So this journey begins. The design brief is to build a horn loaded system top to bottom and that is exactly the direction the development will take. The most complexity, finesse and detail is at the top end and my search starts there.
The space is a large open space with excellent bass and few early reflections and slightly damped (down tilted reverb). The bass modes are less than 10dB with no trapping, testament enough of the space involved. Those same properties are unforgiving as with the room sufficiently reduced in the equation one needs to really deliver an excellent end result. I am very excited to experience a bass horn here
Tweeter
It will likely be a little wider aiming than the one in the 2-ways and as a result I'll need to size up the mid slightly. If I want to have any shot at a simple crossover, I'll have to carefully balance off horn lengths and cutoffs. This covers the range where the ear is most sensitive and in such a well behaved space power response and on-axis response will have to correlate exceptionally well. I will likely go through at least 2-3 different flares, the choice of which will fall by listening as to which best matches the room.
Midrange
The horn will probably be the most sensitive and its role is as much to be utterly transparent as to blend directivity from the bass horn to the tweeter. The handover here will have to be determined by measurement of the Directivity Index and careful matching to the tweeter. Dedicated midrange drivers or large format compression drivers will be considered here, a choice from a narrow field made narrower by the ideal to cross to the bass below 500Hz for power response reasons.
(upper) Bass
The size and depth of this horn will be the primary constraints. It will have to match to the midrange horn and for that reason very rapid flare rates will come under consideration. This will limit the lower bass somewhat but make hand-over the the midrange easier. A custom driver is being commissioned to cover this bandwidth at maximum efficiency, a measure that reduces resonance at the lower part of the horn if I terminate at 90 degrees to the axis of symmetry. The exacting parameters also limit somewhat the rise into the lower mid which will result in sensitivites going from 109dB to depending on phasing plug design as high as 115dB, which would then be filtered to a final response flat and with the acoustical filter of the horn doing most of the work.
LowerBass
Francois is not known for liking systems that lack in the pants department. For a system and room like this there can ideally be only one subwoofer, a horn.
Due to size constraints the subwoofer will be flattened and bifurcated twice, a design that allows one to pack the horn in a larger area but in a slim package along a wall....and what better an opportunity to add some light acoustic treatment in the form of diffusion.
Many details will have to be fleshed out from the above framework. This is an opportunity that I cherish. My mind is not leaving me rest. I have already ordered a set of the bass drivers for myself and changed my own bass horn plans. For those who understand a bit about driver parameters, not many 12s have a BL factor around 30 Tm for an 8Ohm driver.
The space is a large open space with excellent bass and few early reflections and slightly damped (down tilted reverb). The bass modes are less than 10dB with no trapping, testament enough of the space involved. Those same properties are unforgiving as with the room sufficiently reduced in the equation one needs to really deliver an excellent end result. I am very excited to experience a bass horn here
Tweeter
It will likely be a little wider aiming than the one in the 2-ways and as a result I'll need to size up the mid slightly. If I want to have any shot at a simple crossover, I'll have to carefully balance off horn lengths and cutoffs. This covers the range where the ear is most sensitive and in such a well behaved space power response and on-axis response will have to correlate exceptionally well. I will likely go through at least 2-3 different flares, the choice of which will fall by listening as to which best matches the room.
Midrange
The horn will probably be the most sensitive and its role is as much to be utterly transparent as to blend directivity from the bass horn to the tweeter. The handover here will have to be determined by measurement of the Directivity Index and careful matching to the tweeter. Dedicated midrange drivers or large format compression drivers will be considered here, a choice from a narrow field made narrower by the ideal to cross to the bass below 500Hz for power response reasons.
(upper) Bass
The size and depth of this horn will be the primary constraints. It will have to match to the midrange horn and for that reason very rapid flare rates will come under consideration. This will limit the lower bass somewhat but make hand-over the the midrange easier. A custom driver is being commissioned to cover this bandwidth at maximum efficiency, a measure that reduces resonance at the lower part of the horn if I terminate at 90 degrees to the axis of symmetry. The exacting parameters also limit somewhat the rise into the lower mid which will result in sensitivites going from 109dB to depending on phasing plug design as high as 115dB, which would then be filtered to a final response flat and with the acoustical filter of the horn doing most of the work.
LowerBass
Francois is not known for liking systems that lack in the pants department. For a system and room like this there can ideally be only one subwoofer, a horn.
Due to size constraints the subwoofer will be flattened and bifurcated twice, a design that allows one to pack the horn in a larger area but in a slim package along a wall....and what better an opportunity to add some light acoustic treatment in the form of diffusion.
Many details will have to be fleshed out from the above framework. This is an opportunity that I cherish. My mind is not leaving me rest. I have already ordered a set of the bass drivers for myself and changed my own bass horn plans. For those who understand a bit about driver parameters, not many 12s have a BL factor around 30 Tm for an 8Ohm driver.
