Improve your Backline Sound While Tightening Up The Music

by Christopher Buttner

We live in an atmosphere of pressure waves.  Low-end sound pressure (bass) is an everyday occurrence and if it's missing from a musical, or any other, event, the complete sound is not considered faithful, nor is it trusted.  Reality is filled with detailed low-end sound pressure, from the sound of a refrigerator door slamming, to a book being dropped on the floor, to the whisper of your lover's voice in your ear.  Bass is truly a visceral thing, it's the point where you perceive music vibrationally and by bone conduction, it's where you feel it in your gut and your chest.  It's a tactile sensation.  It’s also a very primal, emotional, as well as a sexual sensation.  Bass is an instinctive sensation.  You know and trust true bass when you hear it.  Effective low-end will emotionally move the audience more and it will emotionally move the musicians more.

Bass encompasses all aspects of the musical group, including rhythm, melody and harmony.  With a quality bass system and the technique to sonically contribute to the musical event, the bass player is a contributing powerful voice, as opposed to a 'necessary evil', add-on option.  A bassist does not want his contribution to be reduced to 'wash tub' bass modalities, where all he is doing is making tangential changes on a one pitched 'thump'.  

We're not talking volume here; we're talking control and extension.  Volume is perceived really as an upper bass phenomena.  You can't make low, low bass really loud.  You can't even make it loud enough to hurt someone's ears.  It's only the upper frequencies that can cause pain or cause fatigue.  By adding extended, accurate, low bass, it will actually make music less fatiguing and more soothing, and relaxing to listen to.  This cuts across all genres of music, from rock, classical, jazz, and punk, to wedding, arena, disco and jazz bands. 

The bass set-up that is going to be the most potent and effective is the one that models the real life acoustic and auditory experience of the event.  The bassist is fortunate, due to the fact that the bass guitar is the most dynamic test instrument to use when shopping for a new loudspeaker system.  It allows you to hear all of the faults, flaws and imperfections in the most vital components of the sound system; the amplifier and the loudspeaker cabinet.  The bass has the ability of extreme high-frequencies, 12 kHz to 15 kHz, when tapping, popping, slapping, and harmonics, and it can instantaneously dive into extreme low frequencies of 30 to 40 Hz on the open B string of a five string bass. 

The foundation for a good bass sound is a quality sound system, consisting of a high-quality loudspeaker cabinet, pre-amp and power amplifier.  These components have to reflect reality and deliver the instrument’s dynamic range accurately.  

Tone and nuances, primarily, come from a the front end of the sound system, the preamp, not the amplifier.  If you're going for a particular sound, such as a warm tube sound, then consider a good tube preamp.  If you require more of a high-end tone to your playing, look into a good solid-state preamp, or dual tube/solid state pre-amp.   

On the power side, in order for a quality bass cabinet to reflect reality, you need an amplifier of extended bandwidth that can deliver fast, instantaneous current.  Unlike the pre-amplifier section, the power amplifier section has to be honest, high fidelity, and faithful to the original signal.  In essence, the power amp must be transparent.  A separate professional, high fidelity power amp will deliver to the speaker, by a greater order of magnitude, far more useable transient energy and extended bandwidth. 

The dynamic range of the bass guitar doesn't make an amplifier's job easy.  The high peak-to-average ratio of 'slapping and popping' produces extremely high power peaks.  To keep the sound clean and undistorted, you want plenty of headroom.  An amp has to have enough on-board juice to reproduce fast and complicated musical events and passages; including all open strings, chords, slapping and popping, tapping, vibrato, hammer-ons, etc. 

The amplifier HAS to be able to deliver the sound musically.  Another rule of thumb is, if you're trying to deliver a clean waveform, it takes a lot more power than if you're trying to deliver a distorted waveform, such as with a guitar.  Because bass is a long waveform, the speaker cone is moving slower than when it's reproducing higher frequencies.  If the speaker cone loses control in these lower frequencies, you can hear more distortion.  When a bass note distorts, you lose all articulation in the lower frequencies and the note is reduced to slurred, non-musical resonance.   

The bassist also needs the ability to start and stop the speaker on a dime.  To do this requires lots of power and it also requires a lot of bandwidth.  Your power amp has to provide the ability to control the slow and observable frequencies and keep them clean.  In many cases, a guitar sound is built around the sound being uncontrolled, meaning distorted.  You can entree into distortion with very few watts and overdrive a speaker very, very quickly.  You can only entree into controlled sound by having enough power 'in the bank'.  So, for clean, accurate and articulate bass, you require lots of power and lots of current.  Generally, a 'separate' amp will offer more power than integrated units. 

