Vienna Acoustics Mozart loudspeaker Big 'Uns & Little 'Uns
In discussing the performance of the Dunlavy SC-VI (Vol.19 No.8), SS and JA pointed out that big speakers tend to sound BIG, always reminding us that we're listening to speakers. (They then noted that the SC-VI is unusually free of this characteristic.) This is one of the reasons (space and financial considerations being others) that I wouldn't want to own monster-sized speakers. However, small speakers have the opposite problem: music reproduced by them tends to sound, well, small, as if it's emanating from a pair of small boxes (which, of course, it is).
What, then, should a loudspeaker sound like? This one is easy: just like the musical instruments that were recorded! Putting aside such trivial (Ha!) matters as the recording itself, associated components, and the acoustics of the listening environment, the ideal speaker should not only be able to reproduce the complete harmonic structure of each instrument and voice, but also the specific radiating patterns that characterize a trombone, a lute, a soprano or bass, or a full symphony orchestra. Rather than providing auditory cues about itself—big or small, box or panel—the speaker should sound exactly like what it's trying to reproduce.
Given that, to some extent, every nonideal speaker at times provides cues to its physical structure, what determines whether it sounds "big" or "small"? I think there are several interrelated factors at work here, including bass response, distortion at high levels, dynamics, cabinet resonances, soundstaging, and the size of individual images within the soundstage. Big speakers have bigger woofers and bigger boxes; other things being equal, their bass response is better. Whenever people hear a small speaker with unusually good bass response, they tend to comment on how it "sounds like a big speaker." Similarly, having more drivers (as long as they're good ones) should result in the reduction of high-level distortion that contributes to making a speaker sound like a speaker. Dynamic freedom is another byproduct of having bigger, more heavy-duty drivers: Big speakers are generally more adept at reproducing the full dynamic range of orchestral music.
Driver and cabinet resonances are unavoidable for all speakers, and are often the major cue that we're listening to reproduced sound. Whether the box is big or small, or heavily braced/damped or "tuned" to presumably benign frequencies, and regardless of the materials used in construction, there are always some resonances that are not part of the musical fabric, once again telling the ear that the sound originates from a loudspeaker. The designer's skill is to reduce or camouflage these resonances to the point where they're relatively unobtrusive. Because big speakers have more drivers and bigger panels, their resonant behavior is more difficult to control.
The ability to create a deep, wide soundstage depends on many factors, especially the speaker's placement in the room. The size of the soundstage is often regarded as part of the big speaker sound, but small speakers actually have an advantage in that they're easier to place, allowing more convenient tweaking of positioning.
Finally, there's the matter of image size, including height. Typically, big speakers—often aided and abetted by close-up recording perspectives—tend to exaggerate the size of instruments and voices, giving us guitars as wide as harps and making every singer sound as if he/she is a relative of the Jolly Green Giant. Small speakers err in the opposite direction, presenting everything smaller-than-life. Image height itself is largely a matter of the listener's personal preference. I personally dislike speakers that image in such a way as to make me think that I'm in the balcony, looking down at the stage, but I also don't want sound that makes me feel like craning my neck.
Reproducing a musical event with complete fidelity remains an elusive goal. Big or small, speakers are electromechanical devices that have the task of sounding like something they're not. It shouldn't be too much of a surprise that they perform this task less than perfectly. The wonder is the fact that—with a little help from our brains—they sometimes come surprisingly close.—Robert Deutsch