The sound of real bass from a compact box
Cellular Bass® is the compact loudspeaker box
that can add very deep bass impact to sounds from a Pipe Organ, Grand Piano, Harp, Double Basoon, Double Bass, Bass Tuba and Timpani.
CompBass Immersive® is sub-bass heard at modest sound levels
The Compbass System
The Compbass Patents
Patent description
This patent has been developed over many years of building and testing prototypes based on the closed box and bass reflex styles.
The key feature is the close proximity front baffle and the moving element acting as a piston to compress air in the cavity.
This layout is extremely effective in dampen the normal resonance of a closed box design.
In this sub bass design the driver has a ‘flat face’ which was proved to produce the most outstanding performance within its specific ‘frequency and power range’.
The effect is to flatten the response and extend it over a wider sub bass range, typically from 20HZ to 150HZ with greatly reduced harmonic colouration.
At a given power input level, the sound leaving the wave guide is at much higher pressure than that from the port of a bass reflex design. The resulting sub bass is clean, firm and remains audible at a surprisingly low power input level.
The enclosure vibrates less than the normal closed box because the air pressure between the front baffle and the ‘flat face’ driver dampens the length of travel, resulting in less energy being transferred to the main cavity.
This unique approach produces very deep bass at modest power levels and is particularly attractive for a noise restricted environment.
Patent 2
Patent 1
Active Compact Loudspeaker Systems for Reproducing
25HZ to 120 HZ Audio in a Restricted Space
Patent GB2463529
(Employing a flat fronted driver in a compression chamber)
For Integration into a Home Audio/Visual Multi Media Hi Fi System
Field of research
Long time delay is needed to produce bass pressure waves starting at the driver.
From a reduced power level and below boom resonance, sub-bass at a reflex vent is shallow and the low-impact acoustic pressure is muted in a restricted space by walls that shorten bass waves.
Product Aim
To produce a subjective audible effect of sub bass fundamentals in a restricted space at modest power levels by causing an increase in pressure at an output vent and effectively shielding the driver from direct room reflections so as to cause a bass wave delay effect.
Product development
The present embodiment received a comprehensive range of tests to verify its likely potential to achieve its aims.
TEST BASS TRANSIENT HANDLING (attack handling over sub-bass range e g BBC Radio 2 top of the hour signature music)
Key characteristics for close examination in a restricted space
Please include subjective observations
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Low level line input to sub bass amp between 25HZ to 120HZ
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Removal of all resonant peaks above sub-bass range with a substantial increase in acoustic energy output across the desired sub-bass band and possibly some element of the 21 to 25HZ fundamental range audible at 20Watts. Please indicate measured and subjective findings.
Further observations: please comment
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The box/driver peak resonance (box boom) is heavily damped by the combination of compression chamber and waveguide loading.
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Well defined sub-bass bandwidth in which system peak resonance at about 35HZ is a lower frequency than closed box or bass reflex types of equivalent enclosure volume and driver characteristics (8” 150W rms 28Hz to 150Hz).
The present embodiment does not need a large magnet for bass driver damping.
Reduced internal vibration allows for a lighter construction material.
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The sealed rear cavity and front compression chamber provides approximately balanced front and back acoustic loading, shields the driver face from close proximity room reflections and improves the tracking of long wavelength sub bass input signals.
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Deeper free air penetration by ‘compression generated’ pressure waves at the vent output is more efficient at forcing long waves into a restricted space and sustaining a sub bass delay through acoustic resistance in the chamber and waveguide. The subjective effect is of some audible fundamentals in the critical region between 21HZ to 35HZ and improved musical detail in the overall sub bass range.
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Subjectively a high degree of bass attack/punch within operating limits and improved loudness tracking is observed.
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Environmentally desirable product for the reproduction of sub bass audio as part of an entertainment system in a typical domestic space.
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© Copyright
11 March 2013
R D Hewitt
Product development Tests
Patent 3