Picture of Build a Bike Boom Box
How it all started: I ride my bike in a community ride every week, and the folks there wanted some way to enjoy music on the ride. I tried a regular boom box, but it's just not made for bike mounting. Being an engineer, I decided to make my own bike-mounted sound system. This is what I came up with.

Take a look at http://www.cathodecorner.com/bikeboombox/ showing the system in detail.

The amplifier circuit board is of my own design. It uses a Texas Instruments Class D stereo amplifier chip to provide 15 watts per channel of clean sound with very low battery drain. I designed a circuit board with everything needed for a nice bike system, including a charging port for your MP3 player.

The amplifier board details are http://www.cathodecorner.com/bikeboombox/cdamp/

Step 1: The components

Picture of The components
The bike boom box is made of three main parts: the rack, the tube and the amplifier board. A pair of 6.5" marine speakers and a battery pack round out the system.

The amplifier circuit board is available from my one-man company Cathode Corner for $100 assembled. you may also download all the design info from my website and build your own if you are good at surface-mount assembly.

The 6" sewer pipe is available from any big plumbing supply house (not Home Depot or Lowe's, unfortunately) but needs to be cut carefully, a task that I describe how to do.

The bike rear rack is available at any decent bike shop. You may already have one on your bike.

Parts required:

A fully assembled CDAMP amplifier board with angle brackets
A battery pack, Li-ion 18650x4 series cells with protection circuit (Batteryspace)
A 14.4V Li-ion charger (Batteryspace)
A 5.5mm/2.1mm DC power plug to fit the amplifier board (Digikey or Mouser)
A pair of Kenwood KFC-1652MRB marine speakers (eBay)
Two each .250 and .187 quick-disconnect crimp terminals to fit the speakers
Three feet of two-conductor speaker wire, 18 to 22 gauge
A rear bicycle rack, standard aluminum type (local bike shop)
Two feet of 3/4" Sch. 40 PVC electrical conduit
18" length of 6" Sch. 40 ABS sewer pipe (big plumbing supply house)
One foot of 3/4" to 1"x1/8" 6061-T6 aluminum bar stock (hardware store)
A dozen #8x3/4" sheet metal screws
Two 8-32x1/2" machine screws, flathead preferred
Two 6-32x3/8" machine screws, nuts and lockwashers or nylock nuts

Tools required:

Electric drill and/or drill press
Fractional drill bit set, up to 3/8"
Countersink, #8 screw head
#1 and #2 Phillips screwdrivers
Sharpie marking pen
Small file, square or flat
(optional) Large miter box or the parts to make one and a crosscut saw

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Barry_L2 months ago

Very cool project, excellently designed :)

BryanM11 year ago

In the final portion of Step 9, when you are mounting the steel bars to the conduit - do you just screw into the conduit, or are there connectors (nuts) on the inside of the conduit? I would think these screws could come loose, thus making the metal plates fall off and the entire thing not be secured to the rack?

cjackson114 years ago
How about using a bazooka 8" amplified sub woofer
SG1Oniell4 years ago
Could you perhaps couple this with instructable with the friction drive bike generator instructable to recharge the batteries as well as your ipod and any other device?
That's not a box., it's a cylinder... a boom cylinder. Nice instructable .
The correct term would be tube...a boom tube. Not tobe confused with a theatrical boom tube,or boom stick...
Is it a good idea to use a Pb-Cl battery instead of a li-ion?  for biggest autonomy...
nice engineering & craftsmanship!

it would be cool if you posted a youtube video so we could hear it in action. i like the punchier sound of sealed designs like this than the boomy sound of ported designs. i bet your rig sounds crystal clear.
cool looking install. i haven't seen anyone use a bass tube on a bike system until now. i always pictured them on the sides of bikes in the saddle bag area, but it looks cool on top of your rack like it's a rocket engine.

if anyone is looking for a forum dedicated to bicycle stereos, stop by the bikeology website's forum. the owner of the site has built some pretty ambitious & LOUD trailer systems, but we'd like ANYONE with any kind of bike system or even just interested in them to visit.

