what the usage of speaker surround shell?

[legopart]

I find lot of speakers without it,
can glue this thing can improve the speaker quality or protect it better?

 

[PeteMcK]

Once upon a time, speakers were mounted behind the baffle....

 

[legopart]

Once upon a time, speakers were mounted behind the baffle....

That's all ?
only because vintage drivers installed behind the wood box hole?

 

[wolf_teeth]

It's also a method for securing the outer rim of the surround.
Wolf

 

[johnmath]

Yep.

 

[TBTL]

And it protects the speaker in storage / shipping, when it is lying cone down.

 

[legopart]

Do it improve the sound somehow if I add it ?

 

[Cal Weldon]

It can but I wouldn't worry about it. As mentioned, it's a gasket, it reinforces the surround edge and it's a spacer. If it needed to be there, all drivers would have it. There are plenty without.

 

[fabricadetabaco]

It’s usually on PA drivers for A) rear mounting or B) attach a grill.

 

[johnmath]

Do it improve the sound somehow if I add it ?

No. It is more likely to degrade the driver's performance because the physically symmetrical discontinuity caused by the surround can cause a wavelength related reflection or discontinuity in the radiation impedance seen by the cone, with associated ripples in the frequency response and aberrations in the time domain / step response of the driver.

 

[AllenB]

There are plenty without.

..and it's always the one you want to mount from behind 🙄