Twizy 2.2 DSP corrected sound system with 3D printed subwoofer
I designed a soundsystem for my Renault Twizy around the following elements
- An Active MiniDSP filter
- Class-D 4 ways amplifier
- DC Buck converter
- DIY Subwoofer
- Visaton W 130 X (dual coil)
- Focal 13cm coaxials speakers
Subwoofer
The subwoofer enclosure was designed to fit in the narrow space behind the passenger seat. This gave the subwoofer a kind of rounded/organic shape.
From this shape I got an internal air volume. I looked for speakers that would work in such a small volume and still produce the desired level of bass (I aimed for around 45Hz -3dB). The software popped out a 6.5" Audax with dual coils. The simulation has some compromises though, at full power the vent would produce noticeable airflow noise.
As this was to be put in a noisy vehicle (it barely has doors...), it would not be an issue and I favored the power output and cuttoff frequency over the risk of airflow noise.
The subwoofer had its vent asjusted to fit the speaker simulation, and I printed it using PLA+CF. Retrospectively, this should have been ABS to better handle weather changes. Anyway, at the time I had a large printer with 30cm bed but still needed to print it in two part. The two parts were glued together using a very strongly bonding adhesive.
Calibration
For calibration I used my Beringher calibrated microphone, Room EQ Wizard (REW) and a Mac from work as I have some troubles with REW on Linux with my external I/O card. I calibrated for the driver's seating position.
Installation
28/05/24 The whole thing has been removed for the vehicle that I lended to my mother and is currently sitting unsused.