The challenge, of course, is getting a big bottom without the mud flaps. You want the low frequencies to sound huge but not murky. You want them to be deep and loud enough to vibrate your chair — at least with the subwoofer engaged — yet controlled enough that they don't clip boom-box speakers. At the same time, the lows must sound big on small speakers or else half the population will never hear your genius.

How does one achieve a mix with a monster low end? How do you know when the balance is just right and you haven't gone overboard? I interviewed four top recording and mix engineers — Joe Barresi, Chris Lord-Alge, Roger Moutenot, and Hugo Nicolson — to find out how each approaches this challenge. Naturally, our discussions centered around recording and mixing bass and drums, as that's mostly where the thunder rumbles. I'll begin the quest for the perfect storm with recording tips, followed by mixdown techniques.

Begin with the bass-ics

The surest way to avoid the “garbage in, garbage out” pitfall of mixing is to record a great musician playing a superior rig in the first place. Recording electric-bass guitar is no exception, and it makes no sense to cut corners early in the process.

“I'm a firm believer that the source is the key to the sound,” Barresi says. “Certain amps work better than others, and certain DIs [direct injection boxes] work better on certain songs. You might even need to change strings and picks to get the sound you're after. If it takes all day to get a bass sound, then that's the way it goes.” Barresi expresses a fondness for recording bass through an Acoustic 360 (the same model that Led Zeppelin's John Paul Jones liked to use), saying it has “the most insane amount of bottom end of any amp.”

Moutenot is a big fan of trial-and-error experimentation at the source. “It's like, let me try this DI box, let me see if this amp is going to work, let me put this mic on the amp, and let me move the mic back and put it in this space,” he explains. “It's all about getting the chain right.”

Some engineers prefer to simultaneously mic the electric-bass cabinet and record the instrument through a DI box, combining the two signals at the mixing console. Others prefer the old-school method of using only a mic to record bass tracks. After years of going direct, Nicolson now shuns the ultraclean sound of DI boxes. He prefers to mic the bass cabinet with a (vintage) Neumann U 47 large-diaphragm condenser, placed “right on the cloth.”

“I've always gone for kind of an old sound,” Nicolson says. “I think the sound of a DI has less character than that captured by a mic. If you spend all of your time trying to make everything sound too clean, you lose the soul of the record a bit.”

Barresi and Moutenot share a technique for miking bass cabinets: they use a spare standalone woofer as you would a large-diaphragm dynamic microphone to capture the sound. That is done simply by wiring the woofer's terminals to a mic pre or DI box (using standard 2- or 3-conductor cable) and then aiming the woofer at the sound source.

Barresi recalls his introduction to the technique: “I once read that they recorded Paul McCartney's bass [during the Beatles era] by pushing another cabinet in front of his bass rig and using that as a ‘reverse microphone.’ I've since used the same technique, placing a 15-inch JBL in front of an Ampeg SVT cabinet.” Barresi combines the signal from his “woofer mic” with that of a standard mic, mixing the two signals together at the console.

Moutenot usually prefers to use the woofer mic in tandem with a DI box. “I'll put the woofer right in front of the bass-cabinet speaker, about eight inches to a foot away, and it's awesome,” he says. “Any clarity you want, you get from the DI.” He then delays the DI signal so it's in phase with the signal from the woofer microphone. Moutenot recommends the Demeter VTDB-2b Tube Direct as “a really good DI box” for recording bass.

Kick start

Moutenot also used a woofer as a microphone to record all the kick-drum tracks on Paula Cole's last two albums, This Fire (Imago/Warner Brothers, 1996) and Amen (Imago/Warner Brothers, 1999). Depending on how much low end he wanted to capture (the amount is proportional to the speaker's size), Moutenot used a 10-inch to a 15-inch woofer to record the kick. After removing the front head from the kick drum, he secured the woofer to a spare snare-drum stand and angled it toward the open end of the kick. If a spare snare-drum stand wasn't available, Moutenot would secure the woofer with rubber bands to the kick drum's lugs so that the speaker was suspended in air, facing toward the inside of the drum. In either case, he also miked the kick with an AKG D 112 to add some clarity to the sound. Moutenot printed the two signals (from the woofer mic and D 112) to separate tracks for the greatest flexibility at mixdown.

“In a sense, the woofer is sometimes my EQ,” Moutenot says. “If I want a little more bottom that doesn't have the top, I favor the woofer or blend it in just so there's this nice round tone.”

Barresi is inclined to use a Yamaha NS10 woofer as a “super-duper large-diaphragm microphone” to record kick drum. He mounts the cannibalized woofer to a mic stand, situates the speaker so that it faces the kick drum's opening, and wires a 2-conductor cable to the woofer's terminals. “The last time I did that,” says Barresi, “I ran the signal into a DI, padded the DI down, and routed the signal to a mic preamp in a Neve console.”

