Horn loudspeaker

The horn can be thought of as an "acoustic transformer" that provides impedance matching between the relatively dense diaphragm material and the less-dense air.

The main advantage of horn loudspeakers is they are more efficient; they can typically produce approximately 10 times[3]: p.30  (10 dB)[4][5][6] more sound power than a cone speaker from a given amplifier output.

The small cross-sectional area of the throat restricts the passage of air thus presenting a high acoustic impedance to the driver.

Because the conic section shape describes a portion of a perfect sphere of radiated sound, cones have no phase or amplitude distortion of the wavefront.

[2] The exponential horn has an acoustic loading property that allows the speaker driver to remain evenly balanced in output level over its frequency range.

[17] Radial horns have two surfaces based on an exponential flare rate, and two straight walls that determine the output pattern.

The diffraction horn has been popular in monitor designs and for near-field public address applications which benefit from its wide horizontal dispersion pattern.

[16] A very small version of the diffraction horn was designed in 1991 into the JBL model 2405H Ultra-High Frequency Transducer, yielding a 90° x 35° output pattern at 20 kHz.

[21] The size of the tractrix horn is generated by specifying the desired low frequency "cutoff" or limit which will determine the mouth diameter.

[20] Two incremental improvements over the exponential horn include slightly better support for low frequency extension and a somewhat broader high-frequency coverage pattern.

[16] Don Keele specified in one version of his design a wider horizontal flare for pattern control appropriate to public address purposes.

Keele's paper[24] set forth the relationships between mouth size, frequency and coverage angle, providing a basis for many future developments of horn design.

[25] Unlike previous designs, the apparent apex,[28] which is the focal point of pattern dispersion, is not the same for every frequency, making for an ellipsoidal wavefront rather than spherical.

[2] Ramsa, the professional audio division of Panasonic Corporation, introduced a twin Bessel constant directivity horn shortly after the Mantaray appeared.

The design was very similar to the Mantaray and the Bi-Radial but it used a dual series Bessel expansion formula to determine the flare rate of the secondary horn section.

Rane allowed for greater front panel control of two bandpasses ("hi-mid" and "high") using CD horn equalization including sweepable frequency range on their AC 24 crossover.

Firstly published in December 2019 in a Voice Coil article[38] and then at the 148th AES Convention[39] in June 2020, Dario Cinanni presented a new horns family.

"Tom" Danley of Sound Physics Labs began working on a three-way multiple-entry horn, bringing the SPL-td1 to market in 2000.

[48] In 1999, Charlie Hughes of Peavey Electronics filed for a patent on a hybrid horn he called Quadratic-Throat Waveguide.

Being without a diffraction slot, the QT waveguide was free from problems with apparent apex, making it arrayable as needed for public address purposes.

[2] Oblate spheroid waveguide (OSWG) horn designs improve directivity pattern control above 1 kHz, provide a lower frequency of directivity to better match the mid-range driver, and, as claimed by inventor Dr. Earl Geddes, mitigate higher order modes, a form of phase and amplitude distortion.

EAW horn-loaded loudspeakers that have been processed with this proprietary system show reduced compression driver diaphragm/phase plug time-smear distortion while retaining high output power and controlled dispersion.

Commercial cinema theaters often use horn-loaded loudspeakers for pattern control and increased sensitivity needed to fill a large room.

After WWII, some early hi-fi fans went so far as to build low frequency horns whose mouths took up much of a wall of the listening room.

Audiophiles using low power amplifiers, sometimes in the 5 to 25 watt range, may find the high efficiency of horn loudspeakers an especially attractive feature.

Conversely, the high sensitivity can also make any background noise present at the amplifier outputs noticeably worse.

The high sensitivity of horn loudspeakers aids in achieving movie theater sound levels at the listening position with typical ~100 watts-per-channel receiver/amplifiers used in home cinema.