B
Biffo
Panaflow fans are apparently quieter than Vantec Stealth. Also you can
get PSU's like the Zalman that run the fan in the PSU at very low rpm
unless the temp get's inside the PSU gets over 50deg c.
Panaflow fans are apparently quieter than Vantec Stealth. Also you can
get PSU's like the Zalman that run the fan in the PSU at very low rpm
unless the temp get's inside the PSU gets over 50deg c.
B
Biffo
There is one on the market. Looks pretty ugly though and building this
yourself would be quite easy so long as you have the necesary tools.
J
Johannes H Andersen
Timothy said:
A problem though with this solution is that it also keep the heat
inside. Sound absorbing material is usually also heat insulating.
Secondly, our sound perception follows a logarithmic scale; a
small audible reduction of 3 dB require a 50% reduction in sound
energy.
T
Timothy Daniels
"Johannes H Andersen" replied:
Read the description again. There is no top to this cabinet,
and there is free convection in the rear since there is no floor
under the rear cables, and the front door does not go all the way
down to the desk surface. There is no interference with air flow,
and there is no dependence at all on conduction. All this cabinet
does is force most of the sound to bounce at least once off a
carpeted surface. A reduction of more than 50% of sound energy
is easy. I did a crude experiment of just suspending a 2'x3' sheet
of carpet against the wall behind my midi tower, and the reduction
in sound was surprising.
*TimDaniels*
Read the description again. There is no top to this cabinet,
and there is free convection in the rear since there is no floor
under the rear cables, and the front door does not go all the way
down to the desk surface. There is no interference with air flow,
and there is no dependence at all on conduction. All this cabinet
does is force most of the sound to bounce at least once off a
carpeted surface. A reduction of more than 50% of sound energy
is easy. I did a crude experiment of just suspending a 2'x3' sheet
of carpet against the wall behind my midi tower, and the reduction
in sound was surprising.
*TimDaniels*
G
Gary D.
I didn't go for Panalflow fans because of an article I read on the web
(can't remember where!) that said not all Panaflows were effective in
noise reduction. I was only a matter of having read that article that
made me go for Vantec, simply a matter of one choice over the other,
although I suspect you could be right!
Another factor I think might still be contributing to the noise levels
I'm experiencing is that my PSU unit is a cheap one that came with my
PC and the PSU box fan aperture is not quite as large as the fan
diameter, so some of the air flow is hitting the edges of the box
aperture and this, I guess, must be causing turbulence and thus the
annoying "hiss". To remedy this would involve removing the entire
contents of the box and expanding the fan aperture; even then I reckon
any resulting improved aperture might have rough edges (using just DIY
tools) and it's unlikely I would achieve a professionally smooth job.
The PSU box used to have metal cross-members - which I cut away - and
that helped a lot, but I think I've gone as far as I can on
modifications so I'll just learn to live with the noise.
J
Johannes H Andersen
Timothy said:
Then you have cut out reflections of noise from the wall. It's OK if
you can remove noise by some simple means. It is unfortunate that the
cabinet sometimes amplifies the noise, I've found that opening the
cabinet on my PC actually reduces the noise, but then it diverts the
airflow which you don't particularly want. Hence there are acoustic
considerations as well. I have tried to shield my PC with a plywood
box, but it gave little result and access was cumbersome if I wanted
to do something. Instead I now have a good CPU heat sink with
temperature control (the CPU fan rarely runs) plus a 50 Ohm 3 Watts
resistor in series with the PSU fan. The PSU fan resistor was
carefully chosen by feeling the temperature of the PSU components.
D
dorothy.bradbury
small audible reduction of 3 dB require a 50% reduction in sound
o The letter after dB is the Weighting applied
---- (A) is used for humans - poor at <25dB(A) since it is an approximation
-------- qualitative nature of the noise becomes important
-------- for fans bearing choice, vibration, resonance, blade-to-housing gap
---- (A) is really aimed at industrial noise
-------- hence there is a new ISO standard aimed at super-silent noise
levels
o A reduction of 10dB(A) is a 50% reduction in sound energy
---- 3dB(A) is the margin most people can detect
---- however this too depends on the noise level re 20s or 70s
o Each 180-degree turn you make sound go thro reduces it 6dB(A)
o The most cost effective sound dampening is treating the Cause
---- then treat the Effect - which is much more difficult re sound-proofing
-------- you have lots of holes in a PC
-------- you have case-fans outside the soundproofing inside the case
-------- CPU-fan / drives / soundproofing / case-fan / ear
QuietPC 3-pk soundproofing is very good re price - good peelable stick,
since it's very heavy & ok closed-cell foam. Of course the foam is a bit
lame as it's just ~5mm thick (limited by PC space in present designs).
