Tapped Horn For Car

[Cordraconis]

Originally posted by Volenti

Well mostly it just adds to it just like it would to a sealed/ported enclosure ... I have built many 1/4wave enclosures, and they tend to drop in frequency when loaded in a vehicle ... impedance peak 10hz lower inside the car then outside (measured).

Patrick Bateman's in- and outdoor measurements seem to show this, aldough I am suprised about this. I always tought the cabin gain came from pressurizing at those low freq and it seems to me a tapped horn has a built-in "short cirquit" between the front and back of the driver, below cutoff. So I'd expected this to work only for closed box variants. OTOH, it also works for a bassreflex below cutoff ... why didn't i see this earlier?

The drop in tuning freq in a car is interresting for my BLH. So i might get till 25-ish instead of 30hz and if the backpressure on the mouth is higher than Hornresp models, i even might get less ripples than I catered for!
Do you have some more information or websites about your 1/4WL enclosures?

Originally posted by mwmkravchenko

I drive the tuba sub with my pioneer head unit with the rear channels bridged and get 22 real watts. Those 22 real watts give peaks of 122db.
...I will measure this thing up carefully.

Exactly what I am doing now with my headunit (3100)! May i ask at what volume setting you get this 22 watts? (Assuming this is the unclipped peak.) I never turned it up past 40 and last time I checked I got 115dB peak without sub, so only highs and mids.

It is a pity this thread is about tapped horns and I want to go backloaded horn style. I am waiting for my uncle - who is a capenter - to make some time to cut my panels/angles, but in the mean while I think here is some good info to gather here.

[Volenti]

Originally posted by Cordraconis



Do you have some more information or websites about your 1/4WL enclosures?

There's nothing special about my enclosures, they are just basic straight or tapered transmission lines, it's their response in the car that lets you get away with lines that are far shorter than you would think could work, some have been less than a meter long! (though heavily stuffed)

I have a largish tapped horn using a 12'' with a very strong motor planned for construction soon, I will do some in and out of car tests when it's constructed.

[mwmkravchenko]

Cordraconis wrote:

Exactly what I am doing now with my headunit (3100)! May i ask at what volume setting you get this 22 watts? (Assuming this is the unclipped peak.) I never turned it up past 40 and last time I checked I got 115dB peak without sub, so only highs and mids.

Keep this in mind that I listen to exclusively classical music from Copland and Respighi to Bach and some renaisance masters.

I set the max volume on around 54 to 56 when listening to a large pipe organ or large orchestral recording. There are enormous peaks in classical music that you will never experience with pop stuff. If I try that volume level with a radio station I will buy stock in hearing aid companies. WHAT???

Tonight is the glue up if I get enough work accomplished today. A cabinet makers work is never done.

Mark

[mwmkravchenko]

Ok the dirty deed is done. Long day took plenty of pics and now I'm going to relax. Will try to get the pics and plans up soon.

Mark

[mwmkravchenko]

It all begins with some tape and glue

http://i407.photobucket.com/albums/p...o/IMAG0159.jpg

Along the line exterior

http://i407.photobucket.com/albums/p...o/IMAG0154.jpg

Stick glue here.

http://i407.photobucket.com/albums/p...o/IMAG0155.jpg

Fold up and lay down. It's kind of like origami.

http://i407.photobucket.com/albums/p...o/IMAG0165.jpg

Some weighty thoughts.

http://i407.photobucket.com/albums/p...o/IMAG0170.jpg

Well there are more pics but this is enough to show how I glue these things up. I guess they are not to bad considering they are taken with a cell phone.

I'll work on the plan a bit today and scan and post that to. Still have to apply the other flat side. I think I will do this with screws and foam stripping to properly seal the box. There's no way to get the inner driver out easliy as this is a very small enclosure.

But first there has been some wiring and mounting of the drivers. Have to test out some padding and no padding as well. The odessey begins.

Mark

[MartinQ]

Nice progression in the photos and I like the glue & tape method. I really like the railway anvil ... classic. Awaiting your results and/or measurements.

[mwmkravchenko]

Yep this little thing weighs about 80lbs or about 37 kg. It's as close to heavy metal as I get

Beats leaning on it overnight.

I use PL Premium contruction adhesive to bond the large flats onto the horn outline. The trick is that it expands as it cures so if you don't nail it or hold it down the glue expands and the joint is very weak. If you keep it under some pressure it works like a charm. The plus is that the resulting horn structure is really airtight. Very important in horn design as well as closed or vented box designs.

Mark

[MartinQ]

I've used PL Premium on a number of projects and I like the way it works. For smaller gaps you can use Gorilla Glue which is also polyurethane glue with a viscosity very close to honey or syrup. It'll creep and wick into really small areas and then foam-up as it cures like the PL. Very tough stuff if you're not in a hurry.

I also try to make sure the mating surfaces are either freshly cut and/or sanded and wiped down with a damp sponge/rag. This makes sure they are clean and with open pores to accept the glue. A little added moisture speeds along the curing as well.

I'd prefer to use screws at least until the curing is complete if the aesthetic is acceptable. You can then pull them out and do filling / milling of the edges.

Still, I've had many a time where a good chunk of CP Rail would have been mighty handy!

[mwmkravchenko]

If you don't have the weight of a rail you can buy bags of sand at building suppliers for next to nothing. It works really well to. THe other thing is packing tape. If you dust the wood off you can apply quite a bit of pressure to things by tapping the top of the piece, pulling it over the edge , slightly stretch it and tape it down under tension. I do a lot of solid wood edge banding this way.

As for polyurethane glues they are great but they like to stick to you for a week or so. My advice is to wear gloves when working with them. When I do exterior work I use polyurethane liquid. I have tried a few but not gorilla glue.









Some of the reasons why it takes so long to make loudspeakers. I have to make a living doing other stuff!

Mark

[MartinQ]

All great tips, but hauling sandbags around is such a pain. =/ Anyway that is some masterful woodworking. Looking good!

Now, hurry up and git-er-dun so we can see some results.