Recently I was wandering around Boston Symphony Hall working on aradio project, and as I listened to the luscious reverb of that room, Ibegan 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 wereno microphones, no P.A. system, no gimmicks — just acousticinstruments in a beautiful-sounding space. More than 100 years sinceits coronation, Symphony Hall still reigns as one of the best-soundingorchestral settings in the world.
Nowadays, of course, even the most humble recording studio isequipped with one or more boxes (or plug-ins) designed to digitallyre-create the spacious soundscapes of symphony halls and other sonicenvironments. Thanks to digital reverb, making a violin recorded inyour bedroom sound as though it had been played in a concert hall is aseasy as turning a knob.
Yet for all its wonders, digital reverb is not indispensable, nor isit always the best way to impart a convincing sense of space to yourrecordings. Does anyone really think that, for example, Miles Davis'sKind of Blue would sound better if PCM70s had existed in 1959?Would Led Zeppelin's “When the Levee Breaks” still hold uptoday as a zenith of rock drum tones had the kit been close-miked andswathed in digital reverb? I think not.
The fact is, people were making amazing-sounding recordings longbefore the advent of reverb units (whether digital or analog). And theyoften did so simply by capturing the natural reverberations of therecording space — if they incorporated reverb into theirrecordings at all. There's no rule, after all, that says you must usereverb in a recording. Further, if you do use reverb, nothing says thatit has to come from a binary box. Instead, you can go straight to thesource and use real reverberation — something that happens, tosome degree, in every 3-D space (excepting anechoic ones).
What it boils down to is this: why use approximations of room soundswhen you have the real thing at hand? Even for the personal-studiorecordist who has limited access to reverberant spaces, plenty of othernatural ways exist to imbue your recordings with a sense of space. Inthis article I'll describe techniques for creating“reverb-in-a-box” by capturing and manufacturing musicalreflections and other substitutes that you can use in your recordings.Getting a handle on these techniques will quite likely improve yourproductions and enhance your understanding of acoustics and therecording process. As a side benefit, your proficiency in manipulatingartificial reverb will probably increase — assuming that you everneed to use it again!
BOUNCING OFF THE WALLS
The easiest natural way to give a lush sense of space to a recordingis to record in a lush-sounding room. I have done the majority of myrecording in medium-size (semilush) studios — sometimes they havebeen large enough to create the right reverb for a recording, andsometimes they haven't.
Generally, the best rig for capturing real reverb consists of astereo 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 lessreverberant spaces, though, it pays to walk around the room and listenfor “sweet spots” while the music is playing. Just as thereis a sweet spot where the instrument sounds best in the room —which is the first thing you should determine — there are alsosweet spots in the room where the natural reverberation is mostapparent or best complements the sound. Every room is different, solisten carefully both with your ears and with the mics you choose forthe application.
If the room is neither big nor live enough to give you the depth ofreverberation you desire, try compressing the ambient microphones. Agood squashing can bring up room reflections considerably. (For thatapplication, I especially like photo-optical compressors such as theUREI 1176 and the original Joemeek SC2.) That is a standard approach,especially for drums — slam the room mics, bring them up in themix, and voilà: big, live drums with no need for artificialenhancement. (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 reflectivityof the room. Raise the piano lid, put some sheets of plywood on thefloor or along the walls, turn the extra guitar amps around, or whathave you. You can also get more adventurous with the room mics: aimthem at a mirror or window instead of at the drums, or put them closeto the ceiling or floor, depending on which is more reflective.
FIG.1: Aluminum exhaust tubingmakes for a cool reverb chamber on drums. Shown are two eight-foottubes miked with a pair of Neumann KM 84s. You can tape several suchtubes together to add even more depth to the sound.
If you still can't summon enough life from the space, it's time toget radical. A trick that works in some cases is to createreverberation with long tubes. Try surrounding the drums with a coupleof aluminum clothes-dryer exhaust tubes, positioning one end of eachtube 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 endsfarthest 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 morereflections); putting a room mic in an adjacent garage, stairwell (seeFig. 2), or other reverberant space (with the door between thetwo areas open); and even positioning a room mic inside an open trashcan (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 distancewhenever possible. The studio Rear Window in Brookline, Massachusetts,has a load-in door at the top of the stairs in the main room. I oftenposition a room mic there, pointed at the door (which is closed) tocapture the maximum ambient sound in the room. During mixdown, Icompress the signal and add some tape predelay to increase the apparentsize of the space.
Another classic technique is to record live without isolation— what might be called a Daniel Lanois approach, in today'sparlance. Tear down the gobos, open the doors to the iso booths, andlet the sound bleed. Allow the guitar-amp mic to pick up the drums. Letroom mics capture the instruments from every corner of the studio (orhouse).
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 withbands that can play well and that don't have to rely on punch-ins oroverdubs. Granted, it's not hard to simulate this sound with theassistance of digital reverb — but what can't be simulatedis the vibe you get from recording this way.
