Sealed, Ported and Distortion

[davey g-force]

Just a theory:

In a sealed enclosure, there is more pressure or resistance from the air. Maybe this air moving/vibrating affects the cone when it's trying to do something else? i.e. when the signal changes with a ported sub, the cone is more free to move with the signal rather than having to fight with the air which is trying to do something else?

 

[garfa]

Just a theory:

In a sealed enclosure, there is more pressure or resistance from the air. Maybe this air moving/vibrating affects the cone when it's trying to do something else? i.e. when the signal changes with a ported sub, the cone is more free to move with the signal rather than having to fight with the air which is trying to do something else?

personally i cant see how a ported enclosere can distort more than a sealed one.
sorry aaron but i just cant make sence of what you are trying to say. it doesn't fir together.

if the driver is being pulled back hard and the signal tries to push it forward it will not happen

if a 50hz signal is played and then a 20hz signal is also played, it will mean the cone id moving in and out 10times a sec and while its moving in and out it will also be vibrating at 50hz. so effectively its an ossillation of the ossillating cone.
what you are saying by the cone being extened by a signal and then further extension pushing its past its linear response is just the speaker distorting. a ported box will do this aswell. a free air sub will also do this if its eing pushed past its x-max.
i think that answers that bit.

also as for a cone being harder to push and pull in a sealed box that will definately not introduce distotrsion. the air will be getting pressurised therefore reducing the cone's movement and also its flex.

pretty sure that answers it.

 

[phree]

I origionally brought up this topic in a convo with Garfa about Sealed Enclosures being more prone to distortion than Ported Enclosures. Google "Sealed vs Ported" and in every site it will tell you that Sealed is more prone to it.
Why is this? We have had rough stabs at it but cant seem to make any sense of it. Now we are just confused and curious...

Anybody?

Which sites say that? What type of "distortion"? More the other way round I think. Sealed enclosures are usually chosen when sound quality is paramount. Ported are louder but generally less accurate. This is not really distortion though, more "colouration".

Perhaps it's because the sealed enclosure requires more power to go as loud as the ported. Therefore a given amp is running closer to clipping levels.

 

[azzfox]

sorry i made a mistake, google "sealed vs ported distortion"
iv come up with this site which has alot of info=

http://diyaudiocorner.tripod.com/dilemma.htm
scroll down to second table for advantages/disavantages.

it also had this = "On the downside, a sealed driver reaches maximum excursion at resonance, which adds considerably to the distortion produced at high output levels."

 

[phree]

At normal levels it should be inaudible i think. There is some good reading here:

http://mobile.jlaudio.com/support_pages.php?page_id=147

 

[azzfox]

At normal levels it should be inaudible i think. There is some good reading here:

http://mobile.jlaudio.com/support_pages.php?page_id=147

i also found this on that link = "At moderate power levels all of these enclosure types exhibit pretty decent manners. The ported box and the bandpass designs produce less distortion than the sealed box, but the difference is marginal."

 

[garfa]

ok fantastic to quote sources, but i want to know why. dont care if some one tells me something unless i can see exactly how it works i will not beleive them.

 

[azzfox]

well hey, this thread was started for that exact reason.. "WHY"
im doin tha best i can for now. at least im making an effort.

 

[semi]

jsut throwing ideas out, maybe a sealed box could be more prone to clip, because it will move less 'freely' because its not influencing box presure as much.

Hmm, doenst make much sense, hard for me to describe what im thinking. Can we turn on the 12V-light??

 

[garfa]

semi unfortunately sealed boxes allow the sub to handle more power. and specically the smaller the box the more the sub can handle, because of the air restricting movement.
as for not making an effort, i dont really have time and cant be bothered. i was hoping for 12volt or stone or kal to come in and settle this.