SmoothSwing Explained: How Motion Sensing Makes Your Neopixel Saber Feel Alive (2026)
Technical Guide
SmoothSwing is the technology that turns a static swing sound into a living, speed-responsive audio experience. This guide explains how it works from the gyroscope up — and how to tune it for display, dueling, or cinematic slowmotion use.
Pick up any neopixel saber and swing it. The sound changes with your speed — a slow arc produces a low, controlled hum that builds; a fast snap produces a sharp, high-energy crack. That responsiveness is SmoothSwing, and it is the single biggest reason a high-end neopixel saber feels fundamentally different from a basic sound-activated toy.
Most owners use SmoothSwing every day without knowing how it works. This guide opens the hood. Understanding the physics and the parameters means you can tune the experience to exactly what you want — whether that is the hyper-responsive sensitivity of a dueling rig or the smooth, unhurried audio of a cinematic display piece.
This is part of CCSabers' Proffieboard technical series. If you have not yet set up your board or loaded sound fonts, start with the Proffieboard Setup Guide first. If you want to customize the visual side of your blade alongside the audio, the Blade Style Writing Guide covers that in detail.
1. What Is SmoothSwing?
Before SmoothSwing, saber audio worked on a simple trigger model: the board detected motion above a threshold and played a pre-recorded swing WAV file. The clip started, played through, and ended. Slow swings and fast swings triggered the same file. The result was a disconnect between what your hand was doing and what your ears heard.
SmoothSwing, developed by Fredrik Hubinette as part of ProffieOS, replaces the trigger model with a continuous mapping system. Instead of detecting motion and playing a clip, the board reads the gyroscope 200–500 times per second and maps the current angular velocity directly onto the audio output — adjusting volume, pitch, and layer mix in real time. The sound never "starts" and "stops." It breathes continuously, exactly matching the motion of your hand.
Hold your saber still, then move it in a single slow arc and gradually accelerate. With SmoothSwing, the audio rises smoothly from near-silence to full intensity and back down as you decelerate. With a basic trigger system, you hear nothing, then a clip fires at a fixed volume, then silence again. The difference is immediately obvious the first time you feel it.
2. The Physics Layer: Gyroscope & Accelerometer
Every Proffieboard contains a 6-axis IMU — Inertial Measurement Unit. This single chip does two jobs simultaneously: a gyroscope measures rotational velocity (how fast the saber is spinning around each axis), and an accelerometer measures linear acceleration (sudden impacts and directional forces).
The two sensors serve different purposes in the audio engine:
| Sensor | What it measures | Audio events it drives |
|---|---|---|
| Gyroscope | Rotational velocity on X, Y, Z axes (degrees/second) | SmoothSwing hum modulation, swing layer volume, spin effects |
| Accelerometer | Linear acceleration & impact force (G-force) | Clash detection, stab detection, melt, drag |
For SmoothSwing specifically, only the gyroscope data matters. The board reads the total angular velocity — the combined rotation across all three axes — and converts it to a value between 0 and 1. That value controls two things simultaneously: how loud the swing audio layers are relative to the idle hum, and which part of the audio spectrum is emphasized. Fast rotation = high swing layer volume + bright, crackling texture. Slow rotation = quiet swing layer + smooth, controlled tone.
Why three axes instead of one
A saber can be swung in any direction — left-right, up-down, diagonal, or a circular spin. A single-axis gyroscope would miss anything that did not align with its measurement axis. The 3-axis gyroscope sees all motion regardless of orientation, which is why SmoothSwing sounds correct whether you execute a horizontal cut, an overhead strike, or a spinning flourish. The board combines the three axis readings into a single scalar magnitude and uses that as the input to the audio mapping function.
The IMU sampling rate determines how finely the audio tracks your motion. At 200 Hz, the board updates the audio mix every 5 milliseconds. At 500 Hz (available on v3 / v3.9 boards with recent ProffieOS versions), updates happen every 2 milliseconds. The higher the rate, the tighter the audio follows sudden changes in direction — you hear the reversal of a parry almost instantaneously rather than with a slight lag.
3. SmoothSwing V1 vs V2: What Actually Changed
ProffieOS has shipped two versions of the SmoothSwing algorithm. Both are still in active use — many widely-shared sound fonts are built for V1. Understanding the difference helps you choose the right fonts and explains why some fonts sound better than others on your setup.
- Two audio channels: A and B
- Channels crossfade based on swing direction relative to a reference axis
- File naming:
swng.wav+swng2.wav(or numbered pairs) - Audible grain during rapid direction changes — the crossfade has a slight transition texture
- Lower CPU load — runs well on all Proffie versions
- Still sounds excellent for most use cases
- Up to 16 swing layers, each covering a different directional slice
- Each layer fades in and out as the swing direction enters and leaves its coverage zone
- File naming:
swng1.wavthroughswng16.wav(or subset) - Direction changes sound seamless — no crossfade grain
- Higher CPU and SD read load; fast SD card recommended
- Standard for all professional font releases since 2020
Open the sound font folder on your SD card and look at the swing file names. If you see swng.wav and swng2.wav (or swingh.wav / swingl.wav), it is V1. If you see swng1.wav through swng4.wav or more, it is V2. A V2 font played on a board configured for V1 will use only the first two swing files and ignore the rest — it will work but will not sound as smooth as intended.