as many different systems as people have built, it would be nice to have a community that shares info & ideas as well as a common place for everyone to show their rides off & just hang out.
Dracanse5 years ago
 hey i made one  before i saw this a few weeks ago but it has a amp so check it out
DIY Dave6 years ago
I have never had a good Kenwood product, i have two stereos i will not use just because they are kenwood.
abadfart6 years ago
i might stick one of these on my sisters bike
best idea ever
Gamer64606 years ago
This is a really cool idea. I've decided to build one too... I've got an amp-6BASIC on order from http://41hz.com. I also decided to build and put in a 3 channel EQ. I picked up some halfway decent 3-way car speakers to pop on the ends of the PVC tube. I'm probably going to go with Lithium Ion batteries too.

I designed and dropped in my own Power supply, with 5v for USB, and regulated power for the amp and EQ.

I figure, that with a little bit of work, I can have something nicer than anything I could get at the store.

I'll send a link to some pics when I get it completed
good job, found this from far away
now I is getting ideas.
How much did it cost? This looks like it is a very good system. I have a Terra Trike. Would it be hard to hear if you were going 30 mph? Your iPod cable looks longer than mine. Did they used to make them longer?
I paid about $200 for all the parts. The system is loud enough to hear riding in the bike lane next to heavy traffic at 35MPH. It can't overpower Harley engines, however. It gets REALLY loud when I bring it indoors if it's set to traffic volume. The iPod cable is a couple years old. Yes, they keep getting shorter - my 2003 iPod's Firewire cable is over 6 feet long! . You can get them in different lengths on ebay for cheap.
That's more than I have to spend right now. I have seen ihome bike speakers for $70, but of course they only work with ipods.
jarvist6 years ago
Maybe something like this amp: http://tinyurl.com/c3q5xe would be a suitable commercial product (£9 + £5 P&P)?

Virtualvillage also do a stereo chip-amp made up board for around £4, plus £4 P&P, and a slightly more expensive version of the above with a USB charging socket.
nixiebunny (author)  jarvist6 years ago
The last one you mentioned http://www.virtualvillage.com/Items/007650-009 does have potential. It would best be removed from the case, mounted connector-end-out, and the speaker terminals removed to run the wires inside. But it has most of the features of my board design.

I'll order one to see if the build quality is any good. The generic $20 class D amp board I got from eBay was a dud - it was hand soldered but they didn't solder the chip's heat pad to the board, and the chip itself was made by a defunct company. Nothing I would recommend.

You do get what you pay for.
nixiebunny (author)  nixiebunny6 years ago
I bought one of these units from China just to see its potential. As I feared, it's rather crappy. It had used, not new, power amp ICs in it, and they didn't bother to add heat sink compound when they assembled it. The USB charging port doesn't have the necessary resistors on the data lines to tell an MP3 player to accept a charge. So, yes, you could use one of these cheap amps, but it's not worth the aggravation to me.
Ah well, thanks very much for the update - I was considering getting one of those for a similar battery operated boombox (this one going deep underground on a caving expedition...)
Where on earth did they get used Power AMP chips from? Crazy!

I used one of those T-Amps in a previous 12v project (26ft sailboat I was singlehanding), which was extremely impressive - but they don't seem to be available anymore, and my one is now permanently epoxied to a bulkhead...


