- Joined
- May 12, 2004
Hey guys I have heard that dba is exponential instead of lets say a 12v fan at 50 dba but if i change it to lets say 7v it wud run at 25. What is the formula to calculate the dba for a fan if i was to run it at a lower voltage?
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dBA Calculations
- Thread starter daniel_dynasty
- Start date
- Joined
- Sep 9, 2002
- Location
- under the floorboards
Dba is not exponential, its logrithmic.
It can apply to many things besides sound (one example that comes to mine is measuring antenna power)
Im not sure what good a formula will do. The way to do it is to get a potentiometer and just turn thigs down untill you like what you hear (or dont hear).
It can apply to many things besides sound (one example that comes to mine is measuring antenna power)
Im not sure what good a formula will do. The way to do it is to get a potentiometer and just turn thigs down untill you like what you hear (or dont hear).
dB isn't really a function of voltage, but more of rotational speed.
Rotational speed should be approximately proportional to voltage however, so making that assumption would be close enough. I'm not sure in accoustics, but in electrical signal analysis if you cut the power in half, you drop the magnitude by 3 dB. So, since power is V^2/R, if you cut voltage in half, you decrease power by a factor of 4. This would drop the signal magnitude by 6 dB. I'm not sure if that relates accoustically, but it's probably something similar.
Here is a good site that explains the decibel:
http://www.phys.unsw.edu.au/~jw/dB.html
Rotational speed should be approximately proportional to voltage however, so making that assumption would be close enough. I'm not sure in accoustics, but in electrical signal analysis if you cut the power in half, you drop the magnitude by 3 dB. So, since power is V^2/R, if you cut voltage in half, you decrease power by a factor of 4. This would drop the signal magnitude by 6 dB. I'm not sure if that relates accoustically, but it's probably something similar.
Here is a good site that explains the decibel:
http://www.phys.unsw.edu.au/~jw/dB.html
There's not really an easy way to calculate that. It's going to be significantly quieter, but probably still no less than 35 dB.
I would suggest you get some sort of simple fan controller so you can vary the speed/loudness to your liking rather than do a volt-mod.
I would suggest you get some sort of simple fan controller so you can vary the speed/loudness to your liking rather than do a volt-mod.
