This is a step by step guide to building a pair of two-way stereo speakers, with LED's synched to the audio. The LED's can be shut off when music without lighting is desired. In these speakers, clear acrylic is used so the entire interior can be viewed (along with the LED's).

My intention is for this instructable to be more of an inspirational guide rather than a strict series of steps. Of course I'll give the basic steps that it took for me to build mine, but with projects like speakers, a lot of variation is possible. I want to give you as much freedom of creativity as possible.

This Instructable is to build ONE SPEAKER. For a pair, simply repeat the process. I would recommend reading through the entire instructable before starting. The instructable is going to be split into three main parts: The Enclosure, The Circuitry, and The Assembly.

Another awesome instructable for speaker building can be found here:

This is my first instructable, so any and all feedback would be extremely helpful and appreciated.

If you have any questions at all, feel free to message me and I'll do my best to help.
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Step 1: What You'll Need

Picture of What You'll Need
Here's what you'll need for ONE SPEAKER. Just double and repeat for the second.

Dremel and Bits
Power Drill and Bits
Ruler (T-square works)
Level (T-Square)
Scoring Pen (T-squares usually have one hidden inside)
Wood Glue
Drawing Compass
Soldering Iron & Solder

For the Enclosure (Note, sizes vary depending on what drivers you choose):
3/4"x3/4" Pine Beams
1/4" Oak Wood Boards
1/4" Acrylic sheets (I used Lexan�)
6 Angle Braces & wood screws
8 Bolts and Lock Nuts
6 Furniture Pads

For the Circuitry:
1 Woofer
1 Tweeter
16 LEDs (I used two groups of 8 LEDs each, but you can mix colors if you want!)
2 NPN Transistors (I used 2n4401)
1 Speaker terminal
Insulated wire, 3' per speaker should be fine, but it'll vary depending on how big your speakers are
Speaker wire (12 gauge should be fine)
*Various wire coils
*Various polypropylene capacitors
*Various low-inductance resistors

*These parts are for the Cross-Over (Which separates the high and low frequencies of the audio), the L-Pad (which adjusts the volume of each individual speaker), and the Series-Notch Filter (Which controls the peaks at the resonant frequency of the drivers). Alternatively, you can just buy a pre-made one (which as it turns out, is usually cheaper).
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JonathanR1611 days ago

Hey Shingkai great instructable man! Really appreciate it! Was thinking about adding this to my car. I just need you to clear up some hindrances in the way. So let me try to draw a picture with words. Fuse box(in car) -> LED -> Resistor(optional) -> Transistor(C). Then hook up the + terminal of the speaker wire into the Base (what do I do with the -; connect it to ground?). Connect the rest to ground I'm guessing? Thank u for your time!

shingkai (author)  JonathanR1611 days ago
If you're going to put it in a car, you may want to use a MOSFET instead of a transistor. They do very similar things (act as an electrical switch), but vary slightly in how they operate. There are probably many guides online about how to wire up a MOSFET. The general idea is the same though, you use the MOSFET as an electrical switch to turn on the LED whenever there are voltage spikes (which correspond to spikes in volume during the duration of a song, e.g. heavy bass beats).

Thanks for replying Shingkai! What would you recommend to do? Plug the LED's directly to the speakers or go the MOSFET route? Thank you for shedding some light on this for me!

amelendez61 year ago
I know this is an old publishing but hopefully I can get an answer. I really like the speakers that come with my Sony stereo system, the way they sound and look, so I just want to add LED's to it. Obviously, I can't just wire the LED directly to the speaker because the source is to powerful and the LED's will blow out. So if I hook the LED to it's own small battery as a power source and use the transistor as explained above will I still risk blowing out the LED? How does the transistor work, do it separate the power source from the audio signal to prevent this kind of damage? The speaker in this project looks about as large as mine, and my system puts out about 120 W per channel. I don't know much more than that.
shingkai (author)  amelendez61 year ago
Hi, yea I wrote this a while back when I was in high school and didn't really know what I was doing (just enough to get it to work, but there are better ways of doing this).

Anyway, a transistor is essentially an electronic switch, but it is current based rather than voltage based like a MOSFET. For the most part, the two circuits will be separated, but there are subtleties.

I'm really busy with coursework right now, but if you send me a reminder message in maybe a week I'll try to get back to you and help you out =)
Hello again. So I gave this a go and it worked pretty great, until I put my speakers a little past half way, then the LED's appeared to catch fire and blew out again. I've read online that resistors can help prevent that but I honestly can not figure out what kind of resistors I need. I don't know what voltage my LED's are, I took them from a cheap dollar store toy, but my stereo system says 120 V in the back? I remember you said you there are better ways of doing this, can you help me out?
shingkai (author)  amelendez61 year ago
I'm not that surprised that the LED's blew (sorry about that! I feel partly responsible because the circuit here isn't that good).

What is happening here is that you have excess voltage in the LED circuit that is being converted to heat, causing the LEDs to eventually fry. What voltage is the power source you are using for the LEDs? (not the stereo voltage, the power source for the LEDs).

LEDs are rated for a certain voltage, typically between 2-3 volts. They drop the input voltage by that quantity, so the difference between voltage on the two pins of the LED will be that fixed amount between 2-3v. They also require a certain current to actually light up. When you have a power source with a voltage greater than that 2-3v, the excess voltage generates heat in the wire and LED and cause them to melt. This is why we add a resistor, it lets the waste voltage be safely dissipated as heat, but the ability to do this is determined by the voltage remaining and the operating current of the LED.

