What happens when a TL is open at both ends

[heinz1964]

Hi

What happens if you make a TL designed like this.



How will it perform?

Like 2 TL or like one?

Sorry for the poor sketch, I draw the sketch with a speedmarker and just scanned it.

Thanks

uwe

[speaker dave]

Sketch is fine. Isn't that just the same as a a single opening TL of same length center to end (half of end to end) but double width for two woofers?

David

[badman]

Originally Posted by speaker dave

Sketch is fine. Isn't that just the same as a a single opening TL of same length center to end (half of end to end) but double width for two woofers?

David

So long as the woofers were relatively close together (it'd be hard to do it where they WEREN'T), I'd expect such a beastie to act very much as you described.

[heinz1964]

Hi

Yes but what if the two woofers are not close together, but are unsymetrically to the middle of the enclosure?

Would that make it a double TL´s?

Would each woofer load both lines but with different length for both of them.

Eg. 1. woofer two different TL´s and 2. woofer two different TL´s

Would that then even out some of the dips and peaks of a TL or make it worse?

Best regards

Uwe

[planet10]

The line will be a half wavelength resonantor.

dave

[speaker dave]

As long as there is end to end symmetry you can cut the length in half and "fold it over". If both woofers move well off center or seperate in an unsymmetric way then it becomes a more complex system. Its possible that the unsymmetry will spread the resonance frequencies some.

Search for the Bose "Canon" subwoofer to see a system made with a woofer off center on a double open ended pipe.

David S.

[bacon665]

this actually just peaked my interest for three reasons
1] the scketch resembles a spawn horn
2] going back to what dave said does this mean the lines subtract and you would need two double length lines to get full wave resonance?
3] what if the woofers were on opposite ends with the end of the lines being next to each other could this increase the base output from the line if it was tuned for it? (and if im not mistaken unless you did 1/8 wave lines i know this would be a ridiculously big box)

[planet10]

A line will be 1/4 wave (open at one end, closed at the other) or 1/2 wave (open at both ends, or closed at both ends).

The case of a line open at both ends with driver mounted half-wave gives equivalent resonant behavior as a line half as long, twice as wide, closed at one end, open at the other, driver end loaded at the closed end.

dave

[speaker dave]

I can't really speak to every posibility out there, but the way it was explained to me was this: In a system with perfect symmetry, imagine a barrier between the two halves made of cling film. Any unopposed waveform will go right through it. But since it is a divider between two perfectly symmetrical systems any wavefront impinging on one side will be perfectly opposed by the same waveform hitting the opposite side. The clingfilm will not move and might as well be a perfectly rigid barrier.

This applies to the small gap in your center barrier. It can be closed with no change. That gives you two conventional TLs with woofers at opposite ends and ports in the middle.

David S.