Someone help--explain horn speakers to me

[RFinco]

ok,

I am on a quest to understand--

I know how a woofer/tweeter and such work.

but--can someone explain to me how HORN speakers produce sound?....particularly without causeing me to do massive physics and electromagnetic research to understand the explaination?

I am trying to know your ways...it is not easy.

Thanks in advance for all explainations and wittisisms that may ensue from this question...

[JohnA]

The crude answer:

The cone in a compression driver is little different from one in an inverted dome tweeter. The Horn is attached in front and it "concentrates" and controls the sound to "focus" it into a narrow angle that increases efficiency. In addition, the horn loads the cone, aka diaphragm, so that it pushes on a long column of trapped air also improving efficiency.

The 2 effects, primarily the 2nd are so effective that extreme efficiencies of 110 dB/w/m or more are possible, compared to 93-ish dB/w/m for a cone mid or tweeter.

There are complexities of horn operation and design that are still the subject of PhD theses. Obviously, I skipped over any of that.

[Ray Garrison]

RFinko,

It's not like horn loudspeakers don't have woofers and tweeters. They do. They just have a widget attached to the woofer or tweeter that makes it a lot more efficient at converting power into sound.

What would happen if you took a megaphone (one of those cone shaped things that cheerleaders shout into) and glued it to the front of your speaker over the top of the tweeter? Tweeter would sound a lot louder, right? That's how a horn speaker works.

[D-MAN]

The shortest possible explanation that I can come up with:

You know when you are yelling and cup your hands around your mouth to make it "louder and/or go farther"?

Well, same principle.

DM

[Lone Palm]

Klipsch horn speakers sound like music and not speakers

[Colin]

Lets see if I got this right:

there is a cone and a driver on conventional speakers, there is a horn and a driver on horn speakers; no soft, movable cone.

There are also bass woofers, with cones and drivers, loaded into a long folded enclosure called a horn.

Place a horn and driver atop a bass bin holding a woofer in a folded enclosure and you have a "fully loaded horn speaker."

[WMcD]

Well that is mostly it.

All direct drivers have a motor structure (voice coil and magnet) The voice coil is attached to a diaphragm of some size. The diaphragm moves and creates a pressure increase and decrease in the air in front of it, in time to the music.

But there is a problem. The diaphragm is just trying to push air around in free space. The air being even slightly pressurized, runs away.

What to do.

One thing we could do is put the diaphragm up against a pipe of about the same size as the diaphragm. Now the air is trapped by the sides of the pipe and there is a lot more compression. (Driver-diaphragm combinations made for this application are called "compression drivers".) And the high pressure runs down the pipe.

Then the pressure gets to the end of the pipe (same diameter) and comes out of hole of the same size and has basically the same original problem; plus a lot more. One problem is that the end of the pipe can only influence the air over its small diameter; just like the diaphragm.

What to do.

One thing to do is to allow the pipe to expand in some mathematical function. One classic way is to let the cross sectional area double every x distance down the expanding pipe. It is like a bank account where, because of interest, the area doubles every x in time. Or bacteria doubling every day because of reproduction. Or, going the other way, half life of radio active material.

The equation which describes this sort of doubling or halving is "an exponential equation." The horns which do this in area are called "exponential horns."

Some of the magic is that at the small end of the horn (throat) the pressure is high and the area is small. At the big end (mouth), the pressure is small but it is spread over a large area.

Why do we care, you ask.

The ability to pump a lot of air with small diaphragm movement reduces distortion and increases efficency.

The term "horn" (Dr. Evil makes me use these quotes.) Obviously originates from the use of an animal horn as a musical instrument. The cross sectional area inside increases with them too. Our French friends call them pavilions. The French are indeed accurate.

Of course cupped hands do some of this too. It is interesting to consider that the cave men using cupped hands invented the acoustic horn. Arguably our ears and mouth-throat use some of the same principles.

As a last comment, I'll point out that cardboard megaphones work for the same reasons.

There is a lot more to it. Once you have a horn, it can be made directional to squirt out sound in a particular direction.

Gil

[IB Slammin]

As explained to me many years ago...... Horn loaded and placed in corners......

Have someone speak to you in a normal voice, and then cup their hands over their mouth........(horn)

Have someone stand with their back in a corner, speak in a normal voice and walk away from the corner.....(corner placement)

Terry

[michael hurd]

To quote PWK " you can slosh a piston up and down in a lake all day long, and all you do is make waves. Put a cylinder around that piston, and then you can do some work " ( pump water ).

Therefore, a horn allows a small diaphragm to do a lot of work, by trapping a volume of air in a column in front of it. The movement of the diaphragm is small, and the diaphragm operates more in a linear fashion, resulting in lower distortion.