/diy/ - Do It Yourself

your gonna need an amp

>>156887
I want to make this cheap and I don't look forward to be buying anything, I already have speakers and I don't want to get another one.

>>156879
holy balls your request was difficult to read

> I was wonder if I could take speaker wires and make it so I can plug in headphones into it. Is it possible
>i was wonder
>speaker wires
>plug headphones into it
wow....
ok well that thing you keep calling headphones is commonly called a jack

the other connector is i think an rca plug or whatever

the black thing is a capacitor

if you didnt know these things i dont think this project will be an easy task for you, also you need an amp like the other guy said, otherwise the sound is gunna be so low you wont hear it

my inner /b/tard is trying hard not to flame you right off the internet because i probably used to be a faggot 12 year old like you too once.

>>156897
Where would I go to buy an amp? link?

the speaker you took apart probably had one built in, you are a ware that amps need a power source....

>>156918
yes, I forgot to add that part...


How do I add a power source to this speaker?

Isn't the "+" and "-" where I put the power source? I'm not really so sure myself. :[

>>156929
oh man, you need to do some more research kid lol as im too lazy to help atm sorry..... go look up how speakers work
http://lmgtfy.com/?q=how+do+speakers+work

when you know this then you will realize that you'll need a battery in your back pack, power switch, amplifier, something to attach the speakers to, and depending how /diy/ you get, youll need various connectors or spare wire, solder, and a soldering iron to do the hardwork yourself. and hopefully when this is all said and done youll realize you dont want a speaker backpack because it is unlikely anyone else wants to know how bad a taste in music you have

When I 1st thought of this was...
Add speakers to a backpack with a power source, have an audio input, and plug an MP3 player into it, and that's it. o.o
I guess I was missing the complicated things.

>>156946
perhaps i'm over thinking it as i usually do, but thats why you should really do research first...

you have to consider what kind of power the built in amp needs if youre using that, though you can probably buy one that runs on a nine volt or something

in the end your quick fix i guess is just cut off the rca plug already on the speaker wire

then strip the wire to the 3.5mm jack wire and the speaker wire, and make do with a shitty splice job and some electric tape

Here's a pic of the wires in the rca plug.
So just get a jack wire and slap it on?
What about the power source if it need it?

okay well yea go ahead and strip the wires for the jack now, but keep in mind that most jacks are stereo and youre outputting to one speaker(mono) so you would need to attach the wires appropriately

Is this something would use to make this compatible to an audio jack?
Also guys, thanks for so much help. :]

:s

And so it begins

Read this, research and hope it helps.
You can plug the jack into the mp3 part of the amp.

first of all, anyone that would wear one of these is probably the biggest douchebag of a teenager anyone can imagine. there's a reason headphones/earbuds are popular amongst the majority. no one wants to listen to your shitty music.

second, why dont you just throw a boombox into a regular backpack. its the same fucking thing

>>159441
A 3Ah battery like the one pictured isn't going to last very long at all. Ideally it'd last 1.5 hours, but that's probably not going to be the case.

Here's some interesting info on the subject.
http://www.chem.hawaii.edu/uham/bat.html

Pic not related

how long do you think a 8 AA battery back would last?

>>159628
One standard AA is at around 2Ah, and since you have to put all the batteries in series with each other to get 12 volts, you only get a total of 2Ah.

Now, I assume your device pulls 2 amps, so ideally this would get you 1 hour, but since this isn't an ideal world, you'd probably get a lot less than that. I would guess at 30 minutes. (Mainly because since you'd pull as much power as the batteries can deliver, gas would build up, and the magical innards would deteriorate fast)

If you buy 16 batteries, and make two clusters of 8, then connect them both to the device in parallel, you have 2 x 2Ah, which would last you up to two hours.

The more clusters of batteries you have in parallel, the less the individual cells would have to work to deliver power, so they'd last longer.

>>159718
I should probably clarify that a little.

