tgrisham:
”Multiple subs are not a cult but are scientifically proven to even out bass nodes but are they really necessary? Where do you want to spend your limited funds? Here is their conclusion:” Four subwoofers are enough to get the best results of any configuration tried. Two subwoofers is very nearly as good and has very good low frequency support as well.”
I think tgrisham has it about right and, if xcool would read my previous post from 4-21-20, he will discover I was stating the same thing that Harman had concluded:
” Four subwoofers are enough to get the best results of any configuration tried. Two subwoofers is very nearly as good and has very good low frequency support as well.”
I would first like all readers of this thread to understand that I have always adamantly refused to be a member of any club or Cult that would accept me as a member. After all, I believe maintaining some semblance of minimum member standards is important and I prefer the sharing of knowledge and experiences between independent and honest individuals based on their personal knowledge and experience. Isn’t this basically the purpose of this site? My sole intent for commenting on the virtues of the 4-sub DBA concept so annoyingly often has been to spread the word about an excellent bass solution concept that I researched extensively,,finally purchased and was stunned by how extremely well it performed in my room and system. I learned of the distributed bass array concept on another internet site, had been experimenting for years with single and dual subs trying to incorporate powerful, accurate, detailed, effortless, dynamicand realistic bass which I knew my various models of Magnepan main speakers notoriously lacked. I realized that many Magnepan fans claim the bass is sufficient, however, I believe the accurate and realistic reproduction of the bottom two octaves is the main distinguishing trait betweeN hearing and feeling music played live at a small venue with good acoustics and a recording of the exact same musical performance played back on a home audio system in a domestic sized room. I’m still astounded by the fact that, in over 15 years of reading and participating in thousands of threads here on a boatload of 2-ch music and HT audio reproduction subjects on a giga-plenty number of threads, I.never read a single mention of, or reference to, the DBA system concept. Maybe it was mentioned and I missed it but I would think something this effective would be mentioned, or at least referred to, on a regular basis.
Anyways, I want to make it perfectly clear that I definitely know high quality bass performance can be attained, at a single designated listening position, utilizing both 1 or 2 properly positioned subs. I know this not only from my own knowledge and experience but also from the shared knowledge and experienced numerous fellow Audiogon members. For the benefit of newbies and any others searching for good in-room bass performance, here are some lessons I’ve learned over many years of researching, learning from others and experimenting in the same search:
1. In most rooms, achieving good bass performance is more difficult than achieving good midrange, treble and imaging performance, mainly due to their very different sound wave length and propagation patterns.
2. With speakers having separate bass,midrange and treble drivers in a single cabinet, it’s highly unlikely that the optimum room location for bass performance is so close in proximity to the optimum room location for midrange, treble and imaging Performance. Bass performance is significantly improved with the drivers launching bass sound waves into the room can be independently optimally positioned.
3. Virtually all humans are unable to localize sounds, perceive exactly where the sounds are originating from, that have sound wave frequencies below about 80 Hz. Virtually all humans are increasingly adept at localizing sounds as their sound wave frequencies rise above about 80 Hz, this ability continues to be reliable up to the generally accepted high frequency human audible sound wave frequency limit of about 20,000 Hz, with this upper limit often being reduced by the aging process.
4. Virtually all commercially available audio recordings on all formats, even the audio content on DVD and Blu-ray A/V discs, have all recorded bass below about 100 Hz mixed as mono. Recording engineers mainly do this because they’ve known about point #3 above for at least the past 70 years. They also do this because very deep recorded bass tones on LPs can cause the stylus to be forced out of the groove and many mass consumer grade speakers such as sound bars, mass produced speakers and TV speakers cannot handle very deep bass frequencies without seriously distorting or even being physically damaged. Current recording technology is capable of recording bass frequencies below 100
5. Because of the reality of points #3 and #4 above, it’s fairly obvious that creating and configuring a home audio system capable of reproducing bass frequencies in true stereo makes little sense. The first dilemma is that listeners, assuming they’re all humans, will be unable to localize and perceive discrete left and right bass channels. The listeners will perceive all the discrete left and right channel bass as summed mono bass and this, by definition, prevents even the existence of the required discrete left and right channel components of a true stereo image from becoming a reality, never mind the subsequent perceived 3D stereo illusion like our brains regularly create with discrete left and right channels on sound wave frequencies above about 80 Hz.