So is there really no well-working chip-amp in a box that can be bought ready made for a sensible price?
rhino6 years ago
Thanks, I was looking for a generic mp3 boombox. All the ones I find are dedicated to the expensive, trendy, and far too popular IPod. I need one for one of the more sensible, less expensive, brands. Can you add a power amp to this to kick it up to about 40 watts? Do you take this to Burning Man?
nixiebunny (author)  rhino6 years ago
This device has a 15 watt per channel power amp. It's plenty loud for Burning man - I brought it there last summer. Actually, I had two - one for the camp and one for the bike.
this is very cool, very detailed insturctions, great instructable
Search eBay for TA2024 amp boards... about $25 will get you complete working amp board. Sure Electronics is one source. Maybe the chip manufacturer is defunct, but those chips have a reputation as great-sounding amplifiers.
nixiebunny (author)  bassbindevil6 years ago
Yes, I have one of those boards. Unfortunately, the fine folks at Sure's soldering facility hand-soldered the board and they never soldered the amp chip's heat slug to the PC board! I decided not to use it for that reason and that the connectors are not at all conducive to panel mounting. But don't let that stop any of you from using it.
maestro_au6 years ago
This is awesome! Great work. I have an aunty/uncle who want a sound setup to take with them to the outback and I might well end up asking if I can buy one of those amp boards. I did some quick math - 2 channels at 15 amps would be a current draw of something like 2.5A at 12V. Does this fit your experience with your unit? Also, Can you give me an idea of what the current draw looks like at low vs high volume levels?
nixiebunny (author)  maestro_au6 years ago
The beautiful thing about a Class D amplifier is that the current draw is rarely 2.5A. It only uses as much power as it needs to move the speakers at any instant, so the average draw is well under one Amp. This means that a 2AH battery pack will last for about 4 hours even when played at full volume (but not driven to a high distortion level).
dj.kazb0t6 years ago
Yay! You do Tuesday night bike ride in Tucson, AZ don't you? Hooray for engineering bike mods! And thanks for always bringing the tunes.
milt156 years ago
This project is great simply everything is taken into consideration also a nice option if you added dynamo to charge the battery looks like you are a good engineer
Nicely done-well written and a great idea. I wonder if the plombing supply shop would gut the pipe to size when you bought it. 2 boards wider than the pipe joined together at right angles to make a "vee" could also work to cut the pipe. The end of the pipe needed to be cut can stick out the end, or sawn through the boarfs and pipe at the appropriate place.
Transquesta6 years ago
Cool idea/proof of concept! I don't ride bikes (outside the one at the gym :-)) but the same general design would be great for campsites, shops and such. Now, about that pricey amp and iPod specific hook-up? How 'bout a sto-bought in-line am (est: $50.00 tops ) with standard connections for stereo mini phone plug?
nixiebunny (author)  Transquesta6 years ago
I would be delighted to use a store-bought amplifier if it was easy to mount and had connectors that are practical. I couldn't find one, so I made my own. If you know of a good one that I could buy, please point me to it. Also, the hookup is not at all iPod-specific. It has a USB charging port and an audio jack. I just happen to use an iPod.
That is well. Thats just tight
Punkguyta6 years ago
Why wouldn't you port the box?
nixiebunny (author)  Punkguyta6 years ago
I have thought about that. I'm not really into booming bass; I just want to hear the music. I'm not an acoustical engineer, so I don't have a feel for the best way to do it. I was thinking that a piece of 2" sewer pipe in a 45 degree street elbow would be a clean way to do it, but it may need a much larger port diameter to work well.
I never said you had to be a bass-head, but you will get not only a more natural sound, but also should make the music less distorted at high listening levels. As far as if you were to actually make a port, one or two holes the size of "C" sized batteries, that would be sufficient. The lower the woofer's resonant freq, the bigger the port should be, but even for a 12" subwoofer, a hole the size of a D sized battery, sometimes 2, is often enough, and is not really that much bigger. But basically speaking, a 12" sub is going to be around 40-20hz, whereas your speakers (good choice with the kenwoods btw), are most likely to be hitting up in the 120hz range, 80 at the lowest, and for this, you do not need a large port. Look at the ports on cheap computer speakers (yes the ones with the subwoofer, waste of money, might as well just buy a regular stereo with 2 speakers, it'd sound better *rant end*) The ports are roughly the same sizes I described (circumference of a C cell battery), and those subwoofers are rated closer to the 120hz range aswell. Experiment with it my friend, make a small hole and go bigger, as you can always take more off, but hard to glue plastic shavings back together eh? But if anything any kind of hole in the enclosure (as long as the rest is properly sealed), should make the sound, sound better by some marginal amount.
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