自动响度控制电路 (Automatic Loudness C
自动响度控制电路 (automatic loudness control)
parts:
p1_________________10k linear potentiometer (dual-gang for stereo)
r1,r6,r8__________100k 1/4w resistors
r2_________________27k 1/4w resistor
r3,r5_______________1k 1/4w resistors
r4__________________1m 1/4w resistor
r7_________________20k 1/2w trimmer cermet
c1________________100nf 63v polyester capacitor
c2_________________47nf 63v polyester capacitor
c3________________470nf 63v polyester capacitor
c4_________________15nf 63v polyester capacitor
c5,c9_______________1΅f 63v electrolytic or polyester capacitors
c6,c8______________47΅f 63v electrolytic capacitors
c7________________100pf 63v ceramic capacitor
ic1_______________tl072 dual bifet op-amp
sw1________________dpdt switch (four poles for stereo)
comments:
in order to obtain a good audio reproduction at different listening levels, a different tone-controls setting should be necessary to suit the well known behaviour of the human ear. in fact, the human ear sensitivity varies in a non-linear manner through the entire audible frequency band, as shown by fletcher-munson curves.
a simple approach to this problem can be done inserting a circuit in the preamplifier stage, capable of varying automatically the frequency response of the entire audio chain in respect to the position of the control knob, in order to keep ideal listening conditions under different listening levels.
fortunately, the human ear is not too critical, so a rather simple circuit can provide a satisfactory performance through a 40db range.
the circuit is shown with sw1 in the control-flat position, i.e. without the automatic loudness control. in this position the circuit acts as a linear preamplifier stage, with the voltage gain set by means of trimmer r7.
switching sw1 in the other position the circuit becomes an automatic loudness control and its frequency response varies in respect to the position of the control knob by the amount shown in the table below.
c1 boosts the low frequencies and c4 boosts the higher ones. maximum boost at low frequencies is limited by r2; r5 do the same at high frequencies.
technical data:
frequency response referred to 1khz and different control knob positions:
total harmonic distortion at all frequencies and 1v rms output: < 0.01%
notes:
sw1 is shown in control flat position.
schematic shows left channel only, therefore for stereo operation all parts must be doubled except ic1, c6 and c8.
numbers in parentheses show ic1 right channel pin connections.
r7 should be set to obtain maximum undistorted output power from the amplifier with a standard music programme source and p1 rotated fully clockwise.
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parts:
p1_________________10k linear potentiometer (dual-gang for stereo)
r1,r6,r8__________100k 1/4w resistors
r2_________________27k 1/4w resistor
r3,r5_______________1k 1/4w resistors
r4__________________1m 1/4w resistor
r7_________________20k 1/2w trimmer cermet
c1________________100nf 63v polyester capacitor
c2_________________47nf 63v polyester capacitor
c3________________470nf 63v polyester capacitor
c4_________________15nf 63v polyester capacitor
c5,c9_______________1΅f 63v electrolytic or polyester capacitors
c6,c8______________47΅f 63v electrolytic capacitors
c7________________100pf 63v ceramic capacitor
ic1_______________tl072 dual bifet op-amp
sw1________________dpdt switch (four poles for stereo)
comments:
in order to obtain a good audio reproduction at different listening levels, a different tone-controls setting should be necessary to suit the well known behaviour of the human ear. in fact, the human ear sensitivity varies in a non-linear manner through the entire audible frequency band, as shown by fletcher-munson curves.
a simple approach to this problem can be done inserting a circuit in the preamplifier stage, capable of varying automatically the frequency response of the entire audio chain in respect to the position of the control knob, in order to keep ideal listening conditions under different listening levels.
fortunately, the human ear is not too critical, so a rather simple circuit can provide a satisfactory performance through a 40db range.
the circuit is shown with sw1 in the control-flat position, i.e. without the automatic loudness control. in this position the circuit acts as a linear preamplifier stage, with the voltage gain set by means of trimmer r7.
switching sw1 in the other position the circuit becomes an automatic loudness control and its frequency response varies in respect to the position of the control knob by the amount shown in the table below.
c1 boosts the low frequencies and c4 boosts the higher ones. maximum boost at low frequencies is limited by r2; r5 do the same at high frequencies.
technical data:
frequency response referred to 1khz and different control knob positions:
total harmonic distortion at all frequencies and 1v rms output: < 0.01%
notes:
sw1 is shown in control flat position.
schematic shows left channel only, therefore for stereo operation all parts must be doubled except ic1, c6 and c8.
numbers in parentheses show ic1 right channel pin connections.
r7 should be set to obtain maximum undistorted output power from the amplifier with a standard music programme source and p1 rotated fully clockwise.
浅谈智慧养老机器人
一位架构师写给工程师的一封信
Linux系统中存在的各种进程间通信机制
基站通信电源系统知识科普
Digi-Key Electronics宣布与Red Pitaya达成全新的全球分销合作关系
自动响度控制电路 (Automatic Loudness C
10米、5米和3米法电波暗室的性能和参数解析
继电保护的基本原理和作用
广和通携手合作伙伴发布新一代全互联PC 5G模组FM350
列个清单看看套在制造业脖子上的那些枷锁！
统一通信市场有怎样的趋势
物联网浅析，什么是物联网,物联网有什么用
JDI可以缓缓了，银行同意延长融资额度期限
什么是电源效率标准？如何判断电源效率是否合格？
耐能CEO谈AI新创之路：“99死1生”
智能外呼机器人的优势是什么
交流变频器的作用
任正非谈华为创新观念：不主张盲目“自主创新”
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