John H wrote in message
...
Rod Speed wrote
John H wrote in message

Power values are NOT filtered as pressure values are using the A scale.

Not clear what you think that sentance means.

So converting bels to pressure would give a dB value, not dBA.

Correct.

But I see no reason why power couldn't be measured
using the same filter to give you a 'belA' rating.

That makes no sense. Its the distribution of sound with frequency
and intensity thats relevant to the ear's perception of sound. So
there cant be a simple factor that can be applied between the
two. As should be obvious from the different ration you saw
between bels and dBA with the hard drive and the fan.

I agree that a drive with a lower 'belA' rating could still have
higher sound pressure (dBA) in *some* directions (compared
to the drive with the higher 'belA' rating) even though the average
of *many* directions is lower. But the same is true for bel ratings.

You're mangling the entire story utterly. The only difference
between bels and decibels, B and dB is the usual metric
scale factor. Just like between M and KM etc.

The A signifys a quite different application of the A law to the
sound being measured to allow for the ear's frequency response.

Thats all an entirely separate issue to whether the sound
is being radiated uniformly in all directions. Thats hardly
ever the case with real world sound sources and certainly
isnt whats seen with hard drives or fans.

A drive with a lower bel rating *might* still produce a
higher sound pressure at your ear. Sit at a different
angle to the drives and just the opposite could be true.

Correct. BUT thats an entirely separate issue to the A
law compensation for the frequency response of the ear.

So maybe what you really mean is that
'belA' makes no more sense than bel.

Wrong. The frequency response of the ear is still a very
important factor in the perception of how noisy a drive is.

The problem is that its only part of the story and the other
real problem with quantifying how noisy a drive is is the MINDS
perception of noises. Some sounds produce very little sound
pressure but are very irritating to the MIND. And the reason
that isnt quantified is because its essentially unquantifiable.
Unlike the frequency response of the ear.

The 12dBA, 3.5 bel fan I mentioned (a Papst 8412NGL,
http://www.papstplc.com/downloads/DC/8400n.pdf) would surely
have very differently shaped isobars (is that the right word here?)

Nope. Presumably you mean the spacial contours of equal SPL.

than what a HD would,

Yes, but the much more important factor is the different
frequencys of the sounds produced, and the effect of the
A law filter on those. THATS the main factor in the different
ratio between the dBA and bel values with the two devices.

no doubt with a 'high gain'

There is no 'gain'. Certainly the sound isnt uniformly
radiated in all directions with both types of device.

for the direction the fan is blowing in and much lower in back.

You dont get that effect either with quiet fans.

A hard drive would have pressure variations too
but I don't think anywhere near as much as a fan.

Thats just plain wrong too, particularly with the drives that
have acoustic damping designed in like the Barracudas.
Clearly there wont be as much sound getting thru the thick
rubber mat in some directions. Thats the whole point of it.

If all fans were rated in bels (or belA) only,
would the ratings be useful in comparing fans?

To some extent, particularly because fans are much
more uniform noise sources, particularly if they are
constant speed fans. Uniform in the sense of the frequency
distribution of the noise they make. So dBA is more useful
when comparing fans than it is with hard drives which produce
different noises depending on what they are doing etc.

And its the dBA that matters because that allows for the
frequency response of the ears. But you STILL cant have
a simple ratio between dBA and bels even with just fans,
because some fans produce a lot more high frequency
noise than others, particularly high speed small fans
produce a lot more air turbulence noise than much
slower rotating large fans moving the same volume of air.

I think so because the pattern for the isobars for one fan
shouldn't vary by any significant amount from another fan.

Thats just plain wrong too. The spacial distribution of
the noise will vary significantly between a high speed
very small fan and a big slow rotating fan both moving
the same volume of air. And then you have the other
massive difference between the types of fans, radial
bladed fans and turbines/blowers, cylindrical fans etc.

At the extremes you get quite different effects when
the tip speeds are approaching the speed of sound too.

I suspect the same is true for hard drives of the same type.

You're wrong. Most obviously because the design of the body
of the drive has a big effect on the spacial distribution of sound.

