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Why does port length increase when two ports replace one?

14446 Views 14 Replies 8 Participants Last post by  talunceford
As per title,

Just wondering why two ports are required to be longer than a single port?

For instance if I tune a cab with a single 10" port, but the port velocity is too high and I add another port, these ports are then required to be 22.5" long each?
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Not necessarily - some 15" drivers work quite well in a relatively small (~2 cubic feet) box. However, the efficiency is pretty horrible - expect to use a 1kW+ amp to get the most out of 'em.
I'm sure Moonfly was referring to ported, it would be a challenge to port a high excursion 15" driver in 2 cu.ft.
I was modeling a dayton 12in hf in a 4.2ft³ and wanted the look of the svs with 3 ports. I like how proportional the box looks in regards to the driver and 3 ports.

5 cu.ft. tuned to 21 hz would get the most performance from a RSS315HF with a 500 watt amp. Three 3" flared ports
each need to be 24.5" long. 4" flared ports wouldn't be practical as they would each need to be 44" long.

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