Let's say that we have two batteries. If you put them in series you add the volts together, while the Ah is the same. If you put them in parallel, you add the amps while the volts stay the same.

tl;dr:
Series: add volts
Parallel: add amps

Also, don't mix batteries of different volts and amps - that shit won't fly.

Oh hey guys, OP here :[
So I was being a noob and went all out on this, to clear some things up:
1) I've never worked with other electronic creations
2) This is my first
3) Me cutting the RCA (m) plug off the speaker was so stupid of me cause afterwards, I searched up an adapter and this is what I NOW have. (pic)

Also I never knew what the plug was called oh :[


ANYWAYs, I got the speaker to play a audio through the Audio Jack [see I'm still learning :D] but now the problem is:
The speaker on my laptop is louder then the one I tried out. <<How do I give the speaker power, so that it plays louder?>>
Do I just add a batter pack so it plays louder? If so how much watts does it need and how & where do I add this?


Again, thanks for helping me out :]

>>159764
you absolutely need an amplifier. have a look at what >>159441 wrote, and what I wrote in >>159548 , >>159718 and >>159759 on how to power it

>>159764
Also, there's a chance that you'll fry your sound card if you plug huge speakers into it without an amp, so you really shouldn't.

>>159480
Oh derp, I guess ignore my previous comment, but sweet, so I'll use this and thanks for helping out. I appreciate it. :]
>>159441
I do understand that not everyone likes the same music, but I though it'd be cool to have and show off and yes being a "douche bag" and play some Justin Beiber and Rebecca Black. (srsly no) And you aren't really helping out on this project :[

>>159718
>>159759
I have no idea what Ah is, but ok. Also I was planning on buying Rechargeable Batteries which I think are better :]

>>159770
Ah stands for "Ampere hours", and it's a measure of how long the battery will last.

Basically, if a battery has 1 Ah, it can deliver 1 amp for an hour, or 0.5 amps for 2 hours, etc.

If you look right above the plug on the amplifier in >>159441's picture, you see "DC12V2A", meaning that it requires 12 volts to run, and it'll draw 2 amps. Your battery pack should meet the 12 volt requirement perfectly, while exceeding the amps. The higher the amps of your batteries, the longer they'll last. Use the formulas I gave you.

Rechargeable batteries are a bitch to use, because if you discharge them below a certain point (depends entirely on the chemistry), you may ruin them forever, or severely hamper their ability to hold charges in the future.
You most likely want deep cycle batteries, but bear in mind that they're both expensive as hell and heavy. Think several pounds.

Also, "douche bag" is a pretty good name for your project, isn't it? That's definitely what I'd call it.

>>159781
Ok nice, I'll make a douche bag :D lol
So about the Rechargeable batteries, is it possible if, you recharge them longer than it's supposed to be and it is now ruined?
Oh and thanks for clearing up the Ah thing for me :]

>>159787
No probs. If you overcharge (as in charge too long) certain types of batteries, they turn into gigantic explosions and/or fireballs. Other batteries just boil the electrolyte away, leaving you with a useless hunk of plastic and metal. Do not overcharge your batteries, or you may find yourself in a hospital and/or homeless on the street.

Now, some chargers know when a battery is full and stop charging, others start doing what's called a "trickle" charge, where it provides a magical amount of power that stops the battery from discharging. (All batteries discharge over time when left alone, it's chemistry).

Have you decided on an amplifier yet?

>>159792
Well, I'm not really sure, I'll have to look around and compare prices, but YES, since I want them to be louder and be more of a "douche bag" for my "douche bag" project XD

>>159821
Good luck. I have to catch some sleep now.. I'll be back in a few hours if the thread survives that long.

Yeah, so all I need is:
1)Amp
2)Power Supply
3)Backpack
4)Common Sense

and then I think I am good and this thread can go burn when its time comes.

Wait!!

Quick Question:
Does it matter for the speaker, how much voltage it takes, or does the amp takes care of that? Cause I don't want to blow it out.

