MetaMaitreya Signal Laboratory
Technical Overview — Circuit Gate — Instrumentation Node
MetaMaitreya Signal Laboratory is a browser-based oscilloscope and frequency analysis instrument built entirely on the Web Audio API. It runs as a single static HTML file with no dependencies, no build step, and no server requirements.
It is designed for modular synth users, pedal builders, producers, and educators who need clear, real-time signal visibility inside a modern browser.
WHAT IT DOES
The Signal Laboratory provides:
- Real-time waveform display with zero-crossing trigger
- FFT spectrum analysis (LOG and LIN scaling)
- Digital phosphor oscilloscope (DPO) persistence mode
- Stereo Lissajous (XY) analysis with phase correlation meter
- Radial frequency visualiser — 360 log-spaced bars in a full circle
- RMS, peak, crest factor, spectral centroid, and noise floor measurements
- Eurorack voltage scaling and pedal/line level calibration
- Built-in tone generator with sweeps, noise, AM, and FM modes
- A/B capture and comparison
- Shareable configuration URLs
All processing happens locally in your browser.
HOW IT WORKS
The system is built around a single AudioContext.
Audio input may come from:
- Microphone (clean capture; echo cancellation, noise suppression, and auto-gain disabled)
- System audio (tab/desktop capture via
getDisplayMedia)
- Internal tone generator (demo mode)
For live audio, a ChannelSplitterNode isolates left and right channels into two separate AnalyserNodes for stereo Lissajous and phase correlation analysis. For the demo generator, a mono signal is fed into a short delay line to simulate quadrature stereo.
In demo mode, audio is routed through a dynamics compressor limiter and a GainNode for volume control before reaching the AnalyserNode. The gain slider in the UI scales the display amplitude — it does not insert an audio node in the live mic/system signal path.
MEASUREMENTS EXPLAINED
- RMS — Root mean square amplitude (√(Σx²/N)). Represents effective signal power.
- Peak — Maximum absolute instantaneous sample value.
- Peak-to-Peak (P-P) — Difference between maximum and minimum sample values.
- Crest Factor — Peak ÷ RMS. Pure sine wave = √2 ≈ 1.414. Higher values indicate sharper transients.
- Dominant Frequency — Frequency of the FFT bin with the highest magnitude.
- Spectral Centroid — Weighted mean frequency (Σ(bin × magnitude) / Σ(magnitude)). Indicates perceived brightness.
- Noise Floor — 20th-percentile FFT bin magnitude mapped to dBFS. Estimates the baseline noise level.
CALIBRATION MODES
Eurorack Mode
Assumes normalised ±1.0 corresponds to ±10V full scale (20Vpp). Displays RMS voltage, peak voltage, and peak-to-peak voltage scaled to volts. A REF GAIN multiplier allows adjustment for modules with lower output levels (e.g. ±5V modules use REF GAIN 0.5×).
Pedal / Line Mode
Allows user-defined reference voltage. Displays RMS voltage, peak voltage, dBu, and dBV.
dBu reference: 0.7746 Vrms (1mW into 600Ω) — dBV reference: 1.0 Vrms
Calibration settings persist locally in your browser via localStorage.
DISPLAY MODES
- Scope — Persist — Digital phosphor accumulation. Up to 30 waveform slices rendered in 3D perspective with depth-mapped colour and decay.
- Scope — Normal — Standard zero-crossing triggered waveform display.
- Stereo XY — Lissajous plot of left vs right channel. Pearson correlation coefficient displayed as a numeric value and colour-coded bar.
- Radial — 360 log-spaced frequency bars arranged radially. Not a time-scrolling spectrogram — it shows a single-frame snapshot of the FFT each render cycle.
- Spectrum — Bar-style FFT magnitude display with interactive cursor readout showing frequency and dB level.
PERFORMANCE DESIGN
- Preallocated
Float32Array and Uint8Array buffers — no per-frame allocation
- Offscreen canvas caching for spectrum dB grid and DPO 3D grid — only redrawn on resize or theme change
- Grid lines and frequency axis drawn to cached offscreen canvases
- Glow achieved via double-stroke (wide soft pass + narrow sharp pass) rather than canvas shadow blur
requestAnimationFrame rendering loop — pauses automatically when tab is hidden- Zero CPU usage when frozen —
cancelAnimationFrame stops the loop entirely
The application is optimised for desktop and mobile browsers.
LIMITATIONS
This is not a certified measurement instrument.
Accuracy depends on:
- Your audio interface
- Browser implementation
- Sample rate and latency
It is intended for signal inspection, design, and education.
PURPOSE
The Signal Laboratory exists to:
- Provide voltage context for modular systems
- Reveal distortion and harmonic structure in pedals
- Visualize phase relationships in stereo mixes
- Teach signal fundamentals through real-time analysis
This instrument is not an isolated tool. It is an expression of Circuit Gate — the engineering division of MetaMaitreya.
Circuit Gate concerns itself with structure, voltage, frequency, modulation, and the architecture of signal. Where other divisions work in matter, ritual, garment, or community, Circuit Gate works in waveform and current. It studies how energy becomes pattern, how pattern becomes sound, and how sound becomes system.
The Signal Laboratory is one node in that larger architecture.
It exists to make the invisible measurable.
To render motion as structure.
To expose the geometry of vibration.
MetaMaitreya is organized as a unified ecosystem of Gates, each responsible for a domain of creation. Circuit Gate governs the technological and electronic domain — instruments, signal engines, firmware, and the logic that binds hardware and software into coherent systems.
Within that framework, the Signal Laboratory functions as an open instrument — a public interface into the engineering layer of MetaMaitreya. It demonstrates the principles that underlie all Circuit Gate devices: clarity of signal, respect for voltage, and precision in structure.
It is both tool and thesis.
Through it, signal is not decoration. It is examined, understood, and shaped.
This is Circuit Gate — a division of MetaMaitreya.
↗ metamaitreya.com