If by any chance somewhere exists a betting where you could bet on what the cover photo of this text emphasises, the odds for choosing acoustic panels would be drastically higher than those for speakers, preamplifiers, amplifiers, DACs, or even turntables.
And that’s a fact because room acoustic products are designed to create optimal listening conditions, but in many cases, these acoustic products are usually at the very bottom of priority lists. To make things worse, many don’t even understand what it’s really about, and many of them never realise what they’re missing.
But let’s start from the beginning, and let’s explain what room acoustics actually is, why it’s so important, who needs it, and how to apply it properly for optimal results.
It’s not hard to see that, under normal circumstances, the ceiling or floor surface will have a much greater impact on sound than, for example, a small 40 × 30 cm mirror hanging on the side wall.
However, sound arriving from all these directions will reach you with varying time delays, but usually too short (often just a few milliseconds) that you won’t even be aware that you’re hearing it from multiple sides.
Clearly, it is about the human brain and the ability that plays a key role in how we will ultimately experience music. Simply put, completely or superficially. The brain and auditory system are, thank God, healthy and developed in most people. You don’t necessarily have to be an audiophile with trained listening techniques to feel that you are listening to something that seems incomplete, i.e. unnatural. You simply realise at some point that it is not that, and subconsciously you know that something is missing for the full enjoyment of enjoying music, especially in the long run. And here’s what.
It all comes down to the human brain and its remarkable ability to shape how we ultimately experience music either deeply or superficially.
Fortunately, the brain and auditory system are well-developed in our bodies.
You don’t need to be an audiophile with trained listening skills to sense that something sounds incomplete or unnatural. At some point, you simply realise that something isn’t quite right, and on a subconscious level, you know that something essential is missing for true, long-term enjoyment of music.
There is no person who, while listening to music in their home, has ever had the impression that bass or treble dominates. This is most often an attractive and seductive listening experience, “at first glance” caused precisely by the fact that lower or higher frequencies are uncontrollably multiplied by bouncing off various surfaces in the room. Listening to such music, i.e. such sound, especially at higher volumes, becomes tiring, unpleasant and repulsive after a short period of time, and then the sound is gradually turned down with the remote control or manually, often to the point that the audio equipment is ultimately turned off.
There’s hardly anyone who hasn’t felt that either the bass or the treble where too dominant while listening the music at home. At first, this might seem attractive or even seductive, but in reality, it happens because certain low or high frequencies are uncontrollably amplified as they bounce off the room surfaces.
To listen to music in such an environment, especially at higher volumes, quickly becomes tiring, unpleasant, and even irritating. After a while, the volume gets turned down, and sometimes the audio system ends up being switched off entirely for that reason.
I should also mention that certain frequencies may never reach your ears at all because of the mutual cancellation due to unwanted reflections.
Similarly, some frequencies might disappear because they’re absorbed by elements within the room, for instance, a large sofa upholstered in heavy fabric with thick foam underneath. Add a blanket or a pile of cushions on top, and you’ve basically created an audio sponge right in your listening space.
Now… if you’re aware of these acoustic limitations and you genuinely care about experiencing sound in its purest form, just as you would strive for tasting some top-quality wine or food, enjoying gourmet food, wearing high-quality clothing, or walking in perfectly fitted shoes, you’ll want to improve it. You’ll make the effort to understand how to overcome these challenges, what the solutions that exist are, and what kind of investment they require.
It’s completely understandable and even logical to assume that better sound comes from higher-quality (read: more expensive) audio equipment. But that doesn’t necessarily make the assumption rational.
To be truly rational, you have to consider all the links in the audio chain, not only the components themselves, but also the acoustic environment they operate in.
When the acoustics are right, even a mid-range audio setup can deliver far greater listening pleasure and musical depth than an acoustically untreated room filled with much more expensive audio components.
To put it simply: who do you think performs better across a ploughed field a Tractor or a Ferrari?
