Re: smart fans

[David Christensen <dpchrist@holgerdanske.com>]

On 8/23/21 5:26 PM, Emanuel Berg wrote:
> David Christensen wrote:
>
> > Nice case.  :-)
>
> Yeah, I guess :)
>
> > The purpose of the plate at the bottom is to form
> > a thermally isolated chamber for the the power supply.
> > The unperforated portions of the top surface could be
> > covered with sound absorbing material.
>
> What material would that be?


Whatever you choose.  For example:

https://www.quietpc.com/acousticmaterials


> And, won't it prevent the airflow and/or prevent heat from
> exiting the case?


Choose the material thickness accordingly.  Do not block fans or air 
openings.


> > Conspicuously absent are drive cages; but I do see drive
> > case mounting screw holes. If drives are not needed, the
> > mounting surface could be covered with sound
> > absorbing material.
>
> The HDD is below with the PSU, I think.
>
> I got an idea, aren't the noise specified by the manufacturer?
>
> Here it says "Low-noise operation of up to 14.9dB(A)",
> that's for the Shadow Wings 2 140mm PWM.
> <https://www.bequiet.com/en/casefans/1701>
>
> The CPU fans are "Low-noise operation of up to 15.9dB(A)", the
> Shadow Wings 2 120mm PWM.
> <https://www.bequiet.com/en/casefans/1626>
>
> And the non-PWM Shadow Wings 2 140mm is
> "Low-noise operation of up to 14.7dB(A)"
> <https://www.bequiet.com/en/casefans/1699>
>
> So that's 4/5 fans accounted for, I have to restart the
> computer to see exactly what fan the remaining is. Anyway
>
> db(A): 14.9, 15.9 (2), 14.7
>
> How is it with db(A), if you have x db(A) from one thing, and
> you have two of these, does that mean you perceive that as
> 2x db(A)?
>
> Here is the HDD BTW
>
> $ sudo lshw -class disk
>    *-disk
>         description: ATA Disk
>         product: SAMSUNG HD204UI
>         physical id: 0.0.0
>         bus info: scsi@1:0.0.0
>         logical name: /dev/sda
>         version: 0001
>         serial: S2H7J9EB402836
>         size: 1863GiB (2TB)
>         capabilities: gpt-1.00 partitioned partitioned:gpt
>         configuration: ansiversion=5 guid=db8df009-609b-46e9-a61a-f2f913361b17 logicalsectorsize=512 sectorsize=512


On 8/23/21 5:50 PM, Emanuel Berg wrote:
>> db(A): 14.9, 15.9 (2), 14.7 [...]
>>
>> Here is the HDD BTW
>>
>> $ sudo lshw -class disk
>>    *-disk
>>         description: ATA Disk
>>         product: SAMSUNG HD204UI [...]
>
> Here [1] it says "Acoustics – Idle 2.5/2.6 Bel, Performance
> Seek 2.8/2.9 Bel"
>
> So what does that mean, the maximum is 2.9 Bel or 0.29 dB?
>
> if so 4/5 fans are: 14.9, 15.9 (2), 14.7 dB(A)
>
> and the HDD is: 0.29 dB
>
> [1] 
https://www.storagereview.com/review/samsung-spinpoint-f4eg-review-hd204ui


https://en.wikipedia.org/wiki/Bel_(unit)


Doubling the sound energy adds 3 db.  So, the two loudest fans are 
around 19 dB.


The HDD is 2.9 Bel = 29 dB.


Beyond the fan acoustic noise, there is HDD vibration.  If you mount a 
HDD directly to a piece of sheet metal, the sheet metal will act like a 
sounding board and convert the HDD vibrations into sound.  My Antec 
Sonata chassis has silicon grommets and shoulder screws for mounting 
each HDD into its sled.  This design effectively decouples HDD 
vibrations from the rest of the case.  If you could implement the same 
idea for your HDD or for the drive cage, that would be good. 
Alternatively, you could put vibration dampers between bolted 
connections and/or damp the chassis vibrations.  Applying sound 
absorbing pads to the inside of the case should address both sound and 
vibration.


David