Step 7: Cut and drill the conduit pieces

Cut two 10" long pieces of 3/4" PVC conduit. File the burrs off the ends. Mark each piece for three holes in a row, one in the middle and one 1-1/2" from each end.

Drill three 11/64" holes in each piece at the marked locations using a vise and drill press if possible, but a handheld drill will work. Drill all the way through the pipe since the other side needs large holes to let the screws through into the pipe.

Turn the pieces over and enlarge the holes on this side to 3/8" diameter. I used a Unibit step drill to save time.

The last photo shows what the finished holes should look like.
<p>Very cool project, excellently designed :)</p>
<p>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?</p>
How about using a bazooka 8&quot; amplified sub woofer
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? &nbsp;for biggest autonomy...
nice engineering &amp; craftsmanship! <br /> <br /> 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.<br />
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.<br /> <br /> if anyone is looking for a forum dedicated to bicycle stereos, stop by the <a href="http://www.bikeology.net/" rel="nofollow">bikeology</a> website's forum. the owner of the site has built some pretty ambitious &amp; LOUD trailer systems, but we'd like ANYONE with any kind of bike system or even just interested in them to visit.<br /> <br /> as many different systems as people have built, it would be nice to have a community that shares info &amp; ideas as well as a common place for everyone to show their rides off &amp; just hang out. <br />
&nbsp;hey i made one &nbsp;before i saw this a few weeks ago but it has a amp so check it out
I have never had a good Kenwood product, i have two stereos i will not use just because they are kenwood.
i might stick one of these on my sisters bike
best idea ever
This is a really cool idea. I've decided to build one too... I've got an amp-6BASIC on order from <a rel="nofollow" href="http://41hz.com.">http://41hz.com.</a> 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. <br/><br/>I designed and dropped in my own Power supply, with 5v for USB, and regulated power for the amp and EQ. <br/><br/>I figure, that with a little bit of work, I can have something nicer than anything I could get at the store. <br/><br/>I'll send a link to some pics when I get it completed<br/>
good job, found this from far away<br/><a rel="nofollow" href="http://www.oobject.com/category/boombox-bikes">http://www.oobject.com/category/boombox-bikes</a><br/>now I is getting ideas.<br/>
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.
Maybe something like this amp: <a rel="nofollow" href="http://tinyurl.com/c3q5xe">http://tinyurl.com/c3q5xe</a> would be a suitable commercial product (&pound;9 + &pound;5 P&amp;P)?<br/><br/>Virtualvillage also do a stereo chip-amp made up board for around &pound;4, plus &pound;4 P&amp;P, and a slightly more expensive version of the above with a USB charging socket.<br/>
The last one you mentioned <a rel="nofollow" href="http://www.virtualvillage.com/Items/007650-009">http://www.virtualvillage.com/Items/007650-009</a> 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.<br/><br/>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. <br/><br/>You do get what you pay for. <br/>
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...)<br/>Where on earth did they get used Power AMP chips from? Crazy!<br/><br/>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...<br/><br/><a rel="nofollow" href="http://www.tnt-audio.com/ampli/t-amp_e.html">http://www.tnt-audio.com/ampli/t-amp_e.html</a><br/><br/>So is there really no well-working chip-amp in a box that can be bought ready made for a sensible price?<br/>
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?
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.
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.
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?
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).
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.
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.
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?
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.
<a rel="nofollow" href="http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-380">http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-380</a><br/>-this should work.<br/>...also, check out my solar boombox for ideas-<br/><a href="http://www.instructables.com/id/DIY-Solar-Boombox/">http://www.instructables.com/id/DIY-Solar-Boombox/</a><br/><br/>Nice work!<br/>
That is well. Thats just tight
Why wouldn't you port the box?
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.
How many watts is the amp?
15 watts per channel into 4 ohms. It's a Texas Instruments class D amp chip, the TPA3100D2. You can follow the link on the intro page <a rel="nofollow" href="http://www.cathodecorner.com/bikeboombox/cdamp">http://www.cathodecorner.com/bikeboombox/cdamp</a> to learn more. <br/>
once I finish (ha ha) the atomic zombie chopper I've been working on for <strong>two</strong><br/>years, I may have to add this.<br/><br/>if I ever finish that project =P<br/>
Very good Instructable! The desing is nice and simple. The object looks robust and well finished. The crafting step are well explained and illustrated. Congratulations
nice. could be used as a new housing for that crappy old boombox that's been sitting around. how about installing an Ipod holding compartment? less wires out and aesthetically cleaner.
This is pretty cool, well done and documented. I had a bike with a generator attachment, used to power a light, might be cool to use that to power the boombox.
well i will do this when i make my e-bike i think it look really nice btw
Pretty cool. At first I thought you just mounted a Bazooka (http://www.sasbazooka.com/) on a bike rack, and I was like, how hard is that? :]<br/>
Yeah, I thought of using a Bazooka, but it solves a different problem (making your pickup truck windows rattle) so I rejected it. However, if you like the bikes that go boom, it would work just fine.
Excellent work! Simple idea, that seems to work perfectly. Do you find that you only tend to hear one channel with the speakers facing in two opposite directions?

About This Instructable


205 favorites


Bio: I make Nixie wristwatches and fix radio telescopes and go to Burning Man and deal with dirty water. Look for my bike boom box coming ... More »
More by nixiebunny: Build a Bike Boom Box
Add instructable to: