Loudness
& Miscellaneous Measurements
Using a 100Hz tone and
various music selections, a total maximum output with the sub placed at the
intersection of two walls measured 102dB SPL at 0.5m. The satellites squawked
out 98dB SPL at 1KHz under the similar conditions before clipping (3% THD).
The total usable output from the entire system is 103dB.
Signal to noise, or the
amount of hiss heard was the highest (meaning best) ever measured at TargetPC.
Weighing in at 90.6dBC relative to full output, these units were dead quiet,
even with no input.
Input impedance wasn't
measured to to an DC input blocking capcitor. Yes, I have gear to bypass that
but I did notice that no loading took place even with a 1kHz source, so the
AMR90's input stage won't load most sound cards anyway, which is the point
of checking the input Z in the first place.
The woofer port center
frequency measured 66Hz, which was a reasonable choice for the 4" driver.
This sub unit will have significant output to just under 58Hz, but then dies
rather quickly due to the previously mentioned high Q.
Lastly, the crossover
frequency, the frequency at which the sub stops producing sound and the satellites
start measured a nominal 170Hz.
Pictures
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Amplifier
PCB
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Wart
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Sub
Rear
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Subwoofer
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Satellite
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Instructions
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