Hi Scott,
Excellent. I would be really good with some comparable measurements. I will start measuring on the “Compact Monitor” in a week or so.
Maybe I’m breaking in open doors here, but anyway.
There is actually a very simple way to measure system/cabinet resonance with a minimum of SW & HW. If you can connect your computer to your preamp / power amp and play music from the computer you can do this.
Install a single basic resistor 10W (or higher) with 30-100 ohms in series with the speaker cable from the power amp to the speaker. Just add it in series with either of the plus or minus poles on the speaker. This is to take out any unwanted measurement errors from the power amp.
Connect a basic volt meter after the resistor right across the plus an minus poles of the 2216Nd. The volt meter can be any basic volt meter as long as it can do AC. If you don’t have one it can be a real “el-cheapo” for a basic check, get it from Home Depot or similar. If it can do RMS AC measures it is better, but not really needed for this.
Then you download a sine generator (app / program) to your computer from the Internet and install. Make sure you can hear the signal in you speakers. There are many to choose from and I don’t really know the difference. I normally use an analogue calibrated tone generator… Old School… But my fellow JBL nut's over here do this all the time with their computers.
Then with your computer slowly sweep a sine wave signal (does not have to be loud at all) from say 20Hz to 50Hz. At the frequency point where you get the lowest voltage reading across the 2216Nd on the volt meter is where you have the system resonance in the cabinet.
Simple as that. No mike or other SW & HW needed.
It would be nice to see where you came out. Give the excellent quality of your work, probably spot on.
Kind regards
//RoB