I decided to build a pair of Wayne Parham's Pi 4 speakers that I will eventually use in my home theater. In the meantime, I will be using them for mostly music listening in my living room.
For those who are not familiar with the design, it is a 2-way speaker that uses 15 inch woofers and compression drivers mated to horns. Wayne offers several grades of components depending upon the amount you want to spend. The speakers can be purchased as complete units or in parts for us DIY'ers. Wayne has been gracious enough to share his design plans to anyone who asks. I decided to go the more expensive route by using JBL 2226H woofers, B&C DE250 compression drivers, and quality crossover components.
I wanted more bass extension than the original design calls for so I decided to increase the cabinet size by approximately 1 cubic foot. This was achieved by increasing the height 7 inches. Due to the larger cabinet size, I am using a double-thick front baffle (1.5 inches vs. 0.75 of an inch per plan). This extra thickness will be added to the exterior of the cabinet. The overall dimensions are: 33.5 tall x 18.5 wide x 15 deep. I am also changing the number of ports, their location and dimensions. Further, I am going to recess the drivers.
One area that concerns me is the midrange frequencies leaking out of the ports and blurring the image. There does not seem to be much information on this phenomenon. I could have the ports exit at the rear of the cabinet which would virtually eliminate any problems due to the lag in time before it reaches the listener but I prefer to have them exit in the front. In order to mitigate any issues I plan on using extensive polyfill to absorb some of the back wave and a semi-solid window brace between the woofer and ports (I will post a picture of this in a few days).
Attached are my Sketchup model of how I envision the cabinet to look and a few simulations of the JBL 2226 (per plans vs. my larger cabinet).
For those who are not familiar with the design, it is a 2-way speaker that uses 15 inch woofers and compression drivers mated to horns. Wayne offers several grades of components depending upon the amount you want to spend. The speakers can be purchased as complete units or in parts for us DIY'ers. Wayne has been gracious enough to share his design plans to anyone who asks. I decided to go the more expensive route by using JBL 2226H woofers, B&C DE250 compression drivers, and quality crossover components.
I wanted more bass extension than the original design calls for so I decided to increase the cabinet size by approximately 1 cubic foot. This was achieved by increasing the height 7 inches. Due to the larger cabinet size, I am using a double-thick front baffle (1.5 inches vs. 0.75 of an inch per plan). This extra thickness will be added to the exterior of the cabinet. The overall dimensions are: 33.5 tall x 18.5 wide x 15 deep. I am also changing the number of ports, their location and dimensions. Further, I am going to recess the drivers.
One area that concerns me is the midrange frequencies leaking out of the ports and blurring the image. There does not seem to be much information on this phenomenon. I could have the ports exit at the rear of the cabinet which would virtually eliminate any problems due to the lag in time before it reaches the listener but I prefer to have them exit in the front. In order to mitigate any issues I plan on using extensive polyfill to absorb some of the back wave and a semi-solid window brace between the woofer and ports (I will post a picture of this in a few days).
Attached are my Sketchup model of how I envision the cabinet to look and a few simulations of the JBL 2226 (per plans vs. my larger cabinet).