Barresi often uses more than one mic to record kick. His miking techniques vary, but he'll “always have a mic that's outside the kick drum,” he says. “Sometimes I'll put a mic three or four feet out to capture more of the low-end wave.” To reduce cymbal bleed into the distant mic, he builds a tunnel between the mic and kick drum by draping a blanket over some flanking mic stands. He occasionally varies that technique by placing a second kick drum at the far end of the tunnel. “I'll put a mic inside the second kick and drape a blanket over both kicks so I don't get a ton of cymbal bleed in the mic,” Barresi says. The second kick serves as a low-frequency resonator, bolstering the bottom end of the kick the drummer is playing.

Barresi uses a lot of compression on kick drum while recording to tape and when mixing. “I've been really happy with the Focusrite Red compressor,” he says. “I'll put that on a bus for all of my kick mics and commit them all to one track while I'm recording. I've also used a Teletronix LA-3 or a Urei 1176 on kick.”

Nicolson is also a big fan of recording bottom-end instruments with compression, noting that it makes it easier to balance levels. He prefers to use a dbx 160X compressor on electric bass and a vintage 1176 or Fairchild compressor on kick drum. But when it comes to miking techniques, Nicolson's approach runs counter to Barresi's. “The fewer the mics on everything, the better,” Nicolson says. “I just keep things really simple.” He typically places a Neumann U 47 or an AKG D 112 at the entrance to, or slightly inside, the kick drum's shell (with the front head removed).

Body double

On many records, what seems to be one huge sound is frequently a combination of two or more different sounds. Lord-Alge points out that it's quite common for engineers to beef up the bottom end of a recording by adding Roland SP-808 drum-machine hits, loops that are varisped down in pitch, or what have you. Another technique is to double the electric-bass-guitar part with a unison synth-bass track.

“One of the new trends is having a subchannel for the bass that's just a subharmonic synth,” says Lord-Alge. “You put a little bit of that in just to get it really thundering.”

Of course, it's not appropriate to double bass parts with synthesizers in every style of music. Moutenot never uses synthesizers in that way, and Barresi — who works primarily with organic “stoner rock,” alternative, and rock bands — almost never resorts to using them.

“It's pretty much taboo,” Barresi says. “There might be a section of a song, like a part of a verse, where we might add some synth bass in order to give it a little more push. But for the most part, everything I record these days is a four-piece band: two guitars, bass, and a drummer.”

Tectonic shift

Barresi further beefs up bass and drum tracks at mixdown with signal processors. One of his favorite techniques is to use a subharmonic generator or pitch shifter to detune the pitches down an octave.

“I definitely use some of that when I'm mixing,” Barresi explains, “but never in the tracking stage. I like the Furman Punch-10 [Model PCH-10], which is basically like the original dbx 120 subharmonic synth but a little bit tighter sounding on things like kick drum. I usually put a bit of the kick and maybe the toms through the Furman, and sometimes I put the bass through it, as well. The Furman is stereo in and out, and it has a subwoofer output for suboctave stuff. It has a limiter built in, which I like because I can tighten up how much of the bottom is really coming out of the box itself and not have to go out to another piece of gear.”

Barresi also likes the dbx 120, but he uses it for processing bass guitar instead of drums. He prefers the original 120 to the reissued 120A because the older unit has a dedicated control for tweaking a band in the 20 Hz area, out of the way of other bass-frequency bands. “The dbx unit offers a lot more control than the Furman,” Barresi says. “It seems to work better on bass guitar.”

When he can find a studio that has one, Barresi prefers to work with the discontinued Publison Infernal Machine, which, he says, “blows away” all other boxes that do octave dropping. He likes to use the Publison to detune drum-room mics, bass guitar, or toms, mixing the processed sound in with the original, dry sound.

Barresi also likes AMS processors for pitch-shifting duties. “On a lot of the Melvins records,” he says, “I pumped the drum-room mics back through an AMS DMX 15-80S sampling delay and dropped it down an octave. On slower things, you can hear the sound of the cymbals and kick in the room drop, and it sounds incredibly low and bizarre.

“The guy I learned this from was Jason Corsaro, who I think is probably the most innovative engineer around. He did the [eponymous] Power Station record [Capitol, 1985], which has a drum sound that's just phenomenal. He got a lot of the sounds in a small room, but it sounds huge. He did it with a Publison, detuning the room and the toms. He also engineered Soundgarden's Superunknown [A&M, 1994], which I think has probably the greatest bottom end of any record around. That was a lot of the same kind of thing, pumping the bass through a subharmonic generator. But he'd actually reamp the bass back to a P.A. and mic the P.A. up.”

