& Miscellaneous Measurements
Using a 100Hz tone and
various music selections, the maximum output of the sub placed at the intersection
of two walls measured 103dB SPL at 0.5m. The two satellites pumped out 102dB
SPL at 1KHz under the similar conditions before clipping (3% THD). The total
usable output from the entire system is 101dB. The drop is due to the weak
Input sensitivity, the
amount of output from your soundcard needed to drive the 7500's to full boom
levels was rated at a typical 300mV and measured a reasonable 336mV. Using
an SBLive!, which cranks out a whopping 475mV to four channels, I was able
to easily distort the satellites.
Signal to noise, or the
amount of hiss heard was the highest (meaning best) ever measured at TargetPC.
Weighing in at 91.6dBC relative to full output, hiss was not heard even when
placing the 2.5" driver directly against my ear with the volume all the
way up. Great job MidiLand!
Input impedance measurements
tell whether the speakers will effectively "load down" the soundcard
and possibly cause extraneous distortion. The left channel measured a whoppingly
good 49.2KOhms and the right channel measured an equally good 51.6KOhms. No
sound card worthy of the 3050M's will feel any loading effects.
The woofer port center
frequency measurement raised an eyebrow. Having a double hump curve, the port
peaked at 60Hz and 100Hz. While not completely unheard of, this was unusual
and MidiLand effectively utilized its benefits.
Lastly, the crossover
frequency, the frequency at which the sub stops producing sound and the satellites
start measured 175Hz for the sub in the 2-wall environment. The satellite
crossover frequency was a bit complicated. Technically measuring -3dB at 265Hz,
its curve extended smoothly much lower and will mesh fairly well with the
sub's frequency when the entire system is placed near the walls.