>>159990
Hmm.. I actually don't know. Bumping for interest.

>>160036
>>159990

Did a little googlin' and found this:

"Speakers are rated in watts and have a specific impedance (a complex form of resistance but not something you have to really worry too much about for the calculations we need). Since I could never remember the equation I did a search for 'calculate watts resistance. and I found the following formula.

Watts = Volts X Volts / Resistance

So the square root of (Watts X Resistance) will give you the Volts.

Now how much voltage you get out of the above equation depends on how many watts your speaker is rated for."

From what I gather, you don't have to care that much about the voltage, as long as your wattage is right. It sounds about right, but I'd do more thorough research if I were you.

How do I know how much Watts the speakers need? Here's what the back of the casing to the speaker looks like.
I see an 8 Ohms, what does that mean?

So based on this
http://www.marktaw.com/recording/Electronics/OhmsAmpsandSpeakers.html

And I have 2 speakers that have 8 ohms making a total of 16 ohms right? So I would have to get a 200 Watt amp? I'm not really sure about this. :[

P = V^2 / R = 10^2 / 8 = 12.5 watts

Does this mean that I need 25 watts for 2 of my 8ohm speakers? I'm lost >.>

There is what I was looking at:
http://www.rayfes.com/caraudio/ohms.php

my speakers are a little weird... any ideas where to attatch the speaker wire?

>>160560
Wow, I am tempted to use the k word. See those two prongs on the back side with the holes in them? That is where you solder the wire.

Guys, I'm still here. I don't know how many watts or volts I need to use for my two 8 ohms speakers >.>
A quick comment would help out anytime

>>160583
Without a nameplate rating, we don't know the watts. Most cheapy speakers without the watts printed on them are probably no more rated than 20 watts. You're probably lucky if those speakers are 5 watt.

>>160482
>>160526
>>160583
I'd help if I could, but I actually don't know. Checked youtube? There's usually a video where someone makes and explains everything for you.

>>160583
For stereo you'll need two of these overpriced modules, but they run off of 12V and probably have more than enough power to push those speakers, plus they're easy to wire up.
http://www.mcmelectronics.com/product/KEMO-ELECTRONIC-M031N-/28-6400

Holy fuck. I can't believe this thread is still up and getting attention.

If OP isn't a troll I'm fucking impressed. Good job /diy/ers, and good luck OP.

>>160633
If I sound like I'm trolling I am sorry for the misunderstanding. It's just that I don't know what kind of amp I need to use. I have two 8 ohm speakers and all I just need to know is the volt and/or watts for the proper amp :/
And once again everyone, thank you for you input, this project is almost done, all I need is:
1)Proper amp
2)Proper power supply for the amp
3)Old Back Pack

That would be all.... For now. :]

>>160642
see >>160594; he's probably right.. you may want to invest in some bigger speakers to go with an amp like the one in this picture >>159441

I just don't know what amp will provide enough power to 2 eight ohm speakers.

>>160648
No that's not what I want. I hae the speakers already, I just need the right amp. I DO NOT have an amp. and I'm going to be mounting the speakers onto a back pack. :/

>>160655
Problem is that if the speakers are less than 20 watts (or dog forbid, less than 5), you're not going to get much sound from them, regardless of what amplifier you put on. Actually, a large amp on those speakers may pop them.

I have two "JBL CONTROL-28T-60" speakers on my desk right now, and they're at 60W.. I'd definitely not want to carry anything smaller.

>>160667
That's the problem, I don't know how many watts or voltages it has or can use, if you looked at my previous post, then you'd see me asking multiple times.
If I need to provide anymore information, let me know of what, and I'll see what I can do

>>160674
Yeah, you're giving us Ω (ohm), but that's only the resistance of the device. It doesn't tell us anything about voltage or wattage, which leads us to believe that it's pretty not very powerful. It's likely under 20w.

tl;dr: we don't know, we can't know, and as far as I know, the only way to find out is to crank the power up until it pops.

