The "innovation" of Bass Extension, Fact or Fiction?

[yodnnee]

Hey,

I've recently come across a number of portable loud speakers designed to include a "bass expansion system", which if you are unfamiliar consists of a sort of bellow which extends behind the speaker driver. The idea of which is to increase the bass response of the speaker.

Search "portable bass expansion" for an example.

I was wondering if anyone experienced in loudspeaker design could explain if this is a valid design for increasing bass response and how such a system would achieve this increase? I don't understand how creating an enclosed space behind the speaker driver could increase its sound quality or bass response.

Any assistance or thoughts would be greatly appreciated,
Thanks!

 

[agarwalro]

The only thing remotely on these lines, that I can think of, is the Hsu Research, "turbocharger" and it looks like this,

More than being an innovation in subwoofer technology, this is simply a waveguide. The Hsu "turbocharger" takes some of the sound dissipating at the back ports and focus it towards the room. It is not inconceivable that in some listening conditions, it will increase the tactile feel of the system. Whether it improves the sound quality or extension, I cannot say.

If you want low end extension, there is no substitute for a big quality driver, big well designed box and a beefy amp.

 

[shadyJ]

I don't think you are quite correct regarding the turbo add-on for the VTF3 subs. I believe the point of the Turbo was simply to increase port volume thus increasing output at its tuning point.

I'm not sure if the "bass expansion system" for these portable speakers is either increasing enclosure volume or some kind of porting. For speakers that small, it won't make much of a difference anyway.

 

[agarwalro]

I've recently come across a number of portable loud speakers designed to include a "bass expansion system", which if you are unfamiliar consists of a sort of bellow which extends behind the speaker driver. The idea of which is to increase the bass response of the speaker.

I did not find anything on these lines. Can you link a specific product?

 

[agarwalro]

I don't think you are quite correct regarding the turbo add-on for the VTF3 subs. I believe the point of the Turbo was simply to increase port volume thus increasing output at its tuning point.

This is indeed the case, and the port volume was increased by adding diameter and length to the port. It was the increased port length, while keeping box volume, constant that made it necessary to add the bending tubes (waveguide). From the website, "For a given enclosure volume, putting in a larger port means a longer port length to tune the port to the same frequency. In order to fit two 4" ports into an enclosure the size of the HO, we need to bend the ports."

 

[markw]

These came up when I did that seach the OP suggested,

You mean something like this?? Total marketing bull.

Enclosure size can have an effect on bass response but in the cases I see references here, it's totally irrelevant. These drivers can't be more than about 2 - 3".

If you believe that, I've got a bridge to sell ya.