Hi, I want to build my first subwoofer box by myself. I have a pioneer TSW304R 12" woofer and I used Bassbox Pro software for the calculation.
The software provides the dimensional details. I need to know that the "internal volume" of the box given by the software includes the "port volume" or not.
Anyone please verify the details from the attached images and help me to complete my design.
Udhay
The software provides the dimensional details. I need to know that the "internal volume" of the box given by the software includes the "port volume" or not.
Anyone please verify the details from the attached images and help me to complete my design.
Udhay
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"Volume" is traditionally just the chamber; the port is assumed to be tacked-on externally.
This is something which "should" be in the program's Help/FAQ file? Many folks now using computer tools have never done it from basic theory, so need such clues.
The basic math comes from Helmholtz' study of things we would call "jugs", large bottle with small neck. The volume enclosed in the neck is assumed to be small, and not included in the volume of the bottle.
Your rendering suggests a huge duct. This would cast doubt on the simple equation. However poking the numbers gives a 12l duct with a 170l volume, which seems reasonable. I'd also note that the "170l" volume could probably be (170l-12l) or 158l, for total 170l including duct, without huge change of tuning (about 3% on the frequency scale, half a semitone). So you could read it either way and it would not suck.
This is something which "should" be in the program's Help/FAQ file? Many folks now using computer tools have never done it from basic theory, so need such clues.
The basic math comes from Helmholtz' study of things we would call "jugs", large bottle with small neck. The volume enclosed in the neck is assumed to be small, and not included in the volume of the bottle.
Your rendering suggests a huge duct. This would cast doubt on the simple equation. However poking the numbers gives a 12l duct with a 170l volume, which seems reasonable. I'd also note that the "170l" volume could probably be (170l-12l) or 158l, for total 170l including duct, without huge change of tuning (about 3% on the frequency scale, half a semitone). So you could read it either way and it would not suck.
Only a small number of today's car audio drivers are "suited for a ported box", if we go by just basic T/S parameters. However, there's these additional factors to consider:
1. The in-car transfer function (usually taken to be 12dB/octave below around 80~120 Hz, though it will likely peak around 50~60 Hz)
2. The "vent anyway and fix by EQ" method
3. The increased power handling of a vented alignment
4. The target market for these drivers, who tend towards liking that droning bass that sounds like a tractor on a move and isn't even remotely accurate in nature
5. The impact of "semi-inductance" on the actual response of these drivers in any alignment
Take those all into consideration, and a vented box could be a better choice for this driver, at least for car audio use.
Having said that, if I was considering a vented box with that long a vent, I'd probably go "all the way" and start looking at a TL design instead.
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