>>160679
>>Yeah, you're giving us Ω (ohm), but that's only the resistance of the device. It doesn't tell us anything about voltage or wattage, which leads us to believe that it's pretty not very powerful. It's likely under 20w.

>>tl;dr: we don't know, we can't know, and as far as I know, the only way to find out is to crank the power up until it pops.

Wtf? First 8 ohms is plenty fine resistance wise. I don't know about car speakers but often loudspeakers are 4, 8, 16. So it doesn't tell us anything about the power.

And yes, all you can do Op is crank them. I'd start somewhere around 40-80 watts and see what the speakers do. Overpowering is less of a problem than under powering. You can kill a speaker really fast if it is underpowered.

>>160681
I didn't say anything about the resistance being a problem, all I was saying was that that's the only information we got.

As for the rest, I believe you're trolling, so kindly source your claims or gtfo.

>>160682

No problem. First I will link for under powering.
http://www.avsforum.com/avs-vb/showthread.php?t=1233961

http://www.gearslutz.com/board/so-much-gear-so-little-time/487919-reasons-underpowered-amps-blowing-
speakers.html

http://www.head-fi.org/t/124136/underpowering-speakers

For the links some say under powering is not a problem. I run small live sound (Two 18'' monofold speakers at 16ohms and Two 15'' with horns rated at 8 ohms) and I've blown a couple of speakers because of both clipping and under powering. I was young. I was stupid.

Second point. of Ohms. I know two links are wikis. Deal with it.

http://www.prestonelectronics.com/audio/Impedance.htm

http://en.wikipedia.org/wiki/Loudspeaker

http://en.wikipedia.org/wiki/Constant_voltage_speaker_system

http://hyperphysics.phy-astr.gsu.edu/hbase/audio/imped.html

http://sound.westhost.com/impedanc.htm

http://www.gollihurmusic.com/faq/31-OHMS_AND_IMPEDANCE_FROM_THE_OUTPUT_SPEAKER_PERSPECTIVE.html

For these links you need to note that as you add or remove speakers from the series or parallel you change the ohms of the chain. In addition ohms listed on the speaker are the closest whole number average as they can vary.

>>160691

Sorry, Correction: I listed my 18'' speakers at 16 ohms, they are 8. I apologize about this.

O.O
I found the stereo system the speakers originally came from.
http://dc400.4shared.com/doc/c_8aXrEA/preview.html

I know I'm just throwing out links, but I think the numbers at the bottom might help, but idk

It's the SX-R290

If this doesn't help, I still thank you for trying to help :/

>>160691
Not going through all of that, but from what I've read (on my own and from your links), you're wrong.

What would the difference be between underpowering and simply lowering the volume? And are we talking burning just the tweeters, or the entire speaker?

>>160696
Again, my knowledge is not specific so I apologize and if any /diy/ individuals have better or more accurate information (without trying to cut down others in such a negative manner) then they will be of better resource.

So for the speaker in question it says that it is putting out either: 25w + 25w (that's both sides) with 1%THD or at 35w +35w with a 10%THD. So for all intents and purposes my recommendation of 40-80 was way off. Per speaker you want somewhere around 25 watts.

again, unless someone else disagrees with me.

>>160696
Given the data sheet, they appear to be either 25 or 35w, meaning you should probably get an amp at around 80-100w.

>>160697
Lowering the speaker volume and under powering are two different ideas.

http://www.gmarts.org/index.php?go=216

Go to power rating.

>>160702
This is of course not per speaker. You want something able to crank out 80 watts combined.

This is of course able to make your speakers pop out of their frames if you crank the volume all the way up, so I suggest trying it on a lower setting first. Smiley face.

>>160704
I shouldn't spend so much time on /b/.. I'm getting paranoid.
Thanks for clearing that up.

