2. speakers
  3. 148251-20042

Why the fascination with subwoofers?

I have noticed many posts with questions about adding subwoofers to an audio system. Why the fascination with subwoofers? I guess I understand why any audiophile would want to hear more tight bass in their audio system, but why add a subwoofer to an existing audio system when they don’t always perform well, are costly, and are difficult to integrate with the many varied speakers offered. Additionally, why wouldn’t any audiophile first choose a speaker with a well designed bass driver designed, engineered and BUILT INTO that same cabinet? If anyone’s speakers were not giving enough tight bass, why wouldn’t that person sell those speakers and buy a pair that does have tight bass?
128x128Ag insider logo xs@2x2psyop
noble100's avatar
noble100
2,419 posts
 
audiokinesis:
"Once we relax cost constraints, it might make more sense to build a planar array into the front wall and a corresponding array into the rear wall, reverse the polarity of the rear wall array, and time-delay it such that it cancels the signal from the front wall when it arrives."


Hello Duke,

I always enjoy your posts because I always seem to learn something.

But my main reason for posting is to ask about your quote above.
Was " and time-delay it such that it cancels the signal from the front wall when it arrives." accurate and not a typo?
My rudimentary knowledge of bass room acoustics leads me to believe that equal bass sound waves from the front and rear would cause a standing wave room mode at the point that both waves meet, causing a bass cancellation resulting in a perception of no bass at all at that room location.
Does the time delay or the polarity reversal on the rear planar array alter the dynamics? Please explain if you don’t mind.


Thanks,
Tim
Ag insider logo xs@2x
rauliruegas
13,112 posts
 
Dear @noble100  : """   I've learned that realistic reproduction of the majority of the bottom octave (16Hz–32Hz) doesn't require large woofers in large enclosures, 4 subs with 10" woofers """

well with the ones design you owns you phisically can't achieve that octave ( 16hz-32hz. ) but from 20hz up. A small driver as 10" with that " motor " can't do it at over 110 SPL and with low THD.
Yes maybe some one could design a true sub with 10" woofers but this is other subject, yours can't do it.

"""   I'm not a Bass-Head but I admit ..... "", 

me neither.


""  But I also believe in setting the crossover frequency as low as possible so the subs only engage when required for accuracy and not for an artificial general system bass boost. """

well in my case as low as 78hz.


 ""   I've also discovered that bass quality is vastly more important than bass quantity.  ""


Always in agreement with but my main discovering using true self powered subs was the IMPACT that MUSIC we are listening makes when the IMD distortion kind goes way lower in the main speakers: mids/high ranges really shines with.
As a very important side benefit is the quality level we accomplish in the overall system bass management.

We have to remember that the MUSIC foundation and MUSIC frame belongs/lives in the bass frequency range and its quality levels.


Not for you but for other gentlemans this link could help to understand better the overall bass management:

http://www.soundoctor.com/whitepapers/subs.htm


Regards and enjoy the MUSIC NOT DISTORTIONS,
R.





Ag insider logo xs@2x
rauliruegas
13,112 posts
 
Dear @rodman99999  : I own both Virgil Fox LP volume's ( if I remember: white vinyl. I don't listen it for several years now. ) and just great if you have the system that can showed.

One recording with true subterrean bass range is the Dorian CD with the transcription scores of Pictures at an Exibition by Jean Guilllou. Always not only very good score quality performance but a true test for any system especially in the bass range.

I own too an LP ( I can't remember the label. ) with the Mormom Tabernacle Choir that I remember wa really good recording.

As a fact and as I posted there are " thousands " of recordings with true low bass range and with very good overall quality performance.

Other labels that comes to my mind is Wilson Audio, Athena, Denon, Delos, Chalfont that along Cristal Clear several more are a must to listen it.

Is just grandioso/magnificent that we truly can appreciated in all its grandiosity all those " historic "recordings. Good that some of us can do it.

R.


noble100's avatar
noble100
2,419 posts
 
rauliruegas:
"Not for you but for other gentlemans this link could help to understand better the overall bass management:

http://www.soundoctor.com/whitepapers/subs.htm "

Hello rauliruegas,

   First I read anything from the doctor.   I don't think the Sound Doctor is a good source of info for newbies.  He goes on about bass standing waves, bass room modes,  and bass sound wave timing as if he's not even aware of the scientific research and writings of Geddes, O'toole, Welti, Lejeune, etc. and that most of the in-room bass response issues he mentions can be solved through the use of a 4-sub distributed bass array system.  
     I'm not sure if he's aware of the dba concept and how well it works or not.  I wonder where the good Doctor got his degree from?  Do you think he just bought one on the internet?   
     It seems like he's the one in need of some bass management education.

Tim
audiokinesis
2,753 posts
 

@noble100 wrote: "But my main reason for posting is to ask about your quote above.
Was " and time-delay it such that it cancels the signal from the front wall when it arrives." accurate and not a typo?"

That’s what I meant to write.

My understanding is that the idea is to arrange four subs in a centered, half-the wall’s-scale pattern on the front wall. So if the front wall is 18 feet wide by 8 feet tall, then the subs would be at the corners of a rectangle 9 feet wide by 4 feet tall, centered on the middle of the wall. This mimics the best four-sub geometry Todd Welt found in his study of symmetrical sub arrays, but it’s on the wall instead of on the floor. If the wall reflections cooperate, they should cancel out standing waves in the vertical and side-to-side dimensions.

To cancel out standing waves in the front-to-back dimension, the idea is to use active cancellation based on an identical array on the rear wall. This array is in reverse polarity, with a time delay that corresponds to the length of the room.

So the subs in the front of the room to create a planar wave that moves to the back of the room and then disappears as the active cancellation array cancels it when it gets to the back wall. The "no bass" you mentioned happens at the rear wall, not out in the room, or so the theory goes.

I do not know how well this would work in practice. The answer is probably some variation on "it depends". Nor do I know whether it would sound better than a distributed multi-sub system. I haven’t really investigated it and will never build anything like it myself, but it MIGHT be a competitive "cost no object" approach.

Duke

More to discover