Of course, one man's pleasure is another man's pain. Mix engineer Lord-Alge doesn't like to use subharmonic generators. “I'm not into any of that,” he says. “They can run away on you. If it's built into the track and that's the kind of thing the producer is looking for, then great. But I can generally go in there and get what I want with EQ.”

Moutenot “sometimes, but rarely” uses a subharmonic generator. “I rely on tape speed to get deep bottom end,” he says. “I cut Paula Cole's record at 15 ips on an analog multitrack with Dolby SR, which really gave me a lot of what I was looking for.”

Pleasin to squeeze

Most engineers use compressors to beef up bass tracks, but not always in the way you might think. Barresi often uses an LA-2A as much for its saturation characteristics as for its dynamics processing capabilities. “You can turn the LA-2A into an amazing, smooth fuzz box,” he says. “I prefer turning the input up a bit but not limiting it that hard. That gives you some grit from the tube. I'll also use a dbx, an RCA BA6A, or an 1176 to compress the track further.” In addition, Barresi likes to mix with a Tube-Tech LCA 2B stereo compressor placed across subgrouped drums, feeding mostly kick, snare, and toms into the compressor.

Moutenot and Nicolson both like to subgroup drums and bass at mixdown and send them through a stereo compressor. But on separate bass tracks, Moutenot usually uses relatively small amounts of compression. “If it's a rock song,” he says, “I'll lean toward using an Empirical Labs Distressor on the bass. I usually go for what I've found to be kind of a Fairchild preset: Distortion 3 in, 6:1 [ratio], and 4 and 4 on the attack and release.” (The Distressor's attack and release control-knob settings are not marked in milliseconds or seconds, because the time-constants ranges vary with the unit's different presets.)

To say that Moutenot likes the Distressor would be an understatement — he owns ten of them. Moutenot also likes to use a vintage LA-2A or Neve compressor on bass. On Paula Cole's album Amen, he used a Collins (an old Army tube compressor) to process Tony Levin's bass-guitar tracks.

Lord-Alge owns mostly vintage compressors and asserts that, in general, “you can't beat blackface 1176s” for processing bass-guitar tracks. Then again, if a bass track's dynamics are “all over the map,” Lord-Alge uses a Distressor to rein them in. “The Distressor is for mangling things that really need to get hammered,” he says. He also uses a Distressor on a kick-drum track when “the dynamics are too overwhelming for the song. I'll flatten it out a little bit so you can hear all the syncopation.”

The great equaliser

One of the most powerful tools for sculpting a huge bottom end on a mix is equalization. Though acknowledging that the proper use of EQ is highly contextual (that is, dependent on what each song needs), the four engineers I interviewed nevertheless offered general suggestions on how to approach the task in order to achieve a desired effect.

Lord-Alge usually leans toward using shelving, as opposed to bell-curve, EQ on bass instruments and especially on drums. “When you're equalizing bass,” he says, “the worst thing you can do is start messing too much with adding the wrong frequency in the low end. You don't want one note to stick out in the whole range. You want the broadest boost possible.” To make the bass audible on small speakers, Lord-Alge sometimes boosts around 400 Hz. But that doesn't mean he thinks in terms of frequencies while applying EQ to mixes. Rather, his approach is purely instinctual. “I close my eyes and turn the knob until it feels right,” he says, “and don't get too technical about it.”

Moutenot is in the same camp. “I just don't have methods to my madness,” he says. “I keep my eyes closed, and I'm not even looking when I reach for the EQ — if I EQ at all.” Moutenot does admit that he fairly often rolls off the highs on bass guitar. “It makes it sound cleaner to me,” he says. “You just hear all the bottom and not the garble up top.”

Before he tweaks the EQ on individual tracks during mixdown, Barresi generally adds a shelving boost — often 3 to 4 dB from 40 to 60 Hz on down — on the mixer's master stereo bus. “I'll approach it that way first,” he explains, “so I'm adding a lot less on individual channels. That creates fewer phase problems.”

Speaking specifically about equalizing kick drum and bass, Barresi says, “If I'm boosting a little bit at 60 Hz on the kick to make it pump through, I might need to use a (highpass) filter at around 25 Hz to cut some subbottom. That keeps the superbottom out, which is important because I'm adding some back with the dbx 120 or Furman. But I definitely won't roll any of that stuff off on the bass. I want the bass to be full-range all the way.”

Barresi prefers to use a wide- rather than narrow-bandwidth boost on bass guitar, boosting as needed around 300 Hz for a rounder and warmer sound or around 700 Hz for more edge and growl. “I'll probably add a little top around 3 kHz to make it poke through,” he says, “and pull everything off the top end around 10 kHz and above. Sometimes I'll add some distorted bass in, as well, because that can give it some clarity, and I'll use my main (original) bass track for the subbottom, warm, round part.”