There is no stereo imaging below about 80 Hz, it’s not even a theoretical thing due to physics and human perceptual limitations. The second dilemma is that, even if a human mutant was capable of localizing bass sounds with frequencies below 80 Hz and built an audio system with appropriately positioned left and right channel subs in preparation, there’s virtually no current commercially available recordings on any audio or HT format for our superhuman mutant to play on his hot-riddled audio system.
That’s quite a ‘chicken and egg’ sequencing dilemma, right? But all hope is not lost just yet, grasshoppers, There is one last lesson I learned along my audio journey that I sometimes like to call The Saving Grace, and most other times I just call it point#6.
6. While it’s definitely true that we can’t localize bass sounds that have sound wave frequencies below about 80 Hz, anyone who has one or more subs in their room and systems should be able to attest with absolute certainty that they are perceiving the sound in true stereo from the deepest bass notes to the highest frequency treble notes and every and all the various frequency notes in between. This holds true whether you understand or even believe points #3-5 above or not.
How is this even possible with all the truthful information I mentioned in points #3-5 above? Well, I’ll explain using my own system as an example below:
My system is located in an approximately 23’ x15’ living room with 8’ ceilings. I use a pair of 6’x2’ 3-way Magnepans panels as my main speakers. I run them full range but they only reproduce high quality bass down to a rated 35 Hz +/- 3 db. I use an Audio Kinesis Debra 4-sub DBA system to reproduce bass frequencies between 20 to 40 Hz. A 1K watt class AB sub amp/control unit Is used to power and control the 4 relatively small passive subs that are each 12” x 14.5” x 28” and about 40lbs. Two of these subs are located along my front 15’ wall, with each located at opposite ends of this wall and about 2’ away away from the nearest corner. The other 2 subs are positioned along the 23’ side walls, with one on each opposite side wall about 2’ away from each rear corner. My listening seat is roughly centered on the rear 15’ wall and directly between and about 6’ away from each left right side wall sub. So, with the above setup and me sitting in my listening chair, I perceive a three dimensional soundstage along the front of my room that usually spans the full 15’ width of the room with the soundstage front usually beginning roughly at the front plane formed by the fronts of my main speakers and extending back at least the 3‘-4’ distance from the rear of my main speakers to the front wall behind them, but I often perceive the soundstage as much deeper Zane even wider on very good recordings. Even though I have a sub about 6’ away from me to the right and left, I perceive all of the bass as coming from the solid and stable stereo soundstage illusion existing In front of me at the opposite side of the room, beginning about 16’ away from me. and with the deep bass seeming to originate from the appropriate musical instruments within this illusionary soundstage.
The explanation is that while the 4 subs are reproducing and launching very long and omnidirectional deep fundamental bass sound waves and notes at frequencies as low as 20 Hz in mono throughout the room, the main speakers are reproducing and launching the much shorter and more directional midrange sound waves that are the overtones or harmonics of the original much deeper fundamental bass tones reproduced by the 4 subs. These overtones or harmonics are at frequencies that extend above the approximate 80 Hz threshold and are, therefore, able to be localized by us humans. The final key component is our amazing brains. They are able to associate the deep mono bass fundamental tones that we cannot localize with the higher frequency stereo overtones or harmonics, that extend beyond 80 Hz and are naturally related to the fundamental bas tones, that we can localize. As long as the lower frequency deeper sound waves below 80 Hz and the higher frequency overtone or harmonics sound waves above 80 Hz are both detected by our ears within a few milliseconds of each other, our brains are able to process these sound waves as related and create the perception of the overall bass tone sound and exactly where within the sound stage the tone originated from. For example, it allows the perception that there’s a double bass located at the front left side of the sound stage and the drums are located at the back center of the sound stage.
I believe that even if I configured my system with discrete left and right channel stereo subs, and there were commercially available music formats that had separate left and right channel bass content down to 20 Hz, my overall perception of the sound stage would be very similar to the current overall perception I’ve been enjoying for over 5 years now with my 4-sub DBA system. I think this would be the reality since I’d stil be iunable to localize bass tones with frequencies below about 80 Hz. Tim
