The Bass Bass performance is the most misunderstood aspect of reproduced sound, among the general public and hi-fi buffs alike. The popular belief is that the more bass, the better. This is reflected in ads for subwoofers that promise earthshaking bass and the ability to rattle pant legs and stun small animals. The ultimate expression of this perversity is boom trucks that have absurd amounts of extraordinarily bad bass reproduction. We dont just want the physical feeling that bass provides; we want to hear subtlety and nuance. But we want to know how the product reproduces music, not earthquakes. What matters to the music lover isnt quantity of bass, but the quality of that bass. We dont just want the physical feeling that bass provides; we want to hear subtlety and nuance. We want to hear precise pitch, lack of coloration, and the sharp attack of plucked acoustic bass. We want to hear every note and nuance in fast, intricate bass playing, not a muddled roar. If Ray Brown, Stanley Clarke, John Patitucci, Dave LaRue, Dave Holland, or Eddie Gomez is working out, we want to hear exactly what theyre doing. In fact, if the bass is poorly reproduced, wed rather not hear much bass at all. Correct bass reproduction is essential to satisfying musical reproduction. Low frequencies constitute musics tonal foundation and rhythmic anchor. Unfortunately, bass is difficult to reproduce, whether by source components, power amplifiers, or—especially—loudspeakers and rooms. Perhaps the most prevalent bass problem is lack of pitch definition or articulation. These two terms describe the ability to hear bass as individual notes, each having an attack, a decay, and a specific pitch. You should hear the texture of the bass, whether its the sonorous resonance of a bowed double bass or the unique character of a Fender Precision. Low frequencies contain a surprising amount of detail when reproduced correctly. When the bass is reproduced without pitch definition and articulation, the low end degenerates into a dull roar underlying the music. You hear low-frequency content, but it isnt musically related to whats going on above it. You dont hear precise notes, but a blur of sound—the dynamic envelopes of individual instruments are completely lost. In music in which the bass plays an important rhythmic role—rock, electric blues, and some jazz—the bass guitar and kick drum seem to lag behind the rest of the music, putting a drag on the rhythm. Moreover, the kick drums dynamic envelope (what gives it the sense of sudden impact) is buried in the bass guitars sound, obscuring its musical contribution. These conditions are made worse by the common mid-fi affliction of too much bass. Terms descriptive of this kind of bass include muddy, thick, boomy, bloated, tubby, soft, congested, loose, and slow.Terms that describe excellent bass reproduction include taut, quick, clean, articulate, agile, tight, and precise. Good bass has been likened to a trampoline stretched taut; poor bass is a trampoline hanging slackly. The amount of bass in the musical presentation is very important; if you hear too much, the music is overwhelmed. Excessive bass is a constant reminder that youre listening to reproduced music. This overabundance of bass is described as heavy. If you hear too little bass, the presentation is thin, lean, threadbare, or overdamped. An overly lean presentation robs music of its rhythm and drive—the full, purring sound of bass guitar is missing, the depth and majesty of double bass or cello are gone, and the orchestra loses its sense of power. Thin bass makes a double bass sound like a cello, a cello like a viola. The rhythmically satisfying weight and impact of bass drum are reduced to shadows of their former power. Instruments harmonics are emphasized in relation to the fundamentals, giving the impression of well-worn cloth thats lost its supporting structure. A thin or lean presentation lacks warmth and body. As described earlier in this chapter in the discussion of audio sins of commission and omission, an overly lean bass is preferable to boomy bass. Two terms related to what Ive just described about the quantity of bass are extension or depth. Extension is how deep the bass goes—not the bass and upper bass described by lean or weighty, but the very bottom end of the audible spectrum. This is the realm of kick drum and pipe organ. All but the very best systems roll off (reduce in volume) these lowermost frequencies. Fortunately, deep extension isnt a prerequisite to high-quality music reproduction. If the system has good bass down to about 35Hz, you dont feel that much is missing. Pipe-organ enthusiasts, however, will want deeper extension and are willing to pay for it. Reproducing the bottom octave correctly can be very expensive. Much of musics dynamic power—the ability to convey wide differences between loud and soft—is contained in the bass. Though Ill discuss dynamics later in this section, bass dynamics bear special discussion—they are that important to satisfying music reproduction. A system or component that has excellent bass dynamics will provide a sense of sudden impact and explosive power. Bass drum will jump out of the presentation with startling power. The dynamic envelope of acoustic or electric bass is accurately conveyed, allowing the music full rhythmic expression. We call these components punchy, and use the terms impact and slam to describe good bass dynamics. A related aspect is speed, though, as applied to bass, speed is somewhat of a misnomer. Low frequencies inherently have slower attacks than higher frequencies, making the term technically incorrect. But the musical difference between slow and fast bass is profound. A product with fast, tight, punchy bass produces a much greater rhythmic involvement with the music. (This is examined in more detail later.) Although reproducing the sudden attack of a bass drum is vital, equally important is a systems ability to reproduce a fast decay; i.e., how a note ends. The bass note shouldnt continue after a drum whack has stopped. Many loudspeakers store energy in their mechanical structures and radiate that energy slightly after the note itself. When this happens, the bass has overhang, a condition that makes kick drum, for example, sound bloated and slow. Music in which the drummer used double bass drums is particularly revealing of bass overhang. If the two drums merge into a single sound, overhang is probably to blame. You should hear the attack and decay of each drum as distinct entities. Components that dont adequately convey the sudden dynamic impact of low-frequency instruments rob music of its power and rhythmic drive.
Posted on: Wed, 21 Jan 2015 00:56:07 +0000
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