![]() It was instead imagined that decades down the road, nuclear energy would become advanced enough to find everyday use in domestic settings, and the Ford Nucleon was a design exercise imagining a car powered by nuclear energy as opposed to a gasoline driven engine. Hell, the commonly reposted Ford Nucleon concept from 1958 wasn't even based on technology that existed when it was made, no nuclear reactor in the late 50s was small enough and still powerful enough to both power a car and shield humans inside and outside the vehicle from lethal radiation doses. With that enabled, things got ugly real quick.Because concept car designers don't have to worry about real world considerations like practicality, crash safety standards, manufacturing viability, or anything besides artistic expression and playing around with hypothetics. I thought that I had a pretty good design, I had missed the "Include effect of port resonance" check box. My second mistake.Īfter that came WinISD, UniBox, Vectorworks, MiniDSP, etc. Looking at all of the subwoofer design stuff on the internet, I thought, "This looks easy". This led me to buy a RSS265HO, my first mistake. I was originally going to simply replace the amp in the PSB box, but it turned out that the driver was open circuit. My mains, PSB VisionSound VS400, are a little anemic at low frequency nothing much below about 60-70 Hz. I have a tenant, living downstairs, so house shaking bass would be nice but probably overkill. I was simply looking to replace it with a more robust bass extender. 15' wide x 17' long x 8-9' H (vaulted) open concept with kitchen 9' opening and hallway out back.Ī couple of months ago, my old PSB SubSeries 5i broke, again. Radio most days all day Home theatre, yes: Music, Yes. If you want a ported sub, then the sweet spot for driver Qtc is in the 0.3 to 0.35 range. You can not contemplate a ported design with this driver. In a ported enclosure, in addition to the port resonance the bass will be highly resonant and boomy. The other issue is the Q of the whole system, which can never be lower than driver Qts, Sealed if just gets in below a total system Q of 0.7. For a normal living room I think you will be disappointed. If this is in a small room, like a small office it will be fine. This will give you a practical output of 98 db at 30 Hz. Now to flatten the frequency response requires Eq of 12 d per octave starting at 60 to 65 Hz, so you will have 12 db of boost by 30 Hz. Now even before Eq the cone displacement at 30 Hz is 10 mm, so you have two mm to play with. The Fs of the driver is 26 Hz and that sets the practical limit of the low end response. So you really have no room for Eq to 30 Hz or so at good spl. In an optimal sealed enclosure F3 is 65 Hz, and the xmax of that driver is only 12.3 mm. So this driver can only be placed in a sealed enclosure. ![]() Your first clue is your long port length, which is so long you will have a nasty honky port resonance. The Qts is too high, and suspension too loose. The driver is not suitable for ported loading. That looks like a driver for a small half cu.ft sealed box for automobile use. In my view you have made a poor driver selection for home audio. I am going to be using a 3/4 inch round over router bit to make the inlet and outlet flanges. ((2.1 + 2.945) * 2) + This is the inlet and outlet transitions.Ħ.953 + The straight below the outlet port.ġ5.503 + The U-turn at the bottom of the box.Ĥ7.606" Total port length to middle of adjustment rangeġ20/2.54 = 47.25 Design software port length for 14 cm round port equivalent (3.75" x 6.375") I could shorten it up by moving the u-turn up a little if need be. ![]() I have designed in a sliding exit port to allow me to adjust the length of the port, just in case.Īnyhow, what I need is to have someone take a look at this and tell me if my port length calculation is correct. Or if you prefer UniBox: (For those with MS Excel.) I an using a Dayton Audio RSS265HF-4 10" driver and have run the numbers through WinISD and UniBox they both come up with a port length of about 120 cm for my box - Link to design PDF below: I hope some more experienced Sub-Builders will take a look at my design and give me feedback before I get too deep in sawdust.
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