# Speaker impedance curves: where the numbers come from

Researched 2026-10-18. Values in js/speaker-impedance.js were read from published impedance charts at third-octave frequencies (about ±10% in magnitude, ±3° in phase; larger error on steep slopes either side of peaks). Charts were downloaded only to a temporary folder for reading, not kept. Where only magnitude is published, the renderer derives phase from the curve slope (minimum-phase approximation).

| Speaker | Source | Page |
| --- | --- | --- |
| Polk Monitor 40 | Audio Science Review (Klippel) | https://www.audiosciencereview.com/forum/index.php?threads/polk-monitor-40-series-ii-review-speaker.24146/ |
| KEF LS50 Meta | Erin's Audio Corner (Klippel, 0.1 V); agrees with Stereophile within the reading error | https://erinsaudiocorner.com/loudspeakers/kef_ls50_meta/ |
| Klipsch Heresy IV | Erin's Audio Corner (Klippel, 0.1 V); minimum agrees with Hi-Fi News (4.15 Ω at 118 Hz) | https://erinsaudiocorner.com/loudspeakers/klipsch_heresy_iv/ |
| Magnepan LRS | Stereophile (John Atkinson) | https://www.stereophile.com/content/magnepan-lrs-loudspeaker-measurements |
| Revel F328Be | Audio Science Review (Klippel) | https://www.audiosciencereview.com/forum/index.php?threads/revel-f328be-speaker-review.17443/ |
| LS3/5A | Stereophile (John Atkinson), 1988 "11 ohm" sample; phase not tabulated | https://www.stereophile.com/content/bbc-ls35a-loudspeaker-1989-follow |
| Harbeth M30 | Stereophile (John Atkinson), Monitor 30.2 40th Anniversary as a proxy for the 30.0 (crossover peak clipped at 20 Ω on the chart; 22 Ω assumed) | https://www.stereophile.com/content/harbeth-monitor-302-40th-anniversary-edition-loudspeaker-measurements |
| B&W 805S | Audio Science Review (Klippel); phase not tabulated | https://www.audiosciencereview.com/forum/index.php?threads/bowers-wilkins-805s-bookshelf-speaker-review.16523/ |
| Wilson TuneTot | Audio Science Review (Klippel), probably port open; minimum agrees with Hi-Fi News (6.7 Ω at 174 Hz); phase not tabulated | https://www.audiosciencereview.com/forum/index.php?threads/wilson-audio-tunetot-review-high-end-bookshelf-speaker.29219/ |
| Bose 901 | Erin's Audio Corner (Klippel, 2.83 V); the active equalizer doesn't change the load; phase not tabulated | https://erinsaudiocorner.com/loudspeakers/bose_901_series_v/ |
| Quad ESL-57 | Amateur bench measurements only (quadesl.com and a diyAudio REW measurement), averaged; no magazine measurement found | https://www.diyaudio.com/community/threads/quad-esl-57-impedance-plot-and-ltspice-model.386355/ |
| KEF Blade 2 Meta | Erin's Audio Corner (Klippel, 0.1 V); minimum cross-checked with Stereophile | https://erinsaudiocorner.com/loudspeakers/kef_blade2_meta/ |
| Vandersteen Treo | Erin's Audio Corner (Klippel, 0.1 V) | https://erinsaudiocorner.com/loudspeakers/vandersteen_treo_ct/ |
| Dynaudio Special 40 | Erin's Audio Corner (Klippel, 0.1 V), port open; minimum and phase cross-checked with Stereophile | https://erinsaudiocorner.com/loudspeakers/dynaudio_special_forty/ |
| Wharfedale Linton 85th | Erin's Audio Corner (Klippel, 0.1 V), grille on; traced by color, minimum 3.49 Ω against Erin's stated 3.5 Ω | https://erinsaudiocorner.com/loudspeakers/wharfedale_linton_85/ |
| JBL 4367 | Erin's Audio Corner (Klippel, 0.1 V); traced by color, minimum 5.24 Ω against Erin's stated 5.3 Ω | https://erinsaudiocorner.com/loudspeakers/jbl_4367/ |
| Audio First Designs Cadentia 3 | Erin's Audio Corner (Klippel, 0.1 V); traced by colour, minimum 3.21 Ω at 95 Hz against Erin's stated 3.2 Ω; bass peaks 14.9 Ω at 18 Hz and 19.5 Ω at 47 Hz | https://erinsaudiocorner.com/loudspeakers/audio_first_cadentia3/ |
| Audio First Designs Fidelia | Erin's Audio Corner (Klippel, 0.1 V); traced by colour, minimum 3.19 Ω at 200 Hz against Erin's stated 3.2 Ω above 80 Hz; bass peaks 21.4 Ω near 19 Hz and 20.6 Ω near 66 Hz (the third-octave points at 20 and 63 Hz sit on their flanks) | https://erinsaudiocorner.com/loudspeakers/audio_first_fidelia/ |
| Pi Speakers four π | Pi Speakers' own published graph (magnitude only; phase not published), traced 2026-10-27 at third-octave frequencies, axes calibrated from the gridlines (10 Ω at 392.6 px, 20 Ω at 326.7 px): peaks 37.8 Ω at 15 Hz and 42.9 Ω at 67 Hz, minimum 6.75 Ω at 131 Hz | https://pispeakers.com/Measurements/fourPi.html |
| Klipsch La Scala AL5 | Stereophile (John Atkinson), traced 2026-10-31 at third-octave frequencies (axes fitted to 31 vertical and 11 horizontal gridlines; checks: 4.24 Ω at 70 Hz and 4.21 Ω at 335 Hz against the printed 4.23 and 4.17 Ω). The chart stops at 20 Ω: 50, 1250 and 1600 Hz are estimated (our estimate) from a parallel resonance fitted to the traced magnitude and phase nearby, the phase at those frequencies and where the curve crosses the chart's top (49.5 and 53 Hz; 1.19 and 1.95 kHz): a bass-horn peak near 51 Hz with Q about 8 (21.6 Ω at 50 Hz) and a broad peak near 1.46 kHz with Q about 0.9 (21.0 and 21.4 Ω; the fit matches the six traced points around it within 0.6 Ω and 1.5°). Phases as traced | https://www.stereophile.com/content/klipsch-la-scala-al5-loudspeaker-measurements |
| DeVore O/96 | Stereophile (John Atkinson). The chart stops at 20 Ω: 20, 25, 50 and 63 Hz are estimated from resonances fitted to the plotted phase (lower peak near 18 Hz, upper near 57 Hz with Q about 5), 1.6 kHz is just over the top (20.5 Ω assumed). Hi-Fi News measured 108 Ω at 20 Hz, about twice the fit; we keep Stereophile's chart for consistency with the response data | https://www.stereophile.com/content/devore-fidelity-orangutan-o96-loudspeaker-measurements |
| Arendal 1610 Slim 8 | Audio Science Review (Klippel); magnitude and phase read pixel by pixel against the chart's own gridlines; minimum 2.8 Ω near 100–110 Hz, as the review states | https://www.audiosciencereview.com/forum/index.php?threads/arendal-1610-slim-8-speaker-review.74101/ |

