Need Someone With Real Acoustic Knowledge. Waves

[HHR Ed]

BTW, what I just wrote is why I think its so funny that people put box tuning in there sigs and specs. Like 2.5 cubes tuned to 33 hz, lol

What if you put in different subs, what if you add power, what if its cold, what if its hot, what if you put your AC on, what if its raining, what if you put the box in a different car?

What your box is tuned to isnt really an important spec. Mine is tuned to 20-80hz.

[IH8PunkRok]

very nice info ed very nice.

so in order to really tune a box u need to be able to accurately measure the airspace, density, and relative length of the vehicle it is in? hmm this is a fun subject.

so wut about resonance? why is it that the most common boxes utilize the sound bouncing around aimlessly in the box instead of simply directly the rear wave forward through a tube sorta thing. is there any real benefits to a standard ported box vs say tlines other than relative size?

[Boon]

so wut about resonance? why is it that the most common boxes utilize the sound bouncing around aimlessly in the box instead of simply directly the rear wave forward through a tube sorta thing. is there any real benefits to a standard ported box vs say tlines other than relative size?

The sound isn't 'bouncing' around inside the box - it's a wave so all it's made up of is differing areas of pressure.

The reason we curve corners etc is to try and prevent spots of high pressure. The waves collide in the corners and will interfere with each other - be it constructive or destructive interference. Sometimes we want to create areas of generally higher pressure, particularly around the port mouth.

A ported box generally provides more cone control and power handling than a t-line or horn - although the 'exotic' designs are far more efficient to a point, they are limited because the sub is running virtually free air (hence why they're so efficient) but will quickly get into the realms of over-excursion unless it's an incredibly stiff driver or very restrictive port/mouth. This is why in extremely high power systems the box is usually ported, sealed or a bandpass box - these offer much more mechanical control (and hence protection to the driver) and when power is virtually unlimited (such as in an Extreme vehicle) the ability to control the woofer is more important than a slightly higher efficiency.

This is just my understanding of it

[IH8PunkRok]

good info boon

now think wit me is it possible to create back pressure in a t-line for cone control and power handling while still being much more efficient?

it involves wave compression and a quarter wave length in a funnel type enclosure... i dont like it tho cuz the port mouth on one design came out to be less that an inch in diameter for an 18" woofer.... seems wrong to me

[rusty959]

good info boon

now think wit me is it possible to create back pressure in a t-line for cone control and power handling while still being much more efficient?

it involves wave compression and a quarter wave length in a funnel type enclosure... i dont like it tho cuz the port mouth on one design came out to be less that an inch in diameter for an 18" woofer.... seems wrong to me

Im thinking you may be interested in seeing Forevrbumpn's tline bandpass box? (tline with a sealed airspace on the outside of the cone if you get what im saying)

[aznboi3644]

If you want more info do research on Helmholtz Resonators

http://www.phys.unsw.edu.au/jw/Helmholtz.html

Edited January 11, 2009 by aznboi3644

[IH8PunkRok]

Im thinking you may be interested in seeing Forevrbumpn's tline bandpass box? (tline with a sealed airspace on the outside of the cone if you get what im saying)

linky?