Single Sheet Challenge (with bass) !!!

[Don Snyder]

If you gotta have lower and you're willing to give up a little loudness, have I got a sub for you!!! Made from a single sheet of 4'x8'x15mm (or 5/8") ply, it
should be a quick and easy build for those who must have 35Hz in singles. Bjorno calls it a T-QWP (Tapped Quarter Wave Pipe).

It may need a little dacron or foam, and maybe a reflector or two, to tame the resonances. I'd try to HP @ 30Hz 24dB/oct and X-O @ 120Hz 24dB/oct

[bjorno]

Hi Don,

That fold looks great and when properly stuffed will surely sound good.
Different amount of stuffing is needed if for PA compared to if to be used at Home.
I'll be back tomorrow with a suggestion on of how much(weight) is needed. (MjK-sim. and filter estimation using HOLMimpulse program).

b

[j.michael droke]

Hi there: The dimensions for the sides and back do not compute correctly to match the front and side views, using 15mm wood. Minoe clean-up neded. ...regards, Michael

[Brian Steele]

Originally Posted by Don Snyder

If you gotta have lower and you're willing to give up a little loudness, have I got a sub for you!!! Made from a single sheet of 4'x8'x15mm (or 5/8") ply, it
should be a quick and easy build for those who must have 35Hz in singles. Bjorno calls it a T-QWP (Tapped Quarter Wave Pipe).

It may need a little dacron or foam, and maybe a reflector or two, to tame the resonances. I'd try to HP @ 30Hz 24dB/oct and X-O @ 120Hz 24dB/oct

Interesting.

If the HornResp design can be adjusted a bit to replace that double dip with a single one, it might be possible to get rid of the dip entirely with a constriction about halfway along the pipe (like my "dogfood duct" mod suggestion for the THAM15). The effect would have to be modelled in Akabak though. My testing with my POC#2 suggests that apart from lowering Fb slightly, it has little impact otherwise.

Also, I've got another folding scheme that might work - see The Subwoofer DIY Page v1.1 - Projects : A "Proof of Concept" tapped pipe** - introduction. The "dogfood duct" mod works quite well on that too, but I haven't published the results.

[salzburgsoundsystem]

First off, this is very interesting, good work Don!

On his spud, Danley allows you to move the mouth opening as needed.
To make a stack of these, it would be useful for the mouth to be at the end / on the smallest side.

Is this a simple matter of shifting the opening by 90 degrees, or are there other considerations?

Regards, Ben

P.S. my fiance is not going to be pleased - Jbell Stadium horns, XoC SS15, and now your tapped horn are filling the garage!

[jbell]

Don:

Thanks for this, but I know I've modeled quarter wave pipes, and never came up with anything that really helped me out in the PA department.

Here is an overlay between the ss15 (63v) and the T-qwp(47.7v) The advantage (obviously) to the quarter wave pipe is being able to set your high pass lower. However armed with a 32hz@24db highpass on the ss15 to keep excursion in check, the difference in 35hz output is not dramatic.

thanks don.

[Don Snyder]

Bjorno: Thanks for the help, I'll need it!

Michael: There are many ways of making a box with a clean edge. The cut pattern I included is intended to leave the left and right side pieces protruding
on the top, rear and bottom. Next, it's router time. Using a bit with a ball- bearing pilot, trim the protruding edges. Then, switch to a 1/4" round-over bit
and you've got an edge that looks perfect.

Brian: You've had some interesting ideas in the past. Thanks for your help. This thing is still a work in progress, and any help you can give is welcome.

Jim: Your SS15 is still #1, but you can't fault me for trying. This, a pair of 8" speakers and a Crown XTI would make an interesting 6-string bass unit.

Salzburg: Moving the mouth 90 degrees shouldn't cause any problems.

This box ain't quite there ... but it is interesting!

[weltersys]

Originally Posted by Don Snyder

If you gotta have lower and you're willing to give up a little loudness, have I got a sub for you!!! Made from a single sheet of 4'x8'x15mm (or 5/8") ply, it
should be a quick and easy build for those who must have 35Hz in singles. Bjorno calls it a T-QWP (Tapped Quarter Wave Pipe).

It may need a little dacron or foam, and maybe a reflector or two, to tame the resonances. I'd try to HP @ 30Hz 24dB/oct and X-O @ 120Hz 24dB/oct

Don,

A ported box with a 3015LF can play louder and lower than the TQWP, and uses less wood to build.
The BR will have much smoother upper response, and rolls off a bit less steep below Fb.
The BR will time align at crossover without requiring delay.

Art Welter

[Brian Steele]

Originally Posted by jbell

Here is an overlay between the ss15 (63v) and the T-qwp(47.7v) The advantage (obviously) to the quarter wave pipe is being able to set your high pass lower.

It's also doing the same 35 Hz level with a lot less watts.

[weltersys]

Originally Posted by Don Snyder

Bjorno: Thanks for the help, I'll need it!

This, a pair of 8" speakers and a Crown XTI would make an interesting 6-string bass unit.

This box ain't quite there ... but it is interesting!

Don,

The low "B" on a bass is about 31 Hz.
Your TQWP is already on the uphill swing of a rapid excursion increase above 40 Hz (low E on a 4 string bass).
It will do OK for the upper harmonics of the low bass notes, but the speaker will flap if you push the fundamentals.

Art