Dave,
I recently did an outdoor A/B comparison with the Mackie 1521, the two way version of the 1531, and a Danley SH 100 driven from a mono bridge Crest CC2800 (1190 watts into 8 ohm) HP at 60 HZ.
The 1531 is rated 1 dB louder than the 1521, 126 dB to 125 dB “measured”.
The SH100 is rated 123 dB program, recommended amp power 400-800 watts.
The SH100 coaxial Synergy horn sounded slightly more “detailed”, more “real” than the 1521 in the mid to high range.
The difference was not much, and both had been EQd so they “looked” similar in magnitude response, which required very little tweaking, though the 1521 had much deeper low end.
The 1521 had at least 6 dB more output on the live music source, guitar and voice.
The peak power Mackie claims seems to be real. It was hitting 110 dBC at about 4 meters outside, somewhere between the “measured” and “predicted” published numbers.
I have not heard the 1531, but I would expect the 6” mid driver would make for an even more “defined” sound than the 1521.
The 1521 really met the specs well, the published chart matched my Smaart chart, and I must say that the limiter sounds quite decent.
I had not read the manual, and the owner of the speakers thought the limiter light was tri-color, green, yellow, then red for limit.
He was wrong, the light only goes to yellow, which we pushed it hard into, searching for the red.
It stayed musical even when the limit light was on quite a bit.
I was impressed with the SH100 output for the size, at 2.19 cubic feet it is less than half of the size (and weight) of the 4.9 cubic foot 1521.
I was also impressed with the sound quality, output and cost of the Mackie. Based on your observations of the 1531, and my experience with the 1521, I’d recommend them to anyone that the pattern and SPL level will work for.
Art Welter