>>160579
there is three of them, which i why im confused. if you look closely behind the one on the left, you will see it

>>160691
>>160682
>>160681
>>160679


What the hell is all this faggotry...?

8ohm speakers... P=(V*V)/R (for the most part you can kindly assume they are static, OP isn't building audiophile quality shit here.)

Power rating of a speaker doesn't mean it REQUIRES X watts to run or do anything. Typically individual speakers having a rating of sensitivity measured as db/watt (typically at a fixed distance as well, usually 1m). So if we have an 8ohm speaker with a sensitivity of 80db/watt, 1 watt of input power is going to make 80 decibels of sound. Doubling input power typically yields a 3db increase in volume. So:
2W = 83db
4W = 86db
8W = 89db
16W = 92db
32W = 95db
64W = 98db

And so on. Now all that assumes you start at a sensitivity of 80db/watt. If you started at 90db/watt for the same power input things would be much louder.

So for an 8ohm speaker running from a 12V battery, the most power output you are going to get is 18W.

It also appears they came from a 5.1 surround setup as rear speakers, so I'm guessing they are rated for 20W or so, which for what OP wants to do is fine.

Obviously I left out a lot about clipping and the like, but running 1 watt of clean power to a speaker is not going to destroy it in any fashion. If that was the case speakers would blown everywhere all the time. (Do you listen to your speakers at full volume all the time? I don't.)

The only real issue OP might face is having excessive bass on speakers this small. Really having a high pass filter on the input would help prolong the speaker life more than anything.


>I built an ran a 12" shitty Pyramid sub off a shitty Pyramid 60W amp all powered off a 20W 12V transformer.
>It was loud enough to shake the windows in my room...
>Nothing died, nothing was lost....well maybe sound quality, but it was for gaming more than music.

>>160706
>>160704
Again what I know is for loud speakers.

Lets go down the chain of flow though to better get an idea of where either I am off or you are.

So everything needs power, that's pretty obvious. For this scenario because I haven't read the full thread (sorry Op) I am going to just give a generic amplifier. It needs power.

Power --> Amp

Now we need that amp to go somewhere right?

Power --> Amp --> speakers

So cool, the amp is running and because speakers don't always sound the best we will assume there is some "hum". Now we add in the ipod or other device.

Generic DAP
|
Power --> Amp --> Speakers

Now if you are wanting to just adjust the volume via the DAP then you are fine. If not then we need a volume knob (or a pot of some type) between the DAP and the Amp to speaker setup. Generally this volume pot just controls what is going to the amp and not the power out to the speakers.

Generic DAP
|
|Amp |
|Volume |
| | |
Power -->| Amp |--> Speakers

Now say we want to give variable levels to the amp signal out to the speakers. This is where things get tricky. This is were under powering occurs. What we need here is to make sure our DAP is putting out a nominal level (usually marked at 0) to make sure it is putting out the right amount on its end. Then we need to raise the amp power out to the speakers with the power knobs. So then we have.

Generic DAP
|
|Amp |
|Volume |
| | |
Power -->| Amp - Amp power knob|--> Speaker

Ok so from what I've read so far.... I should try out a 100 watt amp, and if this doesn't work, I can always return the amp and get a higher or lower amp depending on the loudness of the speakers, right?

I'll post a video of me making my dang stereo back pack cause I feel like it's going to be worth it. and then everyone here can troll me in the comments for making a "douche bag" or whatever >>159480

5W RMS is pretty loud depending on the speaker sensitivity. Nice choice in enclosure, this will never have any bass. Just follow what the dude posted in 159441 . Crank it until it is loud and if it sounds like it is distorting then turn it down. If the speakers feel hot, turn it down. I would link you to a good forum for this stuff but would be embarrassing. Good luck!!

>>160709
Look for the data sheet if in doubt, but if I were to guess, I'd go with the ones on the sides.

>>160716

NO.
100W's is probably 4 times as much power as the stereo these were hooked to. That much power and they'll just distort like hell. (That or be able to use about 1/4 of your volume control.)

