Finally, I get to hear Colin's opinions and see the measurements. Both of which confirm what I had felt with mine, that these are seriously good speakers! The measurements look wonderful, although I'd like to see the measurements with the revised port tuning. Congrats Kevin on a job well done!!!
I was wondering if Colin had "stuffed" his speakers or not. I built a pair with polyfill (about 7 oz. each) and a pair without and I really prefer the "stuffed" version better. The low end seems to extend slightly lower, with probably a smoother rolloff (I don't have measurement equipment handy to verify). It makes integration with the sub much more seemless. It also allowed me to crossover lower, which seemed to help with localization issues. For the record, I found I crossed over the the sub at 70 Hz for the unstuffed and 60 Hz for the stuffed version. For much of my music listening I didn't need the sub at all, I simply run the Keplers full range.
I really have to agree with Colin's statement that the speakers have "mojo". I could give up my job and listen to these things all day long. I'm sure my wife will have to drag me off to bed again tonight after another extended listening session.
The anechoic LF measurement probably isn't the best method for knowing what kind of LF extension you are actually going to get. It is at 2M, where the port contribution on the rear of the cabinet is off-set by an additional 0.5M or so and it is a 4Pi measurement. Those two factors make it look much higher than what you will see in-room. Colin's pair where tuned to 36-38 Hz if I remember right. The current production ones with 50% fill in the cabinet gives a much higher 45-46Hz tune. This brings the F3 down but you get steeper roll-off than you would with a lower tune.
Stuff those babies though.... they sound much better with the 50% fill.
The close-mic measurements I've done are much more representative of the LF extension. They are 2Pi space and the port/driver are merged with equal magnitude given to each. Where the anechoic measurement is really useful is for the distortion measurements.
This is my favorite quote and an indication we achieved what we set-out to do with the EX-6.5.
"PLEASE NOTE: Our standard is to provide the THD+N measurement at 90dB with a measuring distance of 2 meters (within the anechoic chamber). Since this speaker produced low distortion levels under those conditions, we have added a second measurement performed at 95dB to give an indication of performance under higher-output conditions."
The 1M levels would be 96dB & 101dB so the distortion measurements are at very high levels. Look at that single midwoofer @ 50-200hz and you can see that the EX-6.5 has excellent LF distortion performance, especially considering the output levels.
