woofer excursion in STF-2

[Dudley]

I am considering the STF-2, but had a question about the woofer itself. So many woofers claim that their long excursion is what gives them an edge in producing deep bass.

What is the excursion of the STF-2 (the surround looks to be fairly small and not capable of suporting much excursion), and exactly how does the excursion effect deep bass? I realize longer excursion means more air can be moved.

[Sasha_G]

Longer excursion has its benefits in increasing maximum output levels, but also increases the risks that a woofer will sound sloppy. Our STF-2 has about +/- 8 mm each way.

[Lwang]

Is that much different from the old 10" driver that were on the VTF-2/10V?

The 12", given the its Xmax of +/-18mm, seem to be able to move 325% the amount of air the 10" could. If that is so, it seems to be literally in another league.

Also, what is the Xmax on the 8" VTF-1 driver? I presume it is a brand new design since Hsu never had a 8" driver before.

[DavidD]

Also, what is the Xmax on the 8" VTF-1 driver? I presume it is a brand new design since Hsu never had a 8" driver before.

Actually, I seem to remember a very short-lived TN825 model from a number of years ago. If memory serves, it did use an 8" driver.

[Michael Bain]

There is a good reason why Hsu is offering a 7 year warranty on their woofers. They are very solid and well built.

There is so much more to subwoofer performance than maximum excursion capability of the driver. Output also does not exactly increase linearly with excursion capability. At very low frequencies on the Hsu models, most of the bass actually comes from the port, and the woofers move very little at these low frequencies. You can note this behavior more easily on a TN-series sub, where woofer is on top.

A quick read of some of the VTF-2 reviews shows how capable this sub is. With only a 10 inch driver, it can handily outperform many other subs with 12 inch or larger drivers in terms of clean and undistorted maximum output levels.

[Dudley]

If more excursion means more "slop", then how does the VTF-3 avoid being "sloppy" with its 18 mm. Also is the STF-2 woofer about the same as the VTF-2, but with a rubber surround and a poly cotton spyder.

I am not hung up this issue. The sound is the most important thing, how it is achieved is secondary. I am just curious because some manufactures hype this item.

On a slightly different note. I saw the HSU designed Gateway sub, and it looks like it has an identical woofer to the STF-2, and is about the same size, has an identical looking amp (though they claim 150 watt rms 400 watt peak), but it has two ports. Is this basically a VTF-2 in max output mode? If so how does it go so low? Gateway claims 112 db average from 27Hz to 100Hz, and a -3db of 23Hz. From what I gather by reading, the VTF-2/STF-2 is about 109 db over this range with similiar deep extention (I assume -2 at 25 Hz is pretty close to -3 at 23 Hz)

Officially how does the STF-2 compare to the Gateway Sub, or are the basically achieving the same end by two different means.

[Ddavidson]

I seem to remember a very short-lived TN825 model from a number of years ago.
Good memory. It was actually a box sub which at the time was well against the Hsu preference for cylinders.
Widescreen Review's Richard Hardesty reviewed the TN825. It had an 8" driver with 75w amp.

Ddavidson

[Michael Bain]

It is not true that more excursion is equal to more slop. It is just a bit trickier to get the driver under control with super high excursion drivers. There are other issues such as motor and magnetic structure that come into play, and that is why the VTF-3 does not sound sloppy in comparison.

[Retread]

[QUOTE]Originally posted by Dudley
[B]If more excursion means more "slop", then how does the VTF-3 avoid being "sloppy" with its 18 mm.

Now you are into the topic of advanced control system theory, having to do with the interrelationships of mass, damping, and a whole bunch of other parameters governed by advanced mathematics, including imaginary numbers, poles in the right half-plane, and a bunch of other stuff I hated studying in graduate school and forgot as soon as I passed the courses. Shudder.

Subwoofer design is also at least as much of an art as a science.

[cschang]

Originally posted by Retread
[QUOTE]Originally posted by Dudley
[B]Subwoofer design is also at least as much of an art as a science.

Very true. I have had a couple of emails from Dan Wiggins of Adire about this as well.

Ofcourse, most of it is physics/science, but more than people think, creativity, interpretation, and art also come into play. I think this is what makes the difference between a good subwoofer and a great one.

You have to study bass...not just know your physics. Judging by Hsu Research's products, Dr. Hsu has this going for him.

[Dudley]

I just noticed that the VTF-2 claims to have an "ultra long throw" driver. Is the excursion different from the stf-2 driver? If it is different how does the STF-2 make up the difference - since they are supposed to sound about the same? If there is a difference in excursion and there are no other sonic differences between the drivers is the extra excursion on the VTF-2 then needless? Are there any other differences between the two drivers.

I only bring this up because the "ultra long throw" of the VTF-2 is listed as if it is a large benefit in HSU's own descriptions.

[Dudley]

By the way - what is up with the times on this forum.

Does HSU run on Greenwich mean time? :D

[Lwang]

You have set your timezone in your profile.

[Dudley]

Thanks - guess I zipped through that a little to fast.