Retro Power Meter
Real-time analogue VU meters driven by your microphone or system audio. Built to replicate 1980s hi-fi amplifier ballistics.
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How to Use the Power Meter
Choose your input source by clicking Microphone or System Audio. Your browser will ask for permission to access the chosen source. Once granted, both VU needles respond to the incoming signal in real time.
The Gain knob boosts or cuts the displayed level by up to 20 dB. The Sensitivity knob shifts the input threshold by up to 10 dB, which is useful for calibrating the meter to your environment. The large Volume knob controls the signal level passing through the meter and can be turned by dragging up or down, or by scrolling the mouse wheel over it.
Use the keyboard to control the volume on the fly. The + and - keys adjust volume in steps of 5, and the spacebar or M key toggles the mute.
- Microphone: measures ambient sound in your room or whatever your mic picks up.
- System Audio: share a browser tab or application to measure its audio output. Works in Chrome and Edge on desktop. When prompted, tick the “Share audio” option.
- Peak hold: the red line on each meter freezes at the highest level for 1.8 seconds, making it easy to track transients without constantly watching the needle.
Frequently Asked Questions
A VU meter (Volume Unit meter) measures the average level of an audio signal, displayed with a needle on an analogue-style scale. The scale runs from -20 VU to +3 VU, with 0 VU representing the standard reference broadcast level. Unlike a peak meter, a VU meter uses ballistic weighting that integrates the signal over approximately 300 milliseconds, making it closer to how human hearing perceives loudness rather than showing instantaneous peaks.
A VU meter shows average or RMS (Root Mean Square) signal levels with a slow ballistic response, taking around 300ms to reach full deflection. This makes it good for judging perceived loudness. A peak meter responds almost instantaneously and shows the absolute highest signal level, which is more useful for preventing digital clipping. Professional audio equipment typically uses both simultaneously.
Analogue VU meters were a standard feature on high-end hi-fi amplifiers and cassette decks throughout the 1970s and 1980s. They gave users a visual guide to recording and playback levels, helping to avoid distortion on tape while maximising signal quality. They also became a design statement — the sweep of illuminated needles became synonymous with quality audio equipment. Many audiophiles still prefer analogue meters for their intuitive, musical response.
Click the Microphone button. Your browser will ask for permission to access your microphone — click Allow. The VU needles will immediately respond to sound picked up by your microphone. Use the Gain knob to increase or decrease the input sensitivity if the needles are reading too low or hitting the red zone.
Yes. Click System Audio. Your browser will ask you to share a tab or your screen — select the source you want to monitor and make sure the Share audio option is ticked. The VU meter will then display the levels of whatever audio is playing through that source. System audio capture works in Chrome and Edge on desktop.
The + and = keys increase the volume by 5 units, and the - key decreases it by 5. The spacebar or M key toggles mute on and off. These work when the page is focused and you are not typing in another field. You can also drag the volume knob up or down with your mouse, or use the scroll wheel over it.
The red peak hold line on each meter freezes at the highest level reached and holds it for approximately 1.8 seconds before slowly decaying. This makes it easy to see the loudest transients in your audio even when the signal is constantly changing. It is particularly useful when setting recording levels, as you can watch the peak approach the 0 VU mark and adjust your gain accordingly.
Gain boosts or cuts the signal level shown on the meters across a range of +/- 20 dB. Sensitivity adjusts the input threshold, making the meter more or less responsive to quieter sounds, across a range of +/- 10 dB. Use sensitivity to calibrate to your environment, then use gain to fine-tune the display range to where you want the needles to sit during normal use.