When recording the band Two Bones and a Pick at Rear Window Studiosin Brookline, Massachusetts, I placed the drums in the main room alongwith an AKG The Tube mic positioned three feet in front of the kit andabout knee-high. For overheads I used an Audio-Technica AT 4051 and aShure 520D Green Bullet. I put the guitar amp in a large isolationbooth and miked it with a Neumann U 47 placed three feet in front ofthe amp and a Neumann KM 88, in omni mode, hanging from the booth's14-foot ceiling. That setup allowed me to use the door as a balancecontrol to adjust how much bleed I wanted between the two rooms.
I positioned the bass amp in the main room with the drums, isolatedslightly with gobos. I put the keyboard player, who alternated betweenpiano and Hammond B-3, in the same room. If a song called for horns, Iscattered the horn players all around the studio. Finally, I used anAudio-Technica ATM33a small-diaphragm condenser, suspended from the14-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 anomaliesbetween the mics. But once you work that out, your mix is close tofinished. I managed to record and mix the Two Bones and a Pick albumButter Up and Go in just three ten-hour sessions, largelybecause 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 inBoston, I decided to take more of a Tom Petty/Rick Rubin approach. Ihad 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 thechallenge of recording the whole production without using electroniceffects.
First, I set up the drums in the main room and made sure the studiowas as reverberant as possible. For room mics I set up a pair of AKG414 TLIIs in a Blumlein array. I ran the mics through a Vintech 1272preamp and a Tube Tech LC2B stereo compressor, then applied a healthydose of compression. Another factor in the drum sound that helped mesidestep effects boxes was that the drummer used a very open-tunedsnare drum with a long sustain.
For the guitar tracks, a quirk at the studio — the door to thebathroom is accessible only from inside the iso booth — allowedme to exploit the sonic relationship between the iso booth and thebathroom. First, I set up a Marshall half-stack in the booth andclose-miked it with a Royer R-121 ribbon mic. Then I positioned aNeumann KM 86, set to omni pattern, inside the bathroom, and I strappedthe bathroom door open with a bungee cord. By panning those two signalsapart in the mix, I achieved a wide, live, rather Stonesey sound thatproved to be perfect for the project. The only trick was remembering tomute the KM 86 when someone had to use the bathroom!
I used the studio's main room again, in a separate session, tooverdub all the saxophone tracks for the 3Ball album. For the closemic, I chose a Lawson L47MP large-diaphragm tube condenser. The roommic was an Audio-Technica ATM33a suspended from the ceiling. Byrecording the saxes in the same room that I cut the drums in, I got acohesive sound that really glued the tracks together. That's a greatbenefit of using real room reverb — it makes everyone sound asthough they are in the same room (which they are, just not at the sametime). I also cut the backing vocals in the main room, using aSoundelux U95 large-diaphragm condenser set to omni mode so as tocapture maximum room reverberation. You can hear an excerpt from one ofthe songs, “Be Alright,” by clicking here.
ECHO YOUR CONCERNS
A common way to add depth and dimension to tracks without usingartificial effects is to use double-tracking. The subtle chorusingeffect that results from the slight differences between double-trackedparts not only thickens the sound but can also provide an illusion ofspace, especially if you cut multiple “doubles” and panthem out in the mix.
Of course, even with every effort made to create and capture naturalreflections during the recording stage, it's often necessary to addmore 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 arestill around that can be enlisted for delay duties —specifically, 2-track reel-to-reel decks (see the sidebar “DelayTactics”). Tape delay, as the technique is called, can workwonders on vocals, creating subtle doubling, rich“slapback,” and even longer delays.
Another way to maximize the natural reverb of your live space is touse some predelay. On some of the 3Ball songs, I employed this type ofpredelay on the sax room mic, which had the effect of lengthening theoverall decay time and thus increasing the apparent room size. (For the3Ball vocal tracks I used short delays, generally low in the mix andwith only a single repeat.)
CHAMBER OF HOLLERS
It wasn't long ago that “artificial” reverb meant areverb chamber, not a binary box. People still tell stories aboutrevered reverb chambers that sounded so good that any song run throughthem was guaranteed to be a hit. Some studios have reverb chambers, butthey are few and far between.
When working at a studio that doesn't have a reverb chamber, I oftenset up a makeshift one in the main tracking room (which is usuallyoutfitted with speakers). It's simple to configure — just feed anaux send to the speakers, set up a stereo mic pair in the room, andbring the mic signals back in on separate channels. I generally preferribbon mics for this application, because they smooth out the sound andminimize high-frequency detail.
A nice advantage of using the tracking room as a reverb chamber isconsistency of sound: because it's the same room that you cut the othertracks in, you can add ambience yet maintain the sonic character of theoverall recording. Of course, nothing says that you have to use thesame reverb sound on every instrument in a mix. I've set up makeshiftreverb chambers in main rooms, console rooms, iso booths, stairwells,and many other spaces, including what is typically the most reflectivespace in any house — the bathroom.