You need mass for low frequency, and closed-cell foam for high frequency.
Most PC sound emitters are few milli-watt, so it's a foam issue vs just
mass.
Resonance is an issue re fan & other motorised object mounting & vibration.
Treat cause, treating effect is more difficult.
The new BTX form-factor will initially solve a lot of problems:
o Blow thro heatsink, blow thro PC design -- like the G5
---- that will allow sub 30dB(A) PCs
o However CPU & Graphics & HD power output are rising fast
---- 125W CPUs are the first, and frankly dual-CPU machines will hit 400W
---- IDE HDs are moving from 7200rpm to 10,000rpm & SCSI beyond 15300rpm
So the silence may be short-lived - but at least better than the ATX
alternative.
Have fun
o The letter after dB is the Weighting applied
---- (A) is used for humans - poor at <25dB(A) since it is an approximation
-------- qualitative nature of the noise becomes important
-------- for fans bearing choice, vibration, resonance, blade-to-housing gap
---- (A) is really aimed at industrial noise
-------- hence there is a new ISO standard aimed at super-silent noise
levels
o A reduction of 10dB(A) is a 50% reduction in sound energy
---- 3dB(A) is the margin most people can detect
---- however this too depends on the noise level re 20s or 70s
o Each 180-degree turn you make sound go thro reduces it 6dB(A)
o The most cost effective sound dampening is treating the Cause
---- then treat the Effect - which is much more difficult re sound-proofing
-------- you have lots of holes in a PC
-------- you have case-fans outside the soundproofing inside the case
-------- CPU-fan / drives / soundproofing / case-fan / ear
QuietPC 3-pk soundproofing is very good re price - good peelable stick,
since it's very heavy & ok closed-cell foam. Of course the foam is a bit
lame as it's just ~5mm thick (limited by PC space in present designs).
You need mass for low frequency, and closed-cell foam for high frequency.
Most PC sound emitters are few milli-watt, so it's a foam issue vs just
mass.
Resonance is an issue re fan & other motorised object mounting & vibration.
Treat cause, treating effect is more difficult.
The new BTX form-factor will initially solve a lot of problems:
o Blow thro heatsink, blow thro PC design -- like the G5
---- that will allow sub 30dB(A) PCs
o However CPU & Graphics & HD power output are rising fast
---- 125W CPUs are the first, and frankly dual-CPU machines will hit 400W
---- IDE HDs are moving from 7200rpm to 10,000rpm & SCSI beyond 15300rpm
So the silence may be short-lived - but at least better than the ATX
alternative.
Have fun
R
Rob Morley
Gary D. said:
Perhaps because they provide a higher airflow instead? There's always a
trade-off between volume and volume, if you see what I mean
J
Johannes H Andersen
dorothy.bradbury said:
I have to correct your science here.
A doubling of absolute signal power represents an increase in dB of 3dB.
Reference http://ccrma-www.stanford.edu/~oded/M151/decibels.html ,
but this is also generally known from any textbook.
Applying a profile as in db(A) makes no difference since dB reduction is
about relative level differences; putting in a profile will preserve ratios.
( Profile * signal_1 )/(Profile * signal_2) = signal_1/signal_2
"3dB(A) is the margin most people can detect" This is correct.
D
dorothy.bradbury
Human Sensitivity:
o 3dB is the difference in noise level a human can perceive
o 1dB is the difference perceivable under laboratory conditions
---- vis., for general purchase use the figure of 3dB applies
Human Perception:
o 10dB increase in noise level is Perceived as a doubling in noise level
o 10dB decrease in noise level is Perceived as a halving in noise level
Energy Intensity:
o 3dB corresponds to halving/doubling the noise sources
o Intensity is important for exposure times as one exceeds ~85dB(A)
The 10dB figure is rough, but standard practice - some prefer to use 6.
