Fostex THX00 Features. Closedback design 50 mm dynamic transducer Magnesium alloy construction Mahogany or purpleheart earcups, brilliant gloss finish. Mark shares his experience with the 200 mm Fostex FE206En driver in the Fostex recommedned BackLoaded Horn Speaker Enclosure included with the FE206En datasheet. Ive always thought a good 12 was the best overall size for a woofer, although many 10 are fine too. The modern craze for undersized drivers is what doesnt. Welcome My intention with this page is to provide information and inspiration to people who build their own horn speakers and systems, primarily for domestic use. Horn loudspeaker Wikipedia. A midrange horn driver used in home speaker systems. A horn loudspeaker is a loudspeaker or loudspeaker element which uses an acoustic horn to increase the overall efficiency of the driving elements. A common form right consists of a compression driver which produces sound waves with a small metal diaphragm vibrated by an electromagnet, attached to a horn, a flaring duct to conduct the sound waves to the open air. Another type is a woofer driver mounted in a loudspeaker enclosure which is divided by internal partitions to form a zigzag flaring duct which functions as a horn this type is called a folded horn speaker. The horn serves to improve the coupling efficiency between the speaker driver and the air. 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. Fostex Loudspeaker Drivers' title='Fostex Loudspeaker Drivers' />The result is greater acoustic output power from a given driver. The narrow part of the horn next to the driver is called the throat and the large part farthest away from the driver is called the mouth. The angular coverage radiation pattern of the horn is determined by the shape and flare of the mouth. A major problem of horn speakers is that the radiation pattern varies with frequency high frequency sound tends to be emitted in narrow beams with poor off axis performance. Significant improvements have been made, beginning with the constant directivity horn invented in 1. Don Keele. The main advantage of horn loudspeakers is they are more efficient they can typically produce 1. B more sound power than a cone speaker from a given amplifier output. Therefore horns are widely used in public address systems, megaphones, and sound systems for large venues like theaters, auditoriums, and sports stadiums. Their disadvantage is that their frequency response is more uneven because of resonance peaks, and horns have a cutoff frequency below which their response drops off. To achieve adequate response at bass frequencies horn speakers must be very large and cumbersome, so they are more often used for midrange and high frequencies. Fostex Loudspeaker Drivers' title='Fostex Loudspeaker Drivers' />The first practical loudspeakers, introduced around the turn of the 2. Due to the development in recent decades of cone loudspeakers which have a flatter frequency response, and the availability of inexpensive amplifier power, the use of horn speakers in high fidelity audio systems over the last decades has declined. Operationedit. Various horn prototypes in the lab of Theo Wangemann, Thomas Edisons chief horn designer. From about 1. 88. Edison cylinders, and another horn was used to amplify the recordings during playback. An acoustic horn converts large pressure variations with a small displacement area into a low pressure variation with a large displacement area and vice versa. It does this through the gradual, often exponential increase of the cross sectional area of the horn. The small cross sectional area of the throat restricts the passage of air thus presenting a high acoustic impedance to the driver. This allows the driver to develop a high pressure for a given displacement. Therefore the sound waves at the throat are of high pressure and low displacement. A good loudspeaker is made of matching drivers in cabinet that is suitable for them, and crossover that take all this into consideration. The tapered shape of the horn allows the sound waves to gradually decompress and increase in displacement until they reach the mouth where they are of a low pressure but large displacement. A modern electrically driven horn loudspeaker works the same way, replacing the mechanically excited diaphragm with a dynamic or piezoelectric loudspeaker. Modern horn designs typically feature some form of conical, exponential or tractrix taper. Fostex Loudspeaker Drivers' title='Fostex Loudspeaker Drivers' />Roughly speaking, the slower the flare rate, the deeper and lower frequencies the horn will reproduce for a given length of horn. For example, a horn area growth rate of 3. Hz 1. 0 times area per foot provides midrange reproduction 1. Modern high output horns also make the throat area of the horn smaller than the diaphragm area. This is called the loading or compression ratio of the horn. The compression ratio is the diaphragm area divided by the throat area. Typically for bass and midrange frequency the compression ratio is from low compression 1. High frequency compression drivers sometimes have compression ratios as high as 1. The higher the compression the greater the horns ability to properly couple the diaphragm to the air at the horns mouth, increasing efficiency, until the compression ratio is so high that it actually begins to impede cone motion. At this point the maximum sound output power from the horn at a given distortion will be reduced. To demonstrate this at an extreme, place a cone woofer face down on a rigid surface. The compression ratio will be very high, however sound output from the back of the speaker will be quite low. Technology historyedit. Francis Barrauds original painting of Nipper looking into an Edison Bell cylinder phonograph. Download Film Video Semi. The physics and mathematics of horn operation were developed for many years, reaching considerable sophistication before WWII. The most well known early horn loudspeakers were those on mechanical phonographs, where the record moved a heavy metal needle that excited vibrations in a small metal diaphragm that acted as the driver for a horn. A famous example was the horn through which Nipper the RCA dog heard His Masters Voice. The horn improves the loading and thus gets a better coupling of energy from the diaphragm into the air, and the pressure variations therefore get smaller as the volume expands and the sound travels up the horn. IMG/2/fostex-PX-5HS-3.jpg' alt='Fostex Loudspeaker Drivers' title='Fostex Loudspeaker Drivers' />This kind of mechanical impedance matching was absolutely necessary in the days of pre electrical sound reproduction in order to achieve a usable sound level. Megaphoneedit. A collapsible cone horn with removable flared bell. This horn was patented in 1. The megaphone, a simple cone made of paper or other flexible material, is the oldest and simplest acoustic horn, used prior to loudspeakers as a passive acoustic amplifier for mechanical phonographs and for the human voice it is still used by cheerleaders and lifeguards. 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. The small megaphones used in phonographs and as loudhailers were not long enough to reproduce the low frequencies in music they had a high cutoff frequency which attenuated the bottom two octaves of the sound spectrum, giving the megaphone a characteristic tinny sound. Exponentialedit. A three way Klipsch loudspeaker from the late 1. The exponential horn has an acoustic loading property that allows the speaker driver to remain evenly balanced in output level over its frequency range. The benefits of the design were first published by C. R. Hanna and J. Slepian in 1. American Institute of Electrical Engineers AIEE. A major drawback is that the exponential horn allows for a narrowing of the radiation pattern as frequency increases, making for high frequency beaming on axis and dull sound off axis. Another concern is that a throat of small diameter is needed for high efficiency at high frequencies but a larger throat is best for low frequencies.