ltspice audio simulation: a loudness control
DESCRIPTION
Bee Technologies Inc. LTSpice audio simulation: A loudness control. 20AUG2012. Equal-loudness contour. - PowerPoint PPT PresentationTRANSCRIPT
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LTSPICE AUDIO SIMULATION: A LOUDNESS CONTROL
Bee Technologies Inc.
20AUG2012
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EQUAL-LOUDNESS CONTOUR
Equal-loudness contour is a measure of sound pressure (dB SPL), over the frequency spectrum, for which the human ear perceive the same loudness when presented with pure steady tones (unit is the phon).
For more info . . .http://www.sfu.ca/sonic-studio/handbook/Equal_Loudness_Contours.html
40
60
80
100
120
10 100 1000 10000
INT
EN
SIT
Y L
EV
EL
(d
B)
FREQUENCY (Hz)
100
90
80
70
60 Loudness level (phon)
Contours of equal loudness (from the Radiotron Designers Handbook).
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A LOUDNESS CONTROL A loudness control is used as an attempt to restore extreme
low and high frequencies. As the sound level decreases, the ear becomes less sensitive to both extreme low and high frequencies. Thus, when listening at reduced levels, if the frequency response of your system is maintained flat, you will not hear those extremes as well.
C 17 6 . 9 7 3 9 p
PARAMETERS:R V O L = 5 0 0 k
V O L = 0 . 0 2 4 5
PARAMETERS:R V O L 1 = {(1 -V O L +1 u )* R V O L }
R V O L 2 = {(V O L +1 u )* R V O L }
R V O L -2{R V O L 2 }
R V O L -1{R V O L 1 }
O u t p u t
V 11 V a c0 V d c
I n p u t
0
R 1
2 0 0 k
0
C 25 8 . 7 8 8 3 n
R 22 . 2 1 1 9 m e g
R 33 3 0
R 42 M E G
L 12 0 m
1
2
R 5
4 . 6 6 9 5 k
C 33 . 9 2 4 4 n
Frequency
100Hz 1.0KHz 10KHz20Hz 50KHzDB(V(OUTPUT))
-60
-40
-20
0
20
DB(V(OUTPUT))
A loudness control and its frequency response (example)
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THE LOUDNESS CONTROL VS. EQUAL-LOUDNESS CONTOUR
10 100 1000 10000-60
-40
-20
0
20
100100(Sim)9090(Sim)8080(Sim)70
FREQUENCY (Hz)
INT
EN
SIT
Y L
EV
EL
(d
B)
Frequency response of the loudness control (simulation) is compared to the equal-loudness contour.
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Loudness Control vs. Flat Volume
C 17 6 . 9 7 3 9 p
PARAMETERS:R V O L = 5 0 0 k
V O L = 0 . 0 2 4 5
PARAMETERS:R V O L 1 = {(1 -V O L +1 u )* R V O L }
R V O L 2 = {(V O L +1 u )* R V O L }
R V O L -2{R V O L 2 }
R V O L -1{R V O L 1 }
O u t p u t
V 11 V a c0 V d c
I n p u t
0
R 1
2 0 0 k
0
C 25 8 . 7 8 8 3 n
R 22 . 2 1 1 9 m e g
R 33 3 0
R 42 M E G
L 12 0 m
1
2
R 5
4 . 6 6 9 5 k
C 33 . 9 2 4 4 n
C 17 6 . 9 7 3 9 p
PARAMETERS:R V O L = 5 0 0 k
V O L = 0 . 0 2 4 5
PARAMETERS:R V O L 1 = {(1 -V O L +1 u )* R V O L }
R V O L 2 = {(V O L +1 u )* R V O L }
R V O L -2{R V O L 2 }
R V O L -1{R V O L 1 }
O u t p u t
V 11 V a c0 V d c
I n p u t
0
R 1
2 0 0 k
0
C 25 8 . 7 8 8 3 n
R 22 . 2 1 1 9 m e g
R 33 3 0
R 42 M E G
L 12 0 m
1
2
R 5
4 . 6 6 9 5 k
C 33 . 9 2 4 4 n
LOUDNESS CONTROL FLAT VOLUME
The High-Pass circuit is
disconnected, the Low-Pass circuit is short
to ground
PSpice
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Frequency
100Hz 1.0KHz 10KHz20Hz 50KHzDB(V(OUTPUT))
-60
-40
-20
0
20
Frequency
100Hz 1.0KHz 10KHz20Hz 50KHzDB(V(OUTPUT))
-60
-40
-20
0
20
DB(V(OUTPUT))
Loudness Control vs. Flat Volume
LOUDNESS CONTROL RESPONSE FLAT VOLUME RESPONSE PSpice
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LTspice Simulation: .WAV IN/OUT Loudness Control
Loudness Control with .WAV input and output Simulation result: input and output signal
Low to high swept audible signal (Input)
-30 dB level down with the loudness control (Output)
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LTspice Simulation: .WAV IN/OUT Flat Volume
Flat Volume with .WAV input and output Simulation result: input and output signal
Low to high swept audible signal (Input)
-30 dB level down with the flat volume (Output)
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.WAV FILES LOCATION
An input file
Output files created by
LTSpice
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USING WAVE FILE (.WAV) AS INPUT
Using audio signal (WAVE file) as an input voltage for LTSpice could be done by replace the voltage expression of the voltage source with a WAVE-file expression: wavefile=“file location" chan=0 (as seen in the example below)
“chan” refers to the respective channel in the WAVE file used for the simulation, can be a number between 1 and 65535 although usually channel 0 refer to the left channel and channel 1 refers to the right channel
A loudness control and its frequency response (example)
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USING WAVE FILE (.WAV) AS OUTPUT
Exporting an output signal as an audio signal (WAVE file) could be done by adding SPICE directive as: .wave=“file location" 16 44100 Output (as seen in the example below)
“16” refers to the bitrate, 44100 is the sampling frequency and Output is referring to a label in circuit.
A loudness control and its frequency response (example)
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LTspice Simulation: music01.WAV IN/OUT Loudness Control
Loudness Control with music01.WAV input and output Simulation result: input and output signal
music01.wav audio signal (Input)
-30 dB level down with the loudness control (Output)
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LTspice Simulation: music01.WAV IN/OUT Flat Volume
Low to high swept audible signal (Input)
-30 dB level down with the flat volume (Output)
Flat Volume with music01.WAV input and output Simulation result: input and output signal
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.WAV FILES LOCATION
An input file
Output files created by
LTSpice
Output files created by
LTSpice
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VIDEO DEMONSTRATION