Note this is a *Subjective* Human-Perception issue not an absolute.
Building data is useful - since PCs are just another noise component:
http://www.n-p.com/engineering/sound.asp gives OSHA data too.
However, for PC use, the "A" weight is poor below ~25dB(A) levels:
1) it pooly represents the profile of human perception
---- it was designed to time & sensitity weight loud noises re H&Safety
2) it poorly represents the perception of noise components
---- frequency, harmonics, white-noise or not components & so on
---- eg, hum, bearing rumble, blade-tip-speed, diagonal v axial flow
---- for a consideration of fan noise components see Neise (1988)
I'm well aware of the electronic usage, but when one is referring to
human perception, human factors, the above figures are standard.
Absolute silence is -20, anechoic chambers background often ~16.
Which is one reason why fan design hits law of diminishing returns,
and unfortunately many PSUs suffer coil-hum as much as fan-noise.
Same with PWM solutions that use 1-2kHz PWM vs 10-20kHz.
The solution is fan-&-system design, since correct use of baffles
and moving fans off the case surface allows soundproofing to work.
Work on sub & supersonic fan noise mgt is more advanced than PCs.
That said, the PC even with BTX is somewhat behind the Dual-G5.
o 3dB is the difference in noise level a human can perceive
o 1dB is the difference perceivable under laboratory conditions
---- vis., for general purchase use the figure of 3dB applies
Human Perception:
o 10dB increase in noise level is Perceived as a doubling in noise level
o 10dB decrease in noise level is Perceived as a halving in noise level
Energy Intensity:
o 3dB corresponds to halving/doubling the noise sources
o Intensity is important for exposure times as one exceeds ~85dB(A)
The 10dB figure is rough, but standard practice - some prefer to use 6.
Note this is a *Subjective* Human-Perception issue not an absolute.
Building data is useful - since PCs are just another noise component:
http://www.n-p.com/engineering/sound.asp gives OSHA data too.
However, for PC use, the "A" weight is poor below ~25dB(A) levels:
1) it pooly represents the profile of human perception
---- it was designed to time & sensitity weight loud noises re H&Safety
2) it poorly represents the perception of noise components
---- frequency, harmonics, white-noise or not components & so on
---- eg, hum, bearing rumble, blade-tip-speed, diagonal v axial flow
---- for a consideration of fan noise components see Neise (1988)
I'm well aware of the electronic usage, but when one is referring to
human perception, human factors, the above figures are standard.
Absolute silence is -20, anechoic chambers background often ~16.
Which is one reason why fan design hits law of diminishing returns,
and unfortunately many PSUs suffer coil-hum as much as fan-noise.
Same with PWM solutions that use 1-2kHz PWM vs 10-20kHz.
The solution is fan-&-system design, since correct use of baffles
and moving fans off the case surface allows soundproofing to work.
Work on sub & supersonic fan noise mgt is more advanced than PCs.
That said, the PC even with BTX is somewhat behind the Dual-G5.
J
Johannes H Andersen
dorothy.bradbury said:
This sounds correct, but you said in your earlier post:
"o A reduction of 10dB(A) is a 50% reduction in sound energy"
So you mixed up 'sound energy' with 'Percieved noise level' .
Strictly, as 3dB reduction corresponds to 50% reduction in sound energy,
it follows that 10dB corresponds to a residual factor of 0.5^(10/3) in
other words 90% reduction in sound energy.
K
kony
Panasonic (Panaflo), like Vantec, makes a variety of fan sizes and
speeds. Their (Panaflo's) dual ball-bearing fans are rare in fans
appropriate for PC applications, but their sleeve-bearing fans are
much better than the typical sleeve-bearing fan. This allows the
noise reduction of a sleeve bearing but without as much of a lifespan
decrease. Certainly there are other good sleeve-bearing fans like
Pabst, but in general most other good fans are ball-bearing.
The fans generally regarded as very quiet are "L1A", as a portion of
the model number where "L" is low, "1" means "with leads", and "A"
simply means it has no sensor option, only 2 power wires. Certainly a
sensor could be useful too, but this is the most common configuration.
Their "M1A" series is also good for noise reduction if you need more
ailrflow than a lower RPM fan can provide. Of course it's louder than
L1A but good noise/airflow ratio.
