Hi! I've been perusing this forum for a while and there's tons of hugely useful information available! Great community here.
Anyway, I'm trying to build a speaker system for my bicycle, and Class D amps seemed like a good idea what with high efficiency and all. I've gone component shopping and sourcing, and here's what I'm looking at:
-12v 8Ah Lead-Acid Battery
-41Hz Amp3 (2x25W @ 4 Ohm)
-2 5x7" Generic Speakers, 25W, 35W Max, 25W continuous; 90 Hz-15 Khz
Reasons:
-12v 8Ah Lead-Acid Battery
I'm not terribly concerned about weight, and the Lead Acid Battery costs < half as much as a comparable NiMH. Also, eventually I will be using dynamos on my wheels to charge the system as I ride, and I feel like it will be easier to beat on a Lead Acid battery with intermittent voltage surges than a NiMH.
($20)
-41Hz Amp3 (2x25W @ 4 Ohm)
Pretty cheap, apparently pretty good, very efficient
($40)
-2 5x7" Generic Speakers, 25W, 35W Max, 25W continuous; 90 Hz-15 Khz
Pretty cheap ($12 each)
Is there anything I'm missing? Would I be much better served with a different combo of parts? Also, I want to make sure that this thing will be pretty darn loud when I'm done, but it doesn't have to run for a long time (the battery can support 4.5 amps for about half an hour before the voltage drops below 12V). I generally ride in heavy city traffic with buses and motorcycles and everything, and I want the music to be clearly audible above all that. Also, are there any tips in particular for not blowing components beyond the usual electrostatic precautions (bringing tools and components to same potential, etc.)?
Thanks for any help!
-Ned
P.S. The project will naturally be well documented and culminate in a project report.
Anyway, I'm trying to build a speaker system for my bicycle, and Class D amps seemed like a good idea what with high efficiency and all. I've gone component shopping and sourcing, and here's what I'm looking at:
-12v 8Ah Lead-Acid Battery
-41Hz Amp3 (2x25W @ 4 Ohm)
-2 5x7" Generic Speakers, 25W, 35W Max, 25W continuous; 90 Hz-15 Khz
Reasons:
-12v 8Ah Lead-Acid Battery
I'm not terribly concerned about weight, and the Lead Acid Battery costs < half as much as a comparable NiMH. Also, eventually I will be using dynamos on my wheels to charge the system as I ride, and I feel like it will be easier to beat on a Lead Acid battery with intermittent voltage surges than a NiMH.
($20)
-41Hz Amp3 (2x25W @ 4 Ohm)
Pretty cheap, apparently pretty good, very efficient
($40)
-2 5x7" Generic Speakers, 25W, 35W Max, 25W continuous; 90 Hz-15 Khz
Pretty cheap ($12 each)
Is there anything I'm missing? Would I be much better served with a different combo of parts? Also, I want to make sure that this thing will be pretty darn loud when I'm done, but it doesn't have to run for a long time (the battery can support 4.5 amps for about half an hour before the voltage drops below 12V). I generally ride in heavy city traffic with buses and motorcycles and everything, and I want the music to be clearly audible above all that. Also, are there any tips in particular for not blowing components beyond the usual electrostatic precautions (bringing tools and components to same potential, etc.)?
Thanks for any help!
-Ned
P.S. The project will naturally be well documented and culminate in a project report.
LOL, a bicycle hi-fi, you are my hero xD
About recharging : don't overestimate human power. Generating 20W with your legs is already athletic...
Also consider driver efficiency. Your battery will last twice as long for every 3dB you gain in driver efficiency. Class D amps are a must for your application but it would be a pity to waste them on unefficient drivers !
About recharging : don't overestimate human power. Generating 20W with your legs is already athletic...
Also consider driver efficiency. Your battery will last twice as long for every 3dB you gain in driver efficiency. Class D amps are a must for your application but it would be a pity to waste them on unefficient drivers !
Great idea!
I like your ideas for building a bike stereo.
Don't know if on your search you have seen this, but I was going to build this project for my bike. I have all the components exept the Sonic Impact stick on speakers. I like this design because it is fairly unobvious that they are speakers. Also the whole kit is removable. It uses a Sonic Impact T-amp but I am sure any D class would suffice. I haven't heard the SI stick on speakers in action, but apparently they knock out a lot of sound for what they are.
http://www.instructables.com/id/ELSP32OPN9EP287JKZ/?ALLSTEPS
I like your ideas for building a bike stereo.