## No measured curve

| Speaker | What exists | What the simulator uses |
| --- | --- | --- |
| JBL 4349 | Hi-Fi News lab report text only: minimum 7.5 Ω at 118 Hz, maximum 47 Ω at 60 Hz, phase −49° at 74 Hz to +47° at 371 Hz, "very easy" load (https://www.hifinews.com/node/131766) | Typical model shaped to those figures |
| Zu Audio Method | Nothing published; specification 8 Ω nominal | Typical 8 Ω ported model |
| Active speakers (Kii Three, Dutch & Dutch 8C, Genelec 8351B, JBL M2, Linkwitz LXmini) | Built-in amplification; no external amplifier load | Amplifier stage replaced by ideal built-in amplification |
| Aperion Novus N6SR | Erin's Audio Corner measured it, but his data policy forbids digitizing his graphs; specification 4 Ω nominal, sealed | Typical sealed model (the 8 Ω one; permission pending) |

## Notes

- Rogers LS3/5A: Stereophile measured a 1978 (15 Ω) and a 1988 (11 Ω) sample; the 1988 sample is used. The spinorama data does not say which version ASR measured.
- Harbeth: the Monitor 30.2 40th Anniversary (Stereophile) stands in for the Monitor 30.0; its crossover peak is clipped at 20 Ω on the chart (22 Ω assumed).
- Wilson TuneTot: ASR curve, probably port open; Hi-Fi News (port bung fitted) gives a 6.7 Ω minimum at 174 Hz and 66.6 Ω maximum at 68 Hz.
- Quad ESL-57: only amateur measurements exist (quadesl.com; diyAudio REW measurement); the two are averaged. A third amateur sample showed much lower bass impedance; the bass peak is level-dependent.
- Bose 901: measured without the active equalizer, which sits at line level and does not change the load.