# A few noobie Q's about box design

Discussion in 'Home Theater Projects' started by David_Moechnig, Jun 27, 2004.

1. ### David_Moechnig Stunt Coordinator

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I just picked up a copy of Vance Dickason's Loudspeaker Design Cookbook 6th Edition and have read almost all of it in the last few days. Today I decided to start using the formulas for vented box design whth various dirvers from the Parts Express catalog and came up with a few questions I would like answered.

1) There are two formulas for minimum port diameter. They both yield vastly different results. I.E. Using a Peerless 850146 10" woofer in a SBB4 alignment (Qts=0.36, Vas=144.4L, fs=22.6 Hz, and Vd=.000297 m3) dvmin= 6.36" or 3.18" Which formula is better? More accurate? Or would taking the average be sufficient? How would you all work this?

2) Say the formula for port diamter yields 6.36"==>6.5" (for round number sake) This is a large port, say I want to make 2 ports with the same area. This would make 2 X 4.6" ports. Now we come to the port length formula which takes into account the port radius. If 2 smaller ports are used do you use their radii or the radius of the single large diameter port to calculate length?

3) Lastly (for now at least), the ports take up internal volume. Does enclosure volume include the air inside the port(s) or would you consider that a solid cylinder and modify you cabinent dimensions (L X W X H) to allow for the volume the port displaces?

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