Paradigm Reference Studio/100 v.2 loudspeaker Measurements

Sidebar 3: Measurements

The big Paradigm's sensitivity weighed in at 89.5dB(B)/2.83V/m, 1dB more sensitive than the earlier version we reviewed three years ago. This is within the margin of error of the older speaker but is still almost 3dB higher than average. The impedance, however, drops below 4 ohms between 55Hz and 210Hz, with a minimum value of 3 ohms at 90Hz (fig.1). A good 4 ohm-rated amplifier should be used with the speaker. The glitch at 26kHz in this graph's traces indicates the frequency of the metal-dome tweeter's ultrasonic resonance, but the graph is otherwise free from any evidence of resonant behavior. Fig.2 shows a cumulative spectral-decay plot calculated from the output of a simple accelerometer fastened to the center of the back panel. The earlier speaker had quite a strong mode present at 300Hz on this panel; the v.2 was much better behaved in this respect.

Fig.1 Paradigm Studio/100 v.2, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

Fig.2 Paradigm Studio/100 v.2, cumulative spectral-decay plot calculated from the output of an accelerometer fastened to the cabinet back panel. (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz.)

The saddle in the impedance-magnitude trace at 20Hz implies that the big port is tuned to a very low frequency. The speaker is also over-damped, as can be seen from fig.3, which shows the individual responses of the port, woofers, and midrange/tweeter section. Note the broad but suppressed output of the port, and the merely vestigial notch in the woofers' output at the nominal port-tuning frequency. Given the usual amount of low-frequency boost present in a typical room, this is probably a good decision.

Fig.3 Paradigm Studio/100 v.2, acoustic crossover on-axis at 50", corrected for microphone response, with the nearfield midrange, woofer, and port responses plotted below 500Hz, 300Hz, and 500Hz, respectively.

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