Double Trouble

Designer: Matt Phillips 2

Project Time: 8-20 hours
Project Complexity: Hobbyist
Project Cost: $500-$1000

Driver Selection
If you have followed any of my other projects, then you know I like to get a lot from a little. So, when Dayton Audio brought in the new Ultimax subwoofers, they piqued my interest immediately. I modeled a few different designs and decided the 10″ would be perfect (of course) –after all, I would be using two of them. The Ultimax subwoofers are incredibly overbuilt, have the stiffest cone assemblies I’ve ever encountered, possess very low-distortion motor structures, and their high-roll surrounds will make most other subwoofers in this class run home to their mommies.

Enclosure Design
I like the look of my cabinets to be deep and narrow if possible, so I came up with exterior dimensions that complemented the proper internal volume. I knew I was going to use overkill bracing and I also wanted to have a sand-filled cavity to help balance out the overall weight of the enclosure. Because of this, my exterior dimensions ended up being 12-1/2″ W x 17-1/2″ H x 19″ D, with a total internal volume of 1.043 cubic feet after driver and bracing displacement. This provided a slightly low Qtc of 0.632. The amount of bracing I used may not be necessary for most people, but I knew that I wouldn’t be happy without it. These drivers will still perform admirably when used with a 1.0 cubic foot Dayton Audio enclosure.

Amplifier/Crossover Configuration
I did not use a traditional plate amplifier for these subwoofers. Instead, I employed a Behringer EP4000 pro audio amplifier that provides approximately 950 watts to each subwoofer driver at 4 ohms. Yes, this is more than enough, but I like to have the headroom available. I also added a Behringer FBQ1000 Feedback Destroyer to operate as a subwoofer equalizer. This has fully adjustable parametric filters down to 20 Hz, which makes it ideal for a subwoofer application. Once I got the EQ dialed in to my listening position, the room response was flat to about 18 Hz.

Enclosure Assembly
These were built using 3/4″ MDF that was glued, clamped, and brad nailed together. I incorporated excessive bracing, a double thick (1-1/2″) baffle, and about 25 lbs. of sand in a rear chamber in the enclosure. I cannot say whether the sand damped the enclosure, although the extra mass does help keep it solidly on the floor during heavy bass passages. The subwoofer driver’s weight means a fairly front-heavy cabinet. They were covered in red oak paper-backed veneer, which was applied with contact cement and stained with two coats of American Chestnut Minwax Polyshades stain.

Conclusion Even before the addition of the FBQ1000, these subwoofers were a pretty large improvement compared to the old ones while playing music. They didn’t reach quite as low as the old subs during movies, but I expected this. Adding the EQ changed everything. I bumped up the crossover point from 40 Hz to 100 Hz, adjusted the response until it was flat, and continued to tweak from there. Now these things will shake the couch and not even break a sweat. On top of that, they are the best sounding subs I’ve had for music playback, as well. I am very impressed with the Dayton Audio Ultimax subwoofers for music and home theater applications alike, and would not hesitate to recommend them to anyone looking for the ultimate subwoofer.

About The Designer
Matt Phillips has been an audio enthusiast for many years. His fascination with cutting-edge products and concepts has been strong ever since the beginning of his speaker building hobby. Building on experience gained from working at Parts Express, he continues to explore new concepts and applications. Matt’s other interests include woodworking, toying with RC cars, drumming for his local church’s praise band, and going to the shooting range.

Project Parts List

Dayton Audio UM10-22 10″ Ultimax DVC Subwoofer 2 ohms Per Co

Behringer EP4000 Europower Power Amplifier 2 x 1400W

Behringer FBQ1000 Automatic Ultra-Fast Feedback Destroyer

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