The acoustic anomalies of a listening room where sound moves uncontrollably and reflections dominate can be partially improved with everyday fixes like thick carpets on the floor, heavy curtains, bookshelves, or large furniture such as sofas. All these elements help to some point in taming unwanted reflections and specific frequency peaks.
However, here’s where the real problem begins: all of these fixes are just decorative fixes, not real acoustic solutions. In the end, you have no idea how much that carpet or curtain has actually changed your sound. Did it simply absorb excess high frequencies, or did it also unintentionally take away valuable midrange detail as a collateral victim?
Now we have an answer to the question: a Tractor or a Ferrari? Both have their purpose, but only one is the winner because it is built for true performance.
Now this is the point where SST Acoustic enters the story. A Croatian company specialising in the design and manufacture of acoustic treatment products that play a vital and irreplaceable role in achieving true high-fidelity sound.
Each product is handcrafted with exceptional attention to detail. While some models can be used universally, most are custom-made for specific listening spaces, following precise measurements and acoustic calculations that determine how much they will improve the overall sound performance of the system in that room.
To suit different interior aesthetics, SST Acoustic offers a wide palette of finish options.
The build quality is superb, clearly reflecting not only skilled craftsmanship but also a strong sense of design and aesthetics. It’s a company that truly deserves recognition for its dedication and quality.
To give you a clearer picture, I’ll roughly classify SST Acoustics’ products into three main categories, explaining their purpose in simple terms.
What all these products share is a common goal to manage how sound behaves across specific frequency ranges, ensuring that unwanted reflections or resonances don’t interfere with the pure musical experience.
The first group consists of elements designed to absorb excess sound energy in the room, the so-called absorbers. Absorbers typically target low and mid frequencies and can be cylindrical or square in shape.
To absorb the lowest frequencies (the bass range), larger cylindrical absorbers are often placed in the room corners. For the midrange frequencies, absorbers are commonly installed on walls and ceilings. These are usually flat, square panels rather than cylindrical in form.
The second group consists of diffusers that are acoustic elements designed to scatter sound energy. Their purpose is to eliminate unwanted sound reflections from various surfaces within the room, from window glass and bare walls to flat reflective furniture or side mirrors.
Diffusers “break up” the sound waves into smaller components, preventing them from interfering with the direct sound coming from your speakers. They are most commonly installed between front speakers, on side walls and on the rear wall.
The third group features “hybrid” acoustic products, known as absorber/diffusers, which combine both absorption and diffusion characteristics. These serve multiple purposes, for instance, they can absorb more in the midrange frequencies while gently diffusing the high frequencies, ensuring balanced acoustic performance. Such panels are typically placed on the side walls, rear wall, and ceiling, where they contribute significantly to the overall control and distribution of sound throughout the room.
The purpose of these acoustic group products is to achieve the most balanced and natural sound within a room. The goal is to eliminate anything excessive, whether it’s an overemphasised bass, a harsh midrange, or bright treble — anything that stands out and distracts from the pure experience of music.
Audiophiles often describe this as striving for linear sound as a response that, when plotted as a frequency curve, shows no dramatic “spikes” or sudden dips, just smooth and even playback across the spectrum.
This hopefully clarifies the essential role that acoustic treatment plays, and how profoundly it can transform both the perception of sound and the enjoyment of music. Even a small acoustic intervention can significantly enhance your listening experience — regardless of what speakers you use or where you listen.
Željko Valentić – SST Acoustic
That brings us back to SST Acoustic and my conversation with Željko Valentić, the company’s founder and chief acoustic designer and the discussion that inspired this article. From the outset, we agreed it would be a shame to limit the topic to a narrow audience of audiophiles or those already familiar with acoustics as a science.
Instead, I made it my goal to make this text accessible to anyone who loves music and wants to hear it at its best, even to readers who might never have heard of acoustic products or understood why they could matter to them.
