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Speaker Asylum General speaker questions for audio and home theater. |
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Speaker Asylum General speaker questions for audio and home theater. |
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In Reply to: Speaker Design question.. posted by mr9iron on December 18, 2020 at 12:36:57:
It would be helpful to know what driver and design you're working with.I really wonder whether you're starting with a valid design. The box and port dimensions are unusual to say the least. A basic calculator will give you a port tuning frequency in the vicinity of 60 Hz. That's questionable for a 10" woofer, which normally have fs in the 20-30 Hz range, maybe low 30s if it's made for higher sensitivity. A typical vented design with a 10" woofer should have a box volume 50-100% greater than the 2 ft^3 you're starting with and with a single longer port.
If you want to use a 10" woofer in a small enclosure i.e. 1.2 ft^3, and are looking to cover the 50-100 Hz range, that screams out for a sealed design rather than vented.
To answer your second question, you can't just double the port length. If you want to replace what is already two unusually short ports with a single port, you need to increase the diameter. With a 2 ft^3 box volume, two 3 x 2.75" ports would need to be replaced by a single 4.5 x 2" port, but that's a bit of a crap shoot because with a stubby port just 2" long, termination effects are going to be dominant and it's going to be hard to predict the result using a calculator.
But honestly, it makes no sense to aim for such a high port tuning frequency in a bass reflex design with a 10" woofer. If you want to design for a 1.2 ft^3 vented box, you should be looking at woofers in the 7" range. Let me give you a hypothetical driver in that size range: Qts = 0.4, Vas = 48l, fs = 45 Hz. Put that in a 1.2 ft^3 box with a single 3" diameter by 5.5" long port (or 2.5 x 3.5) and you'll achieve your desired f3 of 50 Hz with a critically damped and (theoretically) flat alignment.
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Follow Ups
- What design is this? - Dave_K 12/19/2015:09:22 12/19/20 (5)
- RE: What design is this? - mr9iron 12:39:26 12/21/20 (4)
- Not many 10" choices for a small vented box, but here's one - Dave_K 13:24:31 12/21/20 (3)
- RE: Not many 10" choices for a small vented box, but here's one - mr9iron 15:30:31 12/21/20 (2)
- Have you considered a kit? - Dave_K 14:24:44 12/22/20 (0)
- If you go sealed, you can EQ for more bottom end output - Brian H P 11:32:48 12/22/20 (0)
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