TB W6-1139SIF: am I missing something?

[ToloV]

Hi everyone!

I'm new to the world of DIY speakers, and I'm thinking of building a subwoofer for my smaller pair of active speakers (KRK RP5s: 2 ways, a 5 1/4" 30W woofer and a 1" 20W Tweeter).

Looking here and there I came across this sub, the W6 1139 SIF from Tang Band, for which I found many positive reviews but no full project... so, I started designing my own on Winisd... or, at least, I tried 😕
long story short:
I was thinking of a 0.883 ft3 (25 liters) ported box, with a 15" x 0.4" (38x1cm) port tuned @32Hz (port length: 15.5", seems doable)
at 40W of power I should get F3 @29Hz, peak air velocity of 18m/s... but xmax (11.5mm) @23Hz.
How would you modify it? I'm going by trial&error, but I haven't found I way to keep the driver from going in over-excursion except using the filters included in Winisd, but I reckon they're all active (?).
suggestions? what about that f3? to me, it seems very optimistic for a 6.5" ...

Thanks a lot

p.s.: does PE ship worldwide?

 

[wolf_teeth]

I think you're not missing much at all. The 1139 will do that, and do it well.
Wolf

 

[David Morison]

I was thinking of a 0.883 ft3 (25 liters) ported box, with a 15" x 0.4" (38x1cm) port tuned @32Hz (port length: 15.5", seems doable)
at 40W of power I should get F3 @29Hz, peak air velocity of 18m/s... but xmax (11.5mm) @23Hz.
How would you modify it? I'm going by trial&error, but I haven't found I way to keep the driver from going in over-excursion except using the filters included in Winisd, but I reckon they're all active (?).
suggestions? what about that f3? to me, it seems very optimistic for a 6.5"

I'm not sure on the maths behind this, but I've seen recommendations that a slot port should not have a high ration of width to height - 9:1 was the maximum ratio I've seen suggested.
I think the problem with higher ratios is that a high ratio port has a much higher total surface area which decreases the efficiency of the port.
So the first thing I'd change is that ratio if possible.

Second about the excursion - all vented designs exhibit increasing excursion below the box tuning frequency.
However, not all musical styles have much content down there, so although it may look like there is a risk, it is sometimes possible to get useable results anyway.
If you know you will play back material with a lot of very low frequency content (Low Frequency Effects from movie soundtracks, or certain genres of Electronic Dance Music), then it would be best to use an amp (or DSP unit if that is what is providing your crossover) that allows you to set a high pass filter for driver protection.

HTH,
David.

 

[remotion]

I have experience with W6-1139SIF's and W6-1139SI.

I built three enclosures for them, only one worked. Box needs to be big enough and it needs to be reflex tuned, closed does not create any bass.
This is all to my sportscar, I did them first with SIF, but went with neodymium later for weight reasons and for the little bit of extra gained in space inside the enclosure.

My Design:

Building:

Completed:

Finished inside the car:

If I made this for home application I would simply make the box bigger and tune it to 30Hz. But mine is with 2 elements, so yours with 1 and 25 liters seems easily big enough.

 

[ToloV]

I'm not sure on the maths behind this, but I've seen recommendations that a slot port should not have a high ration of width to height - 9:1 was the maximum ratio I've seen suggested.
I think the problem with higher ratios is that a high ratio port has a much higher total surface area which decreases the efficiency of the port.

thanks! I didn't know that, I was going with a high ratio just for aesthetics (and ease of build, I guess)

 

[ToloV]

I have experience with W6-1139SIF's and W6-1139SI.

I built three enclosures for them, only one worked. Box needs to be big enough and it needs to be reflex tuned, closed does not create any bass.
This is all to my sportscar, I did them first with SIF, but went with neodymium later for weight reasons and for the little bit of extra gained in space inside the enclosure.

My Design:


If I made this for home application I would simply make the box bigger and tune it to 30Hz. But mine is with 2 elements, so yours with 1 and 25 liters seems easily big enough.

good design and nice finishing!

is there a difference in how they sound (1139 SIF vs 1139 SI)?
for me size&weight aren't a problem, so if they're otherwise similar I'll save the extra 25$


thanks again to all of you
Andrea