Don't know if on your search you have seen this, but I was going to build this project for my bike. I have all the components exept the Sonic Impact stick on speakers. I like this design because it is fairly unobvious that they are speakers. Also the whole kit is removable. It uses a Sonic Impact T-amp but I am sure any D class would suffice. I haven't heard the SI stick on speakers in action, but apparently they knock out a lot of sound for what they are.
http://www.instructables.com/id/ELSP32OPN9EP287JKZ/?ALLSTEPS
The Altec-Lansing 4" ceiling speakers have good sensitivity and low Vas. TSPs can be seen at
http://www.spectrumaudio.de .
http://www.spectrumaudio.de .
I know you said you aren't concerned about weight, but you should be concerned about size. On a bike there is only very limited amounts of space available. An SLA battery at 8AH is going to be 6 to 7 lbs or maybe more but will be something like 5 x 3 x 4 inches. However with a Class D amp, and the Amp3 like you are looking at doesn't pull that many milliamps, only something like 300ma or so at full volume (don't quote me on that, its just an estimate) and thus you'll be able to run the speakers for hours and hours on an 8Ah size battery. If you don't need them to run for a long time, then you definitely don't need an SLA battery that large. Even at 4AH size you'd still be able to run an Amp 3 for several hours at full volume.
What frame size are you using? Mountain or road bike frame? Is it full suspension or a rigid frame?
How and where are you going to mount this system? the easiest way to mount it would be to hang the stuff from the top tube. Whatever speakers you are using you have to have a box or enclosure design. Speakers in free air aren't very loud and don't sound very good and boxes for 5x7's are overly large if used on a bike, but are pretty small if used in cars. I think those might be way too big to be practical since they would probably throw off your balance, especially if you are using them in downtown traffic.
Since you won't be concerned about sound quality (how can you if you are going to ride in traffic?
you can get away with some cheap car audio dome tweeters. You can find them on ebay really cheap. They weigh nothing and take up no space. You might want to go with smaller drivers too. However, you could get a pair of sealed/closed back 5.25" drivers, since they don't require an enclosure. You would still need to mount them so they aren't blowing in the wind. Pair those with some sensitive tweeters, passive 2 way crossovers, and you can have a bike system. Make sure you get the most sensitive speakers you can find, regardless of which speakers you choose.
What frame size are you using? Mountain or road bike frame? Is it full suspension or a rigid frame?
How and where are you going to mount this system? the easiest way to mount it would be to hang the stuff from the top tube. Whatever speakers you are using you have to have a box or enclosure design. Speakers in free air aren't very loud and don't sound very good and boxes for 5x7's are overly large if used on a bike, but are pretty small if used in cars. I think those might be way too big to be practical since they would probably throw off your balance, especially if you are using them in downtown traffic.
Since you won't be concerned about sound quality (how can you if you are going to ride in traffic?
you can get away with some cheap car audio dome tweeters. You can find them on ebay really cheap. They weigh nothing and take up no space. You might want to go with smaller drivers too. However, you could get a pair of sealed/closed back 5.25" drivers, since they don't require an enclosure. You would still need to mount them so they aren't blowing in the wind. Pair those with some sensitive tweeters, passive 2 way crossovers, and you can have a bike system. Make sure you get the most sensitive speakers you can find, regardless of which speakers you choose.C'mon be a real man.
http://www.radioflyer.com/accessories/minis_1.html
Fill that with two layers of car batteries and a few 12"'s at least
http://www.radioflyer.com/accessories/minis_1.html
Fill that with two layers of car batteries and a few 12"'s at least
bwayr said:
The background noise from heavy traffic can be around 80dBA or more -- you are going to need your music to be at least 10dB above that - and more if you expect to hear any detail.
Wouldn't you be better off using headphones, and maybe making a small electret mic preamp and mixer, so that you could add in a bit of the background noise if you need to hear what's going on round you for safety reasons?
The music would certainly sound better that way.
Unless of course you want those around to also 'enjoy' your music as well!
We have local guy with a car system that's loud enough for the people in the next CITY to 'enjoy' !!
Hang it from the top tube and you'll look real smart trying to pedal, or handling turns with a higher center of gravity.
