Ohhh Vixen.... I had a '74 2500M. Did a 5.0/C4 conversion. Lots of other toys, Morgan, Spit, now a 65 B and a 73 Stag. Clearly I don't learn too quick.
Used the Dayton RSS265HF. It looks like they are best suited as sealed woofers in a traditional floor standing 3-way not as serious subs, though the parameters of the 10 inch CSS work out identically. To get the tuning where I would like it, it winds up with ports over 24 long. Trying to do a BP-6, one solution was 142 inches. I probably require larger ports than some as I am quite adverse to chuff. These require a 5 inch at least by listening. In my testing, anything longer than about 12 caused too big of a port resonance issue. I also found I could not get the alignment anywhere near WinISD simulation. Front chamber just would not behave. Simulation show's for two drivers, 1 foot each chamber, port tuned to 62 Hz. Max flat for good transient, LF roll off well within room gain cut range and HF roll-off just above 100 with about 3 dB gain over ported. Bottom end was fine, but front impedance peak should have been 95 Hz and it would not tune above 75. So a very peaked response.
As a test, I added first 10 and then 20 grams to each cone. As expected, they needed much bigger boxes and shorter ports, tuned lower, and lost a bunch of efficiency. Might have considered that if my crossover was a lot lower, but using pairs of 5 inch mains and their distortion climbs like a wall below 80. 100 is a good target.
BP-4 still holds promise, just have to find the right drivers. I plugged in about a dozen from Madisound and PE, all had similar issues as the Daytons. I was very space/shape limited so 12's or 15's were out of the question. For my education, I wil keep looking and model both smaller and larger. I think some of the 8's I have seen like big boxes so the solution would work, just a lot of them! Or maybe some of the 15's with a higher Fs?
We have SOP for sealed vs ported based on EPB, but I have seen no such guidance for BP.
I was thinking, part of my problem is the port was not much smaller than the front chamber, so it was not really seeing it as a cavity. I was thinking the solution might have been to face the drivers into a center cavity, it being the "front" so there was a relatively larger space between the walls. The rear chambers to the sides. That way a couple of 5's would be considerably less space than taking an 11 x 4 off the end of an 11 x 6 chamber.
I have the old Dayton Titanic to play with. A couple sheets of PB and maybe I can figure it out.
Thinking outside the room, a 6 x 8 heat duct looks a lot like a port for a 15, so maybe a crawl space pair of subs for the living room?
Used the Dayton RSS265HF. It looks like they are best suited as sealed woofers in a traditional floor standing 3-way not as serious subs, though the parameters of the 10 inch CSS work out identically. To get the tuning where I would like it, it winds up with ports over 24 long. Trying to do a BP-6, one solution was 142 inches. I probably require larger ports than some as I am quite adverse to chuff. These require a 5 inch at least by listening. In my testing, anything longer than about 12 caused too big of a port resonance issue. I also found I could not get the alignment anywhere near WinISD simulation. Front chamber just would not behave. Simulation show's for two drivers, 1 foot each chamber, port tuned to 62 Hz. Max flat for good transient, LF roll off well within room gain cut range and HF roll-off just above 100 with about 3 dB gain over ported. Bottom end was fine, but front impedance peak should have been 95 Hz and it would not tune above 75. So a very peaked response.
As a test, I added first 10 and then 20 grams to each cone. As expected, they needed much bigger boxes and shorter ports, tuned lower, and lost a bunch of efficiency. Might have considered that if my crossover was a lot lower, but using pairs of 5 inch mains and their distortion climbs like a wall below 80. 100 is a good target.
BP-4 still holds promise, just have to find the right drivers. I plugged in about a dozen from Madisound and PE, all had similar issues as the Daytons. I was very space/shape limited so 12's or 15's were out of the question. For my education, I wil keep looking and model both smaller and larger. I think some of the 8's I have seen like big boxes so the solution would work, just a lot of them! Or maybe some of the 15's with a higher Fs?
We have SOP for sealed vs ported based on EPB, but I have seen no such guidance for BP.
I was thinking, part of my problem is the port was not much smaller than the front chamber, so it was not really seeing it as a cavity. I was thinking the solution might have been to face the drivers into a center cavity, it being the "front" so there was a relatively larger space between the walls. The rear chambers to the sides. That way a couple of 5's would be considerably less space than taking an 11 x 4 off the end of an 11 x 6 chamber.
I have the old Dayton Titanic to play with. A couple sheets of PB and maybe I can figure it out.
Thinking outside the room, a 6 x 8 heat duct looks a lot like a port for a 15, so maybe a crawl space pair of subs for the living room?
