I am designing ported enclosures for a pair of 12" Jensen Sigma triax speakers (ca. 1960). These have no T-S params available, but original Jensen factory info indicates the woofer has a free-air resonance of 25 Hz, and also gives enclosure design specs which recommends port diameter and length for various box volumes. I have selected a 3.0 cu ft volume which requires a 2" diameter port (can't remember the port length right now but it's not relevant to the current question).
I know the volume is the INTERNAL volume of the box, i.e. I have to properly account for the thickness of the walls, but I have never heard or seen it stated whether the volume of the port itself or the space taken up by the driver(s) inside the cabinet should be counted as internal volume or not? Do I design a box of 3.0 cu ft. PLUS the port tube PLUS the driver volume, so the "net" volume is 3.0, or just make a rectangular 3.0 cu ft box and neglect the volume taken up by the port tube and driver? Obviously Jensen experimented with various port and box sizes, but they didn't specify how they calculated volume. Is there a standard for this?
Another separate question: Where should sound dampening insulation be used if at all? For such a speaker, is it better to use 1" thick insulation on the walls (except the front baffle), or fill with fiberfill, or use none at all?
Thanky thank for your advice. (Glad AK is back up...I missed it...altho it's a little less happy cause of some strife...I hope we get beyond that.)
I know the volume is the INTERNAL volume of the box, i.e. I have to properly account for the thickness of the walls, but I have never heard or seen it stated whether the volume of the port itself or the space taken up by the driver(s) inside the cabinet should be counted as internal volume or not? Do I design a box of 3.0 cu ft. PLUS the port tube PLUS the driver volume, so the "net" volume is 3.0, or just make a rectangular 3.0 cu ft box and neglect the volume taken up by the port tube and driver? Obviously Jensen experimented with various port and box sizes, but they didn't specify how they calculated volume. Is there a standard for this?
Another separate question: Where should sound dampening insulation be used if at all? For such a speaker, is it better to use 1" thick insulation on the walls (except the front baffle), or fill with fiberfill, or use none at all?
Thanky thank for your advice. (Glad AK is back up...I missed it...altho it's a little less happy cause of some strife...I hope we get beyond that.)
Maybe I should mention DeOxit. :thumbsdn: Har har.