Tweeter Test Tones

A tweeter is the small driver in a speaker that reproduces the high end of the spectrum — roughly the top two octaves of music, from a few kilohertz up to the limit of hearing. Common designs include the soft-dome tweeter (the most widespread), the metal-dome tweeter (stiffer, often extending beyond 20 kHz), and the ribbon tweeter or AMT (air-motion transformer), known for extremely low mass. All share the same acoustic job: handling frequencies above the loudspeaker’s crossover point, which is typically set between 2 kHz and 5 kHz in a two-way speaker. This tool generates a pure sine tone with the Web Audio API’s oscillator and routes it through a stereo panner and a gain stage to your speakers or headphones. In stepped mode it sits on each round frequency (2, 4, 6, 8, 10, 12, 14, 16, 18, 20 kHz) so you can step up and down; in continuous mode a slider sets any frequency in the band; in sweep mode it glides smoothly from 2 kHz to 20 kHz over about twelve seconds so a single listen covers the whole top end. Whether you use it as a quick treble test or a methodical headphone high-frequency test, gain is ramped up and down to avoid clicks, and the default level is deliberately low because steady high tones can fatigue your ears without ever sounding loud.

The channel selector hard-pans the tone fully left, fully right, or centres it on both. That is the key to telling a real fault apart from a limit you simply share on both sides: play, say, 14 kHz on Left, then switch to Right at the same level. A working pair of tweeters should sound essentially the same loudness on each side. If one side is silent or noticeably quieter, the suspect is that tweeter, its crossover, the channel of your amplifier, or the cable — not your ears. If both sides go quiet at the same frequency, the far more likely explanation is your own hearing rolling off, or the device/output rolling off (many phones, laptops and Bluetooth links attenuate everything above ~16 kHz). Testing for left/right balance issues is exactly what the channel balance tester is designed for, as a complementary check once you’ve located a suspect frequency.

Two honest cautions. First, browser audio output is stereo (two channels): we can address Left and Right with a stereo panner, but we cannot reliably drive discrete surround channels (5.1/7.1) from a web page, so this tests the front L/R pair only. For checking every channel in a multichannel setup, the dedicated surround sound channel test is the right tool. Second, “I can’t hear it” is not the same as “the tweeter is dead.” Because this is a generator with no microphone, it cannot measure output level, distortion, or frequency response — for that you need a calibrated measurement microphone and software such as REW (Room EQ Wizard), or a real SPL meter. Use these tones to find gross problems and to compare sides, then measure if you need numbers. If you also want to check the low-frequency drivers in the same system, the subwoofer test tones tool covers the opposite end of the spectrum.