Designer:

The Zard

Project Category:
 Portable Speakers

Project Level:
Advanced

Project Time:

20+ Hours

Project Cost:

 $500 – $1,000

Project Description:

Competition Free Style DJ blue tooth boom box
features : BOSS D12F Phantom 12″ Flat Subwoofer, Kicker 12 inch Passive, 4x DS18 comp. pro horn mid tweeters, ported Cerwin Vega mid-woofers with guitar amp, crossed over and band pass selection switches. 36-volt 220 x 2 + 350 watt mini BT amp, 80,000 Mah battery, 36v .8F power stiffing caps, carry strap.
marble front and back with custom raised name plate and both holographic and fluorescent flames, chrome corners and carry handle, custom mesh grills.
A battery voltage gauge, radio voltage & power usage gauge and even a cooling fan.
maximum dimensions in. 25W x 20H x 10D, 40 LBS.

Design Goals:
Original- design and build a boom box with a 12 inch sub that would [ ha ha ] weigh in less then 33 lbs.
speaker spacing
build a box for the boombox.
boombox / sub testing.
component selection – After the sub testing I found that ripping on the sub would kill a 6s1p set of battery’s in 2 songs. so after much thought and electrical system design I decided to go with a 7s6p 80,000 mah mobility chair battery, going through a voltage booster / regulator set at 35.5 volts with a 10 amp max output backed up radio side by a set of 6x 3v 10f cap banks for 36v .834 f of power stiffening.
make every thing fit.- the control section is behind the right tweeter in a box that was 4.5 in x 6 x 5.5 [ 7 ]
Driver Selection
battery mounting
crossover design
final testing – sub failure
enclosure redesign – upon going back to the cu ft calculator, I was able to figure out that a 1.5 inch width mod, and a .75 inch spacer for a flat passive would give me a total volume of .9803 cu ft3 after all modifications.
vinyl design and application

Driver Selection:
BOSS D12F Phantom 12″ Flat Subwoofer

Enclosure Design:
Well I have 2 bumpboxs and looked at the boombox kit here in parts express, I like the idea of a sub, but figured I would have to build my own to get what I want. So I decided to test out the BT receiver from the kit here at parts express, its loud and gave me a good idea what 6.5 inch sub and 5.25 woofers can take. I then looked up what is the most powerful small BT receiver made and got 2 of those.
I looked up in parts express the boss phantom shallow sub, 1 from infinity and 1 from Rockville, as they are all listed as working in as little as .70 Cu Ft3. so I cut out a 24 inch x 20 inch pc of cardboard, and card board shapes for all of the drivers I had gotten from parts express and other sources. I found that I could fit a 12 inch sub, and a choice between several different 5 inch woofer, teeter, mid combinations in a space of 24 x 16 inches.
so, I went to a cubic foot calculator and designed out a box that would be 24 x 6.5 x 16 and have a internal volume of 1.038 cu ft3.
using my card board template I spaced out the sub and the passive.
their were no other internal structures but the subs needed to be tested out. with a earth quake 12 in passive, I first tested the Boss from parts express, it worked great and made the box dance on the floor, the infinity ref1200s would not work with the design and failed out, the rockville also worked good, but not as well as the Boss in this design.
In this design the radio has a sub eq in it and will run directly to the sub like a musical instrument speaker, so adjusting the eq can run it ‘ clean ‘ or ‘ dirty ‘ being guitar amp style.
while looking at the radio installation I decided to make a dampening pad for it to sit on out of a old mouse pad. it is held in place from the bottom of the radio box with 2 nut/ bolt combos.
the power booster is on the side wall over the radio, but can over heat if it getts to hot, so I had to add a small cpu fan and then made a fan grill out of hardware cloth to keep wires from going into it. it is only 12 volt so add a voltage regulator that I have to mount on the top due to limited space and since the fan makes some noise a thermal switch so it only comes on at 113F.
at this point their is no more room so the 2 cap banks are taped together with mouse pad to cushion with transformer tape and mounted on the back side of the panel.
I used the 24 ga speaker wire from parts express for the mid-woofer switches, 18ga amazon wire for left right main feed and mid tweets, 14 ga. rockville speaker wire for the sub, rockville 14ga. power cap wire for battery.
the faceplate for the radio, mid-woofer switch’s, and combo digital gauge was cut from the top case cover from a Motorola cable box.
once all deductions were made the internal volume was .72 cu ft3

Final testing- the subwoofer fell flat and did not sound right, upon contacting Boss they said the woofer would not work with a passive at that volume and the box needs to be .95 – 1.1 cu ft3.
with a new configured volume of .9803 cu ft3 I am ready to move forwards.
after the enclosure mod is done I get to final sanding before vinyl application

custom vinyl is harder to find then you might think, so I got some OSHA noise warning stickers, flame exhaust stickers for a child’s ride on jeep, red pink flames for a motor cycle helmet and holographic blue vinyl.
I found images of flames on the net and used them to make a picture template printed on paper that I taped over the holographic blue vinyl, then cut them out with a razor blade, actually 3 due to glue.

the magic of the mid-woofer switches comes from a handful of components, small maze of wiring and special 6-Pin Rocker Switch’s made for boats and diesel engines.

shrink wrap colors used to strip wires, in the first bandpass test 200uf caps were not enough so the bandpass x-over was re-calculated to a higher x-over point and 100uf caps added
originally JBL 2-way second order crossovers were to be used until one of the second order caps blew out and smoked. after that all cap values checked to make sure 50 volt minimum, and I made my own cross overs.

Crossover Design:
 he sub uses the electronic crossover built into the radio, the mid tweeters are in parallel as a set and use 2 caps also in parallel for each set, the mid-woofers were the pain, they have a switchable direct feed, infinity coils and the coils with caps in combo for the band pass.
so the band pass caps and the coils are up in the control section and the high pass caps are down in the body inline to the mid tweets.
the purpose of so the mid-woofers can be run dirty like a guitar amp, crossed over like a HIFI system and in bandpass for competition, rave, trap n base, etc.

Tips & Tricks:

Ugh, cutting out the metal faceplate for the receiver and switches, the first one I tried to cut out with tin snips and it is ugly, lucky enough I had more metal to use, so I got a small rotary tool with cut off disks, and that made the cuts I need.
when I cut out the vinyl I used a new razor blade with my hand mostly out of the knife to be able to move it around the design, you can get cut proof gloves at a hardware store, if you feel you need them.
predrill holes in areas that will be glued together that you wont be able to get a drill into after and even pre screw in the screws it makes the job that much easier.
Don’t go too crazy second guessing your self or your project will end up like mine.

Laminated bamboo is a hard, heavy, but brittle/fibrous material. If your tools aren’t sharp you may get tear-out when cutting.

I bought a full Samba kit and a baffle-only kit. Since I built my own enclosures I could use the MDF from the complete kit to build the extra pieces I need for the second enclosure.

Conclusion:
I wanted to see what could be done with parts currently available to make a custom boom box, I made this job a lot harder then it needed to be, using a voltage booster and power stiffening caps was just to go over the top in the design and caused additional parts to be added for support.
in the end I decided to make a competition boombox, simply because their is no such thing.

About the Designer:
 
 Previously I was a DJ and worked for tech hifi back in the late 80’s, I built sound off comp. cars before their was such a thing.
now days I run a reptile rescue.

Project Parts List: