Dynaudio Contour 1.3 Mk.II loudspeaker Measurements

Sidebar 3: Measurements

My estimate of the Dynaudio's sensitivity was 84dB(B)/2.83V/m, a little lower than the specified figure. This puzzled me, as my estimate of the original Contour 1.3's sensitivity was 3dB higher, and the drive-units are identical. The Mk.II's impedance is shown in fig.1. The minimum value is 3.43 ohms at 177Hz, with a moderate electrical phase angle above that frequency. The saddle at 43Hz in the magnitude trace indicates the tuning of the port, while the combination of 5.3 ohms impedance and a 42 degrees phase angle at 90Hz implies that a good 4 ohm-rated amplifier would work best with this speaker.

Fig.1 Dynaudio Contour 1.3 Mk.II, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

Using a simple plastic-tape accelerometer to look at the cabinet's resonant behavior indicated that what vibrational modes were present were well-damped. Fig.2, for example, is a waterfall plot taken with the accelerometer fastened to the sidewall. A single mode can be seen, at high enough frequency and low enough amplitude to probably have no subjective consequences.

Fig.2 Dynaudio Contour 1.3 Mk.II, cumulative spectral-decay plot calculated from the output of an accelerometer fastened to the cabinet sidewall. (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz.)

The Contour's quasi-anechoic response, averaged across a 30 degrees horizontal window on the tweeter axis at 50", is shown in fig.3. In the mid-treble and below, this response is identical to that of the original Contour (fig.4). Even the tuning frequency of the reflex port is the same as the 1996 sample, despite the specification claiming slightly lower LF extension. However, the alignment does appear to be a little less damped, which will make the perceived bass seem to go a little lower. In the top two treble octaves, however, the Mk.II has less energy apparent. This will probably explain why its sensitivity measured a little lower than the Mk.I's.

Fig.3 Dynaudio Contour 1.3 Mk.II, anechoic response on-axis at 50", averaged across 30 degrees horizontal window and corrected for microphone response, with the nearfield woofer and port responses and their complex sum plotted below 300Hz, 1kHz, and 300Hz, respectively.

Fig.4 Dynaudio Contour 1.3 Mk.I, anechoic response on-axis at 50", averaged across 30 degrees horizontal window and corrected for microphone response, with the nearfield woofer and port responses and their complex sum plotted below 300Hz, 1kHz, and 300Hz, respectively.

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