Sorry but this really is a job for your typical Ipod, at reasonable volume levels to hear traffic. Be responsible. No one else wants to hear it.
No kidding if I were driving behind a guy like that struggling to peddle a stereo uphill while blasting eminem I'd be way too tempted to give him a push.
This isn't a good idea at all.
Sorry but this really is a job for your typical Ipod, at reasonable volume levels to hear traffic. Be responsible. No one else wants to hear it.
No kidding if I were driving behind a guy like that struggling to peddle a stereo uphill while blasting eminem I'd be way too tempted to give him a push.
This isn't a good idea at all.
My main purpose here isn't to "enjoy" my music, it is to have a loud stereo on my bicycle so that I make as much noise as the car next to me. The biggest problem I have on my bike isn't cars as much as it is people. And yes, I am a dumb college student, but I live in a dumb college student city so people are used to it. I plan on blasting the Beatles and Neil Young, by the way, not Eminem.
As for battery issues:
If I understand right, my amp will be powering 2 x 25W = 50W at 12V, which means it will be consuming 50/12 = 4.17amps (I realize this is the the upper limit), so a 4AH battery won't last me all of an hour if I'm cranking it (I'm not worried about 10% THD, lol).
My bike is a large road bike (you need to be > 6ft to reach the pedals), and the battery is being mounted below the lower tube, between the pedals and the front wheel, so that it's effect on my CG will actually be beneficial. The battery does way 6 lbs, but my packpack weighs 25-30 and it's 4 ft off the ground so the battery is the least of my worries.
Also, the speakers will be mounted in a box similar to the one linked to by kaban, but it will be much more rigidly attached to the frame so that I waste as little acoustic energy wobbling the encolsure back and forth as possible.
As for battery issues:
If I understand right, my amp will be powering 2 x 25W = 50W at 12V, which means it will be consuming 50/12 = 4.17amps (I realize this is the the upper limit), so a 4AH battery won't last me all of an hour if I'm cranking it (I'm not worried about 10% THD, lol).
My bike is a large road bike (you need to be > 6ft to reach the pedals), and the battery is being mounted below the lower tube, between the pedals and the front wheel, so that it's effect on my CG will actually be beneficial. The battery does way 6 lbs, but my packpack weighs 25-30 and it's 4 ft off the ground so the battery is the least of my worries.
Also, the speakers will be mounted in a box similar to the one linked to by kaban, but it will be much more rigidly attached to the frame so that I waste as little acoustic energy wobbling the encolsure back and forth as possible.
Bwayr (of bikes)
The 300 mA figure quoted above is a good average draw for the T-Amp. You will probably be using more because you will be forcing the amp to higher powers, just to get the sound you want. But it's unlikely you will ever draw over an amp. Size the battery accordingly.
For example: When I first got my Sonic Impact I took it to work and ran it very hard, pushed into clipping for about 4 hours before the AA batteries gave up.
You want the most sensitive speaker system you can afford - afford in weight, size, price. The more sensitive, the more SPL you will get for the same power going in. For every 3dB more sensitive the speakers are, you need half the power for the same SPL. You have limited voltage with the T-Amps, so 4 ohms helps. E.G., 2 woofers in parallel.
I have tried the Sound Pads, didn't think much of them. Just not very loud. Maybe a whole bunch of them together on the same surface - maybe.
Best of luck with your project. Let us know how it goes.
The 300 mA figure quoted above is a good average draw for the T-Amp. You will probably be using more because you will be forcing the amp to higher powers, just to get the sound you want. But it's unlikely you will ever draw over an amp. Size the battery accordingly.
For example: When I first got my Sonic Impact I took it to work and ran it very hard, pushed into clipping for about 4 hours before the AA batteries gave up.
You want the most sensitive speaker system you can afford - afford in weight, size, price. The more sensitive, the more SPL you will get for the same power going in. For every 3dB more sensitive the speakers are, you need half the power for the same SPL. You have limited voltage with the T-Amps, so 4 ohms helps. E.G., 2 woofers in parallel.
I have tried the Sound Pads, didn't think much of them. Just not very loud. Maybe a whole bunch of them together on the same surface - maybe.
Best of luck with your project. Let us know how it goes.
