[Russell Dawkins]

Hi.
Just out of curiosity.

You want 3 subs to bring an outdoor rock concert back home or what?
You want the massy LF volume to drive away yr neighbours or you want to enjoy some clean unboomy sub subsonics?

c-J

The thinking is that 2 or three subs do the opposite to what you are suggesting, i.e., the more subs and the more random the placement, the less boomy. According to those who have studied this, including Floyd Toole and Earl Geddes, as mentioned in this interview: http://www.dagogo.com/View-Article.asp?hArticle=1047
2 is much better than one and three is better still, while 4 offers much less gain in quality - but note - this is not about amount of bass, but quality, in terms of more even response with less boom. Boom can indicate either an inferior sub or one room mode being strongly excited.

[poseidonsvoice]

The thinking is that 2 or three subs do the opposite to what you are suggesting, i.e., the more subs and the more random the placement, the less boomy. According to those who have studied this, including Floyd Toole and Earl Geddes, as mentioned in this interview: http://www.dagogo.com/View-Article.asp?hArticle=1047
2 is much better than one and three is better still, while 4 offers much less gain in quality - but note - this is not about amount of bass, but quality, in terms of more even response with less boom. Boom can indicate either an inferior sub or one room mode being strongly excited.

Rightly said sir! Don't diss it till you have measured and tried it.

Anand.

[Freo-1]

I have found integrating a subwoofer(s) an incredible pain in the rear.  I had Acoustat Spectra 33 ESL speakers for years, and a sub was definitely in order, but to get it integrated correctly was frustrating to say the least.
 
In fact, I’ve toyed around with the idea of a pair of subs to go with the Cary Signature Model Ones.  They go down to 38 Hz at the 3db point, so I think a pair of subs would be in order.  However, then a host of questions arise:
1. Should the hi-pass filter be used in the sub?  I have found that most of them actually degraded the sound.
2. Do you try the technical route, and get a sub with a mic input that adjusts the output?
3. Setting the gain is a pain as well.  Trying to work out the gain setting at various volume levels can be difficult at best. 
4. Where to place the subs?  Thankfully, there are some software tools on the market to help out there.
So, I’m open to suggestions for the speakers above.
 
 
Honestly, the best bass I’ve had in my systems to date is from the HT rig, where there is a pair Legacy Signature III’s running.  One does not need a subwoofer with those speakers, and the bass is integrated quite nicely once I worked out where to place the speakers.

[Russell Dawkins]

there are some useful tips for sub choice and placement on this page - see the third FAQ:
http://www.hsuresearch.com/faq.html#4

[Freo-1]

there are some useful tips for sub choice and placement on this page - see the third FAQ:
http://www.hsuresearch.com/faq.html#4

Thanks, Russell.  Looks like some good infomation there.

[cheap-Jack]

Hi.

cheap-jack, read this thread and the included links for the reasons behind the three subs in rollo's system. This thread and the links introduce the Controlled Acoustic Bass System (CABS). http://www.audiocircle.com/index.php?topic=106838.msg1099888#newScotty

We need a bit of common sense sometime, buds.

Should we believe in whatever commercial "white papers" published?
Sorry, I am one of a kind who do NOT.

First off, we have to know what "white paper" defines.

Per Google:-
"Since the early 1990s, the term "white paper" has come to documents used as MARKETING or SALES TOOLS......"

As per yr link, the white paper of CABS was commissioned by Harmon International, a manufacturer & representative of many audio products, which include JBL & Infinity, etc etc subwoofers. Harmon is it an audio vendor by istself. It is obvious the commercial motive behind the scene is to promote the sales of subwoofers.

Put aside the validity of the commercial white paper of CABS based on simulations. The NEED of using more subwoofers for bass equalization indoor  depends on such LF resonance problems existed or not. IF hey do exist, it is serious enough to go go for more subwoofers instead of other bass trap treatments????

In my basement audio den where there is none acoustical treatment ever done, yet as I posted here earlier, I enjoy bigtime clean & substantial sub subsonic bass notes of pipe organ music from my LPs using ONE & only 100W 10" subwoofer. So do I still NEED to drop a bundle to get more subs???

IME, either I were blind & deaf lying or the validity of the CABS white paper is questionable. Suely I never lie to myself.

Consumer beware - not so easily blinded by so called 'science'.

c-J

 

[woodsyi]

According to old (but probably still valid) Bell Labs research, any time you go above 10kHz.


Their golden rule covering this was that for playback to sound natural the upper and lower -3dB (or minus anything dB) frequencies, when multiplied together should equal 400,000.


