To the average person, the term "Super Tweeter" might just sound like a person who spends too much time on the popular social media website Twitter™. But an audiophile sees it differently. Simply put, Super Tweeters are speaker drivers that produce ultra-high frequencies and better sound quality for home audio systems and are an essential part of any hi-fi speaker capable of playing High-Resolution Audio.
Sony's Super Tweeters
Unique Approach to Better Home Audio Quality
To receive the best sound quality, most hi-fi speaker systems require that listeners sit directly in front of the speaker with their ears at the same height as the Tweeters.
But Sony engineer team Tomoya Kato, Kouji Miyata and Masanori Sugiyama realized that this is not how most people listen to music — they want to be able to enjoy quality audio as they move about their home.
The blue areas on the image indicate a conventional speaker's sweet spot, while the yellow areas indicate the sweet spot of the SS-HA1/3.
With this concept in mind, Sony set out to develop a home audio system that would provide the widest possible range of indoor listening — the HA Speaker Series (SS-HA1 and SS-HA3).
What was the key to making this happen? Taking a unique approach with Super Tweeters.
Finding the "Sweet Spot" for the Tweeters
Tweeters come in all different shapes and sizes, all of which affect the sound quality. For starters, Sony chose compact, soft-dome tweeters for the front of the SS-HA1 and SS-HA3 because they reproduce sound with maximum clarity and information density. This means that the audio sounds as close as possible to the master analogue file that comes directly from the music recording studio.
But Kato, Miyata and Sugiyama knew that these two Super Tweeters would not be enough to achieve the widespread dispersion of sound. Therefore, they mounted two more Super Tweeters at the top of the hi-fi speakers to supplement energy in the upper-diagonal directions, guaranteeing sound of consistent quality across the widest possible listening range.
The Sony engineer team found the best relative positions for these two Super Tweeters by creating a special tool that could adjust the positions of the two units by just millimetres (vertically, horizontally and depth-wise). They conducted countless music-listening trials with different measurements and ultimately determined the best position by using a computer simulation program.
Overcoming Sound Quality Obstacles
Super Tweeters with Other Hi-Fi Speaker Elements
While the unhoused small Super Tweeters provided great sound quality during the testing stage, a problem arose when the Sony engineers properly housed the speakers — the effect of the Super Tweeters couldn't be felt at all.
This occurred because the directivity of the small Super Tweeters was so good that the acoustics were reflected by the surface of the baffle. Also, diffraction occurred in the corners of the housing and severely impacted sound quality.
The image shows a speaker with diffraction (on the left) and a speaker without diffraction (on the right).
To combat this, the team made the area of the baffle as small as possible around the Super Tweeters to reduce reflections off the baffle.
They also discovered that a Tweeter with a 45-degree cutaway design achieves a better sound quality than one with a half-sphere design or with an incomplete round edge.
Therefore, they used a 45-degree cutaway design for the left and right side and upward direction of the baffle as well as the diagonally upward direction of the speaker.
The end product? Two hi-fi speakers that deliver the best sound quality for home audio systems with as little diffraction and as big a "sweet spot" as possible.