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The Subwoofer Page


  Subwoofer with grill cloth
  The AR.COM bookshelf speakers I made are supposedly flat down to about 60 Hz, so I needed to build a subwoofer to get the lowest octave. Subsequent measurements show that the speakers are actually flat to somewhere around 40 to 50 Hz, but the 30 to 50 Hz band is still needed. I wanted a musical subwoofer, not a home theater "rumbler". This means that it won't shake your chest in a DVD movie explosion, but it will reproduce the lowest-most bass notes possible from any musical instrument with much more accuracy than a home theater subwoofer can.  
  Subwoofer without grill cloth
  For the driver I chose an ACI model SV-10, with very long excursion. Considering it is only a 10-inch driver, it weighs a ton! Unfortunately, ACI is gone now, and the driver is no longer available. I designed the cabinet myself, and, like the main speakers, it is made from 3/4-inch MDF, covered with edge-mitered, oak-veneered, 1/4-inch plywood, sanded to 220, and finished with three coats of tung oil. The cabinet contains intricate braces, and the front panel (the "baffle") is doubled (1-1/2 inches thick!) I made the subwoofer concurrently with the first round of AR.COM speakers. The completed subwoofer weighs over 65 lbs.  
  Subwoofer back with amp
  To drive the subwoofer, I bought a Parts Express 150 watt subwoofer amplifier. Because the main speakers are good down to at least 50 Hz, the subwoofer amplifier's crossover is set to deliver only the sub-50 Hz signal to the subwoofer. As it turns out, ist seems that the best place to put the subwoofer in my living room is below the left speaker stand.  
  The total cost was about $260, including $100 for the drivers, $100 for the amplifier, $10 for the grill cloth and grill snaps, and $50 for the cabinet materials.  
  So, how does it sound? Again, I haven't heard any high-end subwoofers to compare, but it sure sounds good to me! I can clearly hear the bass player's fingers on the strings when they pluck those ultra-low notes. I have learned not to turn it up too loud - just loud enough to fill in that lowest range without overpowering the main speakers.  
 Black line 
Subwoofer Specifications
Driver Make/ModelACI SV-10 (10")
Driver Impedance4 ohms
Driver Resonance Frequency (Fs)18.5 Hz
Driver Q'sQms = 4.205
Qes = .394
Qts = .360
Driver VAS84 liters
Driver Xmax16 mm
Amplifier Make/ModelParts Express model #300-792
Amplifier Power156 watts/4 ohms @ 0.2% THD
Amplifier S/N98 dB
Cabinet Type2nd order sealed box
Cabinet Dimensions23-3/16" H x 15-1/16" W x 10-13/16" D
Cabinet Volume1.038 cu ft
Cabinet Qtc0.707
Cabinet Resonance Frequency (Fs)36.33 Hz
Cabinet F3/F1035 Hz / 22 Hz