A quick google search led to this LED resistor calculator (below). They have some good recommended values at the top, so try that. Apparently they also give you some recommendations on the LED circuit layout to optimize and take advantage of your power source and number of LEDs.
03111 year ago
How about a wiring diagram?
help me i dont understand how to wire light to my music system. You can call me stupid but I was not understanding.
shingkai (author)  iwanttoolearn1 year ago
Hi! I'd be glad to help you learn haha, is there anything specifically that confuses you?
RoeyLeon2 years ago
Very Nice project!
no video? :( thinking about doing something similar with a full plexiglass cabinet and mounting a ton of rgb leds under acoustic foam (sunk in to the plexi) then sanding the edges so it lights up like one of those fiber optic tree. any thoughts suggestions?
shingkai (author)  bob.the.devil2 years ago
hmm I thought i had a video... not sure what happened to it haha sorry

but that sounds awesome! last year i started to make a small pair of laser-cut acrylic speakers using 4" car woofers I had lying around. I had etched patterns into the faces (pretty much the same thing you're going for, correct?), but unfortunately I never got around to finishing them/installing LEDs.

I guess my only suggestion would be to see if you can get access to a laser cutter, (maybe look for makerspaces around you?). then you can get really creative and detailed with your etchings.

actually another thing just came to mind, I'm not sure how acrylic will sound to the discerning audiophile. or to the average person for that matter... it also might not make any difference at all (although my intuition tells me the sound won't be as "warm" perhaps). google it i guess!

anyway good luck, and i'd love to see what you come up with =)
yeah that is what i am using the acoustic foam for the reverb would be awfull with straight up acrylic of plexi. but i have heard about good results when adding some form of damper (and using a ported design) as far as etching i really wasn't think of. i like simple bold things myself i was just thinking accent lighting ( ) i figure if the leds are sunk into the plexi they will light up the edges fairly well. you should restart your engraved project tho it does sound cool, just not my style.
govind s2 years ago
is it possible to connect leds to a pc speakers which has an output of 9V...?
if do i do it and how many leds can i use...? i would like to use lots...advice pls! and i dont know anything about tell me what to do..!
Resistors are for fools. And those who know Ohm's law. What I would do is find LEDs that can handle the RMS voltage of the speakers. If that is 9 volts, then 9 volt LEDs. But, if the input to the speakers is 9v DC as opposed to 9v AC, you only need LEDs that can handle (9 volts) / (√2) aka about 6.5 volts. That means you could either use LEDs that have a voltage input range that covers 6.5 volts or put multiple in series and add up the ranges to get a working range.

If anyone disagrees with my logic and thinks this would fail, it has worked for me many times and I am not one to argue with success. If you do have critiques though I will be glad to hear.
macwhiz3 years ago
Would this work with a 350 watt per channel speaker?
shingkai (author)  macwhiz3 years ago
It should, though you're going to need to find transistors that can handle whatever power you plan to throw at them
Where would I find such transistors, and can you post a circuit diagram, including powersupply and everything?
kctess53 years ago
My god no pcb! hectic...
vil9j3 years ago
what type of leds did you use? 5mm 3mm 10mm?
shingkai (author)  vil9j3 years ago
These were 5mm, but you can use whatever you want really. Just make sure your power source accommodates for them properly (i.e. the right voltage, then make sure the right resistance is there so the right amount of power is going to the LEDs)
vil9j shingkai3 years ago
alrite thanxs so much and do you know which leds have a hire resistance?
shingkai (author)  vil9j3 years ago
Well the resistance in the LED itself doesn't matter as much as how much power it can handle. Generally speaking you're best off going with the largest LEDs you can find (assuming it's brightness you're after), although if you look at the spec sheets for the LEDs you're considering you can find the luminosity. Then you're going to want to find the continuous power that the LED can handle (which should also be on the spec sheet). Using the equation Power = voltage ^2 divded by resistance, you can figure out how much resistance you need to add based on your voltage source. I hope this makes sense -- what LEDs are you considering?
monsterman4 years ago
does this work with any npn transistor?
diabloboy4 years ago
you shouldve use like tin foil for the inside or something to bounce the light so it could be a bit brighter that would be cool just an opinion
koolcracker5 years ago
 I'm curious, the LEDs are hooked up to the same power supply as the speakers, correct? And it is fine to hook them up without a resistor?
shingkai (author)  koolcracker5 years ago
 Nope, I have an external power supply, in this case 9v batteries. I used the metal screws that hold the terminal plate on and conductors to get through the wood without any obvious wires protruding. And the resistance all depends on how many LEDs you use and what you use to power them.
are you using a resistor with your set-up? With the LEDs arranged in parallel, they would each draw too much current with a 9v source would they not?
shingkai (author)  koolcracker5 years ago
 Yea, they're in parallel, but the screws had a few ohms of resistance so I figured it'd be fine. But depending on what LEDs/screws/power source you have, you might need to add resistors.
 Thank you for the help sir.
shingkai (author)  koolcracker5 years ago
Glad I could help!
Do you know if this poject would work with 2N2222 Transistors?
shingkai (author)  Millenium_Bt5 years ago
I think that should work, the specs are pretty much the same as those of the 2n4401. 
If I use totally different drivers would the LED sync system and the transistors stay the same?
shingkai (author)  Millenium_Bt5 years ago
yea, that would stay the same 
If i buy a Crossover wich one should i take?
shingkai (author)  Millenium_Bt5 years ago
Well it really depends on the frequencies of your drivers. Any should work fine as long as the crossover frequency is within the overlap of your drivers.

If you tell me what drivers you're using, I could try recommending one for you. 
I'm using the same drivers you're using.
shingkai (author)  Millenium_Bt5 years ago

This should do nicely. Good luck! 
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