Traditional speaker systems face a fundamental challenge when it comes to scaling life sized music accurately.
While a small recording microphone can accurately capture the sound waves in a large air volume, playing it back is a daunting task. The reason behind this is that we are now trying to move a large air volume in a room using drivers that are relatively small and heavy in comparison to the air volume which is large and light. We have a huge impedance mismatch!
This can be seen in the relatively low 1% or less (92dB @ 1 watt) efficiency ratings of most speakers. They have an almost impossible task trying to connect their small driver surface areas to a large and light air volume. This usually leads to a small thin uninvolving sound.
To overcome the acoustic coupling problem mentioned above you need an acoustic transformer. A transformer that can effectively transform a high pressure/low amplitude (small area) sound into a low pressure/high amplitude (large area) sound.
A horn offers tremendous benefits when it comes to speaker driver behavior and, ultimately, the connection between the driver and the air in the room. This results in efficiencies ranging from 15% to 50%, with an average of 20% to 30%. This is orders of a magnitude higher than the industry standard of 1% or less offered by most direct radiating speakers.
Nowadays, there is a common belief that power is cheap, so there's no need to invest in high-efficiency speakers. The thinking goes, just add more power and you'll be good to go. But hold on a second, there's much more to this scenario than meets the eye.
In the end, the speaker’s ability to accurately reproduce sound relies on a driver’s ability to precisely track highly complex wave forms.
Have you ever wondered why a pair of good headphones have such great sound and clarity? It is actually very simple. The drivers are small and lightweight, and each moves a very small air volume, so the driver only needs to make tiny but fast movements. The smaller the movement required of the driver, the faster it can accelerate from amplitude peak to amplitude peak. This aspect plays a key role in delivering dynamic, high-resolution sound.
Let's explore the various ways in which horn speakers benefit from their high efficiency coupling. As I mentioned before, high efficiency is just one aspect of horn speakers that impacts the sound. High efficiency offers a wide range of additional benefits.
Horns have an incredible dynamic range and can effortlessly move massive amounts of air. They can go from 0 to 100 in a fraction of a second. Talk about playing big!
Transient resolution is greatly improved in horn drivers compared to traditional direct radiators. This is because the drivers only have to move a fraction of the amplitude required, allowing them to accelerate and decelerate much faster.
As a result, horn drivers are able to accurately and effortlessly track fast and complex musical signals, including the fine interwoven ambience detail that is carried on the main signal. With direct radiators this ambience detail is usually lost except with very simplistic "audiophile type music".
Another benefit of horn-loaded loudspeakers is their low distortion. This is because their high efficiency allows the drivers to move only a fraction of the amplitude for a given sound pressure level, resulting in minimal distortion.
Horns are known for their high efficiency, meaning they can produce a lot of sound with very little power. On the flip side, when you give a horn plenty of power, it can create a massive sound stage.
Horn-loaded loudspeakers have a natural tendency to produce sound that follows the well-known Fletcher Munson curve, which aligns with how humans naturally hear.
In the audio industry, there is a general belief that a flat frequency response is necessary for producing music. To our ears, a flat response may sound cold and uninvolving.
However, when we look at the Fletcher Munson curve, we can see that the output actually rises steadily towards the low registers.
As audiophiles, we're well aware that the lower bass registers require more power compared to mid and high frequencies. This is where horns have a tremendous advantage over regular loudspeakers. They effortlessly provide additional acoustic output within their designed bandwidths in the lower registers without requiring any extra amplifier power. This allows them to naturally follow the Fletcher Munson response curve, resulting in a natural warm sound.
Here's an interesting aspect that often goes unnoticed: it is what we refer to as the "magic zone" in a speaker's axial movement. This is the neutral area or position where the driver is at rest, which is also the softest part of the suspension. It’s ideal for a speaker to operate in this area.
The suspension of the driver works against the amplifier's attempt to move it. The more it's pushed away from its neutral position, the stronger the opposition to the amplifier.
What we need to keep in mind is that low voltage/current from the amp results in small movements, while large voltage/current produces larger movements. The issue arises when these small movements (usually ambience) get lost as the speaker driver is pushed towards the tougher outer part of the suspension.
Horn-loaded speakers are renowned for their high efficiency, as they only require small driver movements. This enables the driver to operate within the soft zone, preserving the interwoven ambience information and resulting in optimized performance.
When all the above elements come together, you get a fast, high resolution loudspeaker that delivers crystal-clear sound with incredible precision, dynamics and scale.