Machinery sound effects
A machine's sound depends on the load it is under. Describe the strain and the space as well as the machine.
Listen: 11 samples from the machinery collection
Every clip shows the exact prompt that produced it. The render script reads its prompts from the same file as this page. Copy one, change a word and generate your own.
Engine startup
via audiocpp-stable-audio-3-sfxsmall combustion engine starting up, initial crank then catching and idling, 2 seconds, outdoor space
Factory floor
via audiocpp-stable-audio-3-sfxfactory floor ambience, layered presses stamping, conveyors running and compressed air releases, large hall
Drill press
via audiocpp-stable-audio-3-sfxdrill press boring into steel, rising motor load with metal shavings and a coolant hiss, workshop
Forklift reverse
via audiocpp-stable-audio-3-sfxforklift reversing, electric motor whine with a repeating reverse beeper, warehouse reverb
Printing press
via audiocpp-stable-audio-3-sfxlarge printing press running, rhythmic mechanical cycling with paper sheets snapping through
Elevator motor
via audiocpp-stable-audio-3-sfxelevator winch motor engaging, cables tensioning under load then running steadily, shaft reverb
Spin cycle
via audiocpp-stable-audio-3-sfxwashing machine entering a fast spin cycle, rising drum whine with an off-balance rumble, close
Chainsaw
via audiocpp-stable-audio-3-sfxchainsaw idling then revving into a log, chain biting wood with sawdust spray, outdoor forest
Pneumatic press
via audiocpp-stable-audio-3-sfxpneumatic press cycling, sharp air release then a heavy stamping impact, repeating, factory reverb
Diesel generator
via audiocpp-stable-audio-3-sfxdiesel generator running under load, rhythmic engine thump with a mechanical rattle, seamless loop
Robot arm
via audiocpp-stable-audio-3-sfxindustrial robot arm moving through a sequence, servo whines with pneumatic clamps and stops
Prompts that work
These models respond to physical description. Name the material, the action and the space.
Engine startup
small combustion engine starting up, initial crank then catching and idling, 2 seconds, outdoor space
"Crank then catching" names the two phases of a real start. Without them the model tends to jump straight to a steady idle and skip the mechanical struggle.
Gear grind
metal gears grinding under load, harsh irregular scraping, mid frequency, close mic, dry
"Irregular" is the key word. Real gear grind is uneven scraping as the teeth catch inconsistently; a steady version sounds synthetic.
Hydraulic release
hydraulic press releasing pressure, sharp air hiss with a mechanical thunk at the end, close mic, dry
The hiss comes before the thunk, as in a real pressure release ending in mechanical contact. In the reverse order it no longer sounds hydraulic.
Conveyor hum
conveyor belt motor running, steady low mechanical hum with a faint rattle, factory room tone, 3 seconds
A "faint rattle" on a steady hum keeps a looped machine sound from sounding like a pure synth tone. Real machinery is never perfectly clean.
Power-down
industrial machine powering down, motor winding down in pitch, mechanical clunk at the end, factory room tone
"Winding down in pitch" describes a motor losing RPM. The direction of the pitch change is what separates power-down from power-up.
Making machinery sounds that fit
Generate one phase at a time
Machines have a start, a running state and a stop. A single generation captures one phase well; all three in one short clip tend to blur together. Startup prompts should describe the mechanical struggle before it catches ("crank then catching"). A running-state prompt should describe a steady character plus one imperfection (a rattle, a faint irregularity) so it doesn't sound like a pure tone. A power-down prompt should describe pitch or speed falling away. Generate the phase you need instead of a generic "machine sound".
Add an imperfection
Real mechanical sound has small irregularities: a belt with a faint rattle, gears that grind unevenly, a motor with a slight flutter in its pitch. Asked for a plain mechanical hum, the model tends to produce something too clean and tonal to pass as a real machine. Naming one imperfection ("faint rattle", "irregular scraping", "slight flutter") is usually enough to make the whole sound mechanical.
Room tone tells you the machine's scale
A servo motor whirring dry and close sounds small, like part of a robot arm or a printer. The same whir with factory room tone and more low end sounds industrial. Machinery prompts range from a wristwatch mechanism to a hydraulic press, and naming the room ("close mic" and dry for small devices, "factory room tone" for large equipment) often sets the scale better than a size adjective.
Why generate locally
The models run on your machine, which changes the cost, the privacy and what you can automate.
Offline after download
Weights are fetched once. After that, generation, the library and the API all work with the network off. Everything lives in one SQLite file and one folder of WAVs under ~/.soundbox, and nothing is uploaded.
Your agent can use it
Soundbox runs an MCP server in the same process, with tools for generating and listing sounds. Generated files come back as absolute paths, so an agent can copy them into a project.
Licences stated up front
Every model's terms are shown before you download it, and non-commercial weights need an explicit confirmation. Soundbox is MIT. The licence of the model that made a sound governs what you may do with it.
claude mcp add --transport http soundbox http://127.0.0.1:17494/mcpcurl -X POST http://127.0.0.1:17494/api/generate \
-H 'Content-Type: application/json' \
-d '{"model":"audiocpp-stable-audio-3-sfx","prompt":"8-bit coin pickup blip","duration_s":1}'Frequently asked questions
- Can I use these sounds in a commercial video or game?
- It depends on the model that made them. Soundbox shows each model's licence before you download its weights. The Stable Audio 3 models use the Stability AI Community License: commercial use is free below USD $1M annual revenue, and above that Stability requires an enterprise licence. ACE-Step 1.5 is MIT. MiniMax's models allow commercial use under a revenue cap and require an attribution notice. Some voice and stem-separation models are non-commercial only. Soundbox itself is MIT, but the audio is governed by the licence of the model that made it. Read that licence before you ship; this summary is not legal advice.
- Does this run offline?
- Yes, once the weights are downloaded. Soundbox runs the models locally and stores everything in one SQLite file and one folder of WAVs under ~/.soundbox. There is no account, API key or upload step. Only the initial model download needs the network.
- What hardware do I need?
- An NVIDIA GPU with 8 GB or more. CPU-only is supported, but each generation then takes minutes. That is fine for a few short clips and slow for a large batch.
- Can my coding agent generate these for me?
- Yes. While Soundbox is running it serves MCP at http://127.0.0.1:17494/mcp, with tools for generating and listing sounds. An agent can generate a sound as part of the task it is already doing and gets back an absolute file path to use in your project.
- How is this different from downloading a sample pack?
- A pack gives you one factory's conveyor belt, recorded at whatever distance and load the recordist captured. Generating gives you a machine sound at the scale and room your scene needs, and a matched startup, run and power-down from the same prompt family. It costs time and a GPU.