Keepin' It Real
Recently I was wandering around Boston Symphony Hall working on a radio project, and as I listened to the luscious reverb of that room, I began thinking about how far we've come since the hall opened in 1900. In those days, an orchestra simply went on stage and played. There were no microphones, no P.A. system, no gimmicks — just acoustic instruments in a beautiful-sounding space. More than 100 years since its coronation, Symphony Hall still reigns as one of the best-sounding orchestral settings in the world.
Nowadays, of course, even the most humble recording studio is equipped with one or more boxes (or plug-ins) designed to digitally re-create the spacious soundscapes of symphony halls and other sonic environments. Thanks to digital reverb, making a violin recorded in your bedroom sound as though it had been played in a concert hall is as easy as turning a knob.
Yet for all its wonders, digital reverb is not indispensable, nor is it always the best way to impart a convincing sense of space to your recordings. Does anyone really think that, for example, Miles Davis's Kind of Blue would sound better if PCM70s had existed in 1959? Would Led Zeppelin's “When the Levee Breaks” still hold up today as a zenith of rock drum tones had the kit been close-miked and swathed in digital reverb? I think not.
The fact is, people were making amazing-sounding recordings long before the advent of reverb units (whether digital or analog). And they often did so simply by capturing the natural reverberations of the recording space — if they incorporated reverb into their recordings at all. There's no rule, after all, that says you must use reverb in a recording. Further, if you do use reverb, nothing says that it has to come from a binary box. Instead, you can go straight to the source and use real reverberation — something that happens, to some degree, in every 3-D space (excepting anechoic ones).
What it boils down to is this: why use approximations of room sounds when you have the real thing at hand? Even for the personal-studio recordist who has limited access to reverberant spaces, plenty of other natural ways exist to imbue your recordings with a sense of space. In this article I'll describe techniques for creating “reverb-in-a-box” by capturing and manufacturing musical reflections and other substitutes that you can use in your recordings. Getting a handle on these techniques will quite likely improve your productions and enhance your understanding of acoustics and the recording process. As a side benefit, your proficiency in manipulating artificial reverb will probably increase — assuming that you ever need to use it again!
BOUNCING OFF THE WALLS
The easiest natural way to give a lush sense of space to a recording is to record in a lush-sounding room. I have done the majority of my recording in medium-size (semilush) studios — sometimes they have been large enough to create the right reverb for a recording, and sometimes they haven't.
Generally, the best rig for capturing real reverb consists of a stereo pair of ambient (room) mics. If the room is large and echoey, you can put the mics up almost anywhere and be in business. In less reverberant spaces, though, it pays to walk around the room and listen for “sweet spots” while the music is playing. Just as there is a sweet spot where the instrument sounds best in the room — which is the first thing you should determine — there are also sweet spots in the room where the natural reverberation is most apparent or best complements the sound. Every room is different, so listen carefully both with your ears and with the mics you choose for the application.
If the room is neither big nor live enough to give you the depth of reverberation you desire, try compressing the ambient microphones. A good squashing can bring up room reflections considerably. (For that application, I especially like photo-optical compressors such as the UREI 1176 and the original Joemeek SC2.) That is a standard approach, especially for drums — slam the room mics, bring them up in the mix, and voilà: big, live drums with no need for artificial enhancement. (You can hear an audio example of this on the song “Across the River” by David Johnston here.)
Need more reverb still? Look for ways to increase the reflectivity of the room. Raise the piano lid, put some sheets of plywood on the floor or along the walls, turn the extra guitar amps around, or what have you. You can also get more adventurous with the room mics: aim them at a mirror or window instead of at the drums, or put them close to the ceiling or floor, depending on which is more reflective.
FIG.1: Aluminum exhaust tubing makes for a cool reverb chamber on drums. Shown are two eight-foot tubes miked with a pair of Neumann KM 84s. You can tape several such tubes together to add even more depth to the sound.
