GOAL

To reuse my 10" Pyle subwoofers for a home theater sub.My current speaker setup is a set of 5 NHT speakers.The NHT front speakers work well.They do lack the really deep bass some movie soundtracks require.

SPEAKERS

        Here are the manufacturer’s specs on the 10" Pyle speakers.They are 4 ohms; I wired them in series to yield 8 ohms.

DESIGN

            Running the numbers through WinISD, I came up with an internal volume of 59 liters,Fb of 37.5 Hz and an F3 ofapprox. 38 Hz.After a post on DIYAudio, I followed the recommendation of using an internal volume of 100 L (200 liters for 2 woofers) and an Fb around 30 Hz.Since my NHTSuperTwos have an F3 of 35 Hz, I figured lowering the F3 of the sub to 30 Hz was not a bad idea.Using an online port length calculator, I came up with a 3.77-inch-long 3" port.I used the standard 3" port from Parts Express and cut it to 3¾" long.The subs will be powered by a Parts Express plate amp. It is 15 RMS watts into 8 ohms w/ 0.1 THD.

Figure 1 Original Calculated Volume, Fb & F3

Figure 2 Optimized Volume, Fb & F3

Port Length Image

Figure 3 Port Length Calculator

CABINET

            By the time I added the volume of the braces, a 200-liter cabinet is large, about 25" square. The center vertical brace is offset a bit. Everything is constructed with ¾" MDF.The corners have painter’s caulk as a sealant.All 6 sides are glued and screwed together with drywall screws.One lesson I did learn the hard way is to plan your cuts beforehand.With a cabinet slightly over 24" square, I could get only half the pieces out of one sheet of MDF, which forced me to buy another sheet. I had to buy two full sheets with plenty left over!A trick I did learn is to build two of your panels big (front & back) and trim with a flush-trim bit on the router. Makes a huge difference.I also filled my screw holes and imperfections at the butt joints with Bondo All-Purpose Putty.It worked well; it spread nice and sanded nice.The only drawback is that it had only a 5-minute open time.You have to mix some batches and work quickly.Once it starts to cure, stop spreading, you will just make it worse!

Figure 4 The main brace all cut out.I rounded over the edges of the holes.

Figure 5 All bracing installed and the corners caulked.

Figure 6 Cabinet assembled and Bondo applied to the butt joints to hide my poor woodworking skills.

Figure 7 Three coats of primer, sanding with 100-grit, 220-grit and finally 400-grit.Notice the

high spots that are now exposed.

Figure 8 Front view after sanding.

Figure 9Semigloss black paint applied. Four coats.Plate amp installed.

Figure 10 New home, in the corner behind the TV.

LISTENING

            I have done very little true listening.I am in the process of trying to select the proper volume (on amp) and crossover freq. to blend with my SuperTwos.It is a little tricky because the sub points in a different direction.The NHTSuperTwos point toward the sofa, and the sub points toward my recliner.Each location has a different sound.


 


 


 


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