Designer:

Taylor Hansen

Project Category:

Portable Speakers

Project Level:

Intermediate

Project Time:

20+ Hours

Project Cost:

Under $100

Project Description:

This is my attempt at going head-to-head with industry leading large form factor portable speakers – resulting in a rugged boombox that outclasses the competition in value and performance.

Design Goals:

I’ve been in the market for a party speaker that can bridge the gap between a handheld Bluetooth speaker and full PA system. The “JBL PartyBox Stage 320” met most of my requirements – but $600 was well out of budget. By pulling their service manual and reverse engineering a few design elements, I set out to beat this benchmark at a fraction of the price.

Driver Selection:

After testing eight pairs of 6×9 speakers across various brands and price ranges – all salvaged from junk yards over the years for just $9 a piece – I found the Kickers offered the most fun “V-shaped” sound profile. Given Kicker’s history of producing the first full-range speaker box for the mobile-stereo market (essentially a shallow boombox), choosing them felt especially fitting. For the subwoofer, I used CES buyout driver (now discontinued) purchased from Parts Express for just $15 at the time. While its limited power handling has been a bottleneck for other potential systems, the roughly 70-watt subwoofer amp in this setup made for an ideal match.

Enclosure Design:

The enclosure’s foundation was a shipping crate from Brazil, who’s rugged styling was just too cool to pass up. The 3/4″ plywood was a bit rough but being light and strong made for a compelling choice. The left and right speakers were housed in 0.33 cubic foot sealed chambers, moderately stuffed with Poly-Fil. The subwoofer was mounted in a 1.6 cubic foot enclosure tuned nearly flat to 35Hz (+1dB bump) via dual opposing PVC ports (2″ internal diameter, 8″ length).

Crossover Design:

The 6×9 Kickers have their factory installed crossover (1st order HPF/LPF). The subwoofer has an active 3rd order variable LPF set around 80Hz. Tone controls are typically set to neutral if enclosure is on the floor, but the treble is often reduced by a few dB if listening on axis. System is powered by a Wuzhi Audio 2.1 Amplifier (TPA3116D2 chipset), 32,000uF capacitor, and a Ryobi ONE+ 18V battery.

Tips & Tricks:

A quick knock test revealed a buzzing sound in the enclosure – despite the 3/4″ panel thickness and excessive bracing. I isolated the source of the vibrations down to the amplifier. This was eliminated by tightening the screws and adding peel and stick sound deadening material to the amplifier and its mounting plate. I also added this material to the subwoofer’s stamped steel basket as a best practice.

Conclusion:

This boombox throws down! It produces surprising amounts of deep bass and a room-filling sound that can effortlessly energize moderately sized rooms. The price to performance ratio of this build is truly quite impressive – costing just under $100 in parts and materials. While the cost could have been further reduced by skipping the corners, handles, and amplifier mounting plate, these small touches add up to make a huge difference in both aesthetics and usability. This build has been a testament to the value DIY can offer and has given me an outlet to practice new woodworking techniques on a non-critical build. Now its time to sit back and enjoy portable music wherever life takes me.

About the Designer:

Taylor Hansen is an electrical engineer specialized in power electronics for the aerospace industry. He has found that speaker building is a great way to couple his professional skills with his many hobbies such as fine woodworking, home theater, and live sound reinforcement. When not tinkering with electronics in the lab or sanding MDF in the shop, he can often be found serving as a pianist for his local church in Fort Wayne, Indiana. But perhaps most importantly, Taylor finds fulfillment in his wife and son, who serve as constant sources of motivation and love.

Project Parts List: