Powered Sub-First Build

Powered Sub-First Build

Charles H Downey

Project Category:

Project Level:

Project Time:
8-20 Hours

Project Cost:
$100 – $500

Project Description:
Driver-Dayton Reference series HSS315HF-4 12″ sub driver.
Plate Amp-Dayton SPA250DSP
Enclosure design-Ported (slot) enclosure based on SBB4 with Qloss between 7 and 3 (first enclosure I made so some wiggle room in allowance. Calculated values were Vb-3.5cf (fair amount of bracing and port volume to be subtracted), 2″ tall by 9.5″ wide by 32″ long slot port.
Box construction done in 3/4″ birch ply. Box joints are double rabbet rather than butt joints. Internal bracing configured to increase box stiffness by increasing sectional I. To minimize internal volume loss, the slot port structure was integrated into the bracing.
Exterior finish for front baffle and back are clear lacquer over black automotive lacquer. Sides and top are clear lacquer over striped african mahogany veneer

Design Goals:
Design and build enclosure for sub with 150W plate amp with DSP for home audio with as clean a sound as possible in 2.1 set-up where used as 50/50 music/HT usage. Setup is in 16’x 32′ living room with 9′ ceilings. As it is in living room, esthetics were considered. Budget $500 or less

Driver Selection:

Enclosure Design:
3.5 cubic foot bass reflex enclosure with slot port tuned to 25.8 hz (calculated)

Enclosure Assembly:
Double rabbet joints, internal bracing. Photos depict only middle third of bracing. First and last third installed after sides were installed

Crossover Design:

Tips & Tricks:
After construction I had a small amount of muddyness that I believe was due to reflection from the rear of the cabinet to the rear of the driver. Poly fill from an old pillow was placed in this area and seems to have cleared up resolution

This project was a blast. I thought it came out not too bad for first project, and it sounds absolutely awesome

About the Designer:
Retired law enforcement, and currently doing a post retirement gig as a geotechnical engineer in Florida. Other hobbies include woodworking including making cigar humidors.

Project Parts List:

Dayton Audio SPA250DSP 250W Subwoofer Plate Amplifier with DSP
Dayton Audio RSS315HF-4 12″ Reference HF Subwoofer 4 Ohm


Add yours
  1. 1

    Because there’s an auxiliary input and output on the plate amplifier, is it possible to use this with powered monitors? Where the source would be sent into the plate amp, a crossover would be created using the built in dsp, and then I could connect my monitors into the auxiliary output?

    By the way, love the finish on the box, very nice👍🏻

    • 2

      John. First thanks for the comments. Second the outputs , while full range, are line level on this particular amp. On my receiver I’m using one of the sub outs with receiver cross over defeated so there is no conflict with the DSP on the plate. If someone wanted to use those line out jacks in that configuration it would be in mono. If I were to use line out jacks on a receiver (newer receivers under 700 or so typically don’t have them to save cost) to line in on the sub amp and then line out from the sub amp to self powered speakers that would work. Hope this helps

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