I look at this size and Karlson's "K12" as practical alternative to small front loaded horns in systems requiring subwoofer, or for small PA work.
an additional chamber could be added to the top of the front chamber - whether worth it = "don't know"
anyhow - if forced to think about making such a speaker, what would you make for best subjective result?
when good coaxial are not available, a K-tube tweeter either internal or on top will do a good job and often sound better than conventional waveguide or horn - If - not run too low.
John Karlson introduced a new 15 inch K-coupler in 1965 which was loaded with a low qts 15" CTS woofer and called "X15". It was only about 1 cubic foot larger in external bulk than his K12 cabinet. It was sometimes advertised as "X15A" which may have designated the change from a 3" peaper cone tweeter in a mini - "klam" to a metal slotted pipe tweeter with 1 inch format compression driver. At ~57% bulk of the original Karlson 15 (aka "K15"), X15 lost about 1/2 octave in low frequency extension compared to K15.
The X15 size varian which appeared perhaps around 1980 and built by a number of companies (Transylvania Power Company, KK-Audio, Westwood, Acoustic Control and at least one more) had a large vent, a tapered rear section, and meausred quite smoothly even without any damping material.
Karlson's X15 side view dimensions (external width was ~19.5"0
K12B - proposed X15 size for 15 inch speaker
Carl Neuser's first X15A size coupler later made with curved
reflector. One can see the vent spacer blocks for adjustment
plus it had an adjustable rear lowpass gap for tuning and testing.
X15A with Fostex Sigma 208 coupler on top. The K-tube in the 15
inch coupler is from a vintage X15 circa 1966-67
Tuning and room response data for Carl's X15A with Klipsch K33E woofer
TB46 plan for a little 15" Karlson aperture woofer
Acoustic Control 115BL (X15 sized coupler) Side view dimensions - external width = 20.5"
115BK works pretty well - I don't know if it scaled up or down well with regards to smoothness. If scaled 1.2:1 then has about the same bulk as the Karlson K15 but will mount an 18". (I've had good luck with 18" K overall)
an additional chamber could be added to the top of the front chamber - whether worth it = "don't know"
anyhow - if forced to think about making such a speaker, what would you make for best subjective result?
when good coaxial are not available, a K-tube tweeter either internal or on top will do a good job and often sound better than conventional waveguide or horn - If - not run too low.
John Karlson introduced a new 15 inch K-coupler in 1965 which was loaded with a low qts 15" CTS woofer and called "X15". It was only about 1 cubic foot larger in external bulk than his K12 cabinet. It was sometimes advertised as "X15A" which may have designated the change from a 3" peaper cone tweeter in a mini - "klam" to a metal slotted pipe tweeter with 1 inch format compression driver. At ~57% bulk of the original Karlson 15 (aka "K15"), X15 lost about 1/2 octave in low frequency extension compared to K15.
The X15 size varian which appeared perhaps around 1980 and built by a number of companies (Transylvania Power Company, KK-Audio, Westwood, Acoustic Control and at least one more) had a large vent, a tapered rear section, and meausred quite smoothly even without any damping material.
Karlson's X15 side view dimensions (external width was ~19.5"0
K12B - proposed X15 size for 15 inch speaker
Carl Neuser's first X15A size coupler later made with curved
reflector. One can see the vent spacer blocks for adjustment
plus it had an adjustable rear lowpass gap for tuning and testing.
X15A with Fostex Sigma 208 coupler on top. The K-tube in the 15
inch coupler is from a vintage X15 circa 1966-67
Tuning and room response data for Carl's X15A with Klipsch K33E woofer
TB46 plan for a little 15" Karlson aperture woofer
Acoustic Control 115BL (X15 sized coupler) Side view dimensions - external width = 20.5"
115BK works pretty well - I don't know if it scaled up or down well with regards to smoothness. If scaled 1.2:1 then has about the same bulk as the Karlson K15 but will mount an 18". (I've had good luck with 18" K overall)