Initial LsPower implementation
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Silas Oettinghaus
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LLM_readme.md
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LLM_readme.md
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# LsPower Session Notes
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## Current Goal
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Build a Python tool to estimate electrical power delivered to a DIY active 2-way loudspeaker from measured DSP-output audio. Current measurement point is the analog DSP output / amplifier input, captured through a MOTU UltraLite input. Amplifier output is not measured directly yet; amplifier gain is modeled as an ideal scalar voltage gain in dB.
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## Project Structure
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- `soundcard_input.py`
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- Single runnable entry point.
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- Provides console voltage monitor, calibration routine, GUI monitor, and console power estimator mode.
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- `lspower/audio.py`
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- Shared sounddevice helpers.
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- `SoundDeviceManager`
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- `QueuedInputStream`
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- channel parsing/formatting helpers.
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- `lspower/impedance.py`
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- `ImpedanceCurve`
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- Loads REW impedance exports with columns: frequency Hz, impedance magnitude ohm, phase degrees.
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- Interpolates complex impedance to FFT bin frequencies.
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- `lspower/power.py`
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- `VoltageSpectrumEstimator`
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- `PowerEstimator`
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- `WayConfig`
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- `PowerFrame`
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- shared Hann/Welch voltage spectrum scaling helper.
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- `impedance.txt`
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- REW impedance export, currently usable directly.
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- `BC 14NDL76.txt`
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- Thiele-Small parameters for B&C 14NDL76. Useful later for safety/excursion/thermal modeling, not required for current power calculation.
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- `dsp_power_estimator.py`
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- Deleted as source. If an IDE tab still shows it, that is stale.
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## Calibration State
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The project uses a path-specific voltage scale:
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```text
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voltage = sounddevice_sample * volts_per_sample_unit
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```
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This is not a MOTU hardware full-scale spec. It includes the Windows/MME capture path, analog gain, routing, and any software gain.
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Built-in reference:
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```python
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DEFAULT_INPUT_CALIBRATION_REFERENCE_RMS_V = 2.32
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DEFAULT_INPUT_CALIBRATION_REFERENCE_RMS_SAMPLE = 0.021384357
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DEFAULT_INPUT_VOLTS_PER_SAMPLE_UNIT ~= 108.490522
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```
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Later calibration files are saved under:
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```text
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calibrations/calibration_YYYYMMDD_HHMMSS.json
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```
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Startup behavior:
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- If `--input-volts-per-sample-unit` is provided, it is used.
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- Otherwise the newest calibration JSON is loaded.
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- If no calibration file exists, the built-in default is used.
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CLI calibration example:
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```powershell
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python soundcard_input.py --device 3 --channels 1 --calibrate-known-rms-v 2.32 --calibrate-only
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```
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GUI calibration saves the same JSON format.
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## GUI Current Behavior
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Start with:
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```powershell
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python soundcard_input.py --gui
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```
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Main sections:
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- Input setup and calibration.
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- Input-side metrics:
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- RMS voltage
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- Peak voltage
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- Crest factor
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- Crest dB
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- Digital peak
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- Estimated amplifier output power:
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- LF/HF enable
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- channel
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- impedance file
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- amp gain dB
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- Vdsp
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- Vamp
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- P
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- Q
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- Sapp
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- Input waveform plot:
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- calibrated voltage y-axis
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- manual Y limit field, blank means auto
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- Input PSD plot:
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- Hann/Welch scaling
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- dB V^2/Hz
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- Output power history plot:
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- P as solid line
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- Sapp as dashed line
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- moving window default 30 s, user-editable
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Important GUI detail:
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- If LF and HF are both used, include both channels in `Channels`, e.g. `1,2`.
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- Power estimation uses the same FFT size, overlap, and smoothing controls as the input PSD.
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## Power Estimation Math
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For each way:
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```text
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V_amp(f,t) = G_amp * V_DSP(f,t)
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G_amp = 10^(G_amp_dB / 20)
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Z(f) = |Z(f)| * exp(j * phase_Z(f))
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S_k(t) = |V_amp,k(t)|^2 / conj(Z_k)
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P_k(t) = real(S_k)
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Q_k(t) = imag(S_k)
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S_app,k(t) = |V_amp,k(t)|^2 / |Z_k|
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```
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Totals:
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```text
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P_total = sum(P_k)
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Q_total = sum(Q_k)
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Sapp_total = sum(S_app,k)
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```
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FFT scaling:
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- DC removed.
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- Hann window.
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- rFFT.
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- Welch scaling to one-sided PSD in `V^2/Hz`.
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- Multiply by `df` to get bin-integrated RMS voltage squared in `V^2`.
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Synthetic validation already performed:
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```text
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1 Vrms sine into 8 ohm with 0 dB gain -> 0.125 W
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```
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## Current Known Hardware Context
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- Audio interface: MOTU UltraLite.
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- Working input path used so far:
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```text
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Device 3: Line In 3-4 (UltraLite-mk5) | MME | 2 in | 44100 Hz
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```
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- WASAPI device 67 previously captured silence for this setup.
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- REW generator was used for calibration and signal testing.
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- At one point, generator was running at 50 Hz, 1 Vrms.
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## Commands
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List devices:
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```powershell
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python soundcard_input.py --list-devices
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```
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GUI:
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```powershell
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python soundcard_input.py --gui
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```
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Console voltage monitor:
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```powershell
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python soundcard_input.py --device 3 --channels 1 --input-volts-per-sample-unit 108.490522
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```
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Console power estimator:
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```powershell
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python soundcard_input.py --device 3 --way LF:1:impedance.txt:34 --input-volts-per-sample-unit 108.490522
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```
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## Verification Commands
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```powershell
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.\.venv\Scripts\python.exe -m py_compile soundcard_input.py lspower\audio.py lspower\impedance.py lspower\power.py
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```
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Synthetic power scaling:
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```powershell
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.\.venv\Scripts\python.exe -c "import numpy as np; from pathlib import Path; from lspower.impedance import ImpedanceCurve; from lspower.power import PowerEstimator, WayConfig; fs=8192; n=8192; t=np.arange(n)/fs; x=np.sqrt(2)*np.sin(2*np.pi*1000*t); z=ImpedanceCurve(np.array([20.,20000.]), np.array([8.,8.]), np.array([0.,0.])); way=WayConfig('test',0,Path('none'),0.0); frame=PowerEstimator(way,z,fs,n,1.0,0.0).estimate(x); print(frame.rms_input_v, frame.total_p_w, frame.total_s_va)"
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```
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Expected output approximately:
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```text
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1.0 0.125 0.125
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```
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## Likely Next Steps
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- Improve GUI visual polish further if needed.
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- Add file picker buttons for impedance files.
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- Add measured amplifier transfer function support `H_amp(f)`.
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- Add driver safety panel:
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- compare P against `Pmax`
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- later estimate excursion against `Xmax`
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- Use T/S parameters from `BC 14NDL76.txt` only for model-based safety/excursion extensions, not for current impedance-based power estimation.
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