& Miscellaneous Measurements
Using a 100Hz tone and
various music selections, the maximum output of the sub placed at the intersection
of two walls measured 108dB SPL at 0.5m. The four satellites pumped out a
total of 106dB SPL at 1KHz under the similar conditions before clipping (3%
THD). The total usable output from the entire system is 109dB.
Input sensitivity, the
amount of output from your soundcard needed to drive the Xtrusio's to full
boom levels was only slightly out of spec. Rated at 130mV, they measured 180mV
before clipping occurred. This was a relief. So many companies grossly underrate
the input sensitivity so that almost no soundcard could ever distort the input
or push them to maximum output levels.
Signal to noise, or the
amount of hiss heard was the lower than stated. Logitech claims >80dB,
but there is no weighing mentioned. Measurements turned up such a varying
noise voltage that I had to average the numbers over time to arrive at a 72.3
dBC figure. Hiss was heard with any input, whether digital or analog due to
the noisy power supply and amps chips.
Input impedance measurements
couldn't be directly taken due to the presence of the dreaded DC blocking
capacitor. Again, Logitech chose the economy route when designing the Xtrusio's
by not using split voltage rails that don't require input blocking. Informal
measurements revealed no appreciable loading of the SBLive! soundcard.
While not entirely sound
related, I did notice the rather good satellite shielding. If the satellites
are placed close to a large monitor or if the volume is loud, a psychedelic
color shift does not rear its ugly head.
Lastly, the crossover
frequency, the frequency at which the sub stops producing sound and the satellites
start measured 189Hz for the sub and 198Hz for the satellite in the nearfield
environment. Sound smoothly crossed over from the sub to the satellites when
listening to music and test tones.