The RTBox - an ultra quick, incredibly impressive (for its size) 2-hour project

[tyger23]

All,

I had to put this together for a work demonstration, and it came out so impressive I thought I'd share. Basically, I needed to build a small speaker box that sounded good so that I could demo some amplifiers for my company. I didn't have much time to throw this together, so I did it as quick as possible. Outside of the time it took for speaker selection, simulations, and gathering the materials, the build itself took about 2 hours.

Materials needed for this project:

• Two Peerless TC5FB00-08 speakers. I chose the 8-ohm version, but the 4-ohm would probably work just as well. Both are rated at 5-W, so choose the impedance that best matches your amp. A Kinter MA-170 would use the 4-ohm while the LP-2020A+ would be better with the 8-ohm.
• A RadioShack 6" x 4" x 2" project box enclosure
• Exterior speaker connectors of your choice. RCA plugs worked best for my project.
• Some 3/16" plywood (Lauan) or wood of some sort. You only need about 1 square foot of this at most.
• Two 1.25" pieces of 1/2" PEX pipe. These form the ports. I had to buy a 5-foot piece to get what I needed.
• A pack of #2 by 3/8" wood screws for mounting the speakers.
• Something to seal the box top with. I used poster putty.
• Some hot glue.
• Some speaker wire.
• A small amount of pillow-fill (optional)

To mount the speakers, I used a compass to draw out a 38mm circle for each speaker. I centered the circles 1.25" in from the side and 1.5" up from the bottom. I wanted to keep them fairly close to the edges to keep some strength in the box top. You could likely put them wherever you want on the box top. I then cut out the holes using a Dremel tool with a multipurpose cutting bit (looks like a regular drill bit). Keep your patience and take your time. Note that I also had to cut out a little bit extra on the corners to allow for the speaker terminals to fit properly.





Once I got done cutting the holes out (and checking the fit), I used the Dremel sanding wheel to chamfer the back edge of the speaker hole. I had to do this because the 4mm thickness of the project box's top was covering quite a bit of the rear of the speaker.



I cut out an ~4" by ~6" piece of the Lauan and notched the corners so that it would fit inside the lip of the box's top. I wanted to do this to give the box top more strength and avoid vibrations. The 3/16" Lauan worked great to fill in the exact amount of "cutout" inside the top. I drilled 1-3/4" holes, centered where the speaker holes should go. This gave enough clearance for the speakers to breathe while maintaining some strength for the top. Once everything was centered up, I hot glued the Lauan to the box's top.



Also using the Lauan, I cut out a center support/divider. You'll notice that there are guides built-into the box for attaching PC boards. I used these as my guide for cutting the Lauan. Because I added the Lauan to the top of the box, I only needed to have my center divider go to the top of those PCB guides. Once the divider fit properly, I hot-glued that guy into place:

[tyger23]

Re: The RTBox - an ultra quick, incredibly impressive (for its size) 2-hour project

Next up, I cut off a sliver of the PEX pipe and placed it on the outside of the box, where I wanted my port holes to go. I used a pencil to trace out the inside of the hole and the Dremel tool to cut out the hole. I did this because the 0.45" diameter of the PEX pipe didn't match any drill bits I had. Once this was done, I used hot-glue to mount my two 1.25" pieces of the PEX pipe to the inside:



I then used a 1/4" hole to mount the RCA jacks. Again, this worked for my purposes, but you may want to use more normal speaker terminals. I soldered in some 22 gauge speaker wire between the terminals and the speakers. For the final assembly, I used the poster putty to line around the perimeter of the box and the center channel. This was to seal up the box when it got screwed down. I did add a small amount of poly-fill (not pictured), but this likely isn't necessary.



Put it all together, and voila.

[tyger23]

Re: The RTBox - an ultra quick, incredibly impressive (for its size) 2-hour project

The overall listening impressions of this are incredible for the size. Please keep in mind that I deal with computer speakers (laptops/AIO's) for a living, so use that as a reference when I say these things kick some serious tail. They're on-par with the best of the TV speakers of the world, and would likely beat 90% of the speakers in modern-day TV's.

Here are the frequency response and distortion plots I measured. Keep in mind that this is WITHOUT any EQ or crossover of any kind. I plan to use an electronic EQ for my demonstration purposes, but it won't require much since the FR came out relatively smooth.





The EQ I add will likely be a 2nd order high-pass at about 100Hz, a -2dB peaking filter at 160Hz (Q of about 1.5), and -4dB peaking filter at 300Hz (Q of about 1). I'll let you know where I end up. I may even post a passive crossover if anyone is interested in me doing this.

Enjoy!

[4thtry]

Re: The RTBox - an ultra quick, incredibly impressive (for its size) 2-hour project

I may even post a passive crossover if anyone is interested in me doing this.

Enjoy!

Nice project! I would certainly be interested in the design of your passive crossover.

Bill

[Paul Carmody]

Re: The RTBox - an ultra quick, incredibly impressive (for its size) 2-hour project

Wow. That might be the smallest DIY speaker project I've ever seen.

[Partagas]

Re: The RTBox - an ultra quick, incredibly impressive (for its size) 2-hour project

You could develop that into a DIY dockable alarm clock radio that you just dock your phone or tablet into as a charging station and speakers for waking up to whatever alarm you use even waking up to specific songs, Pandora etc.