FIG. 3: The dream personal-studiobathroom: this glass-and-tile shower has a decay time of a little morethan a second. The guitar amp is about six feet from the shower door;the microphone, a Neumann KM 140, is aimed up at the showerceiling.
A bathroom reverb chamber is easy to set up and typically soundsgreat (see Fig. 3). Simply put a speaker or guitar amp in thebathroom and position a mic a reasonable distance away, preferably inthe most reflective area (usually the tub or shower). Experiment withthe placement of mic and speaker to get the right level of reverb. Tryopening 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 vocalsblasting through the apartment as you mix at 3:00 a.m.
Reverb chambers can also be “constructed” from variouscommon household items and spaces, often for little or no money. Ofcourse, you're still using the same basic elements — a speaker, amic, and some sort of reverberant space. The cool thing is that thespaces don't have to be large to create spacious sounds — theyjust need to produce a healthy dose of reflections and a sufficientlylong decay time. Both the speaker and mic you select will color thereverb 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 allmetal inside. Put a small speaker inside the dryer and position amicrophone at the opening. You can also close the door partially andpoint the mic at the back of the door. Experiment. Like anything, thisspace sounds great sometimes and like complete garbage other times.
FIG. 4: A bathroom isn't the onlyechoey space found in the average home. You can also use smaller, moreunusual spaces to configure reverb chambers. For this application, Iwould actually move the amp down the hall to add more distance to thesound before it enters the dryer. I positioned it closer here only soit would be visible in the photograph.
That and other “oddball” chambers can also be used asdirect reverb sources (as opposed to using an aux send feeding aspeaker). For example, a mic inside a dryer can be used to capture areverberated sound from a nearby saxophone, guitar amp, or whatever(see Fig. 4). This technique tends to work best with loudersound sources — a vocalist standing next to a dryer might notgenerate enough level to stir up much reverberation inside the chamber(hence the focus here on the more versatile aux-send/speakersetup).
Acquire a long section of rain-gutter downspout. Put a speaker atone end and a mic inside the other. Experiment by putting a blanket ontop of the spout, which will dampen its resonant frequency and changethe character of the internal reflections ringing through. This kind ofchamber can also be made from a length of PVC pipe, a heating duct, orany other long, tubelike item with a reflective “finish”inside.
Many older homes and apartments have big, metal heater grates (thewall type) mounted in one or more of the rooms. First, sing into theheater grate to see if it reverberates nicely — some sound reallygood, sort of like a plate reverb. If you like the sound, bring in asmall speaker and mic and have a go at it.
If you're looking to make something a bit more permanent, go out andfind an old hot-water heater. Install a speaker inside on one end anddrill 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 doingyour part to recycle.
I once used a 1936 Gibson L5 archtop acoustic guitar as a reverbchamber. It was hanging on the wall in a recording room, and, as theband played, the guitar put out a piano-like resonance. I miked it andcaptured a warm, woody reverb that added a nice spice to the mix. Keepyour ears open — you never know what might produce a usablereverberation.
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 alsohighlights the less appealing qualities of the reverb sound, whetheracoustic or digital. Most great reverb sounds don't have a lot ofhigh-frequency information (which is why, when creating acousticreverb, I go for darker-sounding mics).
In general, you can safely roll off frequencies above 3 kHz andstill maintain a rich sense of space. Besides, most of the time youwant the reverb to be sensed more than heard. Keep things subtle,regardless of the source, and, as always, trust your ears.
Before the adventof digital audio technology, delay was generated by feeding the signalto the record head of an extra tape machine and then returning thesignal from the machine's play head. Because the tape passes over therecord head before the play head, there is a short time delay betweenthe two signals. The length of the delay, which can be derived bydividing the distance between the record and play heads by the tapespeed, is typically short.
Setting up a tapedelay requires a tape deck with three heads (erase head, record/synchead, and play/reproduce head). First, use an aux send to bus out thesignal to the input of one track of the 2-track deck. Enable Record onthe 2-track deck and route the output from the deck's play (or“repro”) head into another channel of your multitrackrecorder. That will give you a single, short repeat.
If the deck has atape-speed control or, better yet, a variable-speed control, you canuse that to alter the length of the delay. In addition, you can createmultiple repeats by bringing up the aux send on the return channel,which creates feedback.
You can generatelonger delay times by using two (or more) tape machines. One machine isused to provide a feed of tape, and the second machine is used togather the tape onto its take-up reel. The tape passes over the headsof both machines, but only the second machine plays back the signal.The signal from its play head is returned to the record head of thefirst machine, resulting in a delayed repeat of the signal (when itpasses again over the play head of the second machine).
It's alsopossible to create tape predelay. First, use a prefader aux send to busout the signal to the 2-track deck. Enable Record on the 2-track deckand route the output from the deck's play head onto another channel ofyour multitrack recorder. Now mute the direct source so that only thedelayed signal is returning to your mix.
Sean Carberryis Technical Director of National PublicRadio's The Connection and a reluctant freelance recordingengineer in Boston.