On the other hand, the following section dives deeper into the subject and assumes a certain level of familiarity with acoustics. I’ve decided to present the full content of Željko’s email, in which he describes SST Acoustic products using light and simple words explaining their technical characteristics, intended use, and how to achieve optimal performance. He also outlines why acoustic treatment is such an essential factor in attaining true high-fidelity sound.
I’m convinced that anyone who read the first part and found the insights there intriguing will approach the sequel with the same interest, regardless of how much deeper and more expertly it dives into the full story.
Before handing you over to Željko’s part of the text, I’d like to add a few personal observations. Something that genuinely surprised me was discovering that SSTacoustics also offers a wide range of products.
I’m talking about headphone stands, specifically two models: Moai and Ronnie. The first is made of cement, the second of solid wood. Moai is inspired by ancient culture and resembles the famous stone statues of Easter Island, and honestly, it’s one of the best headphone stands I’ve ever seen. It doesn’t even matter which headphones you place on it.
You can choose from several colour options. Simply… an exceptionally cool stand!
Ronnie, on the other hand, may not grab attention at first glance, but its craftsmanship and finish truly shine. It immediately conveys the impression of a premium product. This is where the “classic” Audiophiles will come into their own.
The following is Željko’s part of the story:
Why Acoustic Treatment?
Flat surfaces create unwanted reflections and muddy bass. Too much absorption results in a dead, lifeless sound. Without any acoustic treatment, you risk muddy bass, loss of detail, reduced stereo width, and a lack of sonic depth.
Tube Bass Traps
SST Acoustic Tube Bass Traps are engineered to absorb unwanted low-frequency energy in the bass spectrum (from 30Hz up to 400Hz, depending on their diameter) while simultaneously reflecting and diffusely scattering most of the frequencies above 400Hz. This dual characteristic makes them a highly flexible and precise tool for controlling reflections in a listening space.
With Tube Bass Traps (depending on their diameter), we control the so-called mud factor in the range between 30Hz and 400Hz. The spectrum above 400Hz, including mid and high frequencies, consists of short wavelengths that are directed and controlled by the diffuse side of the Tube Bass Trap, so that its diffuse surface directs this spectrum in the desired direction for the benefit of the sound image, instead of absorbing it.
By simple rotation of the Tube Bass Traps around their axis, tones above 400Hz will be directed in the desired direction in your room. Even the slightest rotation of any Tube Bass Trap in the room will significantly affect the balance of the sound of your system.
Rotating the Tube Bass Traps to disperse energy (above 400Hz) along short paths of primary reflections within the so-called Haas window can greatly improve stereo imaging and coherence, and eliminate harsh and unpleasant distortions in the colour of the sound. The term Haas window refers to a term in acoustics that describes how our brain perceives sounds when the original signal and its reflection appear very close to each other at some point in time.
For example, if a reflection arrives within 20–30ms of the direct sound, our brain “merges” them and connects them as one sound. In this case (the so-called Haas window), the main experience of the sound comes from the first, direct signal, while the reflection mainly contributes to the impression of loudness and fullness, and does not create an echo. If a reflection arrives after ~30ms, the brain recognises it as a separate sound or echo.
SST Acoustic Tube Bass Traps contain an SST marking on their front topping, which should basically be oriented towards the listening position.
If we want to influence the sound image as previously stated, rotating the TubeTraps around their axis left or right, it will result in reflection and diffuse dispersion of the delayed reverb energy on longer secondary, tertiary and similar paths. In this way, the Tube Bass Trap will improve the spatial perception and depth of the sound.
If we place Tube Bass Traps on the side walls to the left and right of the speakers, we get a concert hall ambience because they absorb unwanted coherent waves that come via a short reflected path from the speakers via the side walls to the listener.
At the same time, they reflect and additionally diffuse and disperse the reverberated energy that came via a long, multiple reflected path and is already incoherent and delayed as such.
