Low Frequency Fury

Low Frequency Fury


Project Category:

Project Level:

Project Time:
1-8 Hours

Project Cost:
$500 – $1,000

Project Description:
The project is a home theater subwoofer. It uses a 12 inch Daytpn Audio Reference HO DVC subwoofer with 15 inch Dayton Audio aluminum cone passive radiator. It is powered with the SPA500 plate amplifier with active crossover and parametric equalizer.

Design Goals:
The goal with this project was to build an extremely strong subwoofer with very durable components for long term use.

Driver Selection:
Dayton Audio RSS315HO-44 12″ Reference HO DVC Subwoofer

Enclosure Design:
The enclosure uses a 15 inch passive radiator and 12 inch subwoofer. The woofer was mounted outside of the enclosure and is inverted under the bottom to save on box volume and give it some distinction from a classic subwoofer. The recommended vented volume from Parts Express for this subwoofer was 1.36 ft^3, also knowing the driver Qts from specification, I was able to determine the theoretical box alpha. The alpha parameter is the subwoofer’s volume to air compliance ratio to the recommended box volume. Knowing alpha and the subwoofer Qts I was able to figure out the recommended alignment and is a SBB4 according to the loudspeaker cookbook. Once the enclosure was constructed with all components in place I used a used a loudspeaker measuring system to physically measure the enclosure alpha parameter. I simply continued to add wood (to decrease enclosure volume) to the inside of the enclosure and remeasure alpha until I got the recommended alpha of the enclosure.

Enclosure Assembly:
The enclosure was really easy to construct. I simple used a jig say to cut the PR, subwoofer, and plate amp holes. I also caulked the removable front and back panels.

Crossover Design:
The plate amplifier has a built in crossover and so I did not add a passive filter network.

It’s awesome!!! This thing is a total beast. I have a large living room and you are completely enclosed in the sound from the subwoofer during a movie. It also work very well with music too. You can tell the subwoofer is higher SQ grade. The 500 watt plate amp with parametric equalizer has plenty enough power to push the sub hard. You can’t though, Its almost too much. It is so powerful, it feels like the air is being sucked out of the room when it hits.

About the Designer:
The project creator is has been building loudspeaker enclosures since the early 90’s. He has developed many subwoofer enclosures and has done development for a few major car audio manufactures. In addition he has built studio monitors for a few recording studios. He has a B.S. degree in Physics and is a working Nuclear Engineer and has been in that industry for 18 years.

Project Parts List:

Dayton Audio RSS315HO-44 12″ Reference HO DVC Subwoofer
Dayton Audio RSS390-PR 15″ Aluminum Cone Passive Radiator
Dayton Audio SPA500 500W Subwoofer Plate Amplifier
Dayton Audio SWC2-BK 2.0 cu. ft. Subwoofer Cabinet Gloss Black


Add yours
  1. 1
    adam webb

    This looks nice.I have been looking at the same parts to build a PR sub. Did you have to use any of the weights on the cone? Also, if you were to invert the active driver. What would you recommend for total internal airspace??


  2. 2

    Nice build. Do you have an approximate amount of wood needed to tune the alpha? For those of us without measuring equipment. Thanks

  3. 3

    I took all of the weights off the cone. They add too much mass to the cone. The natural resonate frequency is already low enough. You will find by removing the weights your efficiency will go way up. I really don’t know the exact volume because of the way I did it. I just added wood until I got the correct alpha. I can give a rough guess though. I would estimate you will probably have to reduce at least 25% of the internal volume. That is assuming the 12 is inverted.

  4. 4

    What test equipment did you use? I’d like to build two of these subs for son and myself. Rather than try to tune it by ear using an assortment of music and films, I’m thinking it would be easier to just test and calibrate them.

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