Question about Fan Loudness

erikiksaz

Diamond Member
Nov 3, 1999
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I've had a black label delta on my golden gate ever since i've assembled this monstrosity, and you guys know that this thing is loud. I could almost hear the computer whizzing away from the living room, which is a good 10 yards from my computer chair. I figure that in the near future, i will replace that golden gate/delta with an Alpha. But the question that comes to mind is what fan i should use. I want something quiet, but i'm not sure if Panaflo quiet will be overkill. I've kinda grown used to the delta, but i still can't sleep in my room when the computer is on, and that annoys me. Since i'm used to the 47 dbas of the Delta, what dba level will sound *nearly* silent? I don't care if the computer makes a sound, i'm fine with that, i just can't stand the squeal of the Delta. What about the 32dba Panaflo? Will that sound quiet compared to the delta?
 

MoFunk

Diamond Member
Dec 6, 2000
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I use enermax adjustable fans on mine. Was running the 80mm now have the 92mm on there. I have 3 other adjustable fans in my case 1 80mm and 2 92mm and the PSU has a 92mm thermal contolled fan and an 80mm adjustable. I can tell you that I love the adjustable fans. I had 2 low speed sunon 92mm in before and I was ot able to leave my computer on at night becuase it would keep my wide up. Now I leave it running 24/7 and it does not bug her. All fans but the top exhaust are set to 1/4 speed with the top on low. With my LCD thermal probe my CPU is 42c full load and 24c ambient. I am running an Athlon XP1600@1544. So I guess I am recommending the enermax adjustables! :)
 

ChefJoe

Platinum Member
Jan 5, 2002
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have you thought about trying to run that delta at 7 volts? it may put out less cfm but it'll probably sound silent to you.
 

erikiksaz

Diamond Member
Nov 3, 1999
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I've never tried voltage modding, i'll read into it. thanks for the suggestions guys.
 

Ionizer86

Diamond Member
Jun 20, 2001
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Hmm, the Panaflo L1A is nearly silent. Even though it's only rated at 24cfm's, most 60x60 fans blow less air than that. I can still hear the Panaflo L1A when not much background sound is bouncing around my room, but it's definitely quiet enough :Q
 

erikiksaz

Diamond Member
Nov 3, 1999
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I wasn't worried about it being too quiet, my main problem was if it was too quiet, would i be losing out on the cfms i need.
 

Neurofreeze

Member
May 12, 2001
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<< I've had a black label delta on my golden gate ever since i've assembled this monstrosity, and you guys know that this thing is loud. I could almost hear the computer whizzing away from the living room, which is a good 10 yards from my computer chair. I figure that in the near future, i will replace that golden gate/delta with an Alpha. But the question that comes to mind is what fan i should use. I want something quiet, but i'm not sure if Panaflo quiet will be overkill. I've kinda grown used to the delta, but i still can't sleep in my room when the computer is on, and that annoys me. Since i'm used to the 47 dbas of the Delta, what dba level will sound *nearly* silent? I don't care if the computer makes a sound, i'm fine with that, i just can't stand the squeal of the Delta. What about the 32dba Panaflo? Will that sound quiet compared to the delta? >>



A 10 dB increase is a doubling in perceived loudness, so your Delta is 2.5 times louder than your Panaflo. 20 dB is generally considered human whisper level (with 0 dB being the threshold of average human hearing).
 

erikiksaz

Diamond Member
Nov 3, 1999
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<<A 10 dB increase is a doubling in perceived loudness, so your Delta is 2.5 times louder than your Panaflo. 20 dB is generally considered human whisper level (with 0 dB being the threshold of average human hearing). >>

Thanks, i was looking for that too. I kept asking my physics teacher how to figure out the loudness between Sound A and Sound B, but the answers were all in intensities, and i had no clue how to convert over to general perceived loudness.
 

Neurofreeze

Member
May 12, 2001
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Sound Intensity Level and Sound Pressure Level (SIL and SPL, respectively)? Yeah, a physics teacher would do that.

Here's a copy of a post I made not too long ago on this subject in another forum, it's a little lengthy, but for people concerned with case noise levels, it's good to know. It's about how to add various sources of sound together.
/******************************************
To add different sources of sound, you have to first know either their Sound Pressure Levels or their Sound Intensity Levels. Both SIL and SPL are referenced to the average human's threshold of hearing, so for simple situations you'll get pretty much the same answer.

SPL is defined as:

L(sub p) = 20log(P/P(sub 0))

where P(sub 0) = 2 x 10^(-5) N/m^2 (the threshold of hearing).

SIL is defined as:

L(sub i) = 10log(I/I(sub 0))

where I(sub 0) = 10^(-12) W/m^2

The difference, of course, is that SPL is the measure of sound's pressure in newtons per meter squared and SIL being the measure of sound energy in Watts per meter squared.

The relationship between the two can be described as:

L(sub p) = 20log(P/P(sub 0)) = 10 x 2log(P/P(sub 0)) = 10log(P/P(sub 0))^2 = 10log(I/I(sub 0))

The second to last step might look a little funny, but you'll just have to trust me when I say it's a funky rule of logarithms.

Now to get either SIL or SPL values of a given dB, just plug that dB value into L(sub p) or L(sub 0), respectively, then solve for P or I, respectively.

For SPL it would be:

P = 2 x 10^(-5) x 10^(L(sub p)/20)

SIL:

I = 10^(-12) x 10^(I(sub 0)/10)

Again, there's a funky rule of logarithms in there, where a = log(b) goes all whack so that b = 10^a.

Now you can combine SIL readings very easily. Just do it. Take your dB values, convert into SIL values, add those SIL values, then convert back to dB values. SPL is a little harder though.

For SPL values, the sum of the squares of the SPL values equal the square of the total SPL value. Meaning, you have to convert your dB values into SPL, then square each of those (individually), then add those together, then take the square root of that sum, then convert back to dB.

All this is for uncorrelated sound sources, which would be what you need. Correlated sounds would be those that have the exact same wave amplitude equidistant to the listener. Adding those is more complex, but you really won't have a use for that in this scenario.
************************************/

There are a lot of other factors contributing, such as distance from the sound sources and how density of mediums (your case) will absorb sound, but getting one big theoretical number is pretty useful in comparisons of ideal system configurations.

On a side note, it's times like these I wish there was more support for MathML.

// Edit: Blargh, reposted the same grammatical error.