Serial bridge on the LAN
A Raspberry Pi owns the RS-232 link to the AVR and exposes safe control over the home network — power, volume, input, and zone commands stay on hardware you own.
Denon AVR-3805: legacy amp, modern control
The AVR-3805 is a solid multi-zone amplifier with no native Wi‑Fi or app stack. This project bridges it into the home network so power, volume, sources, and rooms respond to phone UI, Home Assistant, and voice — without replacing the hardware.
The problem
Older premium AV gear often still sounds great and drives multiple zones, but it lives behind an IR remote. There is no vendor cloud app, no Home Assistant entity, and no clean path for a local voice assistant.
Replacing the amp is expensive and wasteful when the limitation is connectivity, not audio quality.
The solution
Build a local control bridge from the amp’s existing RS-232 port into the home network. A Raspberry Pi talks serial to the AVR-3805 and exposes power, volume, input, and zone commands on the LAN. From there the same bridge feeds a phone/desktop remote, MQTT status for Home Assistant, multi-zone streaming, and a locally hosted voice assistant — so the amp behaves like modern connected gear without a rip-and-replace or a vendor cloud.
How the solution works
Four layers on top of that RS-232 bridge.
Phone & desktop remote
A secured web remote on the private home hub covers day-to-day listening: zone power, volume, sources, and stream selection for rooms like backyard and pool table.
Home Assistant awareness
Live status publishes over MQTT so dashboards and automations can react to the amp without a cloud account for the Denon itself.
Voice & agents
The same bridge feeds a tool layer used by a locally hosted voice assistant (Jarvis), so spoken requests can change zones or start streams without a phone in hand.
Multi-zone listening
Independent streams per zone keep theater, backyard, and pool audio from fighting over a single source. Each zone gets its own renderer path into the AVR inputs the hardware already supports.
Stack: Denon AVR-3805, RS-232, Raspberry Pi, WebSocket control, MQTT, Home Assistant, DLNA renderers, MCP tool bridge, local voice assistant
Why this matters for clients
- Keep what works: modernize control instead of ripping out a capable amp.
- Reuse spare hardware: old PCs or laptops that feel too slow for daily use are often plenty for a local bridge, Home Assistant host, or voice stack — which keeps project cost down.
- Privacy-first: control stays on the LAN; no Denon cloud subscription required for basic remote use.
- Whole-home audio: independent rooms and streams, not one IR remote for everything.
- Voice-ready: the same integration layer that serves the UI can serve a local assistant.
See related work
The live house demo on homatica.online includes this Denon path behind member login. Consulting engagements adapt the same pattern to your rooms and gear.