3.5 mm STEREO TELEPHONE MALE at the cable
The Amstrad CPC6128, released in 1985, features a standard 3.5 mm TRS stereo output socket on its rear panel for direct connection to amplified speakers or headphones. Audio is generated by the AY-3-8912 programmable sound generator, which provides three independent tone channels mixed across the stereo field. The socket carries no video or power signals — it is a dedicated audio output only. The mechanical form is a conventional 3.5 mm three-conductor jack, identical in pinout to standard consumer stereo headphone plugs.
| Pin | Description |
|---|---|
| L | Left Channel |
| R | Right Channel |
| GND | Ground |
Signals
- L — Left audio channel output; carries AY-3-8912 channel A and channel B (mixed).
- R — Right audio channel output; carries AY-3-8912 channel C and channel B (mixed).
- GND — Signal ground (sleeve contact).
Notes
The AY-3-8912 sound generator’s three channels are routed asymmetrically: channel A appears on the left output only, channel B is mixed into both left and right outputs (functioning as a centre channel), and channel C appears on the right output only. The socket is a standard 3.5 mm TRS jack (tip = Left, ring = Right, sleeve = GND) accepting any compatible stereo plug. An internal speaker is also fitted; connecting a plug to this socket does not automatically mute the internal speaker on all revisions. The service manual does not specify output voltage levels or impedance for this jack.