anyone ever tried that and if so have you noticed any difference?
Brad: Joseph, I guess you’ve been using those mats which will decouple the stand if you have the mic stand on the mats that would decouple a bit.
Joseph: Yes and I will get you a photo a second here.
Dennis: Okay. We’re always talking about two main variables: pressure and reflections. So decoupling and choosing the proper room size and that’s why you always well, you don’t always see it but you should see it, you need a lot of ceiling height in a drum room. Because the distance from the floor to the ceiling has the largest impact on the microphones because it’s the closest distance to the sound source, the floor and the ceiling.
So drum rooms, you know I get customers constantly that have drums in rooms with 7-foot ceilings and you know they cant get good sound. Well they’re not going to be able to and this is you know you just have to be honest and say look the pressure created between a 7-foot span of floor and ceiling is just simply not going to allow that. Now that said we can reduce this pressure in the room but you’re going to give up so much space to do that. It would be so much easier to have more ceiling height.
So what we’re talking about here is pressure and reflections. Pressure at the microphone position. Reflections at the microphone position. Their positionally sensitive especially with the bass drum depending on how hard the drummer’s playing or how soft he is playing. That’s all pressure related. So, our two main variables that we have to work with are pressure and reflections. Now the 64 million dollar question is: How do we control the pressure? How do we control the reflections to achieve the sounds that we want?
We choose larger rooms, we decouple the drum kit from the floor, these are all good things. We decouple the microphone from the structure, another good thing. But it’s still the structure, it’s still the volume that influences the pressure and the reflections. So it’s all a scaled scenario. Smaller room, more pressure, more reflection issues. Larger room, less pressure but probably still a similar amount of reflections. So it’s always this pressure in mind that we’re working with, that we’re trying to deal with and thus, we take that pressure then and break it down into two or three areas: low frequency, low middle frequency, whatever the situation calls for whatever the room really dictates based on the instrument.
So it’s always this juggling act between pressure, excessive pressure and reflections and that’s exactly what we deal with in room acoustics constantly. So the drums is the single instrument that deals with the two main variables that we have in room acoustics.
Joseph: Yes I could say from my experience that the smaller the room, the harder the usable sound is.
Dennis: Makes sense.
Joseph: Open all the windows yeah a little more, you have a better chance and that’s just it, period. There’s no way to get around the amount of build up that happens when you have a rock and roll drummer. If you have a jazz kit, its so much easier cause you don’t deal with the impact. The air is not moving the same. But as far as any kind of rock and roll drums are concerned, if you have a 24-foot ceiling and a 10-foot round room, you’re gonna have a heck of a lot better at sound then if you have a 1600 square foot basement with an 8 foot room. That’s just been my experience. You know the higher the ceilings the better it has been.
Dennis: I think as a general rule we could say finding an optimal pressure level, finding an optimal balance between reflection and microphones is the goal. I mean probably that makes the difference between good drum sound and not so good drum sound. I constantly listen to recorded music and I never hear the same drum sound twice. I hear good drum sounds but I never hear good drum sounds spread out through different recordings by different engineers.
I might hear one engineer that got it right on one song and obviously getting it right, what’s that mean? It’s a little bit subjective on my part but it involves a lot of variables attack and decay you know definition, separation. These are all variables that we have to look at so it’s always that juggling act between high pressure and reflections. Now, the reflections are a lot easier to manage than the pressure. So I think its the pressure that we first need to manage just like in room acoustics. If the bass drum is driving a lot of pressure that has an impact on the rest of the microphones doesn’t it?
Dennis: See. There’s an optimal balance between pressure and reflections and that’s the same paradigms we look for in room acoustics. And that’s why the tools that I’ve kind of put together are a direct response to pressure and reflections and trying to figure out what is the best tool to use to control forty and fifty foot long waves of energy in a shoebox, because that’s basically what a room is when you’re talking about drums, it’s a shoebox. I mean let’s be honest that’s what we’re dealing with. How do we make that shoebox sound like a bigger room?
Joseph: It’s usually done artificially, Dennis.
Dennis: I know and you can hear that too. I can hear that.
Joseph: Yes, that’s generally the approach. As much you know absorption as you can get. In other words, a dead dry space and then an artificial environment is then injected into that.
Dennis: Yeah. So it’s an electronic manipulation of the signal?
Joseph: Yep yep.
Dennis: And I understand that cause real estate is expensive. It’s hard to get that but boy when you get a good drum sound, it really makes the recording just stand right out to me because the bass and the drum to me provides a foundation for the rest of the song. Everything else is layered upon that and if you get the low and right, you can almost have a bigger margin of error in the rest of the frequency response curve but if you don’t get the drum and the bass right, I don’t think you really stand a chance with the rest of it. Any thoughts on that?
Joseph: Bassy Bob is probably one of the best guys at getting low end today that is you know in the public eye. I’m sure there’s guys just as good, they’re just not you know on TV. I have to agree with you with the direction that, alright, there was a question that was posed to me by one of my colleagues he said he was asked to make something modern. He was gonna do a mix for a local band and they wanted it modern and he said “you know Joe, what’s a modern mix?” and I had to respond with the low end. I think what makes.. if I listen to something 20 years ago and I listen to something today, or the farther I go back the less low end there is. And I think what makes us a modern mix today in the rock and pop world is the amount of low end and how well it is crafted.
And so to answer you, yes. In today’s business, in today’s pop music especially, low end is so important that it’s kind of.. I’m working on a song right now just as a favor to another local band and I really have come to a conclusion it’s kind of a quasi metal freakin’ weird song I don’t even know what is, what genre and it’s like all low end and mid range and there’s no top end to it. And it’s like I’m not even worried about the top end because that’s it, it stops at around 13k. And yeah the majority of the song is between 40 and 500 Hz.
To learn more about room acoustics and how drums interact with your room, please sign up to download our free ebooks and video series on room acoustics here. And please let me know if you have any questions at any time.