Ultimax 18″ w/Matching Entertainment Center

Ultimax 18″ w/Matching Entertainment Center

Ryan Clark

Project Category:

Project Level:

Project Time:
8-20 Hours

Project Cost:
$500 – $1,000

Project Description:
Entertainment Center w/18″ Ulitmax (sub, media rack, storage)

Design Goals:
Crushing bass, ascetically pleasing and functional

Driver Selection:
18″ Ultimax to replace my two 15″ Dayton Classic subwoofers which were each in a 3.6 cu foot cabinets. This design made my LCR entertainment center actually smaller with improved bass. The rack media section cleaned up all the gear so I don’t have rats nest of cables anymore. Love it!

Crown XTi 1002 – I wasn’t planning on using this amp but got a deal on it used and with its DSP functions decided to go with the smaller sealed enclosure with worked out fantastic. Now that I have this amp, I would buy it new for this project. It’s DSP functions with Band Manager application is amazing!

Enclosure Design:
Essentially replicated the Denovo Ultimax cabinet. Pretty straightforward ~4 cu foot sealed cabinet. I did design all 3 components to match in height.

Enclosure Assembly:
Used 3/4″ MDF with a double front baffle, although I used 1/2″ plywood for the inside part. I did this for two reasons; wanted to make sure it wasn’t too thick for the mounting kit I bought and the T-nuts set so much better in plywood than MDF (bad past experience).

The media section and storage section are made of 3/4″ and 1/2″ cabinet grade plywood.

Painted it all white

Crossover Design:

Tips & Tricks:
Plan every cut! I don’t have a big table saw or a truck so I have them cut down the full sheet in store so I can easily transport and handle.
Use plywood for internal baffle, recess using a spade bit to ensure the T-nuts set in well.
Before securing your baffle to the cabinet, measure, drill mounting holes. Set the T-nuts in place and then make sure they all line up, before you attach to cabinet.
If you build a rack rail cabinet make sure to space it out with actual components. Rack gear is 19″ but you will probably want to shoot for 19.125″ so you have a little wiggle room. I went a little too wide and had to add spacers between the rail and cabinet.


um1822_entertainment_center_with_subs um1822_project


Very pleased!

About the Designer:
I have been an aspiring audiophile since I was a teenager. I still have my first speakers – Infinity SM-62’s I love building with wood – perfectly matched hobbies.

Project Parts List:

Parts Express Cast Frame 1/4″-20 Speaker Mounting Kit
Rack Shelf 2U
Rack Shelf 1U
Penn-Elcom R0828/12 12 Space Full-Hole Rack Rail Pair 12U 21″
Heavy Duty 0.065″ Steel Blank Rack Panel 1U with Flanges
Middle Atlantic HPS #10-32 x 3/4″ Rack Screws 25 Pcs.
Penn-Elcom R1385/1UVK Flat Perforated Rack Panel
Penn-Elcom F1686 Rubber Cabinet Foot 1.57″ Dia. x 0.61″ H
Angled Metal Speaker Cabinet Input Dish
Neutrik NL2MP Speakon Connector 2 Pole Panel Mount
Neutrik NL4FX-4 Speakon SPX 4-Pole Cable Connector with Yellow Bushing
Dayton Audio UM18-22 18″ Ultimax DVC Subwoofer 2 ohms Per Coil
Crown XTi 1002 Power Amplifier 2 x 500W at 4 Ohms


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