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Dr. K's MTM

Dr. K's MTM
Design Goals
Driver Selection
Enclosure Design
Enclosure Assembly
Crossover Design
  Assembly How-to-Guide Conclusion
Parts List
About the Designer
- Enclosure Design -

For simplicity's sake, I chose to use the 1.0 cu. ft. MTM finished speaker cabinet in gloss black. This is tuned to 40 Hz via a 2-1/2" diameter by 7" port. I would call this a "high-output" alignment, which in an actively-XO'd home theatre system should be able to produce over 110 dB of output with no overexcursion troubles. The higher low-end cutoff also allows these speakers to blend well into smaller listening rooms without excessive room gain.

I figured from the beginning of this design that it would be most likely replicated as a floor-standing tower. So, as part of the crossover design process, I actually did most of the testing and optimizing as if the speaker was a tower. This does not mean that the stand-mount version is sub-standard, but rather that the design is suitable for either confi guration. So, don't hesitate to adjust the box dimensions and tuning to your own taste, my only advice would be to try to maintain roughly a 9" wide baffle.

Since I figure this will be popular as a tower, I went ahead and modeled a couple of floor-standing variations just to give people an idea of the alternatives. One is a "standard" alignment that has good bass extension but still a relatively compact size. This is 1.2 cu. ft., tuned to about 38 Hz via a 3" x 8.5" port. Using 3/4" MDF, this would translate into a cabinet of roughly 9" width, 40" height, and 9" depth, externally. A larger "extended bass" version of the tower would be approximately 1.7 cu. ft., tuned to 35 Hz via a 3" x 6-1/2" port. Again using 3/4" MDF, this cabinet would measure roughly 9" wide, 40" tall, and 12" deep. Note for these larger cabinets, a 3" diameter port is preferred, and a 4" port is an option if you are going to be running the speakers at high power.
Enclosure Drawing