A practical frequency-analysis tool for luthiers who want to see what the wood is doing before they commit to the build.
ACOUSONIX FFT turns a simple tap response into a visual frequency map, helping builders identify dominant peaks, compare overlays, and document measurable changes in guitar tops, backs, braces, and assembled instruments. Instead of relying only on memory, feel, or ear training, the system gives the maker a repeatable way to observe resonance behavior across the working process.
The current FFT module already supports live microphone analysis, dominant-frequency display, peak hold, saved overlays, reset control, zoomable frequency ranges, peak labeling, musical-note reference, and PDF export reporting.
What FFT Shows the Guitar Maker
Every guitar top, back, brace system, and assembled body has a measurable response when it is excited by a tap. FFT analysis takes that short impulse and separates it into visible frequency peaks, showing where the wood is most willing to move. For a luthier, this gives a clearer view of the plate’s behavior than pitch memory alone. You are not just asking, “What note do I hear?” You are asking, “Where is the energy going, how strong is the response, and how does it change as I work?”
ACOUSONIX FFT is designed around that practical shop question. The tool listens through the microphone, displays the live spectrum, identifies the dominant frequency, and lets the builder hold peaks long enough to study them instead of chasing a disappearing tap sound.
How to Use It in the Shop
Start with the part you want to study: a free top, a back plate, a braced top, a closed body, or a completed instrument. Place the part in a repeatable position, tap it in the same location each time, and watch the strongest peaks appear on the graph. Turn on Peak Hold when you want the system to retain the response long enough to inspect it. Save an overlay when you want to compare one stage of the process against another.
The practical workflow is simple: measure, change one thing, measure again. Thickness the plate and save an overlay. Add braces and save another. Carve the braces and save another. Close the box and compare the assembled response against the free-plate behavior. The value is not just in one reading. The value is in seeing how the response moves as mass, stiffness, and structure are changed.
Getting Additional Peak Information
After capturing a clean tap, use Save Overlay to store that response. The saved overlay becomes a reference trace that can be compared against the next stage of work. For example, you can save a top before brace carving, carve the braces, tap again, and compare how the peaks moved. This turns the FFT from a live display into a practical building record.
To display the individual peak labels, open the Overlay Manager and click the colored square beside the saved overlay. The frequency labels will appear directly on the graph, showing the selected peaks in Hz. Clicking one of those frequency labels opens the Peak Information window, where the tool gives a more detailed reading of that specific peak.
The peak information view shows the exact frequency, closest musical note, note offset, peak level, -3 dB bandwidth, and the left and right -3 dB points. In practical terms, this helps the builder understand not only where the peak is, but how focused or broad that response may be. A narrow peak can suggest a more concentrated resonance, while a wider bandwidth may suggest a broader or more spread-out response.
Using the Export Function
After you save an overlay, use the export icon in the Overlay Manager to create a PDF report for that specific reading. The export function asks for the user name and project name, then generates a clean report that includes the ACOUSONIX header, the captured FFT graph, the displayed peak summary, and a short glossary explaining the reading. This gives the builder a permanent record of the tap response that can be stored with the project, compared against later measurements, or used as part of a long-term voicing history.
What FFT Does Not Do
FFT does not build the guitar for you. It does not tell you automatically whether a top is “good” or “bad.” It does not replace stiffness measurement, mass, deflection, damping judgment, or the builder’s ear. A frequency peak is only meaningful when it is interpreted in context.
FFT becomes powerful only when the builder controls the process around it. Tap location, support method, microphone distance, room noise, plate condition, and measurement sequence all matter. Used casually, it becomes another noisy graph. Used consistently, it becomes a record of how the instrument is changing under your hands.