I was wondering if someone could give me a description of how many Db they think is too loud. I am looking at fans and I have found one that is really good at 23Db, but I am trying to do some mass cooling so I was wondering how many Db I could do without it becoming a problem. I saw one fan that had a massive cfm, but it was about 50Db. Is that way too much? Will it make a difference when I have sound going? Would it be better to have 2- 50cfm, 25Db fans or 1- 100cfm, 50Db fan? Let me know what you guys think...

The two 23dB fans are a MUCH better option than one 50dB unit. The reason for this is that when you add the noise from 2 23dB fans, the result isn't 46dB, it's 26dB.

This chart will give you some idea of how the dB values translate to typical sounds/music:

SPL Chart


Hope that helps,
Phil.

oooh, nice chart, thanks

syscrush: basically you'll want to stay in the low 30's if you can, ideally under 30 alltogether.

the evercool PCAC's are really nice units (23db/100cfm) i got 2 of them for my design.

How do you calculate the Total dB when combining multiple fans. Is there a formula? How did you get 26dB rom two 23dB fans?

Every time you double your sound making capability you add 3db. Decibel is a logrithmic scale. Adding a 23db and a 50db device would end up at about 50.1db. Its not a very easy calculation.

True, but it's not that hard, either.

Tutorial on adding decibel values

To add two values, A and B to get the result C (where all are measured in decibels), the formula is:

C = log(10^(A/10) + 10^(B/10)) * 10

Where "^" is the exponent operator.

So, for 50dB plus 23dB, we get:

C = log(10^5 + 10^2.3) * 10
C = log(100,000 + 199.5) * 10
C = log(100,199.5) * 10
C = 5.0009 * 10
C = 50.01 dB

Either Kingjamez or I, or both of us have made a mistake - maybe it's a good exercise for someone to figure out what the correct answer is.


Take it easy,
Phil.

My rule is nothing over 30dba. Over that and it just starts getting too loud. I have a watercooled computer and I sleep 4 feet from it so noise is a big issue for me. Panasonic Panaflo, Vantec Steath and Papst fans are all quality fans targeted for low noise. Newegg has most Vantec fans, Panaflos and Papst are getting hard to come by, but you might find some at plycon.com or highspeedpc.com or maybee even case-mod.com. I just got 2 120mm Vantec Stealths for my PJ from newegg they are 53cfm @ 28dBa

Man, I'd better walk on eggshells around here. 50.1db was purely a WAG.... nitpiking over 0.09db.... oh my!

Hee hee - OK -I thought that maybe I had a mistake in my calculations.


Take it easy,