Technical
Beyond the Sweet Spot — Sound by Design® - Part II
True realism in sound cannot be achieved through incremental refinement of conventional loudspeakers, but only by re-thinking how reproduced sound interacts with perception. Founder Ole Siig’s experience in both engineering and attentive listening to live acoustic performances revealed a gap between what traditional systems measure and what the ear perceives.
That gap became the starting point for the TCA-M, a loudspeaker built entirely around the way we hear.
A Personal Note
My journey with Treble Clef Audio is, at its heart, a deeply personal one. I have two daughters who both play music — one of them classically trained at a renowned music school. Neither their mother nor I are musicians, yet music has clearly skipped a generation: my father and my wife’s mother were both keen amateur performers.
Over the years, we have spent countless hours listening to young people refine their craft on acoustic instruments in barns, classrooms, rehearsal halls and concert venues. Those experiences have shaped my ears and my respect for the art — for the years of practice, discipline and emotional honesty behind every note. They have also sharpened my awareness of how the sound of an instrument changes with the space around it, and how our hearing learns to recognise and trust that natural interaction.
Drawing on my background in engineering, and a lifetime fascination with how things work, I began to wonder whether the same care and insight that musicians devote to their instruments could be applied to loudspeaker design. After a career spent tackling complex projects and learning that perfection is always another step further up the mountain, this became a challenge I could not ignore. I tend to get obsessed, I never give up, and I have come to see that the pursuit of realism in sound is not about reaching an endpoint, but about continually climbing towards it — each summit revealing a higher one still.
That climb is what became the TCA-M.
Treble Clef Audio began with no intention of being a commercial loudspeaker brand. The TCA-M Active Loudspeaker grew out of a personal passion project—an engineering and design journey pursued for its own sake, not to meet a market demand or hit a price point. What began as a hobby evolved, through careful thinking and countless refinements, into a low-volume, build-to-order product designed for listeners who value authentic, emotionally engaging sound.
From the earliest sketches to the final listening tests, the TCA-M reflects an end-to-end advanced engineering process that few companies would attempt. We control the complete transfer function—from the incoming electrical signal, through all electronics, ultra-short signal paths, and precisely matched drivers, to the enclosure principles, dispersion characteristics inextricably tied to physical shape, and integrated acoustic output using advanced Digital Signal Processing (DSP) to achieve what physics does not allow with a conventional approach.
Every step is optimised as part of a single, coherent system.
Human hearing is acutely sensitive to timing; microsecond-scale differences define instrument texture and space. To preserve this integrity, the Sound by Design® patented acoustic platform unites drivers, enclosures and amplifiers with digital signal processing as one coherent system.
Operating at 32-bit floating-point precision, the FIR-based DSP crossovers keep all drivers perfectly synchronised in time and amplitude. The result is linear frequency response combined with constant Group Delay and complete time coherence, demonstrated by a clean Step Response where all frequencies rise and decay together.
Timing accuracy translates into spatial realism: instruments occupy their true positions, transients retain their identity, and recorded venues unfold naturally.
Mechanical Design and Material Philosophy
The physical structure of the TCA-M follows the same principle as its acoustics: purity through integration. Its baffle- and box-free architecture eliminates the artefacts that traditional enclosures impose on the wave launch and dispersion of sound. Each transducer is independently suspended within a sculpted open frame that prevents resonance transfer, minimises diffraction and guides the natural flow of sound rather than beaming it increasingly forward off a baffle at higher frequencies.
The front and rear radiation paths are shaped to disperse energy smoothly and with spectral consistency, while the structural frame is contoured to stay acoustically transparent, allowing the expanding wavefront to develop naturally into the room.
Vibration control is achieved through mechanical balance and precision engineering rather than damping or mass. The folded-dipole bass modules channel reactive forces symmetrically, cancelling vibration at its origin. The midrange and high-frequency sections are mechanically isolated from the bass structure to prevent residual motion reaching the delicate transducers.
Materials are chosen for their strength, stability and acoustic neutrality. Precision-milled aluminium and acrylic-glass side panels, hand-finished hardwood and internal cement-based syntactic foam inserts absorb residual low-frequency mechanical energy by converting it into heat. The chassis remains acoustically silent even under extreme dynamic conditions.
Visually, the TCA-M emerged from scientific experimentation as a functional sculpture, an expression of structural clarity where every surface serves a purpose. Its geometry is defined by sound rather than styling, yet the result is inherently elegant — a form that looks the way it sounds: pure, stable and effortlessly natural.
Attending to the Silence
In live music, silence is never empty. The space between notes — the pauses, decays and rests — defines rhythm, phrasing and emotional tension. Each moment of quiet carries the memory of what came before and the anticipation of what follows. When a loudspeaker introduces stored energy, delayed resonances or phase errors, those silences are blurred; the stored energy and room continues to speak after the music has stopped.
The TCA-M preserves the clarity of these moments through precise Time Coherence and exceptionally low energy storage. Notes begin and end cleanly, with no residual bloom or masking of the next transient. This fidelity to silence gives music its natural pacing and breath, revealing phrasing and expression as intended by the performer.
True realism lies not only in reproducing sound, but in honouring the spaces between it.
Five key aspects define believable sound reproduction
- Accurate Direct Sound – The first arrival at the listener’s ear must be a spectrally accurate representation of the recorded signal, maintaining precise tonal balance before any room or preference Target Curves are applied. This ensures that what leaves the loudspeaker corresponds faithfully to the recording itself.
- The Ability to Voice the Loudspeaker – Psychoacoustic voicing through Target Curves adapts the loudspeaker to personal taste and room character, shaping tonal balance while preserving Time Coherence. This is possible only in a DSP-based active design.
- Time Coherence – The loudspeaker must preserve the temporal relationships between all frequencies so that transients, harmonics and overtones remain aligned in time, regardless of Target Curve or Preference EQ. Constant Group Delay across the spectrum ensures that every element of a sound arrives together, maintaining instrument identity, rhythm and spatial realism.
- Controlled Off-Axis Response – Because reflections shape spaciousness, off-axis sound must be spectrally consistent. Smooth and wide dispersion allows reflections to enrich rather than colour the sound.
- A Balanced Room Acoustic – The ideal listening space should feel natural, not artificially controlled. Rooms with moderate or even lively reflections more closely resemble the conditions in which music is created and performed. Because the TCA-M maintains a smooth and uniform Off-Axis Response, these reflections blend harmoniously with the direct sound, enriching spaciousness and depth rather than obscuring detail. As with live acoustic music, our hearing instinctively abstracts the room, allowing the performance itself to become the focus.
