Acoustic treatment

jtcf:
 " Check this out:https://www.psiaudio.swiss/avaa-c20-active-bass-trap/
It looks to me like an expensive alternative to the DBA system

Hello jtcf,

     It seems to me the active bass trap and the distributed bass array (DBA) system operate on almost opposite principles.
     As I understand the active bass trap (ABT) , it uses a built in mic to identify room bass modes, that are within its limited range and up to 150 Hz,  and uses openings in its surface to somehow draw these sound waves into its inner chamber and, through an unexplained process, eliminates or attenuates these room bass modes.  I believe it's only able to identify bass modes that are peaks and not dips but I'm not certain.

     The DBA, on the other hand, takes the opposite approach of distributing 4 subs in the room in order to create many more bass modes (both peaks and dips) throughout the room and then relies on some scientifically proven and well understood psycho acoustic principles.  The following are the relevant psycho acoustic principles that the DBA concept relies upon:

1. Humans are very adept at determining the originating locations (the source) of sounds with frequencies above about 100 Hz, with this ability improving as the sound frequency increases.
2. Humans generally are unable to determine the originating locations of sounds below about 100 Hz but are adept at discerning the volume and pitch, as well as changes in volume and pitch, in these deep bass tones.
3. We need to hear the complete duty cycle of a deep bass tone frequency (the complete bass sound wave cycle from beginning to end is called a duty cycle and it needs to exist in the room) before we're consciously aware of the bass sound.  If less than a complete duty cycle exists in the room, then no bass sound is detected.  This is relevant when the length of the sound wave exceeds any of the room's dimensions; a 20 Hz tone has a total length of 56 feet, so it needs to reflect off a room surface at least once, depending on the room dimensions, before we actually discern the bass sound.
4. We need to detect multiple complete duty cycles of a bass tone frequency to determine pitch.
5. When we detect multiple bass sound waves and bass modes  (peaks and dips) at various frequencies in a room, our brains process this by summing and averaging these.  This psycho acoustic principle is the key to the DBA concept being such an effective bass solution.  

     Of course, all of these psycho acoustic dynamics described above are taking place at a subconscious level and we're just aware of how detailed, fast, dynamic, impactful, smooth, natural and perfectly blended and integrated with the main speakers the bass sounds. 
     I realize I'm seemingly constantly extolling the virtues of the DBA  concept and its only relevance to this thread is that it requires no acoustic treatments, no room correction software or hardware, minimal equalization and no DSP. 
    My main intent is really just to spread the word on how well the DBA concept actually works.  I honestly don't believe it's possible for me to overstate how well this bass solution performs in my system and room.  
     There's also no typical warning of ymmv (your mileage may vary) necessary since the DBA concept performs extremely well in virtually any room and with any pair of main speakers.  So I'll coin a new acronym exclusively for audio solutions that will work for others without qualifications: ymwnv (your mileage will not vary).

Tim

I agree with you Tim.The DBA system has my vote.

I'd never heard of an ABT before.I did a little more reading and understand better how it works.It's simple to implement,but expensive and probably a royal pain if it ever required servicing.

Hi jtcf,

     I just came up with the acronym ABT (automatic bass trap) to avoid having to use its full name on my last post.  
     I restrained from stating it didn't work because I've never tried them and, therefore, I'm not qualified to have an opinion.  
     My opinion is that good bass response is very important but one of the most difficult qualities to achieve in a home audio system.  I actually consider my system as two systems:  a bass system and a midrange/treble and stereo imaging system.
    I also prefer a system focused on producing good bass than one trying to improve bass that's already been produced in the room.

Later,
  Tim

In the case of the wretched CD there are two reason why bass response is really rather wimpy and apparently rolled off and otherwise unimpressive. It’s because of the two problems I have been pointing out of late regarding (1) scattered background laser light getting into the photodetector and (2) the fluttering, wobbly and vibratory nature of the CD itself that forces the laser servo mechanism such as it is to work overtime trying to keep the bloody laser on track. The geometry involved with how the laser reads the nanoscale data is extremely susceptible to vibration of the disc.

Geoffkait, just throw the CD's away and download all your music in MP3 files. That should be perfect for you. Your ear works just like any other microphone. It detects minute changes in pressure. In your case you might want to clean the wax out first. In the office we use a waterpick for that. 1 part hot water to 1 part  peroxide. Careful not to squirt your eye:)