4. Three Sensitivity Modes & When to Use Each
SmoothSwing sensitivity is not a single on/off setting. It is a combination of two thresholds — how fast you need to swing before the swing audio starts rising, and how hard an impact needs to be before it registers as a clash. Getting the balance right for your use case makes a significant difference in how the saber feels.
swing_threshold: 10–15 · clash_threshold: 30–40
swing_threshold: 20–30 · clash_threshold: 10–20
swing_threshold: 5–8 · clash_threshold: 25–35
A lower clash threshold number means the board triggers on lighter impacts. This confuses many first-time configurers who assume "higher number = more sensitive." Remember it this way: the threshold is the minimum force required. Lower the minimum and lighter touches qualify. Raise it and only heavy hits count.
5. Tuning Parameters in Your Config
SmoothSwing parameters live in your Proffieboard config file, inside the prop file definition. With the default SA22C prop, the relevant settings look like this:
What each parameter does in practice
| Parameter | Lower value | Higher value | Recommended starting point |
|---|---|---|---|
SWING_THRESHOLD |
Swing audio rises at slower movements | Requires faster motion to activate | 15–25 for most use |
CLASH_THRESHOLD |
Clashes on lighter contact | Only heavy direct hits register | 12–20 for dueling |
SMOOTHSWING_CWMAXVEL |
Full swing volume at lower speeds | Need faster swing to reach peak volume | 300–500 |
SMOOTHSWING_TIMEOUT |
Audio cuts off faster after motion stops | Swing tail lingers longer | 80–120 ms |
When tuning, adjust a single parameter per flash cycle, then test with real swings before changing the next one. Changing multiple values simultaneously makes it impossible to know which adjustment caused which change in behavior. A typical tuning session takes three to five flash cycles to dial in a feel you are happy with.
ProffieOS 6+ WebUSB shortcut (v3 / v3.9 only)
If your board is a v3 or v3.9 running ProffieOS 6 or above, you can adjust CLASH_THRESHOLD and SWING_THRESHOLD through the ProffieOS Workbench in Chrome without reflashing. Connect the saber via USB, navigate to the Workbench, and the relevant sliders update the board in seconds. This makes iterative tuning significantly faster — adjust, test by swinging the saber, adjust again, repeat until the feel is right.
6. Troubleshooting: Delay, Misfires & Power Drain
-
Symptom
Swing audio has a noticeable delay after motion starts
Almost always an SD card read-speed issue, not a SmoothSwing configuration problem. The board reads audio layers from the card in real time. A slow card introduces latency between when the gyroscope sees motion and when the audio updates. Fix: reformat the SD card to FAT32 (not exFAT), re-copy all files cleanly, or replace with a Class 10 / A1-rated microSD card. Verify the card is fully seated in the slot — a slightly loose card causes intermittent read failures that present as audio lag.
-
Symptom
Clash fires when nothing is touching the blade
Your
CLASH_THRESHOLDis set too low for your grip style. Some people naturally apply lateral pressure to the hilt during a swing, which spikes the accelerometer without an actual impact. RaiseCLASH_THRESHOLDby increments of 3–5 until false triggers stop. If it still misfires during spin flourishes, the angular deceleration at the end of a spin can also exceed the threshold — raising it further or adjusting grip technique both resolve this. -
Symptom
Real clashes are not registering during sparring
Opposite problem:
CLASH_THRESHOLDis too high. During live sparring, blade contact often results in deflection rather than direct impact — the peak G-force is lower than in a hard test strike. Lower the threshold in increments of 3 until clashes register reliably. If this causes false triggers, the solution is finding the right value in between, which may take several test sessions. -
Symptom
Battery drains significantly faster than expected
High SmoothSwing sensitivity (especially with complex V2 fonts containing many swing layers) increases the board's audio processing load and SD read frequency. Three things reduce power draw without compromising performance: (1) reduce
SMOOTHSWING_TIMEOUTso the swing layers cut off faster when motion stops; (2) use a V2 font with fewer swing layers (4–6 instead of 12–16); (3) lower the master volume in your config — blade hum at full volume is the single largest ongoing power draw. A 15–20% volume reduction can extend battery life noticeably. -
Symptom
Swing sound stops abruptly mid-arc
The
SMOOTHSWING_TIMEOUTis too short — the audio is cutting off before your swing completes. Raise it to 150–200 ms and test. Alternatively, if the cut-off happens at a specific point in the arc regardless of speed, it may be a corrupt WAV file in the font. Check the swing files on the SD card for correct format (16-bit PCM WAV, 44.1 kHz) and re-copy from a clean source.