By that reasoning, if you are 6 dB down at 40Hz, you should be 6dB down at 10kHz

This is how telephones can sound reasonably natural with a bandwidth from 200 Hz to 2,000 Hz - the product is 400,000!

I didn't know about this adage, but I can attest to finding some truth to this statement in my experience.  I wrote the following back in 2006 without knowing about this adage in this thread:

They sound a little hot out of the box but they should settle down.  Curiously, some of the perceived brightness of the tweeter went away when I hooked up the subs.  I lowpassed the subs at 50 Hz to augment the Bella/SP1's running full and they sound better.  I quess psychoacoustics does matter.  I will continue to burn these in for awhile then post some impressions and comparisons.

I have always felt that bass is the bones; midrange, the flesh; and treble, the skin of music.  Without good bone structure, you just can't get good looks.  So I experienced a kind of a Zen moment way back when I realized that I needed to get good tight bass extension to get good air in the treble.   I can't stand boomy bass but I can't stand lack of bass either.      

So for me, I need to go below 40hz every time I turn my system on,

[konut]

Don't worry. When you can SEE the tonearm riding the warps, it'd be probably only a few Hz sub subsonic. Not many amp or loudspeaker can reproduce them. Our ears surely can't detect it.

c-J

What, me worry? (insert Alfred E. Neuman emoticon) The fact that you can see your woofer, or sub, move means your amp and speaker are reproducing it. Do you have any idea how this use of largely inaudible sub-sonic garbage does to the headroom available to you?

[poseidonsvoice]

Hi.
We need a bit of common sense sometime, buds.

Should we believe in whatever commercial "white papers" published?
Sorry, I am one of a kind who do NOT.

First off, we have to know what "white paper" defines.

Per Google:-
"Since the early 1990s, the term "white paper" has come to documents used as MARKETING or SALES TOOLS......"

As per yr link, the white paper of CABS was commissioned by Harmon International, a manufacturer & representative of many audio products, which include JBL & Infinity, etc etc subwoofers. Harmon is it an audio vendor by istself. It is obvious the commercial motive behind the scene is to promote the sales of subwoofers.

Put aside the validity of the commercial white paper of CABS based on simulations. The NEED of using more subwoofers for bass equalization indoor  depends on such LF resonance problems existed or not. IF hey do exist, it is serious enough to go go for more subwoofers instead of other bass trap treatments????

In my basement audio den where there is none acoustical treatment ever done, yet as I posted here earlier, I enjoy bigtime clean & substantial sub subsonic bass notes of pipe organ music from my LPs using ONE & only 100W 10" subwoofer. So do I still NEED to drop a bundle to get more subs???

IME, either I were blind & deaf lying or the validity of the CABS white paper is questionable. Suely I never lie to myself.

Consumer beware - not so easily blinded by so called 'science'.

c-J

Yes, Earl Geddes, Floyd Toole, Allan Devantier, Todd Welti, are all out to get our money.

Why don't read the peer reviewed AES publications on this topic first (i.e. multiple subwoofers) and forget about the white paper. The CABS concept is an application of multiple subwoofer implementation. The links to the AES publications are here.

You are entitled to your very subjective non-scientific opinion, but buy a copy of Floyd Toole's book, Sound Reproduction please. It's an exhausting effort on delineating the acoustics and psychoacoustics of loudspeakers and rooms. You may learn something...really!


Anand.

[srb]

Many of the multiple subwoofer proponents recommend several more inexpensive subwoofers compared to one expensive one.  I know one person who sold his JL Audio Fathom 112, bought three small sealed SVS subwoofers, and experienced more even bass throughout the entire listening area.

Others have reported the same increase in bass quality with multiple subs and the results were more than just the typical subjective opinions as frequency response measurements verified what they thought they were hearing.

Is it worth the extra floor space, power cords and speaker wire?  It depends on the person.  I don't have 3-way active speakers with 6 monoblock amplifiers because I don't want the complexity, space requirements or expense, but I don't doubt the results if properly implemented.

Same with subwoofers.  I don't really want three or four subwoofers in the room with their corresponding required power and signal connections.  But I don't doubt the superiority if properly implemented either.  BTW, I do have two budget subwoofers that sound better to me in my room than one that I borrowed that was three times the price.

But for those who are into it, more power to them.  For the person who has 3-way speakers with active crossover and six Bryston or Hypex Ncore monoblock amplifiers, I recommend three JL Audio F110/F112/F113 subwoofers!

