Ballparking new dB's and CFM's

[paco83]

Are the changes in dB and CFM's of a fan linear? (ie 7 volt hacking a normally 28dB 33cfm fan results in a ~17 dB and 20 cfm?)

And anyone happen to know the CFM and dB rating on the antec true powers when they running at max rpm?

 

[mechBgon]

Decibels go on a logarithmic scale like so:

Total dB (sound level) = dB rating of loudest fan + log(10^(dB fan_type1/10) + 10^(dB fan_type2/10) + ... + 10^(dB fan_typeN/10))

Flow is going to depend on certain factors such as how much resistance there is to airflow (like, is the fan trying to push/pull air through small holes or something), but from looking at airflow/voltage graphs for Panaflo fans, it seems like airflow is roughly linear with voltage... close enough for our purposes anyway. If you want to scope out the graphs, here are some for 80mm fans here and here's the page for the rest of the line of Panaflo fans & blowers: link

 

[paco83]

I don't care about how multiple fans dB rating add, but whether or not the relationship between voltage and loudness is linear.

dB = 10log(I/I0)

I would like to know if either I or dB are linear compared to the voltage of the fan.

 

[godmare]

Originally posted by: paco83
I don't care about how multiple fans dB rating add, but whether or not the relationship between voltage and loudness is linear.

dB = 10log(I/I0)

I would like to know if either I or dB are linear compared to the voltage of the fan.

Did you read that post?

 

[mechBgon]

Based on the 28db 33cfm fan, my best educated guess is that 7-volting it will make it noticably quieter and probably about the 22-24dB area. Sorry if that isn't a very precise guesstimate.

 

[paco83]

Ok thanx for the help.

 

[digitalix]

Make sure the fan even runs at 7 v, not all do