Repository for a fully 3D-printed two-way Bluetooth-speaker.
REMARK: This is just the documentation of my personal build and in no way a complete instruction to follow along. I provide everything I used to finish this build as an orientation for similar projects
- size: 280x145x125mm (LxWxH)
- fully printed speaker-enclosure
- 2x 2" full range chassis for mids and higher frequencies
- 1x 3" chassis in own subwoofer-compartment for lower frequencies
- digital crossover and equalizer via a ADAU1401 DSP
- digital volume- (rotary encoder) and tone-control (potentiometers)
- APTX Bluetooth connectivity via a CSR64215 which communicates digitally (I2S) with the DSP
- 6s Li-Ion battery pack with BMS and USB-C charging (PD 20V)
The goal of this project was to design a fully 3D-printable portable Bluetooth-speaker.
The enclosure consists out of 7 parts which can be printed without supports (some screw-holes might be better with) on a 300x300x150mm build-volume. As a material I used simple PLA, although PETG might be a better choice due to its thermal resistance (amplifiers and DC-DCs might get hot).
The enclosure contains three seperated chambers, one for each speaker-driver. The big subwoofer-compartment in the middle of the casing has a looped horn-like opening and holds a 3" speaker for lower frequencies (50-250Hz). The two side-compartments contain each a 2" full-range chassis for mids and highs.
Each driver currently has its own amplifier (TPA3310, 30W), but replacing two of them with a 2x15W TDA3110 (like this) for the two 2" would probably make more sense.
The battery of the speaker consists out of six 18650-cells () which are connected in series to a 6s-BMS. The charging happens over an USB-C adapter with a Power-Delivery chip, which delivers an output-voltage of 20V. This way the attaching DC-DC-converter has only to go up by 5.2V, which results in lower heat loss. The downside is that you can only use USB-PD-chargers to power the speaker.
The "brain" of the speaker is resembled by an ADAU1401 DSP from Analog Devices and a sound-providing CSR64215 Bluetooth-receiver.
The ADAU1401 is a small, self-booting DSP with 4 DACs, so each of the speaker-chassis can have it's own channel. This way, digital audio-processing like EQ, crossovers and other balancing, can happen completely in software. The board also allows using it's GPIOs for manipulating parameters. Volume- and tone-control is realized with rotary-encoders and potentiometers.
The Bluetooth-receiver is connected as a slave via I2S to the DSP to avoid any loss in quality due to unnecessary ADC-DAC-conversions.
- Drivers for the EZ-USB (DSP programmer)
- Analog Devices Sigma Studio (DSP dev-tool)
The software necessary for programming the CSR64215 Bluetooth-module (setting name, I2S-mode, sampling freq etc.) is a little hard to get. Offically this tools aren't made for the consumer-market and therefore only available for business-clients (csrsupport.com). However the software is often shared in forums like in this thread in the German hifi-forum.de.