Why we only need one subwoofer

[Samwise]

Some of you may already know this but I learned this in school recently and thought it was pretty cool. We were learning about the ears and how they perceive sounds from different locations. One way is just through the shape of the external ear and how it amplifies sounds from certain directions, allowing us to localize aounds along a vertical plane. Another way is though the difference in time it takes the sound to travel to one ear compared to the other. The last way is through the difference in sound pressure level for a given sound at the two ears.

What I thought was really cool was the professor explained why we only need one subwoofer. The reason is that the frequency of the sound produced by the subwoofer is so low and the wavelength is so long that the same wave of a sound can be going through both ears at the same time and thus we can't localize it. A normal midrange sound would have numerous waves travel to one ear before the other even receives it just based on the space between your ears and the wavelength of the sound. I guess medical school is good for something. By the way, I have two subwoofers, obviously not for surround sound, just for the extra power.

 

[boyRacer]

You went against your own post.

 

[rudeguy]

I have two subwoofers, obviously not for surround sound, just for the extra power

heres a cookie....go choke on it

 

[MichaelD]

Yes, the fact that sub-bass frequencies are non-directional is not new news. Anything under 80Hz (the books say 100Hz, but I can pinpoint 100Hz everytime!) is non-directional.

But you still need more than one. Want to know why? SPL! That's why.

To make big bass you need two things: Cone area and raw wattage.

In a Home Theater in say, a 15x20 room, two 12-15 inch subs with about 250 watts RMS each are peachy.

 

[rudeguy]

beg to differ mr. mike...cone area doesnt have alot to do with home sub woofers...its more in the design and efficiency of the sub...take a 10" velodyne that has 400 watts and compare it a 15" jbl with a thousand watts...big dif...velodyne will shred that jbl

 

[flood]

what rudeguy5757 said
I like rel and paradigm's servo sub

 

[MichaelD]

Originally posted by: rudeguy5757
beg to differ mr. mike...cone area doesnt have alot to do with home sub woofers...its more in the design and efficiency of the sub...take a 10" velodyne that has 400 watts and compare it a 15" jbl with a thousand watts...big dif...velodyne will shred that jbl

OK, a logical debate. Nice.

I agree that quality is very important when it comes to sound...

But your exact example...well, IMO you dinged yourself. A 15" speaker has 50% more cone area (I am NOT a mathematician!) and w/that much wattage will flat out mow over anything at half that wattage! :Q

Disclaimer: I know a little about HT and a lot about car audio. In a small environment like a car cabin, you need cone area and raw watts to make big bass. Notice I said nothing about QUALITY. Just QUANTITY....

*edit*
In my truck, I have a single JL Audio 12W3-D2 in a 1.25CF (net) sealed and stuffed box powered by 300W RMS. Being that the sub is physically in the same compartment as the listeners (it's a SUV) that's more than enough. Add a second sub and double the wattage and I'd be over 140db easily..however, I like my hauling space in the back.

 

[Cerb]

But the power is why we need more!
If playing Sorrow doesn't at least make the windows rattle, you're not listening to it right .

 

[clicknext]

Geez. How could you not be satisfied with the power of one subwoofer? Unless it's not a powerful subwoofer... my sub's plenty for me at mid-low setting!

 

[rudeguy]

Originally posted by: MichaelD

Originally posted by: rudeguy5757
beg to differ mr. mike...cone area doesnt have alot to do with home sub woofers...its more in the design and efficiency of the sub...take a 10" velodyne that has 400 watts and compare it a 15" jbl with a thousand watts...big dif...velodyne will shred that jbl

OK, a logical debate. Nice.

I agree that quality is very important when it comes to sound...

But your exact example...well, IMO you dinged yourself. A 15" speaker has 50% more cone area (I am NOT a mathematician!) and w/that much wattage will flat out mow over anything at half that wattage! :Q

Disclaimer: I know a little about HT and a lot about car audio. In a small environment like a car cabin, you need cone area and raw watts to make big bass. Notice I said nothing about QUALITY. Just QUANTITY....

