No prob Nanook! Thanks for graphs Owdi. Curiosity has definitely turned out to be a learning experience here. I guess in my earlier years, I simply bought what the Circuit City guy recommended (which has held up ok). Now I want to understand all these technical specs that are thrown at you in the market today. This started when I had to shop for a plasma TV. Thank God I am over that!
Also please note since a woofer is only nominally a fixed impedance and that impedance rises with frequency, a filter without impedance correction will have 3db/octave lower cut than expected, eg. a 2nd order filter will only be 9db/octave, as long as the impedance keeps rising. You also have to take into consideration the actual impedance at the xo frequency in order to get a correct xo without drops or bumps.
Not true at one meter, or at any other distance. You can't multiply watts by dB to get a new dB number, it's not that simple. I recommend Wikipedia as a good starting point if you want further understanding of how and why dB are used for sound measurements.
If your system produces 88 dB at 1W, 1 m, then increasing the power from 1 watt to 1.2 watts increases the SPL by 10log(1.2/1)=0.8 dB, so that your new SPL is 88.8 dB. Not 105.6 dB. That would require 10^[(105.6-88)/10] watts, or 57.4 watts.
[/end ee geek transmission]
Wikipedia says, "Sensitivity – The sound pressure level produced by a loudspeaker, usually specified in dB, measured at 1 meter with an input of 1 watt or 2.83 volts, typically at one or more specified frequencies." This should be true at 1 meter. However, modifying the decibels with an increase in Watts was just a best guess on my part.
Lots of talk about watts, but not all 40W amps are created equal. Two amps with similar power ratings into eight ohms will not necessarily play at the same level into the same eight-ohm nominal load.
When the current needs of the speaker can't be met, it causes grainy mids and highs, a collapsed sound stage and weak bass, and this can and does happen well below rated power output.
When the current needs of the speaker can't be met, it causes grainy mids and highs, a collapsed sound stage and weak bass, and this can and does happen well below rated power output.
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