How to make a portable mp3 amp from old computer speakers

Picture of how to make a portable mp3 amp from old computer speakers
have you got a pair of old computer speakers lying around that you dont need?
want to make a decent iPod/mp3 amp?
these speakers are powered via a PP3 9V battery

snap on clip for 9V batter
9V battery
audio source

soldering iron and solder
screw driver
wire cutters/teeth
wire stippers/teeth

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Step 1: Disassemble speakers

Picture of disassemble speakers
your speakers might not be 9V, if there not you could possibly use AA batteries in series in aholder or use a gel cell, bit heavy though.

disassemble the speaker with volume and power input, unscrew it from the back, there should be a transformer attached to the back, this is what takes the 230V (110V) down to 9V or the working voltage for your speakers.

on the transformer it should say the primary and secondary voltage, the secondary voltage should be lower, 9V hopefully, if it is not 9V you may still be in luck, if it is 3V use two AA batteries, if its 6V use 4, if its 12V use either 8 AA batteries or a car battery or gel cell battery, look online for one.

however, if you want, you can put a batter inside if you have room, or outside if you dont, and put the speaker cases back together.

Step 2: Removing board, speakers, and wires

Picture of removing board, speakers, and wires
now you need to remove the board and speakers from the two speakers. to remove the speakers there should be screws holding the speaker in at the corners. for the board there is likely to be screws holding it into the case, and the potentiometers will probably have nuts holding them on. so pull the knob off the front of the volume control and the nut should be exposed. use needle nose pliers or similar to remove it, then repeat for any other control knobs.
searly21 year ago
I have a question. I took my speakers apart and the output is AC 9.5v. 700 mA. What can I do for this to work with a battery?? Any help would work. Please and thank you!
LazyH searly21 month ago

A simple nine volt battery would be the simplest solution, but 6 AA C or D cell batteries would last a lot longer. To an extent, the lower voltage will only slightly lower the clipping amplitude (max volume) of the amplifier circuit. I tested the amplifier circuit in a set of sony speakers I had and the voltage was originally 12 volts, but I could get to as low as 8 volts before the sound was distorted during louder sections of music when played at normal listening levels.

omendoza21 year ago
i have a qesution. what are the common voltage output in transformer 2ndary, should i remove the tranformer and throw it a way?
can i ask you something?? i dont have 9 volt battery clip and a battery holder.
Tv19965 years ago
can you make this solar
if you have a big enough panel, but ya might wanna put a inductor on it so that the speaker isn't broken by rapid voltage changes.

here's a video that explains in inductors:
I am pretty herp-derp when it comes to electric numbers, but could you use 6 1.5v batteries? because I have a 6 AA battery holder, and they are rechargeable too.
yep, but rechargeables might give you less performance as rechargeables that are "1.5V" are actually 1.2V, because the chemicals that are needed to make the battery rechargeable
jwarburton13 years ago
I have the same set of speakers as you, but cant remove the nut holding the amp board in place :/ WHAT DO I DO?!
Blubber3003 years ago
Would this work if I just left the power supply in and wired it into this?
CDAWWGG4 years ago
You should use a dry cell holder and AAs or C's because they will last longer in the long run. I tried this with some old boston acoustic speakers that got destroyed when my workbench caught fire >_< (now made of concrete..the more you know *ding*) and I needed an amp but didn't want to order parts for a chip amp. Good instructable.
liamhickey5 years ago
batteries are dc.. so soes it matter if the power supply was ac?
on my board i saw 4 diodes in a rectifier looking like thing so i believe you can power the board with a DC battery
Whales4 years ago
Tried it, on a few sets of speakers, So if you are wondering on quality, it really depends on what speakers you use. The better speakers, the better sound. Enough said.
Valgarn4 years ago
And, why did you take it appart? wouldn't it be easier to just take the transformer out and replace it with a battery?
odavidson (author)  Valgarn4 years ago
 In retrospect i should have replaced the transformer with a battery, but these speakers were destined to go in a backpack.
With mine a freshly charged 9V battery lasted me about 5 hours, at about 1/4-1/2 volume. It depends on your speakers but in normal use they shouldn't draw much current.
Valgarn4 years ago

won't you drain the 9v battery like, veeeery fast?
my transformer says: O/P:9V-1A
It's working perfectly though, sound quality is as good as with 230v from the wall^^

magnam5 years ago
hey, i have similar speakers as you, i removed the board from the speakers,
and i connected 9volt battery as power source, and i conect headphones to headphone jack.
it works, but audio quality is very poor. can you tell me what might be the reason?
my speakers are old so maybe its somthing wrong with my board???
hlp pls.
man is it running in 9v battery ?? we have the same speaker but my little brother broke it but my sure the components inside is still working please help me i like to convert it to portable speakers that i can bring in my bag... haha...LOL 
but i'm serious hehe.....great thinking keep it up....
Foaly75 years ago
Could this make a voice changer that someone whispered into loud as normal human voice?
Da Nugesta5 years ago
who removed my comment?! i don't mind but whY?
Da Nugesta5 years ago
(removed by author or community request)
But they don't have that bad quality sound. its not top quaility but enough to bear with
well i tried this on a really cheap ($4.99) dollar speakers ...just for trial run ..and it worked !!!! except for the sound clarity ...which is really bad cos of the cheapness ...i wanted to know if the same thing would work on pair of travel speakers (just connecting the PP3 clip part) cost i just wanna put one 9v battery and not may AAA size batteries .... thanks and great instructable
if u had idea for a casing ud prolly get a perfect score...noone besides u has thought of adding a power source to the speakers other then an ipod or whatever...great instructable buddy XD
Phil B6 years ago
I wanted to play Podcasts over my MP3 player while working in my garage. I just took a pair of old computer speakers and plugged the 1/8" male stereo jack from the speakers into the player's earphone jack. For power I used an old voltage transformer. Mine happened to be AC, so I added four diodes configured as a bridge rectifier and added a 1000 mf capacitor for smoothing. It works well. Had the voltage adapter been rated at too high a voltage, I could have dropped the voltage with diodes in series at 0.6 volt drop at each diode, or I could have added an LM317 variable voltage regulator, or two sufficiently high wattage resistors with a tap to give the proper voltage.
Wolf Seril6 years ago
People have been doing this on instructables for years with TV speakers, but this seems a lot better since there is an amp board in the computer speakers.
mrbob10006 years ago
that is sweet! hows audio quality?
odavidson (author)  mrbob10006 years ago
quality is actually really good, i can even hear the bass guitar in songs!