Steve

[*Scotty*]

cheap-Jack, here is a link to Adrian Celestinos' Ph.D thesis.
http://vbn.aau.dk/files/12831869/AC-phd.pdf
The Ph.D thesis presents a very clear argument for the use of more than one sub-woofer in a stereo system.
 I wasn't blinded by science so much as intrigued by how simple the concept was. This goes right back to the basic principles of wave propagation I first learned about in high school physics.
 It's also easy to apply the CABS approach to achieving flat bass response in your listening room without purchasing anything from Harmon Int'l.
Scotty 

[*Scotty*]

As the thread veered off topic a ways, I also have to cast my vote for extension below 40Hz.
While I have never "heard" 20Hz tones in my room I have felt their presence. I prefer to have the capability of 20Hz reproduction for the reasons mentioned in Photon46's post. The low frequency hall ambiance is down there as well as the foundation of the orchestra anchored by the output of the instruments with fundamentals and harmonics that extend below 40Hz.
 Something that hasn't been mentioned before is the possibility that if you have competent extension to 20Hz maybe your reproduction of the rest of the bass spectrum might be lower in distortion due to linear Xmax limitations that might otherwise  be present in a system that only reached to 40Hz.
Scotty

[James Romeyn]

...Something that hasn't been mentioned before is the possibility that if you have competent extension to 20Hz maybe your reproduction of the rest of the bass spectrum might be lower in distortion due to linear Xmax limitations that might otherwise  be present in a system that only reached to 40Hz.
Scotty

Human hearing is extremely tolerant (low sensitivity) to distortion (THD) in the bass range.  IIRC, in the bass range only, from <1% to 30% THD humans perceive little to no qualitative difference.

Conversely, modal effects caused by boundary interaction are easily perceived.  Not only for swings of +/-12 dB, but even worse for destroying the timing of bass notes (for instance, a 1/16th note hangs in the room for 72% longer than 1/16th beat, droning after the musicians play the next bass note).  Transient distortion, uncertain pitch center, and intermodulation distortion barely describe the resulting a-musical effect.   

Sensitivity and tolerance for THD in the critical mid band are the inverse, where fractions of a percent may be detected.

The whole beneficial philosophy behind multiple subs is centered on flattening the modal effects for flatter response, but more importantly, fixing the timing and pitch errors.  Ultimate power is not the goal. 

It's a strange artifact that properly implemented multiple subs might be perceived as producing less power than if the same exact collection of subs were all located together in the same acoustic polarity.  This is because the latter would activate the modal effects and sound much louder but those louder tones would be selective (their timing would be way off too).  But for each louder tone another tone would be quieter.  The ear might not notice the quieter or absent tones, so it's likely the average listener would perceive it as overall louder, when average output for all bass tones might be equal to the properly implemented multiple sub setup.   



 

[*Scotty*]

While we may be tolerant of gross distortion in the bass frequency range, such distortion is not generally heard in a live performance of acoustic instruments. I would prefer to shoot for less than 3% THD between 20Hz and 100Hz at SPLs up to 105dB. I would also hope to have considerably less than 1/2 % THD between 100Hz and 20kHz at the same maximum SPL of 105dB. 
 
There is a potential problem that can arise when multiple subs are employed. A fairly flat response curve can be obtained without too much trouble and the system/room combination will be mostly non-resonant on a steady state basis. However, if care is not taken when choosing where the subs are placed in the room relative to the listening position the resulting wave-launch produced by the system when it attempts to reproduce bass transients such as drum strokes can incoherent.
 The sound wave originally produced by the instrument was phase coherent. The impact it produced on your body and your ears was a result of all of the energy arriving at the same time. If a series of sub-woofers are located in the room at various distances from the listeners location the arrival times of the wave-launch from the subs will also vary, which will greatly diminish the impact and realism.
 The solution is to break out the tape measure and be sure to place the sub-woofers in the rear or other locations in the room further away from the listening position than the sub or subs that are at the front of the room near the main speakers. This insures that you generate a coherent wave-launch from the front subs and hear/feel the output from them first, before the sound wave is interfered with or canceled by the output from the other subs in the room.
 If the subs are set up correctly, the main speakers and the sub/subs associated with them can still beat you up if the music calls for it and the room will be non-resonant below the Schroeder frequency.
Scotty

[cujobob]

Hi.
We need a bit of common sense sometime, buds.

Should we believe in whatever commercial "white papers" published?
Sorry, I am one of a kind who do NOT.

First off, we have to know what "white paper" defines.