When testing a bass guitar loudspeaker, you have to listen to the transient response of the speaker.  The transient response is the speed at which the speaker cone propagates the note to completion and returns back to its starting position, ready for another note.  It’s the speaker's 'Hit-it-and-Quit-it Factor'.  A speaker system with the greatest 'Hit-it-and-Quit-it Factor' will not display as many perceptible intermodulation, decoupling, and/or distortion problems, and will recreate greater fidelity, more articulate, faithful musical nuances and subliminal cues. 

Okay, you now have a great bass system.  A fatal mistake of all rhythm sections is to place the bass cabinet behind the drummer, so the drummer can hear the bassist.  Low-end energy masks a lot of the highs, which is where the musical and subliminal cues live.  A drummer needs to hear, and cue off of, the high frequency attack of the bass guitar notes, which is the directional 1 kHz to 3 kHz sound output that originates from the center of the bass speaker.   

Any drummer with half a brain does not need, nor does he want, the full impact of the bass cabinet’s massive wash of low-end, 250 Hz to 500 Hz radiant sound impact that comes along with the higher frequency 1 kHz to 3 kHz ‘musical cue’ sound output.  In fact, the speaker output at these 250 Hz to 500 Hz frequencies will mask the harmonic resonant characteristics of the drums themselves.   

A drummer is trying to hear his kick drum.  The kick drum emanates sound from it's front.  When a bass cabinet is placed very close to, and behind, the drummer and he can no longer hear his drums, the drummer then needs to re-establish the sonic importance and perspective of his own instrument.  To do this, the soundman usually winds up giving the drummer a lot of PA monitors so he can hear his drums, including the kick drum.  Then the guitar player is turning up to compete with the additional monitors, then the singer can't hear himself because the band is now blaring, and the fights escalates from there.  The rhythm section, first and foremost, has to shut down the confrontation of ‘I can never hear myself, the stage volumes are too loud!', before it starts and escalates out of control.   

A kick (or bass) drum is one of the highest output, mechanical, acoustic instruments ever produced.  It has been engineered to move air on a major level.  The bassist has to link his mechanical system, i.e., his bass cabinet - regardless of it’s driver configuration - to the loudest mechanical acoustic instrument on the stage, the kick drum.  The drummer and the bassist have to become a unified sound and their output devices have to become one driver in space.  Therefore, proper physical, on-stage placement of these mechanical devices is critical, as it will allow the bassist and drummer to sum the output and energy of the two devices, thereby creating a unified sound output. 

To do this effectively, line up the centerline of the bass cabinet to the centerline of the kick drum.  Granted, the depth of bass cabinets and bass drums all differ greatly, but the law of averages states, if you centerline the two output devices, you're going to be very close to summation. 

Now, with the bass cabinet aligned with the kick drum, the drummer needs a dedicated ‘bass cue’ monitor, with its own volume control, so he can clearly hear the bassist’s 1 kHz to 3 kHz musical cues.  There are several manufacturers who make personal monitors, that mount on drum or mic stands, all of which feature various signal controls, so whomever is using it can adjust his or her own monitor mix.  The bassist’s signal can come right from his amp to the drummer’s dedicated monitor.   

By properly positioning the equipment on-stage, at an ‘acoustic ground-zero’, the band plays at a more acoustic sound pressure level and they hear each other, and the musical cues, much better.  These simple suggestions are integral in lowering the stage volume by as much as 10 dB!  Not only does this improve the timing of the drummer and the bassist, the timing of the entire band improves, as well.  The group’s low frequency sound cue, the pulse, pocket and/or groove, is more clearly defined, and it's also more clearly defined for the audience, because they hear the rhythm section clearer.  Also eliminated are the phase cancellation problems bassists and drummers have suffered from since the beginning of electricity. 

In many cases the relationships between drummers and bass players extend far beyond their personal marriages.  A melded rhythm section has to have as much blend as possible, they have to be as close to one as possible.  As close to one means, you're not hearing every note.  You're going for the totality of the note, you're not going for the individuality of the note.  At some point in your musical development, you're going to become more interested in the totality of what you're creating.  You outgrow the necessity to hear only yourself. 

(END)