What is Horn Speaker and How are They Made?

 Principle of Horn Loudspeakers: How Impedance-Matching Drives Efficiency & Directivity

Horn speaker, horn-loaded speaker, horn loudspeaker design, how horn speakers are made, horn speaker working, horn speaker construction.

Impedance Matching - principle behind a Horn Speaker:

‘Impedance matching’ for maximum power transfer.

The throat ‘A’ impedance of the compression driver (speaker) is matched with the open air by the flaring portion ‘B’ (horn) for efficient sound (loudness) transfer that amplifies sound.

The horn concept is not new. It is our observation that when we shout, we bring our two hands close to our mouths to form a sort of horn structure.

Passive horn (speaking trumpet):

A megaphone:

 It is a practical example of a powered horn speaker for public announcement.

Interesting fact: 

Old gramophones generate sound through a pure mechanical process with the help of a big horn.

FAQ Set:

Q1: What is a horn speaker?

A horn speaker is a type of loudspeaker that uses a flared “horn” shape to improve coupling between the driver (like a compression driver) and air, thereby increasing efficiency and controlling sound dispersion.

Q2: What is the principle behind a horn speaker?

The key principle is acoustic impedance matching — the horn acts as an “acoustic transformer” that gradually transitions the high pressure / small area of the driver to the lower pressure / large area of open air, reducing reflections and improving energy transfer. 

Q3: How does directivity or coverage pattern factor into horn speaker design?

The flare shape, flare rate, and mouth geometry determine how narrowly or broadly the sound is projected (directivity). Horns can focus sound toward the listener and reduce off-axis spread.

Q4: What types of horn flare geometries are common?

Common types include exponential, conical, and tractrix flare profiles. Each has trade-offs in response to smoothness, directivity control, and size. 

Q5: Are there disadvantages or limits to horn speakers?

Yes. Horns can have uneven frequency response, especially near cutoff frequencies; they must be large for low frequencies; also, high frequencies may beam or “narrow” excessively off-axis. 

Q6: What is a compression driver in a horn system?

A compression driver is a small diaphragm driver whose output is “compressed” into a small throat area before entering the horn, improving coupling and achieving higher efficiency. 

Q7: How low in frequency can a horn speaker go?

It depends on the horn size and mouth area. To reproduce very low frequencies, the horn needs a large mouth (often impractically large), so horns are often used for mid and high frequencies. 

Q8: What is a folded horn design?

A folded horn “folds” the horn path inside an enclosure so that the physical size is reduced while preserving horn length, allowing better low-frequency response without an extremely large cabinet. 

Q9: Why are horn speakers more efficient than conventional direct-radiating speakers?

Because the horn better matches acoustic impedance, less energy is lost as heat or reflections, so more of the amplifier’s power is converted into sound, leading to a higher sound pressure level (SPL) for a given input. 

Q10: In what applications are horn speakers commonly used?

They’re used in public address systems, concert sound reinforcement, large venues, megaphones, and in high-performance audio where efficiency and controlled directivity are important. 

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