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Mountain bike sound system
Mountain bike sound system
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Old 13th November 2008, 05:48 AM   #1
Lambda_drive is offline Lambda_drive  United States
diyAudio Member
Join Date: Nov 2008
Default Mountain bike sound system

This is my first post.

I see these things all the time now when I go mountain biking. http://www.amazon.com/iHome-Beach-Sp...551966&sr=1-16

They produce a decent amount of sound, but it's not powerful enough for my likes and the sound quality it a bit too tinny. Plus I'm not the biggest fan of ipods.

I want to create something small enough to fit in a bottle cage, but that's also very powerful.

I'm not that good with electronics so I wanted to do something simple so I bought a pair of small PC speakers hoping that I could take them apart and use the amp and speakers it came with, but the amp and the speakers are a bit too big to fit in a regular bottle, unless I use one of those big Nalgene bottles. A regular bicycle bottle has a diameter of about 2.8 inches, but the speaker I have is 3 inches and the amp is about 3.25 inches square.

Do you guys have any suggestions on how to build a small powerful sound system that'll fit on a bike?
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Old 13th November 2008, 06:59 AM   #2
TheSeekerr is offline TheSeekerr  Australia
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Join Date: Jan 2008
OK, let me get this straight....you want a powered speaker system for a bicycle, that fits in a drink bottle cage, and as a result uses drivers no bigger than 2.5"? Good luck. Do you have the skills to fabricate an enclosure that would fit in that space before tapering outwards to accommodate at least a 3" driver? To reach even 100hz, you're going to need a 3". Your next problem is enclosure volume - you are, by nature, only going to have 2, maybe 3, litres to play with. That's not a lot.

I'm no expert on this....I'm thinking that it might be possible to construct something with a HiVi B3S in a sealed enclosure of 2L, and you'd get an only moderately high Q alignment resulting in a 2dB peak at 150hz - which in the environment you'd be using it in, would be the least of your worries.

For powering it, a small class D amp, ie. a Tripath, is the obvious solution, since they're usually run off 12V supplies. The 41hz Amp32-PS would be near perfect - http://www.41hz.com/main.aspx?pageID=105 - it's absolutely tiny.

For the battery, lead acid is probably too bulky, so you'd be looking for NiCad or Li-poly, and a continuous current delivery capacity of at least 500mA, and a capacity of 2 or 3 amp-hours.
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Old 14th November 2008, 06:55 AM   #3
Lambda_drive is offline Lambda_drive  United States
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Join Date: Nov 2008
A 3" speaker wouldn't be out of the question, I was hoping I could use a regular sized bottle so it would be a bit more stealthy. A 2L enclosure sounds really big to me, how well would that fit on a bike?
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Old 14th November 2008, 07:30 AM   #4
TheSeekerr is offline TheSeekerr  Australia
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Join Date: Jan 2008
About as well as a 2L drink bottle....if it's 3" around, I'd be surprised if it wasn't 2L (8.4 cups, 68 fluid ounces....whatever you crazy folks measure your liquids in).
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Old 15th November 2008, 07:35 AM   #5
Lambda_drive is offline Lambda_drive  United States
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2L is larger than I would like. A 1L enclosure would be perfect though. The bass doesn't have to be amazing, just decent enough that it doesn't sound like a tin can radio.

what would be a good amp to buy that's prebuilt? I'm horrible at soldering surface mount components.
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Old 15th November 2008, 09:47 AM   #6
Bone is offline Bone  United Kingdom
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Join Date: Jun 2004
Location: Dorset, UK
Try one of these they're cheap enough http://cgi.ebay.co.uk/2-8W-8ohm-4ohm...713.m153.l1262

Hope that URL is not too long its item number 230306903023.

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Old 15th November 2008, 10:23 AM   #7
Allen Wright is offline Allen Wright  Switzerland
Join Date: Dec 2001
Location: Schaffhausen Switzerland
As a super keen biker I find this project to be COMPLETELY STUPID!

1/ if you want to noise up forest regions where you ride, wear in ear headphones and allow others some peace and quiet!

2/ if you ride in city/traffic regions, there any noise you make, (and there headphones are DEADLY) will cover up the sound of traffic around you, which is one of the few safety margins a biker has to help him survive the cars.

Stay alive, ride you bike when you are riding your bike, hear your music at home.

Regards, Allen
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Old 15th November 2008, 11:22 AM   #8
kristleifur is offline kristleifur  Iceland
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Join Date: Apr 2006
Location: Reykjavík
Check out V-Bro's Megamini for inspiration:


A high-efficiency 3", an tiny little 41Hz Amp32 and a line-level EQ filter will get you pretty far.

Click the image to open in full size.

(These are unbuilt kits, but there's plenty of builders around, you can probably find one close to you.)

Edit - hold on, I just remembered this, the 3" soda bottle speaker: http://www.diyaudio.com/forums/showt...threadid=79721 - I built one a couple years ago, if the driver is good the speaker is unbelievably good.
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Old 16th November 2008, 08:57 AM   #9
danielwritesbac is online now danielwritesbac  United States
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I'm thinking that the Sure Electronics Tripath on Ebay, with the published mods here at diyaudio.com, could probably fit the bill. I remember publishing an "no soldering" easy mod post or two at that thread.

As for the speaker, well Parts Express does carry a little 2" tang band that's slightly amazing, or there's the larger 3" models. Unfortunately, most have a phase plug. Any dirt would go inside the gap there and stop the speaker cone from moving.

The good news is that there's a sweet little tan colored poly cone from Tang Band, in about a 3" size--a full range with no phase plug. There's a similar driver in a 2x4" size, and those, being poly, are going to handle outdoor weather a lot better.

There are also versions with ultralight magnets, and that may be necessary, considering the weight of batteries, etc. . . when its all combined together as a unit.

I'm thinking about the small tubular handlebar bag from Sunlite on amazon.com. Its about $7 and just about the right size to hold this active speaker. The ends are nylon canvas, while the rest is firmly reinforced plastic--looks good for a portable little speaker dealie!

And, now, howabout just enough solar cell to recharge it? It wouldn't have to be large or strong enough to run the device, but rather just enough to charge up the battery when its not playing. You can use a dpdt on/on switch from Radio Shack. Put the battery on center connect terminals, and then "on" works the amp, but "off" connects battery to solar cells.

It won't be tinny.
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