>>160715
well I screwed this up bad, sorry for the fucked up pictures.

>>160713
I know he isn't building anything "fancy", but I was questioned so I linked.

>>160706
no problem, we are all gentlemen here, learning for the greater good of /diy/

>>160704

This isn't talking about an amp's power output as much as it is dealing with slew rate. The main issue it is showing is distortion caused by the amp not being able to provide a fast enough change in output voltage. Obviously as power output increases this becomes more important, and if left unchecked can cause damage to a speaker.
>Not exactly needed in OP's case.

>>160720
Yeah, what he said. I won't post any more until I've slept for at least 8 hours, I promise.

>>160720
So.... Try an amp with very low wattage (25w) and work my way up to what I see fit?

>>160742
An amp putting out 25w per side.

>>160742

Something with 25Wx2 would/should be fine for this.
One with a lower % THD at or around that power would be better. So 1% is better than 10%, and .1% would be even better, but probably not that noticeable here.

You could go up to as 45 or 50W per speaker and that's going to put you on par with a car stereo (like an aftermarket cd player with no external amp). That will get loud enough to damage speakers and your hearing.

Pt1
>>159441
Same guy that posted this

I reckon that the speakers SX-R290 don't require many watts 20 - 40 watts max.
Ideally you want a really good speaker with high sensitvity for a backpack design. But as a project and as you learn, you'll understand.

For now, OP needs a battery:
Look for SLA 12v 5-7Ah.
http://www.ebay.co.uk/itm/12V-7AH-12-Volt-PIGEON-MAGNET-SLA-LEAD-Battery-FREE-P-P-/190579222177?pt=U
K_SportingGoods_Hunting_ShootingSports_ET&hash=item2c5f6826a1
This will do. This will provide enough power to power the amp suggested below for a most of the day on full power. Look for something similar where you are.

Pt2
Next you need to get an AMP.
Do not go for any car related Audio, Car audio is highly inefficient and so will waste the battery quicker for same output.
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&hash=item3371b2598a&am
p;item=220950845834&nma=true&pt=LH_DefaultDomain_0&rt=nc&si=HUXoJ2LzLtdZB%252BIL9p7K
eiiZqGg%253D&orig_cvip=true&rt=nc
or
http://www.ebay.com/itm/2011-New-Version-Lepai-Class-Tripath-TA2020-Amp-20WX2-B-/400209246440?pt=LH_
DefaultDomain_0&hash=item5d2e5478e8
Either one will do, The first one requires more work to get it going, but its a better board. The second will also do you well for what you need to do.

I would not worry too much about the ohms as its such low power anyway. The amps will run both 8 or 4 ohm speakers no problems.

also, just because it has more wattage or power, does not necissarly make it louder (i can't spell).

Pt3
>>160756
Yes, one with a lower noise ratio is better than one with more power and a high noise to signal ratio.
But don't use car amp/speaker/mechanics for anything outside, totally different principles in effect.

Once all connected, turn it on and give it a go, put mp3 player and amp(if has volume control) on 50%. If sounds good, turn up the mp3 player to 75%. If no distortion then start playing with the AMP, wack it up to 75% as well.
That is what you want to leave it on for maximum output and lowest distortion. You could possibly go higher but then you run into problems sch as clipping/distortion etc.
Then mount the setup in a back pack.

tl;dr
1. Find battery similar to above
2. Buy either amp, 1st is slightly better made, 2nd is easier to use and has controls for bass/treble
3. Connect it together as stated in post >>159441
4. Mount in backpack (up to you on how, would suggest building a wooden box enclosure, and mounting into that, then putting that into backpack, but whatever)

Where can I go to buy an Amp that has at least 25 watts, it does have to be exact, because I don't have a card to buy online items :/
This is the only problem I have obtaining an amp and where.

