Jeffdachef 5,000+ posts
Gunz That Turn on Nunz
Clamp meter, volt meter, oscope, using multiple tones from 25hz to 60hz maping an impedance rise to frequency chart. Multiple real life setups with subs, enclosure and amp all inside the car ready to go. Bench testing is awesome but seeing it real world situations provides its own unique knowledge too.
Other than actually clamping multiple setups, seeing other people's clamps, competing etc... there's not much literature on it since if you just care about music, just get a big enough amp to make you happy(which means WAAAAY more than you would ever hope to need so you can keep its workload very light = clean power/signal) and dont worry too much about specific rise and focus on the enclosure efficiency.
For competing though, smaller boxes tend to have less rise. Boxes with flex will also cause higher rise. Also rise will be different for each frequency. You could have a much lower rise at 30hz than 50hz and vice versa, that will depend on your box tuning and how it interacts with the vehicle cabin. Hence when I clamp with my older setups, I actually do 25hz, 30, 35, 40, 45, 50, 55, 60hz and save it on an excel sheet or a notepad app on my smart phone so I can decide whether to chance half ohm with brazilians.
for example wired to 1 ohm i was rising to 5.9 ohms at 47hz which was my loudest frequency on the meter and was only rising to 2.7 ohms at 33hz which is waaaay less louder with my old two hdc18s at the D pillar setup. Box was a lot bigger than recommended hence more rise but i had efficiency so it was still loud even though I technically got less than 800 watts out of a dc 3.5k at 47hz which was super loud compared to 33hz at 1750 ish watts.
Here's some clamping mistakes people usually make when clamping
No oscope aka fully clipped number on their end depending on the person.
They only clamp their loudest frequency.
they use cheap meters and clamp tools.
