How do you calculate new airflow/noise when using a fan controller?

[? (=Þ)]

............mAmp.....Watt.....RPM......CFM.......db
Low.....180.0......2.2.......1700.....68.9......30.0
Mid......340.0......4.1.......2100.....86.5......35.5
High.....460.0.....5.5.......2500.....103.8....41.5

(i hope this shows up properly, these are all panaflo 120mm fans)

I'm curious exactly how you are supposed to calculate the new specs when you lower the voltage. Am I supposed to calculate the new wattage drawn and then calculate the RPM for that new wattage, and then draw a rough estimate of the CFM and db for that particular RPM?? (like assuming if the RPM falls between two fans above the CFM/db specs should be between too)??

This logically sounds right but would like to know for certain if using a fan controller might require a diff approach at estimating the noise/airflow. And am I supposed to use simple linear calculations for wattage, like does using 6v instead of the standard 12 means the fan does 1/2 the wattage it normally would use?

So basically if I get a High/H1 fan and run it at 7v, it should draw roughly 3.22w (7v*.460amps), and the CFM and db should fall between the values for the Low and Mid speed panaflo fans?

 

[Cerb]

It will be quieter...
BTW, what Panaflo L is 30db?!

Let's see, you've got the fact that it's forcing air around, and is made for 12v, there...you will not have a linear decrease--but it should be close.

The fans use different motors, and while I've never used anything but the Ls, I hear they undervolt a bit differently, so no.

One thing to keep in mind as well, is...how many are you going to have, of what size, and what configuration? There's noise from the fan, vibration noise from the case, noise fromfans fighting for air, pushing against air flowing through them, etc.

 

[THUGSROOK]

effectively, 7v will cut dba and airflow by 50%

i run 3x M1A 120mm on 7v.