If you still can't summon enough life from the space, it's time to get radical. A trick that works in some cases is to create reverberation with long tubes. Try surrounding the drums with a couple of aluminum clothes-dryer exhaust tubes, positioning one end of each tube close to the kit and the other away from it (see Fig. 1). Make a few bends and curls in the tubes, and place mics at the ends farthest from the drums. That typically yields a rather lo-fi sound, but it will definitely add depth and reflection to the drum sound. Other tricks include lining the floor with spare cymbals (creates more reflections); putting a room mic in an adjacent garage, stairwell (see Fig. 2), or other reverberant space (with the door between the two areas open); and even positioning a room mic inside an open trash can (metal ones sound quite different than plastic ones, by the way). In short, think outside the box — or house.
LET IT BLEED
FIG.2: Take advantage of distance whenever possible. The studio Rear Window in Brookline, Massachusetts, has a load-in door at the top of the stairs in the main room. I often position a room mic there, pointed at the door (which is closed) to capture the maximum ambient sound in the room. During mixdown, I compress the signal and add some tape predelay to increase the apparent size of the space.
Another classic technique is to record live without isolation — what might be called a Daniel Lanois approach, in today's parlance. Tear down the gobos, open the doors to the iso booths, and let the sound bleed. Allow the guitar-amp mic to pick up the drums. Let room mics capture the instruments from every corner of the studio (or house).
I've recorded several albums with blues bands that love the “old school” blues sound — the sound of a band, minimally miked, playing live in a large room. This works best with bands that can play well and that don't have to rely on punch-ins or overdubs. Granted, it's not hard to simulate this sound with the assistance of digital reverb — but what can't be simulated is the vibe you get from recording this way.
When recording the band Two Bones and a Pick at Rear Window Studios in Brookline, Massachusetts, I placed the drums in the main room along with an AKG The Tube mic positioned three feet in front of the kit and about knee-high. For overheads I used an Audio-Technica AT 4051 and a Shure 520D Green Bullet. I put the guitar amp in a large isolation booth and miked it with a Neumann U 47 placed three feet in front of the amp and a Neumann KM 88, in omni mode, hanging from the booth's 14-foot ceiling. That setup allowed me to use the door as a balance control to adjust how much bleed I wanted between the two rooms.
I positioned the bass amp in the main room with the drums, isolated slightly with gobos. I put the keyboard player, who alternated between piano and Hammond B-3, in the same room. If a song called for horns, I scattered the horn players all around the studio. Finally, I used an Audio-Technica ATM33a small-diaphragm condenser, suspended from the 14-foot ceiling of the main room, to pick up the entire band.
The challenge in this kind of multimic setup is the phase check; with all that bleed, it can take a while to sort out phase anomalies between the mics. But once you work that out, your mix is close to finished. I managed to record and mix the Two Bones and a Pick album Butter Up and Go in just three ten-hour sessions, largely because we got a great sound, and vibe, on tape from the git-go.
A ROOM OF ONE'S OWN
When recording the rock group 3Ball at Room 9 from Outer Space in Boston, I decided to take more of a Tom Petty/Rick Rubin approach. I had been listening to and loving Petty's album Echo, which, though recorded entirely without artificial reverb, sounds great — clear, punchy, and very rock 'n' roll. So I set myself the challenge of recording the whole production without using electronic effects.
First, I set up the drums in the main room and made sure the studio was as reverberant as possible. For room mics I set up a pair of AKG 414 TLIIs in a Blumlein array. I ran the mics through a Vintech 1272 preamp and a Tube Tech LC2B stereo compressor, then applied a healthy dose of compression. Another factor in the drum sound that helped me sidestep effects boxes was that the drummer used a very open-tuned snare drum with a long sustain.
For the guitar tracks, a quirk at the studio — the door to the bathroom is accessible only from inside the iso booth — allowed me to exploit the sonic relationship between the iso booth and the bathroom. First, I set up a Marshall half-stack in the booth and close-miked it with a Royer R-121 ribbon mic. Then I positioned a Neumann KM 86, set to omni pattern, inside the bathroom, and I strapped the bathroom door open with a bungee cord. By panning those two signals apart in the mix, I achieved a wide, live, rather Stonesey sound that proved to be perfect for the project. The only trick was remembering to mute the KM 86 when someone had to use the bathroom!