Per Google:-
"Since the early 1990s, the term "white paper" has come to documents used as MARKETING or SALES TOOLS......"

As per yr link, the white paper of CABS was commissioned by Harmon International, a manufacturer & representative of many audio products, which include JBL & Infinity, etc etc subwoofers. Harmon is it an audio vendor by istself. It is obvious the commercial motive behind the scene is to promote the sales of subwoofers.

Put aside the validity of the commercial white paper of CABS based on simulations. The NEED of using more subwoofers for bass equalization indoor  depends on such LF resonance problems existed or not. IF hey do exist, it is serious enough to go go for more subwoofers instead of other bass trap treatments????

In my basement audio den where there is none acoustical treatment ever done, yet as I posted here earlier, I enjoy bigtime clean & substantial sub subsonic bass notes of pipe organ music from my LPs using ONE & only 100W 10" subwoofer. So do I still NEED to drop a bundle to get more subs???

IME, either I were blind & deaf lying or the validity of the CABS white paper is questionable. Suely I never lie to myself.

Consumer beware - not so easily blinded by so called 'science'.

c-J

I can't tell if you're serious... a 10" sub can only go so low. There is material below the...maybe...25-29 hz you're hitting with that sub. Since you said it has 100w behind it, I'd guess not below 30 hz. It also can not reach the decibel levels many users would want.

If you're happy with your setup, awesome! There's better out there, but at some point, it costs more money. Do your wallet a favor and avoid hearing better.

[kbuzz3]

This is a related question so if its off topic feel free to move it.  Anyway, what do you guys think is the smallest size single sub that can do sub 40 legitimately for music.  Not talking about a sunfire small box monster amp dinosaur stomping thing, but something that can actually do real world dual duty of for music and HT with obvious emphasis on music. 

By way of reference i have a very small room (13 x 13) and get solid bass to 40 and would like to see how the room does with a sub. But since the room is quite small, i dont really want a monster box. As many have stated above, it may be a situation were one should live with nice 40 bass than something that goes lower but add all sorts of room issues....but curious

Anyway, laws a physics may dictate that anything sub 40 should be at least a 12" or 12" box but curious as to what the board thinks.

As for brands, it assume for dual music/HT you would want to go with a model that does both LFE and speaker inputs ala REL or MJ acoustics.  However, the rythmic stuff seems very nice....

[medium jim]

I'm using a pair of 8" B&W subs and have no problem reaching down to the low 20's and very smooth and natural too.  The idea that you need at least a 12" sub is falacious to my ears.  More to the point, an 8" speaker is generally faster too....

Jim

[*Scotty*]

I think you have to scale your sub-woofers to the size of your room and your peak SPL expectations as well as your low frequency requirements.
I have a relatively large space to fill at about 3600 cu.ft.. My system's main speakers have two 12in. sub-woofer drivers per side which is equal in cone area to one 15in. driver per/ch devoted to the frequencies below 150Hz. The sub-woofers in the room are operated 180 degrees out of phase and are located at the side and rear of the room to cancel out the rooms resonant behavior in the bass below 125Hz.
 I use the system for music 70% and HT 30% and it has to be able to meet THX specs if it is to survive movie special effects; (explosions,etc.).
 If you have a smaller room or no HT requirements smaller sub-woofers may be a good fit in your system.
Scotty

[kbuzz3]

Thanks everyone for the responses!!!  The information is great appreciated.  I was not too articulate in my prior post.  As a follow up and forgetting manfc. claims can we expect any of the smaller form factor subs --less i guess 10 inchers or less-- to truly and realistically output less then 40?

some examples being the

Smaller REL T types: http://rel.net/wp-content/uploads/2012/06/R-218.pdf; http://rel.net/wp-content/uploads/2012/06/T-5.pdf
MJ Acoustics 50, 100 :  http://www.mjacoustics.co.uk/MJ_Acoustics/Product_html/Ref_100.htm
Maybe something by velodyne.....http://velodyne.com/subwoofers/digital-drive-plus-10.html (list is $2700!!!!!!!)  or http://velodyne.com/ds-10.html

[medium jim]

Scotty is right in that the room size dictates the size of the subwoofers.  I'm filling 320 sq ft.  If I moved my system into a larger room, I would need to go larger.  Reference: two 8" = one 10", four 8" = one 12", two 10" = one 12".

A quality 8" driver/enclosure can reach down to the low 20's, of you need to go lower than 22 or 23hz, then a 10" or larger is required. 

Having said that, room treatments will be required in many instances to achieve really low bass no matter the size of the room or speaker.

Jim