>>161537
Can't help you there. Get someone with a card, give them money and a little extra for their time to get it for you.
If you cannot do that, try and look for real cheap headphone amps in audio shops.
If you cannot any of those, then you should just stop this project now. As without any of those items, its not going to work.

>>161595

That's not entirely true, but it would take some more technical understanding to achieve.

-A previous poster mentioned staying away from car audio amps, and for something like this I'd agree. However, cheap/shitty car amps (like Pyramid) typically use an integrated chip style amplifier as compared to individual pieces like a decent/higher quality amp would. This means it might be possible to scavenge an amp ic from one of these. Also car audio head units (aftermarket cd players and the like) would also be another good source.

You might be able to find one of these used/damaged locally to where you are. (Like a car cd player that won't load/play a cd anymore, just plays the radio for example.) The downside to this is the fact you are going to have to dismantle whatever it is you buy and build a new circuit/amplifer. And not to be mean, but given your current knowledge of the electronics going on here might be a bit of a stretch. The other downside is the fact you won't get to pick what chip your get out of this.

>I've been wanting to build a sub why have I never thought of this before...thanks /diy/

I do agree with >>161595 if you can find someone that will let you use their card, or buy the parts for you, that's probably your best bet.

Is it possible for me to get a 100 watt amp and lower them so it would provide 25 watts for 2 speakers?

> Is it possible for me to get a 100 watt amp and lower them so it would provide 25 watts for 2 speakers?

it's only 100 watts when you turn the volume up high. so just keep the volume low.

if you cant trust yourself to be careful, you can add 2 resistors in series with the volume pot to make sure it cant go higher than a certain level, or put high-wattage, low resistance resistors in series with the speakers (say 47ohms at 50 watts)

holy crap how are there people this nice on 4chan? I am impressed

>>161905
because when we're /diy/kes we do it for the smarts.

If you are dead set on building a stereo backpack then what I personally would do is this.

Look around and find someone who is junking a car and pull the car stereo and speakers out. I suggest using a car radio for two reason. 1) you might be able to find one for next to nothing with a powerful enough amp already built into it. 2) the wiring is color coded with what they mean written on the thing. Plus most car radios made in the last decade and a half have an input already on them so you just have to buy the RCA to 1/8 inch jack cable.

Personally though I would just cut up a cheap pair of headphone like the ones you see at dollar stores, wire directly to the input head on the tape player of an old Ghetto blaster. solder two wires BOOM you're done and the space where the tape would normally go even gives you a place to put the MP3 player while you're walking around with it. You can still find old boom boxes for only a couple of dollars. whole project could be done in half an hour for less than $10.

>>162093
If you get a ghetto blaster, might as well get an mp3 to cassette player adapter (assuming the cassette still works on it)
If not, just wire and solder it as this guy said.

>>161638
I know you could do that, but from reading OP posts, i decided it will be better to get an already built solution as not to be offensive, OP has no idea what he is doing. So keeping it simple but sweet.

>>161834
Why are you so get-set on an 100watt amp? Do you have one or seen one around? All i would reckon if you do, just show some self restraint, just label about 25% or until they start to distort and/or crackling with mp3 player on 75% volume and tell yourself that any higher will likely kill the speakers. This is a rough guide i used to keep my speakers from dying.
Not the best way of doing it, but ive not blown any of my speakers testing like above.

>>161834

Do you have a specific 100W amp in mind?

-sigh-
OP Here :[
I was looking around on youtube for a DIY amp, and I found this. So my question is...
Can I use something like this for my speakers? How do I make it for 2 speakers and 1 audio jack?

Next stop: Subway at Mexico city.

>>163806
I hate those fuckers

>>163226

Didn't provide a link, but usually you can use a y adapter to feed each input on the amp, like running them in parallel.

How many AA batteries does it take to make 12v?

>>165800
It depends on the V of each battery. Are they 1.5v or 1.2v?

>>165800
Assuming standard 1.5v AA batteries, 8 batteries.

Mind you, as they deplete, the voltage will drop.