Horns do it better

 
    Horns have been used for sound amplification for thousands of years.  Horns are a effective mechanical means of coupling the the sound reproducer to the air. They operate by converting high pressure, low volume sound waves into low pressure, high volume waves.
    Even though horns have been used for so long, how sound actually propagates from them is still not fully understood. The mouth and throat diameters, the overall length, and the amount of flare all have a effect on the qualities of the amplified sound.
   Some of the best sounding speakers ever made have been horn loaded, but so have some of the worst. Usually the later is caused by compromises made to the design due to aesthetics or cost control. Designing a horn that can play all the full spectrum of human hearing is the holy grail, but basic horns are limited to only playing about 3 octaves in range. As the human ear can hear over ten octaves, a speaker should require at least three separate horns to cover the range. A way to "cheat" is to use different flare profiles, or a combination of flares. Types of flares include conical (megaphone), parabolic, hyperbolic, exponential, bi-radial, and tractrix. While some of these designs perform much better than others at overall sound amplification, how the sound is dispersed into the listening area is also important.

  So why am I interested in horns when most of the speakers made today are not horn loaded? It comes down to distortion. A direct radiating speaker makes up for the lack of horn amplification by increasing cone excursion or piston area. The problem with this method is it requires more power to produce the same SPL levels as a horn and causes higher distortion. Every loudspeaker's cone has at least some amount of mass and the farther and faster it has to move, the harder it is to start and stop it precisely.

What was old is new again

   The first loudspeakers were designed to be highly efficient. A speakers efficiency is described as the level of acoustic output delivered from a given amount of electrical input.. This was due to vacuum tube amplifier of the time only being able to provide a few watts of power. Loudspeakers had to be designed to play loud enough for comfortable listening from the low power available. The trade-off of maximizing efficiency is the speaker will require very large enclosures in order to play the lowest octaves. Explained by Hoffmans Iron Law, it states that out of the three variables of small cabinet size, low bass response and high efficiency, design for two and the other will suffer. This is why many of the speakers from the tube amplifier age of audio (1900's through 1960's) were usually large or didn't go very low in bass reproduction.

  The solid state transistor was introduced in the 60's and quickly replaced the vacuum tube in most home electronics. They were cheaper, more efficient, and capable of much higher levels of power output. This opened the door to speaker designs that were smaller and was friendlier to home decor. This trend continued and still is popular now, as almost all speakers now are very compact.

So why would I want speakers based on technology from a century ago? In one word, it would be dynamics. This is the ability to play all levels, from the softest whisper to the loudest snap of the drums without compression. Modern low efficiency speakers can be dynamic, but require huge amounts of reserve power to faithfully produce the peaks. To help explain this, I will use a average modern speaker rated at 90db @ (1m/1w) or 90 decibel (db) sound pressure level (SPL) at 1 meter using 1 watt (w) of power. To increase the SPL level 3db to 93, it would require twice the power (2w). A increase another 3db to 96db would require another doubling of the power used (4w). This is exponential. The amount of power to needed to play music on these speakers to lifelike levels can reach into the 1000's of watts. There are amplifiers available today that can provide huge power but sacrifices to sound quality are made.

In search of the lost chord....

   For most of my adult life, I have been fascinated with the art of music reproduction. Concepts of music like detail, dynamics, harmonics, frequency range and tone keep me continually searching for the next level closer to perfection.

   Music has been essential to human life throughout history. It can convey emotions words can not describe and transport the listener to the limits of their imagination.

   Until the invention of the gramophone in the early 20th century, all the music was by live performers. The quality of the music depended on the skill of the musician, the quality of their instruments and the acoustics of the environment they perform in. To hear truly great music usually required a high level of social standing.  The gramophone changed everything. It brought the wonderful music of the worlds best symphonies and musicians to the general public's home, whenever and however many times they want to hear it! This introduced a world of great music to people who would not of had the social standing or geographical location to enjoy it performed live.
   
The modern world listens to music on a daily basis with little regard to the quality of the sound they hear. It surrounds us so often that what was once only a privilege of the rich is now taken for granted. We have grown up hearing music being played through boomboxes, car radios, TV's, and other cheaply made sound reproducers. This flood of compressed and mutated sound is what most of us think music should sound like. This is because most of us have no idea what real music sounds like.