Re: smart fans
On 8/23/21 8:09 PM, Emanuel Berg wrote:
David Christensen wrote:
Doubling the sound energy adds 3 db. So, the two loudest
fans are around 19 dB.
The HDD is 2.9 Bel = 29 dB.
So the total worse-case is 35.4 dB?
(With the GPU, PSU and one fan still unaccounted for.)
;;; -*- lexical-binding: t -*-
;;;
;;; this file:
;;; https://dataswamp.org/~incal/emacs-init/audio.el
(defun db (d &rest ds)
(let*((all (cons d ds))
(top (apply #'max all))
(other (- (apply #'+ all) top))
(double (/ other top 1.0))
(res (+ top (* double 3))) )
(format "%.1f dB" res) ))
;; (db 14.9 15.9 15.9 14.7 29.0) ; 35.4 dB
These are the equations and conversion factors needed:
Bel = log10(power)
power = 10 ** Bel
1 Bel = 10 dB
So, your calculation should be:
2021-08-23 23:42:34 dpchrist@dipsy ~
$ perl -e '$p=0; $p += 10**($_/10) for @ARGV; print 10*log($p)/log(10),
"\n"' 14.9 15.9 15.9 14.7 29.0
29.696732023509
That said, I would just add the continuous fan noise:
2021-08-23 23:42:49 dpchrist@dipsy ~
$ perl -e '$p=0; $p += 10**($_/10) for @ARGV; print 10*log($p)/log(10),
"\n"' 14.9 15.9 15.9 14.7
21.4058369416353
And consider the 29.0 dB HDD vibration separately.
David
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