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Loudspeaker Designs and Articles for the DIY Enthusiast
Jim Holtz's:
Finalists

Big sound from a monitor sized
speaker design using high
value drivers.
Enclosure Design
Jim:
My goal for the enclosure was to be small enough to be stand mounted yet large enough to maintain an F/3 in the low 30’s. I also wanted a simple to
build cabinet that would not be too complicated for builders new to DIY to tackle. Another goal was to use 6” PVC for the mid tunnel to explore benefits of a
round vs. square construction.
The cabinet measures 24”H x 11”W x 15 ½”D with a 1 ¼” thick front baffle and a single horizontal window pane brace to add extra stiffness to the cabinet.
This sizing provided a net volume of about 38 liters. We used a 2 ½” adjustable port ( part # 260-386) sized at 7.75 inches for an F/3 of around 32 Hz.
I mounted the PVC mid tunnel by cutting a front and back piece of 3/4” MDF 7 ½” x 9 ½” with a ½” x 6 5/8” deep cutout to accommodate the PVC. That left a
¼” lip for the PVC to butt against on both front and back. I then did a ¾” round over after clamping this piece to the inside of the front baffle for a smooth
transition and to eliminate the “tunnel effect” on the driver. The PVC I bought is the thick walled variety that measures 6 5/8” OD and 6” ID. I cut the mid
tunnel PVC to 13” long.

Curt: Jim and I started discussing a design utilizing a 5” mid some time ago, and when Jim suggested using 6“ PVC for the tunnel, I agreed it would be the
perfect tunnel medium. Because of the cylindrical shape the only standing wave possible is down the length of the tunnel, but this ameliorated by the foam
lining and plugging the tunnel. This also allows for fine tuning of the midrange sound discussed in a later section.

  
Curt 7/04/2016: I added the Classic Transmission Line enclosure drawings at the bottom of this page. The modeled response of the TL version as well as
some notes are shown at the bottom of the crossover design page. All other plots represent Jim's original vented design.  
Links to:

Main / Design Goals

Driver Selection

Cabinet Construction

Crossover Design

Measurements

Listening Impressions
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