Source: https://guthlabs.ai/docs/instruments/pan-law-stereo-balance-level-calculator/
instrument / verified-clean
# Pan Law / Stereo Balance Level Calculator
The current ledger marks this instrument verified clean within the source-bound verification corpus.
Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**
## Inspectable records
[01**Overview**Purpose and lifecycle]()[02**Mechanism**Method and assumptions]()[03**Implementation**Binding and validation]()[04**Qualification**Evidence and errata]()
## Ledger state
The current ledger marks this instrument verified clean within the source-bound verification corpus.
**Area**: Audio, Music, Photography & Color
**Tranche**: tranche-5
**Evidence ID**: t5-106
**Ledger rows**: 1
No ledger note is attached.
## Review findings
The instrument cannot be honestly labeled as computing standard -3 dB, -4.5 dB, and -6 dB center pan laws until panLawGain semantics, pan-position mapping, output-unit conversion, and the exact pan-law curve are specified. The empty honest_label is a concern: the current behavior should not be marketed as a standard pan-law calculator without those definitions.
### Formula and scope findings
- The formula produces linear amplitude gains, but the declared outputs are gains in dB; each nonzero result requires conversion with gain_dB=20*log10(gain_linear).
- panLawGain is undefined: the spec does not state whether it is 10^(panLaw_dB/20), a center-channel gain, or another normalized factor.
- If panLawGain=10^(panLaw_dB/20), the stated pan-law value is not actually the center-channel output at theta=45 degrees: the center result is panLaw_dB-3.0103 dB because cos(45°)=sin(45°)=0.7071.
- A standard constant-power pan law normally uses L=cos(theta), R=sin(theta), with the center attenuation determined by the curve or an explicit normalization. Multiplying both channels by one global panLawGain does not clearly implement standard -3 dB, -4.5 dB, and -6 dB center laws.
- The mapping from the user-facing pan position to theta is unspecified: the spec does not say whether input is 0-1, -1 to +1, a percentage, or degrees, nor which endpoint is left or right.
### Unit assumptions
- The test vectors assume pan position is supplied directly in degrees, with 0°=full left, 90°=full right, and 45°=center.
- The test vectors assume panLawGain=10^(panLaw_dB/20), where panLaw_dB is a negative attenuation relative to unity amplitude.
- Linear gains are dimensionless amplitude ratios referenced to unity gain, and dB outputs use 20*log10(amplitude ratio).
- A zero linear gain is represented as -Infinity dB; JSON has no numeric representation for negative infinity, so it is represented as the string "-Infinity" in expected_outputs.
## Boundary hardening
**BREAK_CLAIMED** · SELF_FLAGGED
Hard-left and hard-right positions produce a zero linear gain on one channel. Converting that channel to dB requires log10(0), so a finite numeric dB output is undefined; the instrument must explicitly return -Infinity or reject the result. The specification also does not state the pan-position convention or explicitly define the linear-to-dB conversion.
## Errata and corrections
No applied erratum is attached to this unique-name record.
## Inspectable example
4 review vectors are recorded. One source-bound sample is shown below.
````
{
"inputs": {
"pan_position_degrees": 0,
"pan_law_db": -3
},
"expected_outputs": {
"left_gain_linear": 0.70794578,
"right_gain_linear": 0,
"left_gain_db": -3,
"right_gain_db": "-Infinity"
},
"working": "panLawGain=10^(-3/20)=10^(-0.15)=0.70794578. theta=0°. L=cos(0°)*0.70794578=1*0.70794578=0.70794578. R=sin(0°)*0.70794578=0*0.70794578=0. 20*log10(0.70794578)=-3 dB. 20*log10(0)=-Infinity dB."
}
````
## Related workflows
No source-defined multi-instrument workflow membership is recorded.
## Sources and evidence
These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.
- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`
- `evidence-tranche5/tranche5-results.json`
- `BOUNDARY_HAZARD_CATALOG.json`