Yeah that’s fine Tim I got it covered. Its called room reinforcement. Every room has it to some extent. 3 dB per octave is rule of thumb. But it varies.
The free Parts Express cabs are all sealed. Frequency response of a sealed enclosure drops off very gradually, which actually turns out fine because the drop off is pretty much offset by room reinforcement. But you never can be sure your room reinforcement will kick in just right to match your speaker roll off. They may roll off early. So what Duke suggested, and I of course did, is build 2 sealed and 2 ported.
This way if it turns out I need the extra extension I’ve got it covered with the ported subs. But if it turns out that’s too much then I can simply plug one or two, in effect turning them into sealed cabs with the earlier/slower roll-off.
Some of this I have known since it feels like forever- from having built a transmission line speaker in 1980, and a ported sub about 10 years later. But a lot of the details used here, the use of room reinforcement, the sealed/ported options, and especially the distributed bass array concept itself, for all of that I owe a huge debt of gratitude to Duke. When it gets into "exactly how he does this" its proprietary info but everything else he has been graciously willing to share. As exemplified in his posts here. I only wish more were able to get their minds around this revolutionary development in subwoofer technology.
The free Parts Express cabs are all sealed. Frequency response of a sealed enclosure drops off very gradually, which actually turns out fine because the drop off is pretty much offset by room reinforcement. But you never can be sure your room reinforcement will kick in just right to match your speaker roll off. They may roll off early. So what Duke suggested, and I of course did, is build 2 sealed and 2 ported.
This way if it turns out I need the extra extension I’ve got it covered with the ported subs. But if it turns out that’s too much then I can simply plug one or two, in effect turning them into sealed cabs with the earlier/slower roll-off.
Some of this I have known since it feels like forever- from having built a transmission line speaker in 1980, and a ported sub about 10 years later. But a lot of the details used here, the use of room reinforcement, the sealed/ported options, and especially the distributed bass array concept itself, for all of that I owe a huge debt of gratitude to Duke. When it gets into "exactly how he does this" its proprietary info but everything else he has been graciously willing to share. As exemplified in his posts here. I only wish more were able to get their minds around this revolutionary development in subwoofer technology.