7. Which Soundboards Support SmoothSwing
| Soundboard | SmoothSwing | Version | Custom tuning |
|---|---|---|---|
| Proffieboard v2.2 | Full V1 + V2 | V1 & V2 | Full — edit config file |
| Proffieboard v3 / v3.9 | Full V1 + V2 | V1 & V2 | Full + WebUSB Workbench |
| Xenopixel | Simplified swing | Proprietary | In-hilt menu only — no parameter access |
| SNV4 Pro | Motion-reactive swing | Proprietary | App-based menu — limited parameter range |
| GHv3 (basic) | Not supported | — | Fixed trigger-based swing only |
The key distinction is between true SmoothSwing (continuous gyroscope-to-audio mapping, configurable parameters, multi-layer V2 support) and motion-reactive swing (threshold-triggered audio with speed-based volume scaling). The latter sounds better than a basic trigger system but lacks the continuous, no-gap audio chain that defines genuine SmoothSwing. If SmoothSwing quality is a priority, Proffieboard is the only board that delivers the full implementation.
Xenopixel's swing implementation sounds convincing in casual use — it responds to motion speed and adjusts volume accordingly. The difference from true SmoothSwing becomes apparent during slow, deliberate movements and direction reversals, where the proprietary system has a small gap before audio responds. For most buyers, this is an acceptable trade-off for Xenopixel's easier setup. For owners who want the finest audio fidelity, Proffieboard is the upgrade path. See our RGB vs Neopixel Saber guide for a full soundboard comparison in a buying context.
SmoothSwing FAQ
What is SmoothSwing in a neopixel saber?
SmoothSwing is a ProffieOS audio system that uses the onboard gyroscope to continuously map your swing speed and direction to audio output. Instead of playing a pre-recorded clip when motion is detected, SmoothSwing modulates the hum and swing audio layers in real time — the sound rises, intensifies, and falls exactly as your swing does. It was created by Fredrik Hubinette and is exclusive to Proffieboard-based sabers in its full form.
Does Xenopixel have SmoothSwing?
Xenopixel has a proprietary motion-reactive swing system that responds to speed but is not the same as ProffieOS SmoothSwing. It does not use the same continuous gyroscope mapping algorithm, does not support V2 multi-layer sound fonts, and cannot be tuned beyond the in-hilt menu options. It sounds noticeably better than a basic trigger system, but the gap between it and true SmoothSwing is audible in slow or directionally complex movements.
How do I know if my sound font supports SmoothSwing V2?
Open the font folder on your SD card and look at the swing file names. SmoothSwing V2 fonts contain multiple numbered swing files: swng1.wav, swng2.wav, and so on — typically four to sixteen files. SmoothSwing V1 fonts use a two-file structure: swng.wav and swng2.wav (or sometimes labeled swingh.wav / swingl.wav for high and low speed variants). If the font's documentation mentions V2 compatibility, it will say so explicitly.
Can I enable SmoothSwing without a Proffieboard?
Not in its full ProffieOS implementation. SmoothSwing as described in this guide is a Proffieboard-specific feature — it requires ProffieOS, a compatible 6-axis IMU, and the ability to run custom firmware. Other boards have their own motion-reactive swing implementations under different names, but none of them support the same parameter tuning, V2 multi-layer font structure, or continuous gyroscope mapping that ProffieOS SmoothSwing provides.
My SmoothSwing sounds choppy during fast back-and-forth movements. What is wrong?
This is most commonly an SD card performance issue. During rapid direction changes, the board needs to crossfade between multiple swing audio layers simultaneously, which requires fast sequential reads from the card. A slow or fragmented card introduces gaps between reads that present as audio choppiness. Format the SD card to FAT32, re-copy all files, and test again. If the problem persists on a fast card, the sound font may have too many swing layers for the board's available memory — try a simpler V2 font with four to six swing files instead of twelve or more.
Does tuning SmoothSwing require reflashing the firmware every time?
On Proffieboard v2.2, yes — every parameter change requires editing the config file and uploading via Arduino IDE. On v3 / v3.9 boards running ProffieOS 6 or above, clash threshold and swing threshold can be adjusted through the ProffieOS WebUSB Workbench in Chrome without reflashing, which makes iterative tuning much faster. Other parameters like SMOOTHSWING_CWMAXVEL and SMOOTHSWING_TIMEOUT still require a full reflash on all board versions.
Will a SmoothSwing V2 font still work on a V1-configured board?
Yes, with reduced quality. ProffieOS will use the first two swing files it finds in the folder and ignore the rest — effectively running the font in V1 mode. The saber will work and swing sounds will play, but you will not get the full multi-directional layering that V2 is designed to provide. To get the full benefit of a V2 font, your ProffieOS config needs to be set up for V2, which is the default in ProffieOS 4 and above for boards running the standard SmoothSwing implementation.
Ready to experience SmoothSwing for yourself? Every Proffieboard saber in our lineup ships with ProffieOS pre-installed and a 32GB SD card loaded with fonts.
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