Dunlavy Audio Labs SC-IV/A loudspeaker Measurements part 3
Fig.7 Dunlavy SC-IV/A, impulse response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).
Fig.8 Dunlavy SC-IV/A, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).
Because of its time coherence, the Dunlavy is one the handful of loudspeakers that can reproduce an acoustic squarewave. Fig.9 shows a 500Hz squarewave captured on the tweeter axis at 100". Note the excellent risetime and the good square shape, broken up by some ripples which may be due to the reflections noted in the impulse and step response but might also be due to room reflections at the this farther mike distance.
Fig.9 Dunlavy SC-IV/A, waveform of 500Hz squarewave at 50" on HF axis (7ms time window, 30kHz bandwidth).
Finally, the SC-IV/A's cumulative spectral-decay or waterfall plot on the tweeter axis at 50" shows an excellent drop in energy once the exciting pulse has passed, this expected from the time-coherent impulse response. But what appear to be slight resonant ridges in the mid-treble might really be the effect of the early reflections.
Fig.10 Dunlavy SC-IV/A, cumulative spectral-decay plot at 50" (0.15ms risetime).
Summing up these measurements, the SC-IV/A is another well-engineered speaker design from John Dunlavy. I am not surprised RD liked it as much as he did.—John Atkinson