millercarbon: "
There is no stereo information at the lowest frequencies. Even if there is, there isn’t. I’m not gonna get into a technical spat over timing either. None of that matters. The simple fact is human beings cannot even hear low frequencies at less than one full cycle. Yes that is a fact. Yeah, science! So timing information or no timing information either way it doesn’t matter because you simply cannot hear it."
As a user of the Audio Kinesis Debra 4-sub distributed bass array (DBA) system for over 5 years now in my fairly small 23'x14' room, I agree with everything millercarbon stated in his quote listed above.
The same debate over stereo vs mono deep bass was being debated over 6 years ago when I first began reading about the DBA concept and was considering buying the AK Debra or Swarm 4-sub complete DBA kit system. I remember the price was $2,800 then and I didn't want to spend that much money on a bass solution, to pair with my then Magnepan 2.7QR main speakers, without being as certain as possible that it would work well and I was still a bit confused about the whole stereo vs mono deep bass issue.
My main concern was the possibility that the mono bass of the 4-sub DBA would smear, or otherwise degrade, the very realistic and detailed 3D stereo sound stage imaging I had achieved in my room and system at that time. I also didn't want to wait for the cows to come home to find out whether or not stereo deep bass was worth pursuing.
I've come to the conclusion that 4-sub DBA systems, in combination with the main speakers, reproduce bass in a very natural and life-like manner. When we listen to live music in a venue, we hear the fundamental sound of an under 80 Hz deep bass tone from an instrument that we're unable to localize (discern specifically where it is coming from) but we also hear the harmonics or overtone sounds, naturally produced and associated with the fundamental tone, that extend above 80 Hz and we are able to localize. Our amazing brains are able to process these different sounds if heard within about 5 milliseconds of each other, determine they're related to each other and create the perception of specifically where the deep bass sound originated from.
A 4-sub DBA system is creating the same audio conditions as live music, the only difference being that the 4 mono subs are reproducing the fundamental tones that are under 80 Hz that are omnidirectional and naturally heard as mono, anyway, and the main speakers are reproducing the harmonics or overtones that are above 80 Hz that are directional and naturally heard as stereo.
Add in our amazing brains to this mixture and we're perceiving all our reproduced music just as we perceive live music.. My opinion is that the above makes the whole debate over stereo vs mono deep bass moot. The truth is we all perceive bass below about 80 Hz as mono and bass above about 80 Hz as stereo. I
Of course there's also the unfortunate reality for the promotion of stereo deep bass reproduction that, even if an individual owned an audio system capable of reproducing stereo deep bass down to 20 Hz with discrete left and right deep bass channels, there's an apparent complete lack of commercially available recorded music source material in any format that contains any stereo bass content below about 80-100 Hz.
I've learned that it's been standard practice for at least the past 70 years for recording engineers to sum all recorded left and right channel bass below about 100 Hz to mono on their mixes for all recording formats. If anyone reading this knows of a single example of a music recording in any format containing stereo bass below about 100 Hz, please post it because it will be the first that I, and I believe most others, would be aware of.
Given all the above facts, the approach that makes the most sense to me is treating our systems as 2 systems:
1. a Mono Deep Bass system for reproducing all frequencies below 80 Hz.
This serves as the solid foundation of the audio system, is operated in mono mode and these deep frequencies are best reproduced through the use of multiple, independently positioned subs with rated bass extension as close as possible to the audible bass frequency lower limit of 20 Hz.
The position of each sub in the room and in relation to the listening position are important. For best mono bass performance, a minimum of 2 subs is recommended but 4 subs have been scientifically proven to provide even better bass performance. The optimum position of a pair of subs in a room is highly unlikely to be in a stereo or symmetrical configuration, with a sub located near each main speaker. If sophisticated and expensive measuring equipment is not available to determine the optimum position of each sub in the room, I've found the free 'sub crawl method' (google it) to be equally reliable.
Also, due to the omnidirectional radiation pattern and very long lengths of sub-80 Hz bass sound waves, the deep bass sound waves detected by our ears at the listening position are a combination of direct sound waves and reflected sound waves that have previously bounced off at least 1 room boundary (floor, ceiling or wall). It's not uncommon for reflected deep bass sound waves to be the initial sound waves reaching the listening position.
None of these deep bass sound waves have a left or right channel identifying sonic signature and all are perceived as mono. Variations in pressure to determine direction, or perceiving deep bass sound waves as left and right channel, makes little sense sense in this context. There is no stereo image created or perceived on bass frequencies below 80 Hz, it's all perceived as mono.
2. a Stereo Mid-range, Treble and Sound Stage Imaging system for reproducing all frequencies above 80 Hz.
This serves as the detail center of the audio system, is operated in stereo mode and these higher frequencies are best reproduced through the use of a pair of independently positioned main speakers with rated bass extension that typically does not reach the audible bass frequency lower limit of 20 Hz.
The precise positioning of this pair of speakers in relation to the listening position improves mid-range and treble performance as well as optimizing the stereo sound stage imaging. Our brains are also able to use the deep bass fundamental tone's harmonics or overtones frequencies, that are above 80 Hz and reproduced in stereo by the main speakers, and associate them with the deep bass fundamental frequencies that are below 80 Hz and reproduced in mono by the subs. This process is what allows us to properly perceive the sound and location of the deep bass instruments within the overall stereo sound stage illusion.
