Spring project.....huge outdoor horn

[weikertball]

Welp, I'm about to do some experimenting during the spring/summer and I'll be building a rather large horn. If anyone remembers the 6090 horn that was posted on this website, that's what I'm trying to emulate. Maybe a huge straight horn tuned fairly low. It's going to be used for outdoor parties in my backyard and just for the fun of it. I'm thinking of a large exponential type horn. I have a few questions though. Is it necessary to have a compression chamber or is that only unique to certain horns? Is it okay to have a pair of paralell sides in a horn? Like say the top and bottom are paralell and the sides are the flared segments? What kind of subwoofers work well in these kinds of horns? I have about 1000 RMS @ 4 ohms available.

[AndrewT]

Hi W,
parallel sides are OK if the gap between is well below the quarter wavelength of the highest frequency you want to pass.

1000W into 4ohm is OK, but 500W+500W into twin 8ohm drivers is better, if you believe that most amps perform better into higher impedance loads. And then there is the performance of 8ohm drivers cf 4ohm drivers.

I have decided on no rear chamber for mine. I just wish I could make progress with it.
Think about all the back loaded horns (BLH) that use the front as a direct driver. They seem happy without the compression chamber, or would they be even better as front loaded horns and a separate driver for the upper registers? (but where would our full range threaders go?)

BTW,
30dbW and 105db/W ~=135db in the passband. I'm buying eardefenders.

[weikertball]

When you talk about the gap, do you mean between the mouth or the throat? My horn only needs to extend to about 20 hz. Should I make the mouth as big as possible? I know increasing the mouth size means a longer horn but how do I know when to stop increasing the mouth size :S

Since I don't know how to design folded horns, I'm going all out with a straight horn I'll probably make some top ends also sometime later. My plan is to call up our local DJ because he has all the tunes and power, then, he can use my horn subwoofer.

[AndrewT]

Is it okay to have a pair of parallel sides in a horn..........the top and bottom are parallel

the gap between the parallel sides.

The DJer won't need to move it. Just point it in the rough direction of his venue!

[AndrewT]

Hi,
for 20Hz the wavelength is 340/20=17m.
the circular mouth circumference should be >=17m giving a diameter of about 5.41m and the mouth area approx 23sqm.
For a horn resting on the ground you have floor loading so the area can be halved down to 11.5sqm.

This will result in a horn mouth about 2m high by 5.8m wide. I think that's quite big for most folk.

For a 20Hz cut off and starting with a throat of 750sqcm, the horn will be about 6m long. But this will become a bit uneven from about half an octave above cut off. Adjusting cut off down to 15Hz to keep a fairly smooth response down to 20Hz requires the exponential flare to be about 9m long.

[Cal Weldon]

A 20 Hz horn? You've got to be kidding. That will be huge as Andrew has pointed out.

Do you have a large piece of property weikertball? Are you planning to crack your neighbours foundation or is the just an easy way to de-feather the chickens?

Oh, and 1000 watts? You really are a madman.

[BassAwdyO]

I like the idea...

HornRESP may be a good friend to you

[chrispenycate]

I don't think anyone builds light cone, low resonance, low excursion big loudspeakers any more. Vitavox used to, but they weren't particularly high power. Basically, cone weights and excursions have increased with power ratings, for wider usage loudspeakers which don't require such huge cabinets.
As for ear plugs; I have actoally slept in a twin eighteen W-bin during the warm-up band's concert. Vibromassage, but considerably less painful than getting in front of a mid/high box (yes, I probably was spoiling the loading. It was only the warmup band, not a festival.

Folded horns are really no more difficult than straight, and actually use less wood (or whatever. For a fixed instalation I'd tend to build something like that out of concrete; saves on sand damping the panels in the high pressure/ low velocity end.) if there's no requirement that they end up a particular shape.

And the final energy will tend to go a long way; I hope not only your immediate neighbours, but even some distant ones share your taste in music.

[weikertball]

I know how long this will be. It should be well over 20 feet when I'm finished. When using Hornresp, I get a nasty dip at 30 hz when I plug in all the parameters. Since hornresp only lets the user go up to 99999 sq. cm. of mouth area, that's the only amount I can plug in and it results in a peak at around 25 hz and about a 8 decibel drop at 30. I'm assuming that means I need a larger mouth area?

Another thing, I don't feel like building a throat chamber so is that cool?

I considering to just limit to a 30 hz horn but I thought, "what the hell?" I should have pictures of the completed project but this is going to be a couple of months away. I do have some neighbors that I don't care for so I might aim the mouth towards them....

[weikertball]

Is there any dimension that I should make the flare? Should it be as square as possible or what?