Introduction: 7-mode Bass-reactive RGB Subwoofer LED's
The basic idea:
I always wanted to wire led's to my subwoofer but was hesitant on doing it because so many people have different opinions about how to do it. Some wire it directly to the woofer and others buy controllers that react to sound levels. A problem is that wiring directly may burn out the LED's over time when supplied too much voltage. Having a seperate controller sucks because it's not attached to the woofer and the response to bass might suck.
I figured something out by combining different strategies people have used. Basically I use a regular cheap RGB led strip (non-adressable) and wire it to 5V+ continuous voltage regulators and 3 switches to control the colors on the back of the woofer.
As many of you know a non-adressable led strip contains 1 positive wire and 3 negatives that decide which colors activate. Normally these are controlled by a LED controller but if you wire them to switches you can seperately activate or disable them and make combinations of up to 7 color modes.
For those that are interested in knowing more:
Firstly, a subwoofer has a low-pass filter, so only amplifies bass. A bass is made by sending alternating current to the speaker cone in a low frequency. So when making 50Hz bass this means 50 times per second the wires will switch from negative to positive. This activates the electromagnet that pulls and pushes the cone out and in 50x per second. We want to use this to power the LED's directly because it will give out a light pattern that corresponds to the bass. But the LED's will only work half of the time because it only accepts current going in one direction. In reality you can't see this, it will affect brightness similar to pulse modulation.
Secondly, when you crank up the volume or when a heavy bass happens, this is because the voltage to the speaker increases, and with that it will pull a certain amount of current (amps). LED's work only within a specific range of voltage. A low voltage isn't a problem because it will just do nothing. A high voltage is a problem because it will burn out the LED's over time. So we need to cap the maximum voltage they can recieve. You can do this by adding 5V+ regulators to the positive wire. This basically means that once the voltage increases to 6 (or 7) volts, it will output 5V and it will never exceed this.
So in the end, when the volume is turned up enough and a bass happens that exceeds 6 or 7V to the speaker, the LED's will activate on the moment the current goes in the right direction. Beware that I have a quite powerful subwoofer, and I never crank up the volume to max. This is relevant since depending on the amount of LED's you use, there will be more strain on your amplifier. It might also affect sound quality, but I can't notice this really. Never crank up volume to max when doing this because you might draw too much current from your amplifier and break it.
There are 1 off and 7 color modes:
- All toggles OFF: nothing
- 1 Toggle ON will be Red, green or blue
- 2 Toggles ON will be Yellow, pink or cyan
- 3 Toggles ON will be white-ish
I added 2 video's. One is to show me cycling through some colors. The other is to show what it looks like on a very bass-heavy music track (good old dubstep). On video it looks like it flashes incoherently sometimes, but this is due to how the camera records the fast pulsing in the lower frequencies.
- Subwoofer (duh)
- 3 Simple toggle switches
- 5V non-adressable RGB LED strip (measure the lenght you need)
- Some wires (measure)
- Soldering iron
- Optional: Sugru or silicone to adhere the switches to the back. You can also probably use duct tape.
Step 1: Specifics on Some Parts
For the voltage regulator:
I used L7805CV but there are others that are also fine. Make sure to buy 3 or 4 of them.
Biggest difference between types is they activate at slightly higher voltage and may give a little more current. The point is they should have a wide voltage range. From 6 or 7V up to 30+ volts input and output a continuous 5V on the plus wire.
They only cost a few cents per piece, so buy a couple of them and also different types. You'll pay mostly shipping. This gives you the opportunity to put them in parrallel to increase the current they can give and try different ones if you mistakenly buy the wrong ones. I put them in parallel because LED's draw quite some current and the regulators heated up and shut down out of protection after a while.
LED strip: non-adressable:
Should have 5V+, R, G, and B connection. Some sellers rip you off by providing LED strips that have this pinout, but the Red, blue and green LED's are actually seperated far from eachother and not in one piece, so this ruins the colors when making combinations. So pay attention. I bought mine on aliexpress.
I accidently bought Double Pole Double Throw Switches (DPDT) but they serve the same purpose as SPST switches when wired correclty. (overview of switch types: https://www.electronicshub.org/switches/)
Thin copper wires will do
Step 2: Wiring Outside the Subwoofer: Positives
Measuring up your subwoofer and wiring
- First of all you need to think about how you are going to wire everything
- Where are you going to put the led strip? Can you easily wire the switches to the back of the subwoofer by removing the back panel?
- Then draw a scheme to estimate how long your wires have to be. You need 4 very long wires for example to connect the RGB to the switches.
Wire the whole thing first outside the woofer so you can troubleshoot when it doesn't work.
First the positives:
- Solder a few voltage regulators in parallel. Do this by soldering the left and right arms together. Pay attention to the orientation. When the text of the regulator is facing in your direction, then the left arm is input (coming from the woofer). The right is output (going to the LED's).
- When you soldered this together, wire the output to the 5V+ connection on the LED strip.
- Connect the input wire to the positive side of your subwoofer wires (this is the red one)
Step 3: Wiring Outside of the Woofer: Negatives to Switches
- One wire is connected to the negative of the subwoofer. This wire extends to the back or wherever you will be installing the switches.
- This wire splits to three different wires (just solder the 4 ends together).
- Each of the wires go into their own switch. To wire them look up the type of switch you have. If you have a plain SPST one it's real simple. If it's DPDT then connect pin 2 to pin 1 OR 3. Or connect pin 5 to 4 OR 6 (look at the picture).
- The three outputs of these switches go to the RGB channels of the LED strip. This means you have to wire the three wires back to the front. Solder them onto the R, B and G connections on the strip.
- If this is done you're ready to test
Step 4: Testing Out Before Final Assembly
Now do a last visual check of what you made. Does it follow the diagram as it should?
Turn on the woofer and play some basses on good volume. Make sure to not go overboard because playing a woofer outside it's enclosure might damage it because it can move more freely.
Make sure that:
- The led strip lights up
- You can change the colors with the switches
- The regulators don't become extremely hot by the touch (they turn off when they do)
Nothing happens at all
- Is the volume high enough?
- Are the wires still connected to the woofer cables?
- Are the regulators wired in the correct orientation? (input-output)
Only certain colors work
- Are any solderings shorting out: the wires at the switches or the connections on the RGB strip
- Did you connect the wires correctly to the switches?
- Best thing to do is grab an extra wire and bypass parts of the circuit to see where the problem is (eg bypass a switch by connecting in- and ouput directly)
Step 5: Final Assembly
If everything works then start wiring the thing
- First extend the switches to the back through the back panel and secure it back on.
- Secure the wires in your subwoofer! Stick them to the insides where they can't obscure the woofer. Also secure the regulators inside tightly.
- Wire the led strip just outside of the front. Now screw the woofer back in your enclosure.
- Test the setup again. If it doesn't work then something came loose or is touching.
Very last steps
- Now stick the RGB strip where you want it. I just went around the speaker to make a circle.
- To not have the buttons hanging around on the back and making noise due to vibrations, secure them.
- You can buy sugru to mold an enclosure and stick it to the back panel (like I did). But it's quite expensive, so you can use a silicone gun instead. Some 2-part glue might also work.
- As a last option you can try duckt tape, but this isn't very strong as a long-term solution.
Now you have a 7 color mode reactive subwoofer to visualize your tunes. Enjoy!