AND when the frequency of the sounds vary from drive
to drive, there cant be a simple conversion between
dBA and bels either, just because of the A law curve.

But you can't compare bels for a fan to the bels for a HD to
determine which will appear louder (as my examples show very well).

You cant with hard drives either as I pointed
out in your original list of particular drives.

Wonder why they don't do it that way?

Because it aint even possible.

I still think it's possible

You're wrong. It aint. While ever the frequency of the
noise produced by drives vary from drive to drive, there
cant ever be a simple ratio between dBA and bels.

even if of no value. If the pressure readings made
for computing sound power were all "A" filtered, the
bel value would be "A" filtered too it seems to me.

You're wrong again. The is NO filter applied the bel reading.
Thats the whole point of the A letter in dBA, it signifys that
THAT value has the A law filter applied.

Going by what the A filter looks like in the link I gave
(attenuated highs and lows), a 'belA' value would be a
lower number and therefore look better to some people.

And here you are massively mangling in the basic metric scale units
into a MUCH more complicated concept. The difference between
dB and B is just the metric scale unit. Like between M and kM.

I don't know what you're talking about here. Bel is used for acoustic
power, dB or dBA for acoustic pressure. I haven't used B anywhere.

B is just Bel. dB is decibel. dB aint the same as dBA.

This seems to make a dBA rating a better indicator of
how loud a drive will appear than what a bel rating is,

Yes.

and yet most manufacturers don't give
you the dBA rating. Doesn't make sense.

Thats because even the dBA is pretty hopeless with
hard drive noises for the reasons I already pointed out.

Still better than nothing.

Sure, and thats why its quoted.

What I wish they'd do is provide an FFT of a drive's
noise so you could see the amplitude of all frequencies.

That would be useless as far as how irritating it is TO THE MIND.

A sizable spike at some frequency (which would add practically
nothing to the bel rating) would be a clear sign to avoid the drive.

Nope. Some frequencys are barely audible. True in spades of
TVs where the line frequency isnt even audible for most people.

HD Reviewer's should do this. All they'd
need is a PC with a sound board, a
good microphone and the right software.

And that would be completely useless when the main
problem today is how irritating the sound is TO THE MIND.

You dont even get general agreement on that. Some find
that white noise is quite soothing and produce it deliberately.
Some find that the residual whistle you end up with with
very quiet systems not objectionable at all, others hate it.

Some find soft sounds produced by a drive seeking
quite acceptible and the sound like a cricket in a small
cardboard box very irritating indeed in comparison.

OTOH, all the acoustic power generated
by a drive has to be dissipated somewhere,

Yes, but thats not relevant to how noisy the drive itself is.

much of it in the case frame and covers
which can resonate and make things worst,

And particularly the Barracudas can choose
to add sound damping to the drive itself too.

so I guess knowing the unfiltered power rating is good too.

Trouble is that that brings up yet another problem. Some of
the higher frequency sounds are rather easier to damp by
how the drive is mounted, and that resonance effect can never
be quantified with the drive itself, it depends on the case etc.
So cant be stated by a drive manufacturer on a datasheet.

They should provide everything, bels, dBA, sones, FFT
plot and let potential buyers go by whatever they want.

Might as well cut to the chase and include a wav
file measured under standard conditions, say the
drive running bare, outside any housing at all and
captured at the maximum SPL direction.

But even that would be pretty useless because some
sounds would be muffled much better by the typical case
than others. Non fluid bearing whine is particularly bad there.

And that opens up a whole nother can of worms, the
variation in bearing noise over time, and from copy to copy.

Its a lot simpler to quote the dBA and accept that that is
only useful for the most gross differences between drives.

What would really help with HD noise is switching
to 2.5" drives, even 10,000 RPM models.

Thats mad. It depends entirely on where the noise is coming from.
If the drive rotation system is very quiet at 7200, and the bulk of
the noise is from head activity, you wont get that effect necessarily.

All else being equal, a smaller drive will be quieter.

Bull****.

There's no doubt about it in my mind.

Your problem.

3.5" drive storage capacity is actually getting too
big for most home systems unless used for video.

