Introduction: The Multiglow Concrete Speakers

About: Hello I am Brian from Belgium. you know......the small country of chocolate beer and french fries. My hobbies are: aquariums, jeet kunne do (martial arts) ,small 4 stroke motor bikes, and Arduino projects I…

Hi I'm Brian from Belgium.

I proudly present my second intructable.

What is it?

diy concrete speakers with an embedded rgb led that reacts to the music.

The story

We all love music,No doubt about that.

But face it, the speakers that provide our beloved tunes are not always great in design. They are most of the time made of plastic and they do not look very nice on a desk. Besides playing music they do nothing.I thought I could improve some crappy old computer speakers with the power of RGB. I made them out of concrete to expand my materials knowledge and also because it looks very "design-ich" .They turned out very well .Let me show you what I created.

Step 1: Part List, Tools Used

There is quite a bit of parts. but i found them easily on eBay and in local hardware store's

  • 2 rgb led's (common cathode) sold here
  • 1 TIP 31 transistor sold here
  • bag of concrete ( i used 4 kilo's)
  • mouldable glue (you guys call it sugru i think)
  • 2 white plexiglass disc's thicknes=4mm diameter= 64 mm(i used my hole saw for this)
  • 2 clear plexiglass disc's thickness=4mm diameter= 64mm(i used my hole saw for this)
  • speakers * (bought at second hand store)
  • 2 x 50 cm wire (speaker cable)
  • 2x 50 cm wire whit 4 wires inside
  • 3.5 jack to jack cable
  • 12 volt power supply (mine was rated 1500 miliamps )
  • 2 empty cans of nuts *80 mm diameter
  • arduino *** (i used a pro mini first.but halfway the production it stopped working so i switched to a arduino mega,thats the reason there is no case for the arduino and the amp)

The cans of nuts can be replaced with every shape that you want.HOWEVER your speakers must fit inside.later you will see what i mean


  • concrete mixing tools (bucket,shovel)
  • soldering iron
  • flux, soldering tin
  • wire cutter
  • tape
  • gloves
  • shrinkable tubes (to protect he wires)
  • patience (ALLOT)
  • sanding paper grid 180-250
  • hole saw 64 mm

Step 2: The Round Object

Take you're empty cans and look for a object that fit inside it. For example if you're can is 5 cm in diameter the round object must be 3 cm in diameter.leaving you a thickness of 1 cm .Take you're round object and place it in the center of you're mould. You're "round object" must be slightly larger than the speaker you using

(Read: the speaker must fit inside the hole created by the round object)

You're also noticing a black line on the round object.This is the height of you're mould minus 1 cm.

Note you're round object can be damaged in the process.So make sure its not of a big value and you have no problem to rip it apart if it get stuck inside a mould

Step 3: Lets Get Dirty

Welcome to the dirty part.

After you eaten some nuts (you have 2 empty cans,so a bet you have some) you're ready to make some concrete.

I made 2 kilos (and there was plenty left over)

Fill the mould with concrete.but not entirely full.take you're "round object" and press it gently inside the mould until you're black line reaches the rim of you mould.The concrete will rise and spill over the edge of you're mould.This is not a problem simply cut it off wit a shovel .Now gently tap the mould whit a piece of wood for about 30 time's to let the air out of the concrete.Make the mould smooth whit you're shovel.and wait,wait for at least 48 hours.My round object flouts on concrete,so I secured it whit some tape.

Every hour you can rotate the object so that the concrete has no chance to stick to the mould.

Step 4: Let There Be Light

Meanwhile we make the leds react to music.

There are other instructables that show you how to make leds react to music

The difference with my design is that I use rgb leds.So now you enjoy all the colors instead of one .

Solder a wire on each pin of you're led. Solder the black wire to the longest (witch is the ground pin) do this for the 2 leds.

Next take one white plastic disk en one clear Plexiglas disk.sand the surface and the side of the clear plastic disk. Glue the two discs together.put the led inside the hole in the centre and bend the legs down(see picture)

Secure the legs with some hot glue and glue 4 square pieces (5mm x 5mm) of plastic onto the discs

The 4 pieces will create a gap between the concrete and the disk.So sound can go out and it also creates a hovering effect

Step 5: Assemble Time

Assemble time

Good you waited 48 hours :)

So now you can demould the it gently.Because you don't want to spend another 48 hours making new me it sucks =)

Before inserting you speaker putt some household foil (to help keep things fresh) inside the speaker.this will improve the sound quality.Putt some kneading glue onto the 4 mounting holes of the speaker en put the speaker in the hole.Press firmly in place until the glue comes out of the holes.Then put the "disc assembly" onto of the speaker.With the 4 pieces of plastic aligned with the holes.reinforce the 4 points with some more glue.

Step 6: Twisted

So where finely going to test the colors on our speakers right? No just a little more patience.

First take some shrinking tube and put it over the wires of the speakers.You should have a wire for audio and one for the rgb led.

Next twist the rgb wires of both speakers together.

Step 7: Wires

Wiring it all up :) This is the step where the soldering fanatic has been waiting for.

But first a little warning/disclaimer from me:

You may noticed that I used no resistors in this project.I did use them in the prototype fase but the leds where not glowing bright enough .So I got rid of them.with no resistors in the way the leds glow very nice.

When connected to my arduino pro mini, it worked fine for 9 day's. But then suddenly it stopped working.i tested the pro mini with another program and it still works perfectly.The reason why the pro mini will not run my rgb sketch is still unknown.Because a new pro mini is in the mail (4 weeks shipping time) I switched to my trusty old genuine arduino mega.No problems encountered whatsoever.

However I take no responsibility if you blow you're arduino. Even when I say mine performed perfectly fine.

Now with that aside lets move on shall we?

As you can see I made a schematic in paint :)

Connect the rgb wires (twisted together in the previous step) as follow:

your wire for the red leds to pin 9 your wire for the green leds to pin 10 you're wire for the bleu leds to pin 11 the ground wire connects to the middle pin on the tip 31 Locate where the input jack is onto you're speaker circuitboard (see photograph)

Solder a wire to the left (or right, it doesn't matter) audio input pin (seriously see photograph)

Solder the other end of this wire to the left pin of the tip31

Locate the ground pin on the amp circuitboard an solder a wire to it (you guys-->see picture)

Connect the other end to the ground of the arduino and the most right pin of the tip31

Install the rgb mood library (if you prefer to use another rgb sketch feel free) and upload the cycle sketch found in examples

You're done

Now when connected properly you have nice rgb concrete speakers.

As you can see there is no enclosure for the arduino/amp.if I got a replacement arduino pro mini I will show you how to make that.


Turn the output from the source to the Max (you're pc) an lower the volume whit the knob on the circuitboard.This way you always have a nice powerful audio signal traveling to you're tip 31 Apply a layer of varnish to the concrete to make them shiny Feel free to ask questions.I will answer them as soon as i can.

And yet again,sorry for my terrible English


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