The TDL® model 912 is a complete and compact subwoofer system using an 8 inch dual voice coil (DVC) loudspeaker in a small, sealed enclosure. The 912 is based on Daniel L. Ferguson's design as described in his article in the September 2004 issue of AudioXpress magazine.*
One of the two voice coils is driven by the built-in power amplifier. The output from the other voice coil is used as a feedback signal to broaden and flatten the frequency response. This makes it possible to get low frequency bass (down to 25 Hz) from an enclosure measuring just 12 x 12 x 12 inches (one cubic foot) in outside dimensions.
We first built the system (using a 12 inch speaker) as described in the AudioXpress article. After listening to it for about a year, we were able to simplify it so there are only three front panel controls: Set Input Level, Crossover Frequency and Volume. This makes the 912 very easy to setup and to use. The crossover frequency can be set in 5 Hz steps from 75 to 125 Hz. This range will match virtually any set of main speakers.
The 912 is a complete subwoofer system and includes all interconnecting cables. Just connect a stereo input from your sound system and start listening.
There is an array of ten LEDs (level indicator) on the front panel to help you set the stereo input level and there is a built-in 50 watt power amplifier to drive the speaker. Complete Setup and Operating details as well as all the circuit diagrams and parts list are in the User Guide which can be freely downloaded from our web site. We have also written extensive notes on both the 8 inch and 12 inch prototype systems. You may download a copy from our web site at www.tdl-tech.com/dualvc.zip The file size is about 1.42 MB and all pages are in Adobe Acrobat pdf format or jpg photos.
The 912 control unit is housed in a rack-mount enclosure measuring 19 wide by 3.25 high by 9.5 deep (overall) inches. Four stick-on rubber bumpers (enclosure feet) are included if you don't want to rack mount it.
The 912 system is shipped in two cartons and the total shipping weight is approximately 46 pounds. Packing and handling are included in the purchase price so your only additional cost is the actual shipping charge to your location.
ENCLOSURE FINISH: Acrylic eggshell enamel in either "Wind Rush" blue or "Canyonland" beige. Color chips will be sent on request.
FURNISHED:
Model 912 Control Unit Wall mount power supply 8 inch DVC speaker in sealed enclosure with spike cone feet Speaker driver cable with connectors (specify needed length -- 8 to 25 feet) Control unit feedback cable with connectors (specify needed length -- 8 to 25 feet) (2) "Y" adapters Stereo input cable with connectors -- 6 foot length (4) Rack mount screws (4) Stick-on rubber bumpers Piece of rubberized fabric (see User Guide) Printed copy of the User Guide
AVAILABILITY: Stock to 6 weeks.
PRICE: See price list. PRICES