Maybe. But 2.5" drives of what you consider to be a
suitable size are much slower and much more expensive.

That's because they're made for laptops.

Nope, thats the inevitable result of having to be smaller.

So far, the primary design goal for 2.5" drives has
been low power consumption, not high performance.

The primary goal for 2.5" drives is the physical form factor.

A 2.5" drive's performance should be able to exceed that of a 3.5"

Bull****.

for the same reasons 3.5" exceeds 5.25": lower mass in every part.

More bull****. And when the drive is essentially
silent when its idle, just rotating, reducing the size
of the platters cant make it any quieter than that.

Do you think 3.5" is some kind of magic
number for hard drives, that anything bigger
or smaller must have poorer specs?

Obviously not. But like I said, if the 3.5" drive is already
essentially silent when its idle, just rotating, reducing the
platter size wont have any effect on that noise, and you
are just wasting your money on the higher cost of the
smaller platters. Particularly when a single platter 3.5"
drive has already got ample space for all except video
with desktop systems.

Makes a lot more sense to say buy a very quiet 60GB
single platter 3.5" drive like a Samsung P80 and revel in
the tons on space and forget about analy comparing pretty
useless dBA numbers and just revel in the quiet drive.

That may be ok for now, but what would you want in 5 or 10 years?

Likely a much bigger drive to replace my current collection of video
tapes. They're a pain in the arse physically, just excellent value
per GB. And I only use those for time shifting, not for archival.

Wouldn't you prefer a 1TB+,

Yes.

2.5" or less drive

I dont care about the physical size.

with much faster access times,

Nope, that has no effect on what I do now.

lower power consumption

Dont care about that either except that a little less
would be easier as far as being able to stack drives
adjacent and ignore the drive temp is concerned.

AND lower noise?

Already got that. Its already so low that I cant detect
it being powered down or not. Already lower than ALL
the laptop drives I use. Amd thats with the 3.5" drive in
a case with never useing the case covers for convenience.

I'm a little surprised that somebody isn't
making a high performance 2.5" drive
(better than any 3.5" drive) for desktops yet.

Because that is completely pointless when clearly
its easy enough to make a very quiet 3.5" hard drive.

You're probably one of those guys who said
"64KB is enough memory for anybody."

Nope, never did.

I'm not as anti-progress as you seem to be.

I'm not anti progress at all. I've got the sense to have noticed
that the drive is ALREADY completely silent in the sense that
I cant detect when its been turned off and the sense to realise
that it would be stupid to use a 2.5" drive that wont perform
as well and which will cost significantly more in that situation.

I would welcome that drive available in multi TB
size at as low a cost as the video tapes per TB,
but that wont be happening any time soon.

When it does, I'll bin the video tapes as quickly as I have floppys.

The modern reality is that its only something that a couple
of hard drive manufacturers care much about and one of
those has blown both feet right off on that by disabling
AAM which is an excellent way of making a drive quiet.

I wonder how long Seagate will continue to do that if other
manufacturers never follow suit and get away with it?

I doubt too many of the mug punters who buy the
absolute vast bulk of hard drives would even know
what AAM was if it bit them on their lard arses.

If they're worried about a patent then they should just pay
for it - probably wouldn't be over $0.25 or so per drive.

Yep, thats what I meant.

IBM/Hitachi has been stupid enough to have the deliberate
movement of the heads to avoid them staying on the same
track for too long when idle, irritatingly noisy for no good
reason at all. The fool responsible for that terminal insanity
should be taken out the back and shot.

How do other manufacturers avoid the problem of heat buildup?

Basically move the heads silently.

They don't move the heads too?

Yep.

BTW, how S.M.A.R.T. is your Samsung? Can it do temperature?

Yep.

How about the error rate attributes?

Its fine, as complete a set as with any.

For some reason reviewers never talk about
S.M.A.R.T. capabilities or lack thereof.

Yeah, most of them wouldnt know what
SMART was if it bit them on their lard arses.

I dont recall any of them actually citing the SMART
temperature rise seen in active use in their reviews.
Tho admittedly I dont bother with reviews much.