Tapped Horn For Car

[mwmkravchenko]

I've been messing with this for a while. I got my inspiration from the smallest tapped horn thread. It seems that if you design a horn with a falling response of about 12 db/octave starting at 10 hz you will end up with a pretty flat response once the puppy is in the car.

I worked up an example with some CSS SDX7 drivers. They are quite a bit like to 6.5 inch Tang Band stuff only made a little better. The specs are measured and the simulations are linked below.

Mark

http://i407.photobucket.com/albums/p...CarSubMa-1.png
http://i407.photobucket.com/albums/p...arSubMaxim.png
http://i407.photobucket.com/albums/p...eTappedhor.png

P.S. If anyone knows how to properly embed pictures into posts please let me know how.

[littlemike]

I've got a few ideas I'm messing around with too. Modeling non-flat responses is trickier than it looks. I probably should measure the cabin gain curve of my car to get some sort of idea of what response curve to target.

As far as posting pictures - all I do is attach the file by selecting it in the attach file dialog below the edit window.

Other people use web-hosted images, I think that is done with the IMG button, though I have never posted image files that way.

[littlemike]

Response curve for the previous model. It is only a 40L box, it has the falling response I was after, but I do not think I'll waste time building it. The impulse response looks terrible (rings like a bell). Back to the drawing board.....

[mwmkravchenko]

I think I finally got it!

Mark

[mwmkravchenko]

This particular box is about 95 litres. Or around 3 1/2 cubic feet. As dimensions take something like this. I.D. 8"x 24"x 30" Small enough to fit in the back of my Toyota Matrix. The size I chose is to go all the way down to the basement for listening to Organ music and the like. There are obviously much smaller combinations.

Normal music cuts out around 40hz so I'll post one for that shortly. I'm going to build the one I simmed first. It will replace the tuba 18 that is currently hogging all my space in the back. The tuba 18 is just great if you are listening to anything above 50hz. I rapidly dies if you ask it to produce anything below that. It only gives a hint of 30hz which really sucks.

This tapped horn will be what the doctor ordered. More or less flat from 100hz down to about 18hz.

Mark


Impulse response. Not to bad for a subwoofer.




With a little bit of power we get a lot of noise.

[mwmkravchenko]

This is better for most music

Here is the Schematic diagram:



Here is the SPL for 100 watts. Almost scary.



Mark

[mwmkravchenko]

A quick check on the realities. This CSS SDX7 driver is rather amazing. You get more efficiency and X-max than anything I know of within the price range. Plus the second design is almost a qualifier for the smallest tapped horn thread. Less than a cubic foot. actually with a quick calculation of Inside Dimensions of 20.3 cm x 30.48cm x 32 cm. Or 8"x 12" x 13" that is pretty small. And the SPL's available from a single nominal 6.5" driver are Pretty Darn Good!

Mark

[jason_watkins]

Very interesting idea.

One could also use an ELF subwoofer design (that is, a sealed box driven below Fs) to also get the same -12dB per octave response. It'd be interesting to compare some of these designs, but I'd hazard a guess that the tapped horn will come out as the best value, but multiple sdx7 ELF subs might be best on a SPL per box volume basis for 40hz and up.

[Henkjan]

that 35Hz, the 19 liters, is that with 1 or 2 drivers?
could you put some plans up, this size is what I was looking for for in my car

btw: a TH with an SDX15 tuned at 50Hz could be a winner for an SPL contest

[mwmkravchenko]

Hello Henkjan

The design is for one driver. The total size with the driver volume displacement and the box volume displacement would be over 21 maybe 22 liters.

Two drivers will give a boost of about 3 db mechanical efficiency and 3db in potential electrical efficiency. Depending on how the drivers are wired. Series or parallel would make the difference. And according to real world results expect 3 to 4 db over a broad bandwidth.

I could simulate two drivers but the box will increase in size. Do you have a maximum size or is this just fooling around a bit?

Mark