The Truth

     About Bass

When designing speakers, the objective is for each subsequent model to outperform typical speaker choices or previous TiFi models. Beyond functionality, there's a constant aspiration to craft superior speakers at a more affordable price. A superior speaker contributes to a richer sound image in a real-world environment. Naturally, part of achieving this enhanced sound image involves delivering lower bass tones. From a cost perspective, the low bass of 3D-printed speakers poses challenges. To elaborate on the bass aspect, it entails a tenfold increase in the volume of the speaker cabinet. For a proper speaker cabinet from 80 Hz and above, a few liters of volume are needed. Going lower, even when aided by a parametric equalizer, requires a dozen or two liters (translating to hundreds of hours of printing). At a moderate listening volume, achieving 30-35 Hz is feasible. Should you desire to go even lower or forego an equalizer, the volumes continue to increase exponentially. Thus, the exploration of the bass topic deserves dedicated attention.

The research findings are both natural and counterintuitive. Indeed, low bass is essential, constituting a natural element of a high-quality sound image. While very low bass is seldom required in music, for film sounds, the lower, the better. Contrary to intuition, it's acknowledged that determining the location of bass sound is challenging. This may seem like an absurd assertion, considering one can identify where the bass guitar or the large drum is in the orchestra. However, blind tests reveal the truth. Deconstructing the issue, each bass sound also carries a high-frequency component. Consequently, the brain assigns the direction of the bass based on the perceived high-frequency component. This deconstructed result finds practical confirmation in real-life scenarios—such as the location of the subwoofer. Immediately after installing or relocating the subwoofer, the location is distinctly audible; the brain instinctively knows where it is. However, over time, when you cease contemplating the location, the right bass still emanates from the regular speaker housing the high-frequency component of the corresponding bass sound.

The subsequent insight delves into the collaboration between bass and the room. Audio authorities recommend leaving the sound profile of a good speaker undisturbed above 300 Hz, refraining from correcting the room's peculiarities in that range. Essentially, the sound frequency range of a good speaker (300 - 20 000 Hz) should remain untouched. However, considerable attention should be given to the room's resonances below 300 Hz. Four possible approaches are used: damping, outsmarting, ignoring, and starving.

Damping low-frequency sounds pose challenges, and no carpet alone suffices. Bass traps must be proportional to the room, with resonators measuring in meters, not millimeters or centimeters. Solutions exist, with a practical compromise often involving a room with sound-damping characteristics but not damping resonances. Clever incorporation of elements like wardrobes or suspended ceilings, when well-designed, can effectively serve as resonance-damping measures if you are in the planning stages of home construction.

Outsmarting is a simpler and less bulky method. Strategically placing the bass sound source in the room at the null point of resonance—typically in the middle or quarter point between relevant walls—ideally involves suspending the subwoofer precisely in the room's center. Since this is impractical, multiple identical subwoofers (2 or 4) are usually symmetrically positioned, typically at the center of the walls.

Ignoring is more sophisticated than outsmarting. Multiple subwoofers are placed in both the front and back walls of the room. Their sound is configured so that front ones play natural bass, while back ones absorb the corresponding bass sound, playing it time-delayed in the opposite phase. Ideally, this creates a cylindrical sound wave that travels through the room, being completely absorbed at the opposite end. However, the topic is complex, and the more common result is complete chaos. The clear advantage of this approach is the equalization of all listening positions; there is no need to be in the sound focus.

Starving involves intervention before presenting bass sound. With a parametric equalizer, the sound's intensity is slightly reduced at the room's resonance frequencies. This way, the room's natural resonance remains, but it is not disturbingly strong. Often, this is the simplest and most cost-effective measure to control bass sound. It is recommended to use it in conjunction with outsmarting.

Remarkably, none of these recommendations touch upon timing the bass or its relative position to the channel speakers. Even more noteworthy is the difference in spatial layout recommendations. The best spatial sound is created with side channels directly in front of the listener, spanning 30 - 60 degrees to the side. However, the rule of thumb for placing the bass is in the middle of the room's wall—whether in the front and back walls or in both side walls. Consequently, to achieve truly exceptional sound in a listening room, powerful speakers with bass are insufficient. Separate stereo channel speakers for 80-20000 Hz and separate bass speakers for below 80 Hz are imperative. (An exception exists for those listeners who can position their speaker at the room's main resonance zero—such as on the room's side walls, near the center of the room, slightly away from the wall.

While there's a desire to develop a more sophisticated and larger speaker with even lower bass, it's an ill-conceived notion for achieving superior sound. For excellent bass in a real room, separate subwoofers are requisite, and there is a diverse selection available on the market at reasonable prices. Unfortunate, as pre-projects for large hammer speakers already existed. Additionally, there were pre-projects for the bass part with ribbon filters, where the filters are solely acoustic—eliminating the need for DSP or a regular crossover filter. The sound is timed and at the right strength. While this type of speaker aligns with existing prejudices, including mine, selling them at a high price would be unjust. If it is known that this is not the best method for achieving optimal sound in the room, it must not be pursued.

This makes the development work more intriguing. Small desktop TiFi Argos and wall-mountable TiFi Hestia now assume greater significance. The development phase is largely concluded; the sound profile is commendable, and the sound is timed without digital intervention. (As of the current writing, they are not yet available for sale, requiring a bit more time.)

Playing with the numbers, it becomes evident that this is indeed the right path. A high-end HiFi speaker with a low bass part costs at least 20,000 EUR. If two to four quality subwoofers are purchased, they are quite competent at under 1000 EUR, with the bass ranging from 2000 - 4000 EUR. Crafting high-quality speakers for the frequency range of 80-20 000 Hz is entirely achievable within the 2000 EUR price range. This renders the price more favorable, and the sound quality in the room surpasses that of two pairs of speakers with low bass.

For a reference short presentation on subwoofer placement: https://www.harman.com/documents/multsubs_0.pdf