[Newbie] Stuffing a Tapped Horn?

[stochastic]

Hey, I'm working in a space constrained build and am trying to fit a tapped horn into the space. Currently with folds I've managed to get the length up to 130" - should give me a 26Hz tuning but from what I've read so far the ideal F3 for my css sdx10 is 17Hz. Is it possible to use poly-fil to slow the sound down, effectively lowering the tuning of the horn? Is there a best place to stuff the horn - throat, mouth, middle, somewhere else? What effects will stuffing have on a tapped horn?

I also have some rigid fiberglass board I could add in anywhere if that would help any - but I doubt it.

 

[weltersys]

Is it possible to use poly-fil to slow the sound down, effectively lowering the tuning of the horn? Is there a best place to stuff the horn - throat, mouth, middle, somewhere else? What effects will stuffing have on a tapped horn?

I also have some rigid fiberglass board I could add in anywhere if that would help any - but I doubt it.

Polyfill or fiberglass can be used to dampen upper peaks, but won't lower the F3 by much at all, the change in the speed of sound is not much.
Reverse tapered TH (AKA TQWP) can have a much lower Fb than a "normal" expanding taper TH.
Stuffing reduces level, the proper place to put it so upper peaks and dips are reduced without loosing too much low frequency depends on the horn design.

Martin J. King has papers describing where and how much fill to put in a TQWP.

 

[Brian Steele]

Hey, I'm working in a space constrained build and am trying to fit a tapped horn into the space. Currently with folds I've managed to get the length up to 130" - should give me a 26Hz tuning but from what I've read so far the ideal F3 for my css sdx10 is 17Hz. Is it possible to use poly-fil to slow the sound down, effectively lowering the tuning of the horn? Is there a best place to stuff the horn - throat, mouth, middle, somewhere else? What effects will stuffing have on a tapped horn?

I also have some rigid fiberglass board I could add in anywhere if that would help any - but I doubt it.

See The Subwoofer DIY Page v1.1 - Projects : A "Proof of Concept" tapped pipe** - introduction for some measurements on a tapped pipe before and after stuffing. Stuffing half the pipe worked out well.

When I tried to stuff my POC tapped horn though, the results weren't as impressive. In fact, I lost a bit of gain. If you're going to try this, I suggest using as little stuffing as possible, and measure before and after to determine if there actually is a benefit.

 

[Oklahoma Wolf]

While the SDX10 does like to be around 17Hz or so in a TH, you likely wouldn't enjoy the result of using just one at that frequency. One simply doesn't move enough air by itself. Polyfill won't make the horn any longer either, I'm afraid.

It's not ideal at 130," but if you just have the one I'd leave it alone. I'd really be looking for a driver that likes being around 30Hz a little better though... the SDX10 doesn't model too well that high up.

 

[TheBaronGroog]

stochastic-gald you found us🙂

Do have a look at a TQWP, I'm about to start cuttting wood for one for my two KEF B139s. I looked at TH and ported etc but this gave the widest flatest repsonse at decent SPL

Can't get this all out of bold! Damn PCs

 

[epa]

you could add a chamber or make s2 bigger to lowers fb.

 

[bjorno]

See The Subwoofer DIY Page v1.1 - Projects : A "Proof of Concept" tapped pipe** - introduction for some measurements on a tapped pipe before and after stuffing. Stuffing half the pipe worked out well.

When I tried to stuff my POC tapped horn though, the results weren't as impressive. In fact, I lost a bit of gain. If you're going to try this, I suggest using as little stuffing as possible, and measure before and after to determine if there actually is a benefit.

Hi Brian,All

Here is a simulation showing your design of a T-QWP is very sensitive for to much stuffing:

b🙂