I used the studio's main room again, in a separate session, to overdub all the saxophone tracks for the 3Ball album. For the close mic, I chose a Lawson L47MP large-diaphragm tube condenser. The room mic was an Audio-Technica ATM33a suspended from the ceiling. By recording the saxes in the same room that I cut the drums in, I got a cohesive sound that really glued the tracks together. That's a great benefit of using real room reverb — it makes everyone sound as though they are in the same room (which they are, just not at the same time). I also cut the backing vocals in the main room, using a Soundelux U95 large-diaphragm condenser set to omni mode so as to capture maximum room reverberation. You can hear an excerpt from one of the songs, “Be Alright,” by clicking here.
ECHO YOUR CONCERNS
A common way to add depth and dimension to tracks without using artificial effects is to use double-tracking. The subtle chorusing effect that results from the slight differences between double-tracked parts not only thickens the sound but can also provide an illusion of space, especially if you cut multiple “doubles” and pan them out in the mix.
Of course, even with every effort made to create and capture natural reflections during the recording stage, it's often necessary to add more effects during mixdown. One thing I often use is analog delay, which can fatten a vocal track without making it sound “soupy” or obviously processed. Fortunately, devices are still around that can be enlisted for delay duties — specifically, 2-track reel-to-reel decks (see the sidebar “Delay Tactics”). Tape delay, as the technique is called, can work wonders on vocals, creating subtle doubling, rich “slapback,” and even longer delays.
Another way to maximize the natural reverb of your live space is to use some predelay. On some of the 3Ball songs, I employed this type of predelay on the sax room mic, which had the effect of lengthening the overall decay time and thus increasing the apparent room size. (For the 3Ball vocal tracks I used short delays, generally low in the mix and with only a single repeat.)
CHAMBER OF HOLLERS
It wasn't long ago that “artificial” reverb meant a reverb chamber, not a binary box. People still tell stories about revered reverb chambers that sounded so good that any song run through them was guaranteed to be a hit. Some studios have reverb chambers, but they are few and far between.
When working at a studio that doesn't have a reverb chamber, I often set up a makeshift one in the main tracking room (which is usually outfitted with speakers). It's simple to configure — just feed an aux send to the speakers, set up a stereo mic pair in the room, and bring the mic signals back in on separate channels. I generally prefer ribbon mics for this application, because they smooth out the sound and minimize high-frequency detail.
A nice advantage of using the tracking room as a reverb chamber is consistency of sound: because it's the same room that you cut the other tracks in, you can add ambience yet maintain the sonic character of the overall recording. Of course, nothing says that you have to use the same reverb sound on every instrument in a mix. I've set up makeshift reverb chambers in main rooms, console rooms, iso booths, stairwells, and many other spaces, including what is typically the most reflective space in any house — the bathroom.
FIG. 3: The dream personal-studio bathroom: this glass-and-tile shower has a decay time of a little more than a second. The guitar amp is about six feet from the shower door; the microphone, a Neumann KM 140, is aimed up at the shower ceiling.
A bathroom reverb chamber is easy to set up and typically sounds great (see Fig. 3). Simply put a speaker or guitar amp in the bathroom and position a mic a reasonable distance away, preferably in the most reflective area (usually the tub or shower). Experiment with the placement of mic and speaker to get the right level of reverb. Try opening and closing the shower curtain or door to change the decay. Just make sure not to turn on the shower while the mic is inside!
You can use this same setup in any reflective space, of course — kitchen, hallway, garage, laundry chute, or what have you. Thankfully, using a reverb chamber is a fairly low-volume operation, which means you won't have to torture your neighbors with vocals blasting through the apartment as you mix at 3:00 a.m.
Reverb chambers can also be “constructed” from various common household items and spaces, often for little or no money. Of course, you're still using the same basic elements — a speaker, a mic, and some sort of reverberant space. The cool thing is that the spaces don't have to be large to create spacious sounds — they just need to produce a healthy dose of reflections and a sufficiently long decay time. Both the speaker and mic you select will color the reverb sound, so choose wisely.
A washer or dryer can make a distinctive-sounding reverb chamber. The dryer is usually the better choice, because it's larger and all metal inside. Put a small speaker inside the dryer and position a microphone at the opening. You can also close the door partially and point the mic at the back of the door. Experiment. Like anything, this space sounds great sometimes and like complete garbage other times.
