I keep seeing marketers and posters (elsewhere) say that they don't like horn speakers or they can't stand the sound of a metal tweeter. Is there any truth to all this? I'm sure different designs lead to different compromises, but in the end, a properly engineered speaker should get the job done without any "coloration" or, as some put it, "colouration".
There are inherent traits.
The inherent characteristics of how drivers sound—whether they're ribbon, dome drivers, or utilize horns—are significantly influenced by their shape. This is because the shape directly affects how each type of driver disperses sound throughout a room.
For example, Ribbon drivers, with their slim, elongated form, produce sound waves in a manner that allows for broad horizontal dispersion but limited vertical spread. This trait can enhance the perceived width of the soundstage, making the audio experience seem more expansive.
scientific explanation of why the shape of the driver gives them inherent traits:
These phenomenons are related with the sound wave diffraction, which is a fundamental aspect of wave physics. Diffraction refers to the bending of waves around obstacles and the spreading out of waves through openings. The amount of diffraction (or spreading) of sound waves is influenced by both the size of the sound source and the wavelength of the sound.
When sound waves pass through a narrow opening (small compared to the wavelength of the sound), they tend to spread out more widely on the other side. This is because the sound waves are 'squeezed' through the small opening, and upon emerging, they spread out in a wider pattern due to diffraction.
A smaller sound source can be considered as having a point or small area from which sound waves originate, allowing for a wider dispersion pattern as the waves move away from the source. Conversely, a larger sound source may produce sound waves that are more directional, with less spreading, especially if the dimensions of the source are large compared to the wavelength of the sound being produced.
Results:
I explained a bit above but let me summarize it again:
Given their distinct dispersion patterns, ribbon drivers often project sound more directly in vertical plane and more wider in horizontal plane. This characteristic makes them less likely to interact with the floor and ceiling, focusing the sound more narrowly in the vertical plane. Such directivity lends ribbon drivers an edge in clarity over dome drivers but might also contribute to a sound that some perceive as less natural, due to the reduced presence of floor reflections which we are accustomed to in most listening environments. Also because of this narrow vertical dispersion they have very narrow sweet spot.
On the horizontal plane, the narrow physical profile of ribbon drivers facilitates an expansive spread of sound. This wider dispersion can engage more with room boundaries, like side walls, potentially enriching the immersive quality of the audio with reflective sound. This effect can vary with the type of music and the acoustic properties of the room, potentially making some recordings feel more enveloping.
Horns have a unique influence on sound dispersion. Their design can significantly narrow the spread of sound, making the audio output more focused. This characteristic tends to reduce the speaker's interaction with room boundaries, potentially enhancing clarity. The sound from speakers equipped with horns can appear more concentrated and less affected by room acoustics, which is often desirable for achieving a precise and clear auditory experience.
Note for audio science enthusiasts: when I say higher clarity I refer to a cleaner impulse response with a response with less small dips and peaks.
Metal (insert the material) dome vs Metal(insert the material) dome.
The debate around materials like Beryllium versus Aluminum in dome drivers often centers on inherent timbre, which is a misunderstanding. The material's stiffness is what's crucial, influencing the first breakup mode or the point at which the driver no longer moves uniformly. This frequency is beyond the range of human hearing for metals commonly used in driver construction, indicating that material choice impacts performance through mechanical properties rather than inherent sound qualities.
metal domes vs soft domes
When comparing metal dome drivers to soft dome drivers, it's important to understand the concept of breakup frequency. This is the point beyond which a driver can no longer move in a uniform, piston-like manner. For aluminum domes, the breakup frequency typically falls between 23-28 kHz; for beryllium, it ranges from 30-55 kHz; and for diamond, it extends from 40-80 kHz. The material's stiffness primarily determines this threshold, with stiffer materials like those used in metal domes maintaining pistonic movement up to higher frequencies than their softer counterparts.
Soft dome drivers, by contrast, begin to lose this uniform movement at lower frequencies. (around 1200hz usually if I can recall it correctly) Once a driver deviates from pistonic motion, its sound radiation pattern also shifts away from being linear. As a result, the sound reflections from soft dome drivers might differ significantly from the direct sound, potentially sounding more 'dynamic' to untrained ears. To those more trained in hearing, however, this variation might be perceived as a flaw.
Moreover soft domes show a tendency to 'beam' sound at higher frequencies, meaning their sound dispersion narrows, particularly in the vertical plane. This characteristic reduces their interaction with the ceiling and floor, similar to ribbon drivers, often resulting in clearer sound in typical home environments. This clarity, combined with a more subdued reflection compared to metal domes(because they beam), allows soft domes to deliver a sound that is both clear and rolled off in the treble region. This quality can effectively conceal issues in the treble range of the speaker's voicing or the recording itself, offering a forgiving listening experience.
Soft domes are inherently flawed compared to metal domes. Probably for nostalgia reasons, people still like their sound.
Examples:
Dispersion plots of a well designed ribbon driver.
dispersion plot of an extremely large ribbon driver: