T-TQWT for a theatre stage

[tb46]

Hi Scruffyht,

Can't see why not. Main difference would be the location of the terminus (vent).

Regards,

[bjorno]

[QUOTE=J. L.;2985834..If I ever feel ambitious, I'll model my 18" Avalance drivers in a T-TQWT enclosure and see what they can do. I'll bet the pair of them will be more than sufficient for most movies in a home-theater...[/QUOTE]

Hi Joe,

Thank you for posting the links..Nice readings..I've made a HR template using the Ascendant Avalanche18 inch driver and more:

b

[J. L.]

Originally Posted by bjorno

Hi Joe,

Thank you for posting the links..Nice readings..I've made a HR template using the Ascendant Avalanche18 inch driver and more:

b

Well, thank you...If I'm interpreting the graphs correctly, T-TQWT would have a flatter response as you go below 30Hz. My sealed subs need a bit of equalization to keep a reasonably flat response. (I use a BFD Equalizer)
As you might guess, most of the time my subs are loafing.

I am impressed though with the T-TQWT design, even though my aging ears don't hear much at 12Hz, even though it seems the drivers can easily get that low in the simulation. (and you only simulated it with one driver) I can tell you for sure you can feel it.

I can share with you that I had to weatherstrip the closet doors in my theater, as they vibrated in their door frames at about 17Hz so much they were a distraction.

As I said earlier, these designs are more than sufficient for our home theaters. (most people do not know what they are missing) thanks again.
I'll be curious to see what can be done with the 10" height requirement the original post requires.

Joe L.

[tb46]

Hi bjorno,

Your Hornresp simulations in Post #22 have Vtc and Atc values. Is this intentional?

Regards,

[bjorno]

Originally Posted by tb46

Hi bjorno,

Your Hornresp simulations in Post #22 have Vtc and Atc values. Is this intentional?

Regards,

Hi Oliver,

Yes,I calculated with a double thickness of the internal divider, i.e. 2 x 18 mm Ply for the sturdiness of the enclosure baffle and to gain some driver clearance too.

b

[Scruffyht]

Originally Posted by tb46

Hi Scruffyht,

Can't see why not. Main difference would be the location of the terminus (vent).

Regards,

Hi Oliver ... can we model it with the vent in the back corner as you suggested?

Thanks

Steve

[Scruffyht]

Any chance you guys can help with the dimensions of the box ... would be appreciated? ... dual or single tang band drivers like what permo used?

Thanks

[tb46]

Hi Scruffyht,

I've been trying to find the time to look at this with Hornresp and AkAbak.

When I use Hornresp I can arrive at a smoother response with the port slightly out of the corner (venting to the top in the middle between the two drivers), and a slightly longer tube path. The result looks reasonable. Trying to enter this into AkAbak I have not had any success duplicating the Hornresp result. I get the SPL boost you would expect from a corner, but do not get the smooth extended response I get in Hornresp (which results from shortening the L34 distance, i.e.: moving the port closer to the middle of the drivers). The shape of the SPL curve in AkAbak looks a lot like the 2pi response for the same enclosure in AkAbak while the response in Hornresp is a lot "cleaner" in 0.5pi than in 2pi.

Anyway, I'll attach a Hornresp input screen, and the 2pi/0.5pi SPL comparison. I'm not sure when I'll find the time to improve on the modelling in AkAbak; but from this simulation, and hopefully bjorno's input, we should be able to arrive at a folding/stuffing that should work for you. The dimensions always change a little when you transfer from paper to wood. I don't mind doing the drawing, but I want to wait to see what bjorno has to say to this simulation.

Bye the way, do you have a supplier for this driver?

Regards,

[Scruffyht]

Hi Oliver ... thanks for all your efforts ... yes ... we do have a Canadian distributor

[bjorno]

Originally Posted by tb46

...Trying to enter this into AkAbak I have not had any success duplicating the Hornresp result. I get the SPL boost you would expect from a corner, but do not get the smooth extended response I get in Hornresp (which results from shortening the L34 distance, i.e.: moving the port closer to the middle of the drivers). The shape of the SPL curve in AkAbak looks a lot like the 2pi response for the same enclosure in AkAbak while the response in Hornresp is a lot "cleaner" in 0.5pi than in 2pi...

Hi Oliver,

The cure is to remove a foot from the closed end or stuff the first foot with very dense damping material like dense Rockwool 1-2lb/ft^3 =16-24kg/m^3.

This could be simulated in AKAbak too by changing the waveguide sections into Ducts and invoke the 'damping material' switches.

b