KeyslamBuckling spring · sound test
IBM Model F keyboard sound test: a Model F XT
An IBM Model F XT from the early 1980s, recorded by Fractal_ and released as CC0. It's a short, busy 16 seconds of typing on capacitive buckling springs, cut into 39 takes you can play band by band.
Updated
Short answer: An IBM Model F sounds loud and crisp: each buckling spring snaps sideways under the key, and the board registers the press capacitively, with a deep clack as the keycap bottoms out. This pack is an early-1980s Model F XT recorded by Fractal_ and released as CC0 on Freesound, cut into 39 takes in four strength bands.
IBM Model F sound test
Each button plays real strikes from one strength band of this recording. Natural mix lets every key vary, like normal typing. Headphones help.
Press a band to hear “model f” typed on Model F strikes from that band, then type below.
About this recording
- Keyboard
- IBM Model F XT, early 1980s (per the uploader)
- Switches
- Buckling spring over a capacitive circuit board
- Keycaps
- Not stated
- Recorded by
- Fractal_ on Freesound
- Uploaded
- December 29, 2019
- Original file
- WAV, 16-bit, 44.1 kHz, stereo, 0:16
- Microphone
- Not stated
- License
- CC0 1.0 (public domain)
- In Keyslam
- 39 takes, 5 of them key-up
“Typing on an IBM Model F XT buckling spring keyboard from the early 1980s.” — Fractal_, on the Freesound page (checked November 2, 2026)
Capacitive buckling springs: how a Model F reads a key
Under every key of a Model F stands a coil spring in a barrel, pressing on a small pivoting hammer that Model F owners usually call a flipper. Push the key and the spring compresses, then buckles sideways in one snap, and the buckle swings the hammer. What the hammer does next is the Model F's trick. There's no membrane and no metal contact to close: the hammer's movement changes the capacitance between a pair of pads on the circuit board, and the keyboard reads that change as a keypress.
The mechanism is Richard Harris's “buckling spring torsional snap actuator”, patented for IBM in 1978. The Model F first appeared with the IBM System/23 Datamaster and was made mainly from 1981 to 1985. Its best-known form is the 83-key keyboard that came with the original IBM PC in 1981, known to collectors as the Model F XT.
Measured from the app's pack files
What the IBM Model F pack contains, band by band. Peak is the median take's loudest sample; audible length is how long it stays within 30 dB of that peak. Soft to slam spans 9.3 dB. How the bands are made.
| Band | Percentile of strikes | Regular-key takes | Space, Return, Delete | Median peak | Audible length |
|---|---|---|---|---|---|
| Soft | 8th–30th | 6 | 2 | −13.4 dBFS | 67 ms |
| Medium | 38th–62nd | 6 | 4 | −10.1 dBFS | 73 ms |
| Hard | 70th–88th | 6 | 3 | −5.8 dBFS | 69 ms |
| Slam | 92nd–100th | 5 | 2 | −4.1 dBFS | 69 ms |
Model F vs Model M
From 1985 IBM moved to the Model M. The spring stayed and the capacitive board went: in a Model M the hammer strikes a plastic membrane sheet to close a circuit, and IBM's 1985 patent for that design put its cost at approximately half that of the capacitive mechanism. The Model M's hammer is also smaller and its springs have fewer coils, so the two don't feel quite the same.
Collectors generally rate the Model F as crisper to type on and louder and sharper to hear. Keyslam has one board from each branch: this Model F XT, and a Unicomp built on the Model M design. They come from two different uploaders, and this one doesn't name a microphone, so hear the comparison below as one real keyboard against another, not a controlled test of the two designs.
What this recording adds
The upload is a 16-bit, 44.1 kHz stereo WAV file, 16 seconds long, the shortest typing recording behind any Keyslam pack, posted by Fractal_ in December 2019. Its one-line description, quoted above, is all the page says about the board: no microphone, keycaps or modifications are listed.
A burst that short limits how many clean strikes the slicer can choose from. This pack has 5–6 regular-key takes per band, 2–4 per band for Space, Return and Delete, and 5 key-up takes, 39 in all. The slicer gives Space, Return and Delete the darkest, longest-ringing strikes it can find, but this burst has no clearly darker group of strikes to give them, so the big keys sound much like the regular ones. Like the Unicomp, it sits in the narrower half of the soft-to-slam ranking: the slam band peaks 9.3 dB above soft, the 14th widest of the 15 packs.
The stereo is unusually wide: its left and right channels correlate at only 0.09, where 1.00 would mean identical, the least alike of the 15 packs. Headphones show it best. On laptop speakers, which sit close together, the two channels partly cancel in the treble, so the pack can sound a little duller and quieter than it does on headphones.
Model F vs Unicomp and MX Blue
Start with the Model M-family buckling spring, then Cherry's clicky switch, and listen for the shape of each keystroke.
- Unicomp: a Unicomp board on the Model M design, where the hammer lands on a membrane instead of capacitive pads. It comes from a much longer session, recorded with a clip-on microphone.
- MX Blue: a modern clicky switch for scale. Its click comes from a plastic collar snapping inside the switch, not a spring buckling.
| Pack | Type | Recorded by | Soft to slam | Audible length (medium) | Hear it |
|---|---|---|---|---|---|
| Model F | Buckling spring | Fractal_ | 9.3 dB | 73 ms | |
| Unicomp | Buckling spring | SamsterBirdies | 10.4 dB | 78 ms | |
| MX Blue | Clicky | EricsSoundschmiede | 12.0 dB | 58 ms |
Who it suits
Pick Model F if you want the sound of an early IBM PC keyboard, crisp and loud, and you mostly listen on headphones, where the wide stereo comes through.
Pick something else if you mostly listen on MacBook speakers or want more variety between keys: the Unicomp is a buckling spring with no stereo width to lose and more takes. For a quieter desk, try Topre.
IBM Model F: questions
Is the Model F XT the keyboard that came with the original IBM PC?
Yes. The 83-key Model F known as the XT keyboard was released in 1981 with the original IBM PC and also came with the PC XT that followed. The uploader dates this one to the early 1980s and gives no exact year or part number.
Model F or Model M: which is louder?
Collectors usually call the capacitive Model F the louder and crisper of the two. Keyslam, though, levels every pack to one target, −28 LUFS over a medium-strength typing passage, so when you switch between this pack and the Unicomp, what changes is the shape of the keystroke, not its volume.
What does capacitive mean on a buckling-spring keyboard?
That no contact closes when you press a key. The buckling spring pivots a hammer above pads on the circuit board, and the keyboard reads the change in capacitance between them as a keypress. The membrane Model M uses the same kind of spring, but its hammer presses the layers of a plastic membrane together to close a circuit.
Why does the Model F pack have fewer takes than most?
Because the source runs only 16 seconds. Every strike has to be clean to become a take, with nothing clipped and no second key landing in its tail, and a short, busy recording offers fewer of those. It still fills each band, with 5–6 regular-key takes per band and 5 key-up takes.
Keep exploring
Hear an IBM Model F on every keystroke.
$3.99 once after a 7-day free trial. On MacBooks with the motion sensor it follows how hard you type; on other Macs you pick the strength.