2.1 Bluetooth Sound System - Fully Printable
Introduction: 2.1 Bluetooth Sound System - Fully Printable
Strictly speaking, fully printable is a slight exaggeration. To be honest, I am still struggling with printing PCBs (although this would be reeeeally nice), drivers, and a few electronic components... ;D No, seriously, all you need in addition to the printed enclosures is a small amplifier board (and power adapter), the speaker drivers, cables to connect all this to the amplifier, and a few screws. All in all this should be a very economical project. All parts print on an 18x18 cm printer bed, assembly is super easy and (virtually) does not require any soldering or electronics knowledge.
First a little background. So what is a 2.1 sound system? In essence this is a stereo system with an added subwoofer. Stereo, or stereophonic sound is a “method of sound reproduction that creates an illusion of multi-directional audible perspective” (Wikipedia). Stereo sound is recorded by positioning two microphones relative to the source of sound (e.g. music) so that they simulate the experience of listening. They record simultaneously but not he same sound. E.g. the sound of the instrument that is closest to microphone A will reach A before it reaches microphone B and vice versa. Together this creates a stereo record that is similar to the listening experience created by your ears (which are “mounted” to your head, not unlike microphones, so they can distinguish the direction which the sound comes from). When reproducing stereo sound the speakers are positioned in a way that allows these two channels to give you the best feeling of the room the sounds were recorded in.
Now why would you want to add a subwoofer to a stereo system and why only one? The problem is that small drivers / speaker enclosures are not very good at reproducing lower frequencies. So you would need two pretty large stereo speakers (e.g. 1003
in a 2-way or 3-way design, which means each speaker has a woofer, a mid range speaker and a tweeter) to reproduce the full range of frequencies in stereo (this would be called a 2.0 system). However, while our ears/brain are pretty good in distinguishing directions in mid and higher frequency ranges, this does not apply to lower frequencies. The good thing is that this means that you don’t actually need stereophonic reproduction of lower frequencies. In fact you only need a single subwoofer for the lower frequencies, which can be placed pretty much anywhere in the room, and two small satellite speakers for the mid and upper ranges placed so that they give the best stereophonic experience (typically front right and left). The separation of the lower frequencies is done by a crossover (in essence a simple filter) e.g. integrated into a 2.1 amplifier that filters out the lower frequencies from both channels and pools them in a single subwoofer channel (this is what the #.1 in 2.1 stands for).
Step 1: The Amplifier (2x50W+100W TPA3116D2 Bluetooth 5.0 Amplifier 2.1)
A little background. TPA3116D2 is a Texas Instruments chip that has been around for a number of years and has turned into one of the most popular chips in compact class D amplifier boards. It is extremely power efficient and hence only requires small heatsinks (if any). These boards are also very popular among manufacturers of budget amps (the majority of those 50-100$ amps on the market are TPA3116 and some of these are really good). However, sound quality very much depend on board design. This board is definitely my favorite, good sound, no noise... Another advantage is that this board has separate bass / treble controls for the satellite speaker plus frequency and bass volume for the subwoofer, which is particularly helpful with printed designs.
So here is what you will need for the amplifier:
- The actual amplifier board: ZK-TB21 Bluetooth 5.0 2x50W+100W Amplifier Board (around $ 25) (from Amazon: ZK-TB21 Bluetooth 5.0 2x50W+100W Amplifier Board). Comes with a basic top/bottom plate (which I am not using), connector, and shiny knobs (also not used in this project, but you can).
- Plus a 12-24V switching power supply (from Amazon: 24V 3A external power supply. The TPA3116 operates on a wide range of voltage. However, I would definitely recommend a 24V/3A+ (72W) power supply to get the full output.
Filament. Use your favorite color / material. 552