I wont debate the car audio thing...except the fact that your box and amp is more important than your sub...that being said, its true for home audio too...if the sound cant get from the sub to your ear, then it sucks...and cheaper subs are downward firing, wich shoots them into your carpet...would be the same as having a big ol 15 pointed downwards in your trunk...no good

 

[Beau]

Originally posted by: MichaelD

Originally posted by: rudeguy5757
beg to differ mr. mike...cone area doesnt have alot to do with home sub woofers...its more in the design and efficiency of the sub...take a 10" velodyne that has 400 watts and compare it a 15" jbl with a thousand watts...big dif...velodyne will shred that jbl

OK, a logical debate. Nice.

I agree that quality is very important when it comes to sound...

But your exact example...well, IMO you dinged yourself. A 15" speaker has 50% more cone area (I am NOT a mathematician!) and w/that much wattage will flat out mow over anything at half that wattage! :Q

Disclaimer: I know a little about HT and a lot about car audio. In a small environment like a car cabin, you need cone area and raw watts to make big bass. Notice I said nothing about QUALITY. Just QUANTITY....

Car audio benefits from the low frequency gain of being in a small enclosed place, that why cone area and raw wattage matters. It's like being inside one of the chambers of a bandpass box.

Home audio doesn't have that convenience. So by using well-engineered enclosures (like Bose), you can reproduce powerful sound at lower wattages, and still get the same compression, but at a lower volume.

at least, that's how it was explained to me a while back....

 

[rudeguy]

Bose=all high no lows

thanks, that is all

 

[glen]

What matters in subs is "swept air." This is the cone area times the X-mas, how far in and out it moves.
pi x R ^2 is area so:

a 15" sub has about a 74" surface area
a 12" sub has about a 59" surface area

to equal the potential volume at any given frequency, a 12" would ahve to have 25% greater excursion than the 15%.

some small exceptions:
a 12" in a band pass could have more output over a very narrow frequency range than say a 15" in a sealed enclosure.

 

[Spac3d]

Originally posted by: MichaelD
Add a second sub and double the wattage and I'd be over 140db easily..however, I like my hauling space in the back.

Easily?

I would like to see the print out of your W3's doing that.

 

[flood]

Originally posted by: glen
What matters in subs is "swept air." This is the cone area times the X-mas, how far in and out it moves.
pi x R ^2 is area so:

a 15" sub has about a 74" surface area
a 12" sub has about a 59" surface area

to equal the potential volume at any given frequency, a 12" would ahve to have 25% greater excursion than the 15%.

some small exceptions:
a 12" in a band pass could have more output over a very narrow frequency range than say a 15" in a sealed enclosure.

Thats true for pure SPL, but when you factor in the quality of the sound youre getting, it gets a lot more complicated.

 

[AlienCraft]

Originally posted by: rudeguy5757
Bose=all high no lows

thanks, that is all

Well, maybe in your world.
But my BOSE installs kick a$$.
I can prove it to you @
Marin Academy Theatre, any day of the week...... San Rafael, CA. Come on over
4 : MA-12 Line Arrays and 2 MB-12 subs with 2: Crown Macrotech 1200's powering them.

BOSE Pro for your perusal.....

 

[rudeguy]

Originally posted by: AlienCraft

Originally posted by: rudeguy5757
Bose=all high no lows

thanks, that is all

Well, maybe in your world.
But my BOSE installs kick a$$.
I can prove it to you @
Marin Academy Theatre, any day of the week...... San Rafael, CA. Come on over
4 : MA-12 Line Arrays and 2 MB-12 subs with 2: Crown Macrotech 1200's powering them.

BOSE Pro for your perusal.....

you payin my way to cali??? lol...lets not bring pro systems into this...cause thats a whole new ballgame

 

[AlienCraft]

Originally posted by: MichaelD
Yes, the fact that sub-bass frequencies are non-directional is not new news. Anything under 80Hz (the books say 100Hz, but I can pinpoint 100Hz everytime!) is non-directional.

But you still need more than one. Want to know why? SPL! That's why.

To make big bass you need two things: Cone area and raw wattage.

In a Home Theater in say, a 15x20 room, two 12-15 inch subs with about 250 watts RMS each are peachy.

