MOTIONAL FEEDBACK BASS SYSTEM
The Basus subwoofer system consists of a bass driver with motional feedback in a sealed metal enclosure, a 1kW power amplifier, and an active crossover system with switch-selectable preset frequencies that allows the Basus to be used with any speaker/amplifier combination. The Basus subwoofer project was started as a bass extension unit for the Lyra speaker that evolved into the ultimate universal woofer - a matching stand to mount the Lyra on top of the Basus is provided making it one system visually. The Lyra/Basus/Teres combination creates an active speaker system with unmatched synergy and visceral impact.
Undistorted bass at high enough levels creates a different perception of the music. When the group delay is very low pulses and percussive instruments become solid and with well defined body, cleaning up the murkiness in the soundstage creating a see-through effect allowing one to hear the reverb and reflections in the back of the soundstage. You don’t hear more bass but more music!
BASUS AND THE NEED FOR BETTER BASS
In Music school we are taught music has three main elements; rhythm, harmony, and melody. The bass notes lay the foundation for two of these three elements - Rhythm and Harmony. Numerous studies confirm that people react to low frequency beats and can detect timing errors more accurately in the bass than in mid and high frequency ranges. Bass is not rumbling noise associated with a passing starship, but the foundation of a musical passage. It is the lowest note that defines the harmonic structure in frequencies above it. It can make music sound sad or bright, or mellow. Music contains two very different types of bass; one that is continuous and sustained, and the other pulsed and very short (percussive).
Proper phase alignment in sustained bass creates the correct waveform allowing you to identify the instrument and discern its sound texture. The pulse of the bass provides us the beat and timing of the piece. Any delay there and the sound is ever so slightly off the beat making the music less impactful. Small ported speakers and home cinema subwoofers exhibit very large group delay giving meaning to the term “murky bass”. Large ported enclosures behave better and exhibit this problem only in the very low bass. The best overall performance is achievable with sealed enclosures - especially large sealed enclosures. In large sealed enclosures the group delay is the lowest and least obtrusive. Unfortunately, the efficiency of sealed box systems is very low. For any given cut-off frequency, the box size will have to double for each 3dB higher efficiency.
Now you can understand how manufacturers "misinform" you. Below are the maximum theoretically possible efficiencies for sealed box speakers expressed as SPL per watt:
2 cu ft 30hz = 84dB
4 cu ft 30hz = 87dB
8 cu ft 30hz = 90dB
16 cu ft 30hz = 93dB
32 cu ft 30hz = 96dB
The conclusion is that to have deep bass at high levels you need large speakers and a lot of power
Cabinet’s re-radiated energy- think of a drum, vibraphone or an organ pipe. The speaker enclosure is a resonator in its own right. If you create a pulse at its opening it will quickly respond with its own voice - like an echo in the mountains.