Do not be misled by the speculative prattling of Jonmarsh... the technology of the Old Republic is well known to the core cognoscenti, and steps taken to revive it are much farther along than the pitiful efforts of nostalgic experimenters...
Just recently I found a cache of artifacts from the old days, and completed initial testing on a bandpass design created in the prime of the Old Republic...
SPL response
Impedance
For one skilled in the Dark arts, there are a multitude of potential solutions waiting to be unlocked, depending on how you prefer to fine tune the end solution- all of the next possibilities use the same rear chamber volume, but are tuned by changes in the front system design alignment. This allows a degree of voicing control not feasible with conventional sealed and ported cabinets... but note the inevitable interaction with sensitivity- either a blessing or a curse, depending on your choices.
The most important factor is the availability of improved technologies in both drivers and cabinet materials- it is completely possible that a new level of performance is now achievable.
Fb = 50Hz - This is tuned for the lowest bass extension with a slight peaking of the very low frequency response. But this compromises sensitivity. Note the F3 point.
Fb = 60Hz - This is a "nominal" configuration close to the theoretical nominal optimum for this driver, assuming a roughly flat response and good extension- note the F3 point.
Fb = 65Hz - this is a configuration that might be said to optimize the mid bass level and articulation, as well as overall sensitivity. Note the F3- still very good by music standards.
As you can see from the graphs, these tuning efforts also interact with the basic sensitivity- this is an inevitable characteristic of bandpass enclosures. Here, the span of change in sensitivity is 4 dB- all for the same driver and rear enclosure volume. The Bandpass enclosure is relatively unique in how much the enclosure takes control of the driver behavior....
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Just recently I found a cache of artifacts from the old days, and completed initial testing on a bandpass design created in the prime of the Old Republic...
SPL response
Impedance
For one skilled in the Dark arts, there are a multitude of potential solutions waiting to be unlocked, depending on how you prefer to fine tune the end solution- all of the next possibilities use the same rear chamber volume, but are tuned by changes in the front system design alignment. This allows a degree of voicing control not feasible with conventional sealed and ported cabinets... but note the inevitable interaction with sensitivity- either a blessing or a curse, depending on your choices.
The most important factor is the availability of improved technologies in both drivers and cabinet materials- it is completely possible that a new level of performance is now achievable.
Fb = 50Hz - This is tuned for the lowest bass extension with a slight peaking of the very low frequency response. But this compromises sensitivity. Note the F3 point.
Fb = 60Hz - This is a "nominal" configuration close to the theoretical nominal optimum for this driver, assuming a roughly flat response and good extension- note the F3 point.
Fb = 65Hz - this is a configuration that might be said to optimize the mid bass level and articulation, as well as overall sensitivity. Note the F3- still very good by music standards.
As you can see from the graphs, these tuning efforts also interact with the basic sensitivity- this is an inevitable characteristic of bandpass enclosures. Here, the span of change in sensitivity is 4 dB- all for the same driver and rear enclosure volume. The Bandpass enclosure is relatively unique in how much the enclosure takes control of the driver behavior....
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