Bwayr...
well your Ipod, pull outta the bag plexi system would be cool, or a variation of it. Mount it on a rack, or build it into an aluminum case and hang it off a rack...should annoy the hell outta some o them dumb $@* car stereo freaks (nuthin wrong with good car audio, but most of the stereo freaks have ultimately no regard for any body else).
Might I also suggest a small launching device for sharp ceramic bits? Glass (even automotive safety glass) doesn't stand a chance. Then they can tell all their buddies "Mmmaan, look whaat ma kickass stereo did, yaaahhhhh".
well your Ipod, pull outta the bag plexi system would be cool, or a variation of it. Mount it on a rack, or build it into an aluminum case and hang it off a rack...should annoy the hell outta some o them dumb $@* car stereo freaks (nuthin wrong with good car audio, but most of the stereo freaks have ultimately no regard for any body else).
Might I also suggest a small launching device for sharp ceramic bits? Glass (even automotive safety glass) doesn't stand a chance. Then they can tell all their buddies "Mmmaan, look whaat ma kickass stereo did, yaaahhhhh".
Here is the way I taught about solving the problem with the bike audio system:
- go loud with less energy: just putt 2 small speakers on the handlebar pointing to your head, and equalize them
- how to make a big enclosure: just use the triangle off the frame, the whole space available between the bars off the frame, and use two "short" (thin) car speakers designed for the doors, both connected to the same air volume. you will probably have to use something else then wood for the two panels
- if you really want to ennoy the audience, then this is the way: buy a few tweeters with the highest sensitivity.. and cheap too because you don't need anything hi quality... lets say 2 x 3 tweeters off the same model. Step two is to find a way off playing a 7000 Hz tone continuously. It will have the effect of ultrasounds on dogs. Nobody will realise whats happening... they may not even determine whose making the sound. And to go even louder - there are certain frequencies at which if you put something in front of the speaker it "resonates".. it's probably a horn loading effect. Find that frequency and there you go... original and disturbingly loud. It even saves energy, space, weight...
- go loud with less energy: just putt 2 small speakers on the handlebar pointing to your head, and equalize them
- how to make a big enclosure: just use the triangle off the frame, the whole space available between the bars off the frame, and use two "short" (thin) car speakers designed for the doors, both connected to the same air volume. you will probably have to use something else then wood for the two panels
- if you really want to ennoy the audience, then this is the way: buy a few tweeters with the highest sensitivity.. and cheap too because you don't need anything hi quality... lets say 2 x 3 tweeters off the same model. Step two is to find a way off playing a 7000 Hz tone continuously. It will have the effect of ultrasounds on dogs. Nobody will realise whats happening... they may not even determine whose making the sound. And to go even louder - there are certain frequencies at which if you put something in front of the speaker it "resonates".. it's probably a horn loading effect. Find that frequency and there you go... original and disturbingly loud. It even saves energy, space, weight...
Forget the whole idea.
As a cyclist myself, you seem determined to give other cyclists a bad name. Maybe you want to hear your music, but who else does? Just because a car is disturbing the peace doesn't entitle you to try to outdo them. Personally, I find the Beatles just as offensive as Eminem.
I can guarantee if you pursue your proposed course of action that someone will take offence - and as a cyclist you are extremely vulnerable to being clipped by a car or having a wheel kicked by a pedestrian...
bwayr said:
As a cyclist myself, you seem determined to give other cyclists a bad name. Maybe you want to hear your music, but who else does? Just because a car is disturbing the peace doesn't entitle you to try to outdo them. Personally, I find the Beatles just as offensive as Eminem.
I can guarantee if you pursue your proposed course of action that someone will take offence - and as a cyclist you are extremely vulnerable to being clipped by a car or having a wheel kicked by a pedestrian...
Here's whaqt I did a while ago, but my present system is totally kicking behinds :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=95089&highlight=
Don't expect PA levels from AMP3 (I'd rather use AMP32 by the way...) You could go for AMP9 in low profile version (it's smaller and modified to use at max 14.5Vdc...)
AMP9 goes massively loud with the right speakers attached....
:http://www.diyaudio.com/forums/showthread.php?s=&threadid=95089&highlight=
Don't expect PA levels from AMP3 (I'd rather use AMP32 by the way...) You could go for AMP9 in low profile version (it's smaller and modified to use at max 14.5Vdc...)
AMP9 goes massively loud with the right speakers attached....
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