FIG. 4: A bathroom isn't the only echoey space found in the average home. You can also use smaller, more unusual spaces to configure reverb chambers. For this application, I would actually move the amp down the hall to add more distance to the sound before it enters the dryer. I positioned it closer here only so it would be visible in the photograph.
That and other “oddball” chambers can also be used as direct reverb sources (as opposed to using an aux send feeding a speaker). For example, a mic inside a dryer can be used to capture a reverberated sound from a nearby saxophone, guitar amp, or whatever (see Fig. 4). This technique tends to work best with louder sound sources — a vocalist standing next to a dryer might not generate enough level to stir up much reverberation inside the chamber (hence the focus here on the more versatile aux-send/speaker setup).
Acquire a long section of rain-gutter downspout. Put a speaker at one end and a mic inside the other. Experiment by putting a blanket on top of the spout, which will dampen its resonant frequency and change the character of the internal reflections ringing through. This kind of chamber can also be made from a length of PVC pipe, a heating duct, or any other long, tubelike item with a reflective “finish” inside.
Many older homes and apartments have big, metal heater grates (the wall type) mounted in one or more of the rooms. First, sing into the heater grate to see if it reverberates nicely — some sound really good, sort of like a plate reverb. If you like the sound, bring in a small speaker and mic and have a go at it.
If you're looking to make something a bit more permanent, go out and find an old hot-water heater. Install a speaker inside on one end and drill a hole or two at the other end so you can insert the mic(s). Hot-water heaters make great reverb tanks, and you'll also be doing your part to recycle.
I once used a 1936 Gibson L5 archtop acoustic guitar as a reverb chamber. It was hanging on the wall in a recording room, and, as the band played, the guitar put out a piano-like resonance. I miked it and captured a warm, woody reverb that added a nice spice to the mix. Keep your ears open — you never know what might produce a usable reverberation.
DARKER DOES IT
Here's a final bit of advice that applies to mixing with any reverb, whether real or artificial: keep an ear on the high-frequency content. Too much high end competes with other sounds in the mix and also highlights the less appealing qualities of the reverb sound, whether acoustic or digital. Most great reverb sounds don't have a lot of high-frequency information (which is why, when creating acoustic reverb, I go for darker-sounding mics).
In general, you can safely roll off frequencies above 3 kHz and still maintain a rich sense of space. Besides, most of the time you want the reverb to be sensed more than heard. Keep things subtle, regardless of the source, and, as always, trust your ears.
Before the advent of digital audio technology, delay was generated by feeding the signal to the record head of an extra tape machine and then returning the signal from the machine's play head. Because the tape passes over the record head before the play head, there is a short time delay between the two signals. The length of the delay, which can be derived by dividing the distance between the record and play heads by the tape speed, is typically short.
Setting up a tape delay requires a tape deck with three heads (erase head, record/sync head, and play/reproduce head). First, use an aux send to bus out the signal to the input of one track of the 2-track deck. Enable Record on the 2-track deck and route the output from the deck's play (or “repro”) head into another channel of your multitrack recorder. That will give you a single, short repeat.
If the deck has a tape-speed control or, better yet, a variable-speed control, you can use that to alter the length of the delay. In addition, you can create multiple repeats by bringing up the aux send on the return channel, which creates feedback.
You can generate longer delay times by using two (or more) tape machines. One machine is used to provide a feed of tape, and the second machine is used to gather the tape onto its take-up reel. The tape passes over the heads of both machines, but only the second machine plays back the signal. The signal from its play head is returned to the record head of the first machine, resulting in a delayed repeat of the signal (when it passes again over the play head of the second machine).
It's also possible to create tape predelay. First, use a prefader aux send to bus out the signal to the 2-track deck. Enable Record on the 2-track deck and route the output from the deck's play head onto another channel of your multitrack recorder. Now mute the direct source so that only the delayed signal is returning to your mix.
Sean Carberryis Technical Director of National Public Radio's The Connection and a reluctant freelance recording engineer in Boston.