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Total Fan Noise - how to calculate ??

 
 
Ken Roberts
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      Apr 21st, 05, 1:51 PM
For example, if I have the following:

5 case fans - 28 dBA
1 CPU fan - 15 dBA
1 PSU fan - 23 dBA
1 Video Card fan - 12 dBA
------------------------------------------
Total = 190 dBA

Now, I am certain that you cannot calculate the amount of noise you
will hear by adding all the fan's dBA rating together. I am also sure
it would be an extremely complex formuyla to calculate, because there
are so many variables (placement of fans, distance from user's ears,
vibration, etc).

What I am wondering though, is if there is a very general ballpark way
to estimate how much noise a system will create. TIA
 
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Al Dykes
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      Apr 21st, 05, 2:03 PM
In article <>, Ken Roberts <> wrote:
>For example, if I have the following:
>
>5 case fans - 28 dBA
>1 CPU fan - 15 dBA
>1 PSU fan - 23 dBA
>1 Video Card fan - 12 dBA
>------------------------------------------
>Total = 190 dBA
>
>Now, I am certain that you cannot calculate the amount of noise you
>will hear by adding all the fan's dBA rating together. I am also sure
>it would be an extremely complex formuyla to calculate, because there
>are so many variables (placement of fans, distance from user's ears,
>vibration, etc).
>
>What I am wondering though, is if there is a very general ballpark way
>to estimate how much noise a system will create. TIA



Google for "how to add dba" came up with this...

http://www.overclockers.com/articles607/

To simplify, if you have two 28dBA fans, combined they are 31dBA. Do
that again (2x2 fans) and you're up to 34dBA, so your 5 case fans are
about 35dBA. The rest of the fans, combined bring you up to maybe
37dBA.

It'll generate high numbers (ie lower perceived sound) because, for
example, given identical fans, one moving air into the case and one
exhaustiong air out, the exhaust fan will be a bit louder.

Nobody needs 5 case fans for anything like a standard desktop PC. It
the're not set up right they are fighting each other. One on and one
out should do it.
--
a d y k e s @ p a n i x . c o m

Don't blame me. I voted for Gore.
 
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Matt
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      Apr 21st, 05, 8:32 PM
David Maynard wrote:

> dB = 10 * log 10 (power in W/m 2 ) + 120, to get the dB(A) sound level


W/(m^2) is a unit of intensity, not power.
 
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Patrick
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      Apr 22nd, 05, 7:21 PM
> Sensitivity also changes with the volume, which is what the 'loudness'
> control on stereos is for: to boost them when the volume level is turned
> down.


To boost what? Does the loudness control do more than increase/decrease
the volume?
 
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Matt
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      Apr 22nd, 05, 7:21 PM
David Maynard wrote:

> Sensitivity also changes with the volume, which is what the 'loudness'
> control on stereos is for: to boost them when the volume level is turned
> down.


To boost what? Does the loudness control do more than increase/decrease
the volume?

 
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Matt
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      Apr 22nd, 05, 7:21 PM
David Maynard wrote:

> Sensitivity also changes with the volume, which is what the 'loudness'
> control on stereos is for: to boost them when the volume level is turned
> down.


To boost what? Does the loudness control do more than increase/decrease
the volume?
 
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Matt
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      Apr 22nd, 05, 7:21 PM
David Maynard wrote:

> Sensitivity also changes with the volume, which is what the 'loudness'
> control on stereos is for: to boost them when the volume level is turned
> down.


To boost what? Does the loudness control do more than increase/decrease
the volume?

 
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Matt
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      Apr 22nd, 05, 7:32 PM
sorry, having a little trouble with my news server ...
 
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Al Smith
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      Apr 22nd, 05, 10:06 PM
>> Sensitivity also changes with the volume, which is what the 'loudness' control on stereos is for: to boost them when the volume level is turned down.
>
>
> To boost what? Does the loudness control do more than increase/decrease the volume?


It exaggerates the base and treble, fooling your ear into thinking
that you have the volume higher than it actual is.
 
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ric
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      Apr 23rd, 05, 6:13 AM
Matt wrote:

> sorry, having a little trouble with my news server ...


Are you with HOTMAIL? They had a major burp at 1421 ET.
 
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