# larger woofer is harder to " push " ?



## lurch (Jan 20, 2014)

i keep seeing this mentioned in reviews and lately by a friend. 

is it true that driving larger woofers is more taxing on an amplifier,
especially given that the voice coils and motors are identical ?


----------



## Bayboy (Dec 29, 2010)

Nope

Sent from my SM-G900V using Tapatalk


----------



## annoyingrob (Aug 24, 2007)

To elaborate a little more on that, the motor force is orders of magnitude stronger than the force of the air acting on the surface of the woofer. So, if you step from a 12" to 18" woofer which has about double the surface area, even though there is twice as much resistance on the cone from the air, it's still proportionally small compared to the force the motor can exert. For all intents and purposes the drivers will be the same, with the larger one being more efficient at producing sound with the same amount of power due to the larger surface area.

HOWEVER, there's another factor that is significant, your enclosure. The air volume of your box needs to increase proportionally with surface area of the driver to maintain the same Q. So if you double the surface area, you need to double the box volume to achieve the same response curve. Many people don't, and end up with undersized boxes for larger woofers which is where a lot of the "Larger drivers are slower or muddier or whatever adjective" sort of thinking comes from.

Edit: Off Topic, but Lurch you wouldn't happen to have owned a white 1JZ swapped Supra in the past would you?


----------



## lurch (Jan 20, 2014)

thanks guys, i wanted to argue the point with mentioned friend but did't want
to be wrong with my own understanding of the physics involved. 

annoyingrob :
nope, never owned a white supra, although i did own an older first gen brown supra. 
loved the car, didn't own it long enough to install a worthy stereo though. 
and thankyou for elaborating on the topic, much appreciated !


----------



## t3sn4f2 (Jan 3, 2007)

To put it into perspective, below is an example of how much that motor force can be.........

Velodyne Digital Drive DD-18 powered subwoofer | Stereophile.com

"The woofer occupies the rest of the enclosure. Its 18" cone is made of paper reinforced with carbon fiber, with a high-density surround and a linen spider. Four sets of five holes each punched in the cone break up standing waves and ventilate the voice-coil. *The motor structure is capable of developing 100 lbs of force, *and is almost as wide in diameter as the 18" cone itself. The motor uses a 24-lb magnet, two copper voice-coils, and two spiders. The voice-coils, one inside and one outside the former, are precisely wound in opposite directions onto the former, which is made of a woven-glass polyamide resin that is stable up to 400 degrees C. Although the driver's excursion has been increased to 1.25" from the HG-18's 0.75", the DD-18 can reach 1.75" on transients.


----------

