I intended this to be in response to Jerry Love's and Seth=L's interpretation of our graphs but I couldn't find his post. Maybe he deleted it, I dunno. Howsomeever.., what he said was,
"The T/S alignment looks superior to the ETL alignment from the FR graphs you provided. Just like Jerry said in the other thread, the T/S graph is smoother, flatter and less variable. Can you explain that?"
Yes, I can explain that. Ohms law dictates current flow. With Thiele/Small, when amplifier power is delivered, the change in impedance will cause different current deliveries. Follow Ohm’s law for power (P=E²/R) to determine power transfer to the woofer. Compute the power delivery over the entire 10-100Hz range of the subwoofer. Notice that T/S will not control the SW but instead the woofer is controlling itself… hence the boominess.
The phase curve with ETL illustrates that it never crosses zero until driver resonance; e.g., above the SW range. This is an intrinsic indication of sound quality. The several zero crossings of T/S indicate a lack of quality due to resonance.
These curves have never been produced by any alignment known to man – they are not “bogus” and they cannot be faked. Don’t rely on “flat” frequency response curves for an indication of quality loudspeaker sound reproduction… they’re really meaningless on their own. See Sean Olive’s article, “What loudspeaker specifications are relative to sound quality?”
http://seanolive.blogspot.com/2009_01_01_archive.html. Olive says, “Current industry loudspeaker specifications are woefully inadequate in characterizing the sound quality of the loudspeaker. The commonly quoted '20 Hz - 20 kHz, +- 3 dB' single-curve specification is a good example. Floyd Toole made the observation that there is more useful performance information on the side of a tire ...compared to what’s currently found on most loudspeaker spec sheets…”
As far as the complete sound system goes, any amplifier will perform at its best and up to its theoretical capabilities if its impedance curves remain flat. Some amps will actually blow up if they have impedance curves and phase deviations that are too wacky.
