An RCA Y-adapter for stereo to mono downmixing to connect subwoofers with a single RCA input to sources with stereo RCA outputs. The box design is simple and not very fancy.
The circuit is inspired by multiple sources [1, 2] and should work fine for most line-level signals in consumer audio. No warranties, though. You will need to re-tune the subwoofer level after installing the adapter.
Bill of materials
- 2 male RCA cable ends (approx. 15 cm long)
- 1 female RCA socket with M7 or M8 thread
- 2 resistors with roughly 5 kOhm
- 2 short pieces of flexible cable (about 4 cm each)
- 1 M4x12 screw (M4x10 should work as well)
- 2 cable ties for strain relief
- Soldering equipment
Build process
- Print both case parts
- Install the female RCA socket into the bottom part of the case
- Solder one resistor each between the positive (center) lead of each RCA cable and the RCA socket
- Solder one short wire each between the negative (outer shielding) lead of each RCA cable and the RCA socket
- Insulate blank metal parts with tape, where required
- Install one cable tie on each RCA cable inside the printed case as a strain relief
- Put on the top case and install the M4x12 machine screw to secure it in place
Print settings
- Layer height 0.2 - 0.24 mm
- Line width 0.42 mm
- Infill 25 - 35%
- 4 wall lines
- 5 top & bottom layers
- Supports enabled (only on build plate)
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