Why Must Dynamic Driver Or Most Headphone Driver In Round Shape?

[BillsonChang007]

Hi!
 
Weird question but when ever I see a picture of headphone driver, this question pop out of my brain. 
 
Billson 

 

[ultrabike]

Dunno for sure, but probably because it is easier to manufacture, and minimizes non-linear behavior.

 

[ProtegeManiac]

Quote:

Originally Posted by BillsonChang007 /img/forum/go_quote.gif
 

Why Must Dynamic Driver Or Most Headphone Driver In Round Shape?

 
Hi!
 
Weird question but when ever I see a picture of headphone driver, this question pop out of my brain. 
 

 
You can include most speakers too - they're usually round, save for what's usually found behind the passenger's heads in 90's sedans, or woofers in some tower speakers. I think some recent cars have oval speakers on the front too, like the first gen Mazda3.
 
It's mostly for stability. Have you ever seen a dynamic driver in action? Even a car audio subwoofer bass test YouTube vid will suffice - you can see it pumping air back and forth. The diaphragm is suspended on the surrounding foam and some other bits, like the electric coils, on or near the center. If you had an oval driver, not all points along where the diaphragm meets the foam surround will not be equidistant, and will very likely to enhance distortion.
 
So then why were oval speakers made? Simply to maximize surface area - hence bass response - given a restrictive mounting point, like a (relatively) slim tower speaker or the backboard in a sedan. The latter I honestly do not understand given the actual holes on the body/chassis on most cars are round, and only the cosmetic plastic cover holes are oblong along with the speakers, when there is enough space on most of these cars to just take in an 8in coaxial (or replace them with 8in subs when, unlike a manufacturer, you want all music up in front for soundstage instead of sharing with your rear passengers), but I have no idea how speaker sizes are decided in the automotive industry.

 

[kramer5150]

Well, there are square subwoofer drivers.  I am not sure about headphone drivers though.... why they have to be round.

 

[proton007]

Good question.
The most common reason I read is that the surrounds are easier to make in a round shape,  since they are the ones stretching while the cone moves. Making them in some other shape may induce some non-linearities.
 
Also, the dispersion of a round cone is well, same on both horizontal and vertical axes. Oddly shaped speakers can have a different dispersion on x/y axes, hence the 'beam' of sound can be controlled for closed spaces like cars.

 

[ProtegeManiac]

Quote:

Well, there are square subwoofer drivers.  I am not sure about headphone drivers though.... why they have to be round.

 
Quote:

Originally Posted by proton007 /img/forum/go_quote.gif
 
Making them in some other shape may induce some non-linearities.

 
And the older Kicker Solobarics have slightly shorter suspension travel than their competitors, not necessarily because the extra surface area compensates, but because it will distort easier. That's in theory, but in practice, SPL competitions are usually decided as much by box design. Haven't been catching up with the technology since I'm more of the "cut the crossover as low as the front mids can go then fine-tune with the processor's time alignment" listener but for all I know maybe they've gotten better on that regard by now.

 

[MpX5]

I guess round driver potentially has better performance because force distribution from coil to edges is even in all directions.

 

[zmoney]

A circle is balanced. Compare this to a square- the surround would have to be a different thickness at the corners causing all sorts of unbalance, not to mention the manufacturing of how to bring the two straight edges together, the cross sectional design would change as it hits the corner.
 

 

[proton007]

Quote:

A circle is balanced. Compare this to a square- the surround would have to be a different thickness at the corners causing all sorts of unbalance, not to mention the manufacturing of how to bring the two straight edges together, the cross sectional design would change as it hits the corner.
 

Well I'm not sure how cones are made nowadays, but you can always weave one around a shape, or maybe mould it.

 

[BillsonChang007]

Take a good look at the above picture of my home speaker. It's square? & it does cause me to scratch my head. Anywhere, I find all the responds very legit but just curious why my speaker in such shape yet with good surround for movie(never use it for music thought).

Sorry for the bad quality picture.
Thank you all for all the great respond! ^_^

 

[proton007]

Quote:

Take a good look at the above picture of my home speaker. It's square? & it does cause me to scratch my head. Anywhere, I find all the responds very legit but just curious why my speaker in such shape yet with good surround for movie(never use it for music thought).

Sorry for the bad quality picture.
Thank you all for all the great respond! ^_^

 
Not sure if its square or round, unless you remove the grill.
Still, its not uncommon to find shapes other than round, for example:

 
Or electrostatic speakers:

 

[Roly1650]

Quote:

 
Not sure if its square or round, unless you remove the grill.
Still, its not uncommon to find shapes other than round, for example:

 
Or electrostatic speakers:

I know that the dimensions of the KEF B139 woofer, (the black driver in the IMF(?) transmission line speaker behind the Sony's in the first picture) where chosen because at the time the UK's Purchase (Sales, VAT) Tax, penalized the minimum speaker dimension. So a 13" x 9" elliptical speaker carried less tax than the roughly equivalent 12" diameter driver would. This "design" compromise didn't stop the KEF driver becoming one of the most widely used bass drivers for domestic loudspeaker applications and particularly loved by transmission line speaker designers.

 

[BillsonChang007]

Not sure if its square or round, unless you remove the grill.
Still, its not uncommon to find shapes other than round, for example:



Or electrostatic speakers:

It don't look like a grill to me. It's made of glass & when sound playing, it moves a lil...

 

[proton007]

Quote:

It don't look like a grill to me. It's made of glass & when sound playing, it moves a lil...

So maybe it is square then. As long as it sounds nice!

 

[BillsonChang007]

It's pretty decent I would say. Movie explosions are very "ground shaking" feeling and surround are decent. It's a wireless speaker at the back and wired for the front speaker. Hardly turn on the wireless as the plug are pretty far away from my living room xD but when you do turn it on, BOOM! 
Quote:

So maybe it is square then. As long as it sounds nice!