Ding , we have a winner, sorta.
Room Volume also enters the equation. It is possible to have a subtractive phenomenum (sp) so as to be counterproductive.
Placement of the Sub(s) can also affect performance.
The famous Klipsch Horn relys on corner placement for accurate LF reproduction. Some Mfg's Subs have ports that may need to be a minimum distance from the wall for effective reproduction, or in a minimum sized room for best performance.

you payin my way to cali??? lol...lets not bring pro systems into this...cause thats a whole new ballgame

Hey Rudeguy..... Anytime you're out here, I'll show you some interesting sound installs.
Physics, acoustics and electronics... the life of a sound installer. Speaking of whole different Ballgame, Next time you're at the ballgame, take a critical listen to the system. Vocal Intelligibility is a SERIOUS issue for Pro Sports. Some systems are definately better than others.

 

Monster cables make your life better.

 

[rudeguy]

Originally posted by: AlienCraft

Originally posted by: MichaelD
Yes, the fact that sub-bass frequencies are non-directional is not new news. Anything under 80Hz (the books say 100Hz, but I can pinpoint 100Hz everytime!) is non-directional.

But you still need more than one. Want to know why? SPL! That's why.

To make big bass you need two things: Cone area and raw wattage.

In a Home Theater in say, a 15x20 room, two 12-15 inch subs with about 250 watts RMS each are peachy.

Ding , we have a winner, sorta.
Room Volume also enters the equation. It is possible to have a subtractive phenomenum (sp) so as to be counterproductive.
Placement of the Sub(s) can also affect performance.
The famous Klipsch Horn relys on corner placement for accurate LF reproduction. Some Mfg's Subs have ports that may need to be a minimum distance from the wall for effective reproduction, or in a minimum sized room for best performance.

you payin my way to cali??? lol...lets not bring pro systems into this...cause thats a whole new ballgame

Hey Rudeguy..... Anytime you're out here, I'll show you some interesting sound installs.
Physics, acoustics and electronics... the life of a sound installer. Speaking of whole different Ballgame, Next time you're at the ballgame, take a critical listen to the system. Vocal Intelligibility is a SERIOUS issue for Pro Sports. Some systems are definately better than others.

I love checking out installs...and I do have respect for you (i take you are an) installers...lots of grunt work, but still have to be smart enough to do all those fancy equations!!!!

 

[glen]

Originally posted by: flood

Originally posted by: glen
What matters in subs is "swept air." This is the cone area times the X-mas, how far in and out it moves.
pi x R ^2 is area so:

a 15" sub has about a 74" surface area
a 12" sub has about a 59" surface area

to equal the potential volume at any given frequency, a 12" would ahve to have 25% greater excursion than the 15%.

some small exceptions:
a 12" in a band pass could have more output over a very narrow frequency range than say a 15" in a sealed enclosure.

Thats true for pure SPL, but when you factor in the quality of the sound youre getting, it gets a lot more complicated.

For sound quality, the larger driver has a real advantage because,
The tension on the spring and the resistance of the magnet are not linear!
Also, in almost all drivers, the larger the box, the flatter the response.

 

[Zim Hosein]

Originally posted by: SammySon
Monster cables make your life better.

:Q

A regular hanger wire will transmit as much digital sound as a coaxial cable when talking about digital signals from a DVD player to a DD/DTS receiver

 

[rudeguy]

Originally posted by: Zim Hosein

Originally posted by: SammySon
Monster cables make your life better.

:Q

A regular hanger wire will transmit as much digital sound as a coaxial cable when talking about digital signals from a DVD player to a DD/DTS receiver

zim...arent you supposed to be elite by now?

 

[Zim Hosein]

Originally posted by: rudeguy5757

Originally posted by: Zim Hosein

Originally posted by: SammySon
Monster cables make your life better.

:Q

A regular hanger wire will transmit as much digital sound as a coaxial cable when talking about digital signals from a DVD player to a DD/DTS receiver

zim...arent you supposed to be elite by now?

It's not my call rudeguy5757, it's up to the mods and users opinion here

 

[rudeguy]

Originally posted by: Zim Hosein

Originally posted by: rudeguy5757

Originally posted by: Zim Hosein

Originally posted by: SammySon
Monster cables make your life better.

:Q

A regular hanger wire will transmit as much digital sound as a coaxial cable when talking about digital signals from a DVD player to a DD/DTS receiver

zim...arent you supposed to be elite by now?

It's not my call rudeguy5757, it's up to the mods and users opinion here

well you know my feelings

:::Looks at sig::::