Ok, playing with numbers.
8" tang band W8-2145 in 3/4" wood box, 33" x 20" x 12" ported (3.54ft3 not including driver area or port area).
1 : 1.618 ratio box
Since driver's qtc is .45, tune at 34.5hz for F3 near 31.8 hz.
All approximate...
How large diameter should the port be ?
My old numbers crunched say 3.62ft3 with a 2" port .5" deep makes for a 34.47hz tuning...…………
With a little stuffing, my thoughts would be keep port small as possible for 2 reasons.
1. The port is basically acting like a brake, not likely to get more than a few watts in b4 modulation distortion at my listening levels.
2. The larger the port, the more upper frequencies sneak out, badly mixing with the front cone sound.
On most any speaker, I hear plugging the port is a positive on the voice, but not for bass.
Looking at the fern and roby "Raven" (8" seas exotic), I'm unsure of the port diameter, seems like 2" though. They tune in 30's I think.
Fern & Roby Raven Loudspeakers | Review | Part-Time Audiophile
What are your thoughts ?
8" tang band W8-2145 in 3/4" wood box, 33" x 20" x 12" ported (3.54ft3 not including driver area or port area).
1 : 1.618 ratio box
Since driver's qtc is .45, tune at 34.5hz for F3 near 31.8 hz.
All approximate...
How large diameter should the port be ?
My old numbers crunched say 3.62ft3 with a 2" port .5" deep makes for a 34.47hz tuning...…………
With a little stuffing, my thoughts would be keep port small as possible for 2 reasons.
1. The port is basically acting like a brake, not likely to get more than a few watts in b4 modulation distortion at my listening levels.
2. The larger the port, the more upper frequencies sneak out, badly mixing with the front cone sound.
On most any speaker, I hear plugging the port is a positive on the voice, but not for bass.
Looking at the fern and roby "Raven" (8" seas exotic), I'm unsure of the port diameter, seems like 2" though. They tune in 30's I think.
Fern & Roby Raven Loudspeakers | Review | Part-Time Audiophile
What are your thoughts ?
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Unless duct CSA is sufficient to unbaffle the driver / box load, you don't really get midband 'leakage' as such. What you can get is noise via excess air velocity through a duct of insufficient CSA, or self-harmonic modes in an excessively long duct (ducts being 1/2 wave resonators). It can be a balancing act between the two. With my 'practical' hat on, for this application I would say a 2in or 3in diameter duct should be ample.
Well, vent mach ideally needs to be < ~ 4% vent mach, so use HR to find what size drops it to < ~13.76 m/s, then critically damped to quell any audible pipe harmonics/spurious driver resonances [the latter are best done by loosely covering the back of the driver with an acoustic 'blanket' with reflex, smaller/shorter ducts].
GM