I had some computer hardware issues that are now rectified but I was unable to continue following this thread as closely as I was over the past 3 days.
Catching up today, I was disappointed to discover that a few posters have been attempting to debate some facets of how deep bass soundwaves behave in smaller domestic rooms and how our human ears and brains detect and perceive these deep bass soundwaves as deep bass. I just want to restate and remind thread readers and posters of a few things that have been scientifically proven by acoustic experts and are generally considered to be true by the vast majority of them. In other words, facts that we should not be wasting our time and effort by debating or misleading others about:
1. The vast majority of humans are unable to localize bass sounds/tones below about 80 Hz. This means an inability to determine where these omnidirectional deep bass soundwaves/sound tones are originating from and, therefore, means there’s no need or sense to operating deep bass drivers (including subwoofers) in any other mode than mono since there is no such thing as stereo deep bass. This is why virtually all commercial music recording engineers sum the bass at about 80Hz or below to mono on their recording mixes. Even if a system were configured for stereo bass below 80 Hz, it would be useless since there’s virtually zero music source content material to play on it. If you doubt this, try to name even a single exception to this statement.
It’s very important to note, however, that most individuals will still be able to perceive the deep bass sounds/notes as directional and properly localized within their system’s soundstage illusion. That is, deep bass sounds/tones will be perceived as coming from the proper instrument position within the stereo soundstage.
This is due to the fundamental deep bass tones, being below 80 Hz and coming from the bass drivers, not being directional but the overtones/harmonics of the fundamental bass tones, being above 80 Hz and coming from the main speakers, being directional and our brains being able to associate the directional overtones/harmonics with the omnidirectional fundamental deep bass tones and thereby perceive specifically where in the soundstage the deep bass tones are coming from.
I utilize 4 relatively small, 12"x14.5"x28", subs with 10" long-throw aluminum drivers in a distrbuted bass array (DBA) in my room operated in mono mode from 20-40 Hz with my main speakers run full range with bass extension down to 35 Hz. I can attest that I definitely perceive the deep bass as coming from the appropriate soundstage location.
I not only perceive the increased bass extension and dynamics as seamlessly integrated within the soundstage illusion in my room, this high quality bass also provides the perception that this soundstage is wider, deeper and more open with individual images that are more solid, stable, palpable and natural. I’m able to focus in on individual mages/instruments and follow their musical notes, beat as well as volume and pitch changes. This high quality audio reproduction is easy to perceive in the midrange and treble frequencies, but extending this perception all the way down to the deepest bass frequencies is unique in my experience and something that really enhances my involvement and enjoyment of all the music I play.
2. Humans can’t even perceive the exitance of sound tones in their rooms until the complete full cycle (fully formed) soundwaves exist in the room to be detected by our ears and processed as a perception of sound at a certain pitch/frequency, volume and duration. It also takes several full cycle soundwaves to be presented into the room for changes in pitch and volume to be perceived.
This is simple, matter of fact and routine with the relatively short and highly directional midrange and treble frequency soundwaves in a room but becomes more complex, less matter of fact and routine with the relatively long and omnidirectional frequency soundwaves in a room. As I’ve stated previously, a 20 Hz soundwave is 56’ long, a 30 Hz is 28’, a 40 Hz is 19’, an 80 Hz is 14’, a 500 Hz is 2.7’, a 5,000 Hz is 2.7", a 10,000 Hz 1.4" and a 20,000 Hz is a fraction of an inch long.
It’s easy to see from these soundwave length examples that as bass frequencies get deeper, their complete full cycle soundwaves at some point may exceed the physical dimensions of an individual’s typically sized domestic room and inevitably it requires the soundwave to reflect off of at least one room boundary (floor ceiling or walls) for the entire soundwave to exist in the room.
These long deep bass soundwaves continue to reflect off room boundaries until they’re are absorbed, diffused or run out of energy and invariably collide with other reflecting and more direct bass soundwaves which cause bass room modes. These room modes are perceived as specific room spots at which the bass sounds exaggerated, attenuated or even non existent. Without using at least two independently and properly positioned deep bass drivers reproducing frequencies below about 80 Hz in a room, there’s no ability to ensure your listening seat position is bass room mode free.
The above are proven facts and realities that need to be accepted and taken as givens in any meaningful discussion concerning the attainment of very good bass response performance in any room and with any pair of main speakers. If you just positioned your main speakers at specific room spots, in relation to your listening seat, to optimize the midrange. treble and imaging performance and are also getting very good bass performance there as well without at least a pair of external and independently positioned subs, then consider yourself very lucky since you just happened by good fortune to avoid any serious bass room modes.
Of course, there could also be bass room modes at your listening seat and you’re just unaware of them.
Tim
