Hey All,
Art had asked me to do this, so I figured instead on burying this or adding onto 2 other very long threads, I would start a new one.
Pretty much I will list the data and how all the measurements were taken, then I would probably need Art and others to see what can be gotten out of it, since Art explained what I was looking for but I don't have a ton of experience doing these measurements.
_ _ _ _ _ _ _ _ _ _ Overview _ _ _ _ _ _
So here we go, I placed our DUT, SRX718, with the grill off in the middle of the field on our 3 acre lot here. (Closest thing was our house at ~125ft)
I placed our measurement mic, ECM8000, and basic Rat-Shack SPL meter at 10 meters away on ground plane.
I used Adobe Audition to produce the test tones and a QSC PL380 with the 718 on channel 1 to power the sub.
I used 60hz to set the levels since I don't know for sure how accurate the multi-meter is at other frequencies. Once I set the level at 60hz, I didn't change any levels when going to the other frequencies to keep things consistent.
I am going to try and separate the data below I ended up having to set everything at 85V because it seemed like I couldn't get close to 10% distortion without giving it that much power. I will list some data where I gave it all that the PL380 would give without clipping at 50hz. It ended up being about 100V with the load. So I will list that data as well.
On the excursion measurements I would say they are probably in the neighborhood of being with 1-2mm with the eyeballing, as I did do them pretty slowly and several times spread out to see if I got similar numbers.
_ _ _ _ _ _ _ _ _ _ Data - SPL at 10M and excursion _ _ _ _ _ _
First off I seemed to find Fb to be about 40-41hz, as on either side of that the excursion started to increase.
Besides using the RTA function in Smaart in Log view to get the distortion measurements I also took down the Peak to Peak excursion and SPL at 10M, I will list that below:
SPL at 10M2.83V60hz - 81dB (Equates the the 101dB I found at 1W/1M several weeks ago, so that was encouraging)
85V80hz - 109dB
70hz - 110dB
60hz - 111dB
55hz - 107dB
50hz - 106dB
45hz - 102dB
100V50hz - 106dB
Peak to Peak Excursion85V80hz - 14mm
70hz - 23mm
60hz - 31mm
55hz - 24mm
50hz - 21mm
45hz - 14mm
100V50hz - 23mm
_ _ _ _ _ _ _ _ Data - Smaart Distortion Measurements _ _ _ _ _ _
So all of these are taken in the same conditions as above. I ended up using 85V since it seemed like I couldn't get the 2nd harmonic any closer to 20dB below and 85V was already about 900 watts. The last one will be at 100V, the most I could get out of one side of the PL380 before the "Clip" light came on, with the AC power I had.
Distortion - 80hz @ 85VDistortion - 70hz @ 85VDistortion - 60hz @ 85VDistortion - 55hz @ 85VDistortion - 50hz @ 85VDistortion - 45hz @ 85VHere is the one measurement at 100V
Distortion - 50hz @ 100VI decided to stay above Fb for now just for safety reasons, so hopefully there is something useful that I can learn from, and exactly what I am looking at!
The one thing I didn't expect was in a single to be hitting 109-111dB at 10M, equating to about 129-131dB at 1M. But this is before any decent power compression I am guessing, although the 2268H is rated at only 3.2dB at 800 watts, IIRC. (I was hitting it with the sine waves for about 15-20 seconds at a time, probably about 35 different times in all to check measurements etc...)
Thanks Art again for the directions and looking forward to your insight!
Thanks,
Phil