Why is Klipsch so Horny?
Have you ever wondered why Klipsch is so horny?
From Wikipedia, the free encyclopedia…
“Horny is an adjective that can describe any one of the following conditions:
• An animal that possesses a horn
• A slang term for sexual arousal and/or desiring sexual gratification
• Having a rough, knobbly surface — e.g., a horny skin, found in some lizards“
Hmm… Well some of that may be true but it didn’t really help describe Klipsch as a whole.
Looking under the term acoustic horn…
“A horn is a tapered sound guide designed to provide an acoustic impedance match between a sound source and free air. This has the effect of maximizing the efficiency with which sound waves from the particular source are transferred to the air.”
Getting closer….Looking at Horn Loudspeaker…
“Acoustic horns convert large pressure variations with a small displacement into a low pressure variation with a large displacement 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 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. 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… “
Now we are getting some where. At least the term tractrix is used.
“…Horn technology history
Photograph of the original painting of Nipper looking into an Edison Bell cylinder phonograph with a horn loudspeaker.
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 Master's 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. This kind of mechanical amplification was absolutely necessary in the days of pre-electrical sound reproduction in order to achieve a usable sound level.[3]”
Ironically there is no mention of Klipsch in this entire article whatsoever. That will have to be remedied later. Klipsch didn’t invent the horned loudspeaker, but it has stuck true to its principles. What we can learn from this is that PWK was correct in pursuing high efficiency designs for his 10 watt amplifier. The laws of physics haven’t changed.
So lets understand a little more about why Klipsch is so horny and why you should be horny too.
Acoustics 101
To start off, we need to define general concepts about acoustics, starting with what an acoustic wave or waveform is.
Sounds are waves of pressure variations moving through the air. These waves can be compared to waves moving in the ocean, although they move much more quickly and in three dimensions, unlike water waves, which are confined to a two-dimensional surface. When we hear sounds, what we are actually experiencing are minute vibrations of air. As waves of these small air currents pass through our inner ears, they stimulate the nerves in tiny hair-like projections. Our brain then translates this stimulation into the audible sound that we hear.
Since a sound wave consists of a repeating pattern of high pressure and low pressure regions moving through a medium, it is sometimes referred to as a pressure wave. If a detector, whether it is the human ear or a man-made instrument, is used to detect a sound wave, it would detect fluctuations in pressure as the sound wave impinges upon the detecting device. At one instant in time, the detector would detect a high pressure; this would correspond to the arrival of a compression at the detector site. At the next instant in time, the detector might detect normal pressure. And then finally a low pressure would be detected, corresponding to the arrival of a rarefaction at the detector site. Since the fluctuations in pressure as detected by the detector occur at periodic and regular time intervals, a plot of pressure vs. time would appear as a sine curve. The crests of the sine curve correspond to compressions; the troughs correspond to rarefactions; and the "zero point" corresponds to the pressure which the air would have if there were no disturbance moving through it. The diagram on the next page depicts the correspondence between the longitudinal nature of a sound wave and the pressure-time fluctuations which it creates.
A simple two-dimensional plot will partially describe the entire three-dimensional pattern. Sound travels in a spherical 3D pattern, but this is difficult to document on a piece of paper. The waves depicted in this line of the plane wave tube are just that. (Plane as in one geometric plane) Imagine if you will that these are travelling to all areas of space as the sound moves away from the vibrating cone that originally created this wave. This is where directivity is of concern for an design engineer at Klipsch.
Polar Directivity Introduction
Wavelength of Sound as a Function of Sound Speed and Frequency...
Now that we know a little more about sound waves lets discuss the why Klipsch uses horns to project sound wave patterns.
When a sound wave is generated, it travels away from its source in a beam, in similar fashion to a beam of light emanating from a flashlight. The angle of the wave propagation is determined by the ratio of its wavelength to the size of the opening through which the beam is projected.
The acoustic radiation pattern is a function of the frequency of operation and the size, shape and acoustic phase characteristics of the vibrating surface of the diaphragm.
Transducer Radiation Patterns
The beam width is usually defined as the measurement of the total angle where the sound pressure level of the main beam has been reduced by 6 dB on both sides of the on-axis peak.
When describing the beam patterns of transducers, two-dimensional plots are most commonly used. They show the relative sensitivity of the transducer vs. angle in a single plane cut through the three-dimensional beam pattern. For a symmetrical conical pattern, such as that shown below.
At low frequencies (when ka is small) a loudspeaker radiates sound equally well in all directions (a boxed loudspeaker will even radiate low frequency sound into the region behind the box). As shown in the animation below, sound waves radiating from the speaker spread out evenly in all directions. This behavior is primarily why the location of a subwoofer doesn't really matter - you can place it pretty much anywhere and it will still fill the room with sound.
As the frequency gets higher, but assuming the speaker diameter does not change, the value of ka increases and the speaker becomes directional. That is, the sound energy produced by the speaker becomes channeled into a preferred direction and very little energy is radiated at other directions. In the animation below the radiated sound is pretty much contained within a cone of 55 degrees from the center axis.
As the frequency becomes even higher (and ka becomes much bigger than 1) the sound field radiated by the speaker becomes even narrower and side lobes appear. Now the main lobe of radiated sound is limited to about 20 degrees on either side of the central axis, and the pressure amplitude falls off rapidly as you move away from the central axis. Notice that the side lobes are much lower in amplitude than the main lobe. Also note that the sound waves in the side lobes have the opposite phase as the sound wave in the main lobe.If you were using the same speaker (a large woofer) to produce both low and high frequencies, you would definitely notice a severe drop-off in the loudness of the higher frequencies as you step away from in front of the speaker. Fortunately, well designed loudspeaker systems from Klipsch don't attempt to send all frequencies through the same speaker but instead use a waveguide or horn for high frequencies.
3D Directivity Maps are Another way to view directivity in a 2D or 3D plot Amplitude (color), Angle vs. frequency.
So the next time you are thinking about loudspeakers, and LOUD is one of those terms, think about Klipsch. We are still sticking to horny!
