At 4.5 cu. feet and a 4.5 inch port it would seem that the 2-Pi tower would have a port frequency of 49 hertz. Does the insulation slow down the airspeed this much ? Or is it because the sound has to pass thru 2 sheets of insulation ? Does the insulation act like a air-port like the dynaco used ? Thanks.
Wayne Parham Messages: 18787 Registered: January 2001
Illuminati (33rd Degree)
If you measure it, you'll find it resonates around 40Hz to 42Hz, somewhere in there. I've seen some Helmholtz calculators that show values a little higher, some a little lower. Mostly I think it's the difference in the area offset, sometimes called "corrected length". If you try two or three different calculators, you'll see what I mean.
The tower two π is a little trickier than some bass reflex cabinets in that standing waves are developed within the passband. That makes port and driver location pretty important. It also makes the insulation even more important than usual, so be sure to install it as described in the plans.
Wayne Parham Messages: 18787 Registered: January 2001
Illuminati (33rd Degree)
Well, not necessarily. It probably is, and I think most of the software out there does a pretty good job modeling. But I also think that real short ports and/or those with large area start to deviate more due to length correction. Insulation has an influence too, as do other factors. The good thing is if you get it close, you're fine because this isn't a place where being spot-on is required or even possible. There are too many parameter shifts in this kind of system.
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