Dynaudio Contour 3.3 loudspeaker Measurements

Sidebar 3: Measurements

The Dynaudio Contour 3.3 was measured with DRA Labs MLSSA system in the Stereophile listening room, mounted on an Italian Outline speaker turntable (footnote 1). I calculated its B-weighted sensitivity as a lowish 84.5dB/2.83V/m. However, its impedance (fig.1) only dropped below 4 ohms briefly in the upper bass. Note the absence of any wrinkles in the impedance traces, implying a corresponding freedom from cabinet resonances. This graph was plotted without the foam in the ports. The tuning of the ports is indicated by the "saddle" in the magnitude trace at 32Hz. With the foam, the speaker behaves pretty much as a sealed enclosure, the twin peaks in the bass being replaced by one centered on 43Hz, implying only moderate LF extension for what is actually quite a big speaker. My preference was very much to use the Contour 3.3 in reflex mode, it sounding considerably too lean as a sealed box.

Fig.1 Dynaudio Contour 3.3 without foam in ports, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

The combined response of the two woofers in reflex mode can be seen in fig.2, as can that of the two ports. The ports are indeed tuned to 32Hz, shown by both the peak in the ports' output and the minimum in the woofers' response. The Contour 3.3's overall response on the tweeter axis is shown in fig.3. The top curve in the bass is the complex sum (taking amplitude, phase, and driver location into account) of the woofer and port outputs without foam; the bottom curve is with the foam, confirming the bass-shy behavior in this mode. With the foam, the -6dB point lies, as expected, at the port tuning frequency. Higher up in frequency, the lower midrange looks a little recessed, perhaps due to a crossover mismatch on this particular axis at the 50" microphone distance. In the treble, you could either consider the low-treble a little prominent or the mid-treble recessed, depending on which frequency region the listener's ear takes as its "anchor."

Fig.2 Dynaudio Contour 3.3 without foam in ports, nearfield woofer and port responses.

Fig.3 Dynaudio Contour 3.3, anechoic response on tweeter axis at 50", averaged across 30 degrees horizontal window and corrected for microphone response, with the complex sum of woofer and port responses plotted below 150Hz without foam in ports (top) and with (bottom).

Footnote 1: For details on how I measure loudspeakers and what measurements I consider subjectively most important, see "Loudspeakers: What Measurements Can Tell Us—And What They Can't Tell Us!," AES Preprint 4608, presented at the 103rd Audio Engineering Society Convention, New York, September 1997, and available from the AES. The paper was reprinted in somewhat different form as three "Measuring Loudspeakers" articles in Stereophile, starting in November 1998. JA
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