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Divide & Conquer: Optimizing The Kick Drum-Bass Guitar Relationship In The Mix

Balancing the power and nuance of these two elements can be crucial to the level of emotion and/or excitement a mix can convey.

Mixing drum kits can be fun. Banging on something to produce a rhythm may have been our first musical experience as a species. Modern recording tools finally gave musicians the ability to share that emotion with a much wider audience of fans and other musicians than live shows alone could reach.

Rock ‘n’ roll can be traced back to early blues and folk music that was popularized in the late 1800s and early 1900s. The excitement of listening to W.C. Handy play his Boogie Woogie piano was intoxicating. Right hand playing melody, left hand pounding out bass counterpoint, foot stomping in rhythm with the bass line the whole time. A very plausible precursor to the modern concept of drums and bass.

Kick drums grew in popularity starting in 1909, when the Ludwig brothers secured the patent for a successful kick drum pedal. The bass guitar has been completing the rock rhythm section since the beginning of the genre.

The 1953 Chess Records recording of “Hoochie Coochie Man” by Muddy Waters, featuring Willie Dixon on upright bass and Elgin Evans on a four-piece drum kit, was probably the first rock ‘n’ roll rhythm section in audio recording history.

The rhythmic beat of the kick drum and the upright bass were synced up. The blues beat of the kick drum lay on the same beats as the notes on the bass. The bass and kick drum melded into a single groove, forming a rhythmic backbone supporting the sinuous flowing flesh of melodic instruments and vocals.

I find the kick drum/bass guitar relationship crucial to the level of emotion or excitement a mix can convey. The way I approach that combination is by separating and optimizing different aspects of each instrument.

Controlling The Ratio

To sculpt my kick drum sound, I use two transducers with vastly different techniques and results. I want to be able to control the ratio level between the midrange beater attack and the low frequency thump and decay. Divide and conquer. Inside I have a Shure BETA 91A half-cardioid condenser microphone on a Kelly SHU mount, which does a great job of capturing the impact of the beater head and the decaying resonances of the shell.

The author’s approach to kick drum, with a Tang subkick style speaker outside and a Shure BETA 91A inside.

In the console, I apply both a high-pass and low-pass filter to tailor the bandwidth of the BETA 91A to fit my mix. The high-pass filter rolls off at 80 Hz and the low-pass filter varies around 4 kHz. In some rooms I raise or lower that frequency for more or less high-frequency detail from the beater impact. If the room is boomy and reverberant, the low-pass can be as high as 6 kHz, but if it’s a sterile room with a short reverb decay time (RT60), it may be as low as 3 kHz.

For the low end of the kick drum, I use a subkick style speaker, the Tang Band W6-1139 (6.5-inch), which has a free-air resonant frequency of 38 Hz. The speaker is mounted on a stand in front of the kick drum, close to the head. In the console, I don’t need any filters since the speaker naturally rolls off very rapidly above 80 Hz.

I do delay the BETA 91A signal to align with the subkick. Neither kick drum signal has inline compression applied, although I use parallel subgroup compression to reduce the overall dynamic range of the kick drum. This makes it much easier to mix with the dynamic range of the bass guitar. I also sometimes apply a gate on the speaker using the BETA 91A as a key input, depending on room acoustics.

Focusing On The Tone

The sound I want to get from the bass guitar is a bit more complicated and nuanced. Ryan Stasik of Umphrey’s McGee is a great bass player and loves using effect pedals to create unique tonal textures. When I began mixing the band, Ryan was playing through an Ampeg SVT Classic amp driving one Ampeg 4 x 10 cabinet and one Ampeg single 15-inch cabinet. That rig had a hard time playing at his preferred volume, in addition to sounding muddy and indistinct.

Ryan asked me to help improve his tone and power, so I played around with a few things and arrived at my ultimate bass guitar rig. After his pedalboard, his signal goes to a Gallien-Krueger 2001RB amp, which feeds the same 4 x 10 cabinet, but with B&C 10CL51 PA drivers replacing the old 10-inch Ampeg woofers. This greatly improved the midrange tone. Measured distortion on the 10-inch speaker was reduced from 15 percent to less than 2 percent.

Octave dividers and sub-harmonic generators are among Ryan’s favorite pedals. To help reproduce those, we chose a pair of Bag End SE18E-I single 18-inch subwoofers powered by a QSC CX702 amplifier, processed with a Bag End ELF-M2. This combination does a phenomenal job of reproducing his thunder tones. The 18-inch subs cover from 8 Hz to 80 Hz and the 10-inch drivers take over at 80 Hz, continuing out to about 5 kHz. The Bag End ELF is fed from the XLR direct out on the GK amp.

Capturing the full range of his tone also takes a divide and conquer approach. I divide the audio spectrum into two frequency ranges, treat each differently, and mix them back together for the final result.

From about 250 Hz down, I prefer the accuracy and low distortion of the direct signal from his direct box, a custom tube DI based on a Telefunken ECC83. In the console, I use a low-pass filter to roll off those higher frequencies. For the midrange portion, I prefer the sound of his 10-inch drivers. The amp and speaker impart a pleasant “hairiness” and texture to the midrange of the bass guitar.

A beyerdynamic M88 hypercardioid microphone on the upper right 10-inch driver, with high-pass and low-pass filters set to trim the bandwidth, passing signal from 250 Hz to 5 kHz only. Both signals are compressed with onboard Midas compressors. The ratio and threshold are set to act more as mild limiters to keep the level in check when he turns on all of his pedals. Most of the time he’s only tickling the compressor, with 0 to 3 dB of gain reduction. I add 0.33 milliseconds of delay to the DI so that it aligns to the microphone signal.

Ready To Go

The big advantage to this approach is that I can use my faders to quickly change the tone of the kick and bass by varying the ratio of the midrange and low-frequency parts of each. If the song will benefit from more kick drum attack but less bass guitar midrange, it’s an easy change in fader level without upsetting any EQ or compressor settings.

Umphrey’s McGee is known for prodigious use of improvisation and a wide song selection. I don’t use scenes but need to be ready for any song style at the drop of a hat. I personally prefer to have a lot of beater attack from the kick drum, without being clicky, and speaker midrange from the bass guitar in almost equal amount, high in the mix. The subkick and DI should combine effortlessly. The subkick signal has a peak at 38 Hz, well below most of the range of the bass guitar.

When Ryan does use his sub octave pedals, the parallel compression of the kick drum signal allows them to be heard equally in the mix without resorting to subtractive EQ to allow them to coexist. Some engineers will sculpt the low EQ of the kick drum and bass guitar, applying complementary cuts aimed at preventing a muddy result.

I don’t do that, but my kick drum and bass guitar are well defined with power and nuance. The kick drum drives the downbeat, perfectly timed with the strumming of a bass guitar string. The thunderous low-frequency decay of the subkick melds seamlessly into each sustained bass note, dropping in level just enough to usher in the next kick drum downbeat.

I get excited just thinking about it.

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