question about fan noise and setup

[jmg873]

yet another question for my upcoming build. if i have a double heatercore will i get more noise with 4x 30db fans in push/pull or from 2x 42db fans?

thanks for the info

 

[Arcygenical]

4x 30dba fans = 39dba (30 + 3 + 3 + 3)

So, roughly the same amount really... But the 4 fans will be quieter.

 

[jmg873]

4x 30dba fans = 39dba (30 + 3 + 3 + 3)

So, roughly the same amount really... But the 4 fans will be quieter.

so does that figure mean that it's a 10% increase in db for every fan added of the same spec?

so for instance, would 4x40 be 52dba (40 + 4 + 4 + 4)?

 

[Arcygenical]

Since the loudness scale is logarithmic, doubling the noise source only increases the total sound by about 3dba.

2 50dba fans would be 53dba.

3 50dba fans would be 56dba.

 

[jmg873]

i see, so for every fan that is added i should assume approximately a 3db (or 4 at most) increase per fan?

edit----

ok, so all that being said, assuming that the increase in CFM's i get from using 4 fans in a push and pull format on a 2x120 heater core instead of 2 fans is 50% (that figure is taken from another thread).

my adjust dba and cfm would be

44dba (total noise) and 88cfm (per fan) with a 2 fan setup of yate loon 40dba 88cfm fan

or

42dba (total noise) and 105cfm (per fan set) with a 4 fan setup of yate loon 33dba 70.5cfm fan

does that look correct?

 

[Betrayer00GT]

You are better off with the quieter fans, if those dB ratings are equivilent (big assumption).

As to figuring out dB increases from going up in fan units:

Once you have two fans, you do go up 3dB from one fan.

But you then need to go to four fans to pick up the second 3dB.

So:

30dB fan plus 30dB fan = 33dB

33dBs worth of fans (2) + 33dB worth of fans (another 2) = 36dB

So, four 33s will be rather more quiet than two 40s, since you are at 39 vs 43. Again, it matters if those are equivilent measurments (like silentpcreview testing or something).

 

[jmg873]

very useful information.

thanks for the help everyone.