The (SST) marking indicates the middle of the Tube Bass Trap that diffuses the midrange and treble. If you “stack” Tube Bass Traps on top of each other, then the lower Tube Bass Trap should be positioned with the SST mark facing more towards the side wall for maximum absorption, while the upper Tube Bass Trap should be positioned with the SST mark facing towards the listener position. If your ceiling is high enough to use three Tube Bass Trap columns, position them so that the middle Tube Trap is oriented the same as the lower one.
Why the different rotation of Tube Bass Traps?
Because the speakers and the listener’s ears are closer to the floor than to the ceiling. So, we solve the unwanted short path that we want to absorb with the lower Tube Bass Trap. The upper Tube Bass Trap “sees” mainly the long wave that has already had multiple reflections. That’s why we orient the lower Tube Traps for greater absorption, and the upper ones for greater reflection and diffusion. Of course, these details vary from listening room to listening room.
About Diffuser ID2 type
What is the difference between an absorber and a Diffuser?
When a sound wave reaches an absorber, it absorbs sound energy. The result is a reduction in echoes, reflections, and distortion of the sound’s colour.
Diffusers, unlike absorbers, contribute to better sound by dispersing sound energy in multiple directions, giving the space a feeling of spaciousness and liveliness.
This is possible because of their irregular surface shapes, which deflect sound waves at different angles, dispersing them within the room while retaining the sound energy. The Diffuser must be at least one meter wide to notice the difference.
SST Acoustic is capable of producing a Diffuser for this purpose according to the customer’s specification, in terms of its width and height. The diffusion effect is more effective if the greater is number of diffusers (the greater the number of periods), because the sound energy is distributed more evenly, and an even distribution of sound is exactly what acoustic diffusion is supposed to be. If the Diffuser width is less than one meter, you probably won’t hear a significant difference.
Where to place diffusers?
Front wall
If you’re an audiophile and have already treated the back wall with diffusers and want to give your music an even greater sense of spaciousness, this is the option for you.
By covering two opposing walls (front and back) with Diffuser arrays, sound energy is rarely reflected off a flat surface, creating the effect of a true concert hall with depth and width of the sound image.
Back wall
This is how it is done in most music studios, listening rooms, home theatres and other HiFi spaces. If the listening position is far enough from the rear wall (at least 1.5 m), the wall-mounted diffusers have enough space to evenly distribute the energy and thus ensure the best acoustic experience.
Side walls
Installing diffusers with absorbers at the first reflection points ensures that sound energy is not reflected from flat walls directly towards the listener, thus helping to preserve the liveliness of the room for a superior experience of what your system can deliver.
Should diffusers always be used?
I recommend placing the diffusers on the wall only if the distance between the rear wall and the listening position is at least 1.5 meters. If not, the sound energy will not have enough space to disperse evenly before reaching the listener’s ears. In this case, it is better to focus on controlling low frequencies and eliminating flutter echoes.
Can SST Acoustic make custom diffusers and absorbers?
Of course! SST Acoustic offers acoustic solutions tailored to the specific needs of clients. Our Diffusers, Absorbers, Abfusers Tube Bass Traps are high-quality, handmade, elegant in appearance and will certainly enhance the visual appearance of the listening room because we can use finishing decors and colours that fit into any space.
The ID 2 Diffuser is extremely effective in making a space feel alive and natural. Its unique and attractive shape disperses sound evenly in all directions, ensuring a natural and wide sound stage.
The SST Diffuser ID 2 type provides the perfect balance between acoustic efficiency and a premium and distinctive design. The ID2 Diffuser’s operating frequency range starts at 500Hz, and its full potential is expressed in the frequency range of 1140Hz – 3500Hz.
Its dimensions determine its efficiency, and size 61×122 cm has proven to be an ideal combination to start using them.
This text has been created in collaboration with Željko Valentić from SST Acoustic. Thank you for your response, friendliness, and help in creating the content.
SST Acoustic
Osječka 1
10410 Velika Kosnica
Croatia
Phone: +385 95 749 4733
Distribution:
Rotary Audio
Ulica Lavoslava Ružičke 2
10000 Zagreb
Croatia
Phone +385 1 5512 705
