Bandpass woofer and method
AssigneePolk Investment Corporation
InventorMatthew S. Polk
Life of this patent
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Abstract
A single-vented bandpass woofer loudspeaker system design and method for enabling operation in smaller enclosure volumes with only moderate loss of efficiency. The bandpass system has an enclosure with a partition dividing it into a first sealed chamber and a second chamber having a passive radiating port communicating with air outside the enclosure. A driver is mounted in the partition. Novel, empirically determined tuning ratios which depend upon system variables are defined. By adjusting the system variables to keep the tuning ratios within empirically determined values, a good relationship between flat response, bandwidth and efficiency is achieved. Unexpectedly, using a higher than normal moving mass of the driver leads to an acceptable system with a very small enclosure volume.
Claims22
A bandpass woofer loudspeaker system comprising an enclosure having a partition dividing said enclosure into a first chamber and a second chamber, said first chamber being sealed and said second chamber having a passive radiating port communicating with air outside said enclosure, a driver comprising a transducer of the type having a diaphragm with front and rear sides, said driver mounted in the partition, and wherein said bandpass woofer loudspeaker system has a plurality of design variables including the following:
- Mmd=moving mass of the driver in kilograms
- fc=the resonance of the driver in the first sealed chamber
- MAS=acoustic moving mass of the driver
- CAT=acoustic compliance of the driver suspension and the first sealed chamber
- R0=the acoustic resistance of a moving coil of the driver
- MAP2=the acoustic mass of the passive radiating port
- CA2=acoustic compliance of the second chamber having the passive radiating port
- and wherein there are defined a first tuning ratio Q.sub.mc, a second tuning ratio Q.sub.tc, and a third tuning ratio Q.sub.tp dependent upon the values of said variables as follows:
- ##EQU4## and wherein said bandpass loudspeaker system is constructed such that said variables result in said first tuning ratio Q.sub.mc having a value in excess of 5.0, said second tuning ratio Q.sub.tc falling within a range of from about 0.75 to about 1.25, and said third tuning ratio Q.sub.tp falling within a range of from about 0.75 to about 1.25.
A method of configuring a single-vented bandpass woofer loudspeaker system to operate satisfactorily in smaller enclosure volumes with only moderate loss of efficiency, wherein the loudspeaker system is of the type having an enclosure with a partition dividing the enclosure into a first chamber and a second chamber, with the first chamber being sealed and the second chamber having a passive radiating port communicating with air outside the enclosure, a partition mounting a driver of the moving coil transducer type, the bandpass woofer loudspeaker system having a plurality of design variables including the following:
- Mmd=moving mass of the driver in kilograms
- fc=the resonance of the driver in the first sealed chamber
- MAS=acoustic moving mass of the driver
- CAT=acoustic compliance of the driver suspension and the first sealed chamber
- R0=the acoustic resistance of the moving coil of the driver
- MAP2=the acoustic mass of the passive radiating port
- CA2=acoustic compliance of the second chamber having the passive radiating port
- comprising the steps of defining a first tuning ratio Q.sub.mc, a second tuning ratio Q.sub.tc and a third tuning ratio Q.sub.tp as follows:
- ##EQU5## and controlling the design variables such that Q.sub.mc has a value in excess of 5.0, Q.sub.tc has a value falling within a range of from about 0.75 to about 1.25, and Q.sub.tp has a value following within a range of from about 0.75 to about 1.25.
Dependencies are inferred from the claim text.