Please note that all this data is now furnished as "information only." These products are not available for sale.
"12 inch Dual Voice Coil Servo Subwoofer System" by Daniel L. Ferguson,
AudioXpress, September 2004 absolutely qualifies! Mr. Ferguson is
to be congratulated for this design. It's one of the most innovative
audio ideas I've seen in nearly 50 years of working in this field. It
makes true sub bass in a small box a reality for anyone who wants to
I have built Mr. Ferguson's original 12" version and an 8" version and both perform wonderfully. I've designed a circuit board for the filters and servo controller. I have made frequency response curves, taken photos and written several pages of notes. All of this information is included in the file dualvc.zip which you can freely download and use. (Size is about 1.4 MB) All the text and drawing files are in Adobe pdf format and the photos are color jpg's.
My good friend and speaker building mentor, Tom Simmons, passed away last October (2004) from ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease). He will be missed by many, myself included.
During the past year, Tom and I discussed several speaker designs at length... which I've named the Tom Simmons Memorial Designs, numbers 1 and 2. For more info, please click on the buttons below.