Cheap power supplies often have small heatsinks and can produce more
heat per power output, and also may have a more aggressive fan speed.
Replacing the power supply would be the best alternative, and since
your current power supply is still working, if you wanted to modify
the new power supply you have ample time to do it, system downtime
wouldn't be a factor.
Also if the cheap power supply has a likewise cheap sleeve-bearing fan
it may be subject to failure, is "usually" one of the first parts to
fail in such a system.
Dave
T
Timothy Daniels
Johannes H Andersen said:
Yes. The intention is to keep the noise from getting to
one's ears, not from keeping within the tower.
That is one purpose of the carpeting - to damp out vibrations
of the cabinet walls. Cheap foamed-backed stick-on
carpeting squares would be perfect for this.
If you leave a 6-inch clearance in the back and a 3-inch
clearance in the front, the interference in air flow will be
negligible. Remember that both the rear and the front walls
of the cabinet do not contact the desk or the floor of the
cabinet but leave large gaps for air flow.
Try it again with carpeting lining the inner surfaces.
An access door in the front, and that 6-inch clearance
at the back would help with that.
Yes, my fingers are the calibrated type, too.
But you must remember that the PSU fan contributes
to the overall air flow in the tower, and if it has an intake
on its bottom wall, it helps to ventillate the CPU.
*TimDaniels*
T
Timothy Daniels
dorothy.bradbury said:
In the audio world, 1 dB is the accepted limit of human
perception (if they're listening for it). 3 dB may be the
limit for casual (or "unprepared") listening.
As long as you're referring to human perception by adding
the "(A)" to your dB figures, you might as well add
"apparent" to "sound energy" terminology.
And "db" is a measure of power, not energy; and instead
of "energy", you ought to be saying "intensity" for perception
effects. In short, you mix your terms from the physics basket
and from the psychoacoustics basket. In the physics (and
engineering) world, 10dB equals one Bell - a change in
power by a factor of 10, not a factor of 2. A factor of 2
entails a change in power of 3dB.
<groan> And if you spin around 10 times the sound will
reduce by 120dB! If you merely mean "fluctuate" by 6dB(A),
you have some explaining to do about how that sound does
or doesn't reflects of walls, refracts around the edges of the
ears, how it conducts through flesh and bone of the ear/head,
etc., instead of that blanket one-size-fits-all statement. In
college, conclusions stated without any comment on the
methodology was called "hand waving".
*TimDaniels*
R
Rob Morley
In engineering "rule of thumb" is adequate in many places, although ITimothy Daniels said:
wouldn't expect a physicist to be happy with that
J
Johannes H Andersen
Timothy said:
Yes, I already knew that it is strictly sound power which is rate of energy.
However, to simplify I also wrote 'sound energy', assuming everybody would
understand this the right way. But in usenet there is always someone needing
to nitpick (myself included).
T
Timothy Daniels
"Rob Morley" pointed out:
Nor a mathematician.
BTW, my "rule of thumb" is: If it don't work the first time,
press harder.
*TimDaniels*
In engineering "rule of thumb" is adequate in many places,
although I wouldn't expect a physicist to be happy with that
Nor a mathematician.
BTW, my "rule of thumb" is: If it don't work the first time,
press harder.
*TimDaniels*
S
Strontium
-
Rob Morley stood up at show-n-tell, in
(e-mail address removed), and said:
We call that 'fudge factor', in Chemistry and PCHem.
Rob Morley stood up at show-n-tell, in
(e-mail address removed), and said:
In engineering "rule of thumb" is adequate in many places, although I
wouldn't expect a physicist to be happy with that
We call that 'fudge factor', in Chemistry and PCHem.
B
Boffo
Perhaps because they provide a higher airflow instead? There's always a
trade-off between volume and volume, if you see what I mean
Actually, the Panaflows are only 1500rpm and the Vantec is 2050rpm. I
have a Vantec stealth myslef and haven't actually used a Panaflow yet,
but the reviews I have read said it is quieter than Vantec Stealth.
T
Timothy Daniels
Johannes H Andersen said:
Hey! Nitpicking is one of the invaluable services
provided by Usenet. It's like primate grooming -
you pick my nits and I'll pick yours and together
we'll be nitwits, er... nit-free. Or whatever.
*TimDaniels*