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 “What Are The Biggest Issues Faced 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.
Dennis Foley: Let’s talk a little bit about the things that we can control and change electronically versus the things that we can’t. What are some major issues in the recording process that we can work with electronically? We can add reverb, we can do a lot of different things? Those are additions. Do we get in situations in a recording where we need to subtract and what are those differences? What are those differences that we can work with electronically and what are those things that “Oh my gosh! I can’t do anything with this!” Give us some examples of those situations.
Joshua: Mainly with drums the attack and decay, there are plug-ins and things like that that you can soften the attack or you can shorten the decay on the actual sound to a point. Those are like the main things especially for drums. It’s always attack and decay for drums.
Dennis Foley: So we have the ability to electronically to manage the attack and decay. Okay. What are some issues that we can’t manage that’s just are not at all good to have?
Brad Pierce: Yeah, you can adjust maybe through the use of compression and expanders. You can use those to attenuate or accentuate the room sounds but when you set up a drum kit, the issue is the drummer’s playing the instrument as a whole and when you mic with your overheads your overheads will be further away from the source. He’s playing the instrument as a whole so the individual hits of the drums you’re not going to be able to manage this well through the use of electronics to control the room sound.
So there’s really only so much you can do controlling the room sound using compressors and expanders things tools like that. If you just had one drum in a room, you know, whatever conga or Djemba or something like that then you might be able to control the room sound through the use of compressors, expanders that type of thing because the attacks are not overlapping other drum attacks while one is decaying.
So you have an attack and decay and may be during that decay the drummer is playing another instrument so you have another attack. So using tools that work on level like current compressors, expanders that type of thing you’re really not going to be able to control the room sound as much as if you had a discrete a one drum instrument say.
Joseph Baffy: Okay, Brad have you ever gotten a track sent to you and you listen to the drum kit and all you hear is ring? You hear a ring through the whole thing, it’s a ring and it only changes in how loud that ring is?
Okay, yeah. Have you ever gotten that sound? What is that sound?
Brad Pierce: It’s a resonance/resonates in the room or in one of the drums.
Joseph Baffy: Yeah I would say that if I have to bet I would say that it’s a resonance in the room and I’ve always, this is more of a question than me giving an answer. Okay. My bet was that, you know I’ve gotten a lot of tracks that are sent to me and I know they’ve recorded them on manage base because I get this whistling sound. I get this ringing sound for a lack of better words for it that is constant until the drum stops.
Brad Pierce: Where about in the frequency spectrum is the ringing like for example say?
Joseph Baffy: 400 Hertz. Between 400 and 500 Hertz sometimes it’s even down to you know at 217 recently I had one at 217 and I think my thought was that it was a standing wave due to over pressurizing of space. I don’t know if that’s correct or not.
Brad Pierce: I would say it’s maybe two answers to that situation. The tuning of the drum kit is really, really important. When you play one of the toms or snare and you listen to see what other instruments or what other parts ring or vibrates sympathetically.
The tuning of the interaction between the drums is really important so you want to take the drums and tune them so they have the least amount of interaction as far as sympathetic vibration that will be one of the answers.
And the other answer is it could be just a room mode that is exciting one of the resonant frequencies of the drum.
You know you have your drum kit in the room, say and you’re playing it and if the room has a very bad peak at 217 or something like that, if the drums are tuned so they vibrate easily at 217, that room mode will enhance the ringing of that kit and you might go and try to tune the toms or something a little bit off trying to minimize that. But that room mode is still going to vibrate that instrument at that particular frequency so you might be able to minimize it a little bit but you may not ever get rid of it you know and that would be the other answer I would see.
Joshua: Okay would that happen more if you’re in a room that didn’t have carpet on the floor or something like that?
Joseph Baffy: It might happen easier not necessarily more.
Joshua: Or easier, well I’m just thinking in a room that’s carpeted maybe it wouldn’t happen, like they wouldn’t be as audible I guess.
Brad Pierce: Yeah, I think the carpet scenario is not going to help you down where it needs to because the carpet material is not going to be absorbing you know lower mids, you know mostly absorb mids and high-mids, high frequencies so that pressure, that low ends the low-frequency issue is not going to be managed by carpet. You’re going to think it is managed because you hear less high ends and less things are going on in the mid and highs but it’s still there if you listen carefully you’re still going to hear the issues that in the low end that you had even with carpet.
You really need a ceiling treatment so that you minimize the standing waves and the pressures on the room by ceiling treatment.
Joseph Baffy: When I think of carpet I think of clapping. That’s what it’s good for, I mean whatever that you know, frequency is that’s about all carpet can handle.
Joshua: Well I guess that ringing would be one of those things that you just couldn’t do anything about unless you change the space that you are in or re-tuning the actual kit.
Joseph Baffy: Okay, let’s just say the kit is completely tuned and it resonates at you know whatever it does but the ringing is as there is no loose parts on it let’s just go with this theory this hypothesis that you know the drums are well maintained and it’s well tuned. The key word that Brad had is resonance. I did a 27 or 30-min video on this for a colleague on resonant frequency and natural frequency and unfortunately through a lot of transfers I don’t know if it’s going to get published this month because it’s really crappy. You can’t have a sound engineer create a video that doesn’t sound right.
The resonant frequency you know the way I tried to explain in this video was everything in your room has an EQ curve and there’s technology to measure that. I mean everything your coffee cup right down to your speaker stands to everything. Every single thing does. So if you have a bunch of shelves with clutter on it you have all kind of EQ on that shelf right?
I think Brad hit me on the head when you excite a certain mode inside that room. Personally, I think what I hear more is that in other words I hear crappy room sounds you know to put it generically than I do crappy maintained drum sets.
Joshua: Would you like kind of minimize that with absorption or with absorption products? Or how would you try to change the mode in the room?
Joseph Baffy: Right now I have a combination of 3 quarter inch plywood and an absorption material that I either turn one way or another depending on what my needs are. Sometimes I turn the hardwood toward the mic to reflect, I turn it on an obtuse angle so that it reflects away from my mic.
And other times I turn it opposite so my microphone is you know, the plywood side it’s a cabinet plywood, that is facing the large space blocking the, I’m not trying to absorb the you know the 27 foot reverb tail, I‘m just trying to make it go away you know reflect it back off out of my space you know that I’m working in.
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.