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Audio impedance loading
Estimate loaded line voltage and level change from source and input resistance.
Source resistance (Ω): 0–100000; Input resistance (Ω): 1–10000000; Open-circuit voltage (V RMS): 0.000001–100
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Audio impedance loading
Source resistance (Ω): 100 Input resistance (Ω): 10000 Open-circuit voltage (V RMS): 1
- Loaded voltage (V RMS)
- 0.990099
- Level change (dB)
- -0.086427
Ratio = input resistance / (source resistance + input resistance). Loaded RMS voltage = open-circuit RMS voltage × ratio; level change = 20 log10(ratio). A negative result is attenuation, not positive loss. Use total line-to-line resistances and voltage for a balanced connection, or consistently ground-referenced values for an unbalanced connection; do not mix per-leg and differential specifications. Source resistance accepts 0–100,000 Ω, input 1–10,000,000 Ω, and open-circuit voltage 0.000001–100 V, including fractions. The voltage must be the unloaded source voltage, not an already loaded measurement. This is a purely resistive, small-signal model at the frequency of interest. It excludes cable capacitance, transformers, reactive loads, output current limits, distortion and clipping. It does not certify equipment compatibility, phantom-power wiring or speaker/amplifier loads. Check manufacturer specifications and measure the actual signal. Six decimals are displayed without intermediate rounding.
Methodology
How it works
Ratio = input resistance / (source resistance + input resistance). Loaded RMS voltage = open-circuit RMS voltage × ratio; level change = 20 log10(ratio). A negative result is attenuation, not positive loss. Use total line-to-line resistances and voltage for a balanced connection, or consistently ground-referenced values for an unbalanced connection; do not mix per-leg and differential specifications. Source resistance accepts 0–100,000 Ω, input 1–10,000,000 Ω, and open-circuit voltage 0.000001–100 V, including fractions. The voltage must be the unloaded source voltage, not an already loaded measurement. This is a purely resistive, small-signal model at the frequency of interest. It excludes cable capacitance, transformers, reactive loads, output current limits, distortion and clipping. It does not certify equipment compatibility, phantom-power wiring or speaker/amplifier loads. Check manufacturer specifications and measure the actual signal. Six decimals are displayed without intermediate rounding.
Method and assumptions documented by Techrider.live
2026-10-29
Frequently asked questions
Does equal impedance preserve the voltage?
No. Equal positive source and input resistances halve the voltage: the change is about −6.0206 dB. Modern line-level connections commonly use a higher input resistance; confirm the actual specifications.