Ok, here are my findings. Please note - I'm not an engineer and don't have expensive equipment. Hopefully these results will at least give a clearer picture. I understand that my SPL meter is not the same as say using an expensive faster/more accurate meter like an audio toolbox.
With some help from Mojo I wanted to verify the accuracy of my meter. So, I took my digital multimeter which measures AC voltage up to 1000V. I verified that I was getting 120 volts from my wall outlets (actually 122). So we would have a voltage of 60hz at the outlet. I then played a 60hz WAV tone (2mb filesize) and took measurements with my meter hooked to the speaker wire terminals from various volume levels to compute power. We know the ohm ratings of the 80's per the graphs from the NRC, so I'm off to the races.
Now I also made note of when I noticed distortion starting to kick in, as the results would then become less meaningful. Following this, I ran a 100hz tone, assuming it would be fairly accurate at this freq also as it was close to 60hz. And finally, I played some music.
Below are my results from my lab.
It appears based on my defense above, that the amp is not defective, and functioning as designed. Again, you guys need to remember I'm trying to fill 8,000 cubic feet. Plus, I've acoustically treated my room pretty well with OC703 which is actually helping the potential problem of rooms that have no treatments.
Also, if you look at the music peaks before it shut down, and the 100hz tone(which is easier to drive than higher freq's) the amp actually went beyond its ratings.
I will need to work with Emotiva to discuss my options.
Volume Knob, Voltage, P=Vsquared/5 60hz tone
-25, .64, .08
-20, 1.11, .24
-15, 1.99, .79
-10, 3.40, 2.31
-5, 6.08, 7.39
0, 10.75, 23
+2, 13.48, 36
+4, 16.85, 56.7
+5, 18.8, 70.5
+6, 21.1, 89
+8, 26.2, 137 (buzzing/distortion started)
+10, 33, 218
+12, 36.7, 269
+13, 38.5, 296 (clicking sound, amp shut down)
Volume Knob, Voltage, P=Vsquared/4 100hz tone
-25, .64, .1
-20, 1.11, .3
-15, 1.99, .99
-10, 3.40, 2.89
-5, 6.03, 9.09
0, 10.67, 28.46
+2, 13.36, 44.62
+4, 16.71, 69.8
+5, 18.69, 87.3
+6, 20.9, 109.2
+8, 26.2, 171.6
+10, 33, 272
+12, 36.7, 336 (Buzzing/distortion started)
+13, 40, 400 (clicking sound, amp shut down)
Music Listening - I picked 2 songs from my brother inlaws band "Left is West" which
is a very popular Des Moines based band that I would put up against any of the
bigger city bands. Their CD was recorded last year in Omaha by Barely Bias Label. I
would describe them as pop-rock with similar influences from bands from the 70's to
today, just a whole mishmash.
Anyway, I picked 2 songs that had a very fast
rock beat that didn't change or fluctuate much, just very intense and powerful.
I used 4 ohm for figuring power, the results would be slightly lower had I used say
4.5-5 ohms for an average. Both songs had similar results except for the last
reading.
Volume Knob, Voltage, P=Vsquared/4 Music
-20, 2, 1
-15, 3.3, 2.7
-10, 6.1, 9.3
-5, 13.3, 44.2
0, 19.8, 98
+2, 24.5, 150
+3, 28.8, 207
+4, 40-50, 400-625