Nicolson notes that getting the kick and bass to complement each other is a big part of getting the bottom end of a mix in proper perspective. That said, he has no set rules for equalizing the two instruments. In fact, he feels that getting the correct fader levels is generally more important than tweaking the EQ of individual sounds.

Gaining gain

For situations in which you can't get the bass to cut through by tweaking the EQ, Lord-Alge has a solution: bring the track up on two faders. “I'll print the bass — the exact same performance — on two tracks just to have more juice, more gain hitting the console,” he says. “It makes a huge difference. Sometimes one fader isn't enough.” He usually EQs both tracks the same way.

What's the benefit of using two faders for the same bass part? “Headroom,” says Lord-Alge. “Would you rather push the fader all the way to the top or put it at the absolute sweet spot? It makes a huge difference where the fader is. If an important part of the mix isn't going to ‘happen’ on one fader, bus it to an aux that adds to the level, put it on two faders, and send it to a subgroup and more EQ. It's all about making it large without taking up all the mixer's headroom.”

Barresi, too, usually ends up with the bass on more than one fader at mixdown. Part of his process typically entails reamping the bass track in order to make it distort. “I'll just reroute the DI track back through a pedal and an amp and remic it,” he says. “Or I might use a Sovtek head and a Palmer PDI-03 speaker simulator.” To preserve the original, clean DI track, Barresi will mult it (split its signal into two audio paths) before reamping it. “I normally have three tracks of bass: DI, amp, and reamp,” he says.

Judgement day

I've discussed a lot of techniques for beefing up the bottom end. But all the signal processing in the world will get you nowhere if you can't accurately assess the end result. If you really want a killer bottom end on your mixes, you need to mix in a familiar control room that has good acoustics, a reasonably flat frequency response, and accurate reference monitors.

“Don't even think you're going to get the bottom in the ballpark if your monitors don't make sense,” says Lord-Alge. “And trying to get the bottom end right in a room that you're not already familiar with — whoa, you're already wrong. It's like saying, ‘I'm not really familiar with driving this car, but I'm going to get in this race anyway.’”

Lord-Alge goes on to note his preferences for studio monitors: “I have Yamaha NS10s and a $300 sub made by Infinity. That's rig No. 1. Rig No. 2 is a pair of M&K [Miller and Kreisel] MPS-2510P powered monitors and their big powered sub, which is situated right underneath the console. M&K makes the best powered speakers, I think. They are just unbelievable. The low end is a little bit over the top, but I'd rather have it that way. That way I know I'm not going too far.”

When asked about the monitors Moutenot prefers to check the bottom end on, he says, laughing: “You're going to freak out: NS10s — that's all I use, except for Sony headphones. I'll put my hands on the NS10's white cone and feel what's happening with the speaker. I've used them for so long that I can tell what's going on with the bass. I've tried so many other speakers where I go, ‘Man, the bottom end on these is awesome.’ But after a week, they're making me do things I don't want to be doing.”

Nicolson also checks the bottom end on NS10s. “I know that sounds really stupid because NS10s are crap on the superlow end,” he says. “But at high volume, you can judge the bass end on NS10s pretty well. If you're really driving the NS10s and it still sounds good, then you know you're on a winner — you don't have too much or not enough. I also have a pair of KRK 6000s that I switch to.”

Barresi's favorite reference is his car stereo, but he also uses NS10s to judge the low end of his mixes. “If the bottom is distorted on NS10s and the notes aren't ringing out true,” he says, “then you've probably gone too far because the speaker can't handle what you're doing. I also walk around the control room when I'm mixing. There are certain areas where the bottom end is superapparent. You might want to sit there for a while to listen to what the bass is actually doing and to check if any notes are dropping out.

“I'm not a big fan of mixing with subwoofers,” Barresi adds. “If I'm hearing too much low end, then I'm adding less and am usually disappointed in the final result.”

The lowdown

In the end, of course, determining how big the bottom should be on a mix depends on the style of music and the song in question. “Some poppier songs don't dictate having this massive low-end thing,” Lord-Alge says. “Sure, you want to have something solid down there, but I don't ever want it running away on me. It just mushes the whole record up.”

When in doubt, it's usually best to err on the side of having too much bass rather than having too little. “I find it's easier in mastering to get rid of bottom than to add it,” Barresi says, “so I'm not afraid to put a little extra down there. If it does get out of hand, then it's easy to filter some of that out.” On the other hand, you can't boost something that's not there to begin with.

If your budget doesn't allow for mastering, your best bet is to make sure your mixes sound good on as many different systems as possible. Then again, that's a good idea whether or not you'll be mastering the project. “If you can get it to make sense on lots of different systems,” says Lord-Alge, “then you're in good shape.”