I believe this 2 system approach makes it initially simpler to understand how to create a very good quality overall home audio system and then how further improvements to either individual system will result in the overall audio system's performance improvement over time.
Tim
As a user of the Audio Kinesis Debra 4-sub distributed bass array (DBA) system for over 5 years now in my fairly small 23'x14' room, I agree with everything millercarbon stated in his quote listed above.
The same debate over stereo vs mono deep bass was being debated over 6 years ago when I first began reading about the DBA concept and was considering buying the AK Debra or Swarm 4-sub complete DBA kit system. I remember the price was $2,800 then and I didn't want to spend that much money on a bass solution, to pair with my then Magnepan 2.7QR main speakers, without being as certain as possible that it would work well and I was still a bit confused about the whole stereo vs mono deep bass issue.
My main concern was the possibility that the mono bass of the 4-sub DBA would smear, or otherwise degrade, the very realistic and detailed 3D stereo sound stage imaging I had achieved in my room and system at that time. I also didn't want to wait for the cows to come home to find out whether or not stereo deep bass was worth pursuing.
I've come to the conclusion that 4-sub DBA systems, in combination with the main speakers, reproduce bass in a very natural and life-like manner. When we listen to live music in a venue, we hear the fundamental sound of an under 80 Hz deep bass tone from an instrument that we're unable to localize (discern specifically where it is coming from) but we also hear the harmonics or overtone sounds, naturally produced and associated with the fundamental tone, that extend above 80 Hz and we are able to localize. Our amazing brains are able to process these different sounds if heard within about 5 milliseconds of each other, determine they're related to each other and create the perception of specifically where the deep bass sound originated from.
A 4-sub DBA system is creating the same audio conditions as live music, the only difference being that the 4 mono subs are reproducing the fundamental tones that are under 80 Hz that are omnidirectional and naturally heard as mono, anyway, and the main speakers are reproducing the harmonics or overtones that are above 80 Hz that are directional and naturally heard as stereo.
Add in our amazing brains to this mixture and we're perceiving all our reproduced music just as we perceive live music.. My opinion is that the above makes the whole debate over stereo vs mono deep bass moot. The truth is we all perceive bass below about 80 Hz as mono and bass above about 80 Hz as stereo. I
Of course there's also the unfortunate reality for the promotion of stereo deep bass reproduction that, even if an individual owned an audio system capable of reproducing stereo deep bass down to 20 Hz with discrete left and right deep bass channels, there's an apparent complete lack of commercially available recorded music source material in any format that contains any stereo bass content below about 80-100 Hz.
I've learned that it's been standard practice for at least the past 70 years for recording engineers to sum all recorded left and right channel bass below about 100 Hz to mono on their mixes for all recording formats. If anyone reading this knows of a single example of a music recording in any format containing stereo bass below about 100 Hz, please post it because it will be the first that I, and I believe most others, would be aware of.
Given all the above facts, the approach that makes the most sense to me is treating our systems as 2 systems:
1. a Mono Deep Bass system for reproducing all frequencies below 80 Hz.
This serves as the solid foundation of the audio system, is operated in mono mode and these deep frequencies are best reproduced through the use of multiple, independently positioned subs with rated bass extension as close as possible to the audible bass frequency lower limit of 20 Hz.
The position of each sub in the room and in relation to the listening position are important. For best mono bass performance, a minimum of 2 subs is recommended but 4 subs have been scientifically proven to provide even better bass performance. The optimum position of a pair of subs in a room is highly unlikely to be in a stereo or symmetrical configuration, with a sub located near each main speaker. If sophisticated and expensive measuring equipment is not available to determine the optimum position of each sub in the room, I've found the free 'sub crawl method' (google it) to be equally reliable.
Also, due to the omnidirectional radiation pattern and very long lengths of sub-80 Hz bass sound waves, the deep bass sound waves detected by our ears at the listening position are a combination of direct sound waves and reflected sound waves that have previously bounced off at least 1 room boundary (floor, ceiling or wall). It's not uncommon for reflected deep bass sound waves to be the initial sound waves reaching the listening position.
None of these deep bass sound waves have a left or right channel identifying sonic signature and all are perceived as mono. Variations in pressure to determine direction, or perceiving deep bass sound waves as left and right channel, makes little sense sense in this context. There is no stereo image created or perceived on bass frequencies below 80 Hz, it's all perceived as mono.
2. a Stereo Mid-range, Treble and Sound Stage Imaging system for reproducing all frequencies above 80 Hz.
This serves as the detail center of the audio system, is operated in stereo mode and these higher frequencies are best reproduced through the use of a pair of independently positioned main speakers with rated bass extension that typically does not reach the audible bass frequency lower limit of 20 Hz.
The precise positioning of this pair of speakers in relation to the listening position improves mid-range and treble performance as well as optimizing the stereo sound stage imaging. Our brains are also able to use the deep bass fundamental tone's harmonics or overtones frequencies, that are above 80 Hz and reproduced in stereo by the main speakers, and associate them with the deep bass fundamental frequencies that are below 80 Hz and reproduced in mono by the subs. This process is what allows us to properly perceive the sound and location of the deep bass instruments within the overall stereo sound stage illusion.
I believe this 2 system approach makes it initially simpler to understand how to create a very good quality overall home audio system and then how further improvements to either individual system will result in the overall audio system's performance improvement over time.
Tim