说说为声卡更换运放吧～～以SQ200AT为例，，说一下

sd-iori

3 b. W: d! {* I7 ]8 Q
- A, O6 Y) @: O* i# Q5 ?" q8 KSQ200AT上面，，有一个运放插座，，
0 M- h  g  M4 |' N4 A- {这个插座，，能方便大家更换运放，，
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! H# t, a+ }% I: E% Z: p( E:charles: 水平菜，这里电子高手超级多，，，有错误的地方，，欢迎指正:charles:

我说说选择打磨声卡运放的方法，，这是自己YY出来的
7 O: g9 [* T+ i; r" D2 O( F* U由于声卡和攻防，，DAC一类的不同，，受电压的限制，，不能随意选择运放，，
: I0 w6 @3 `8 n& |9 ^) t3 X攻防等，，直接给运放最佳电压，，运放就有最好的表现，，所以选择运放，，看参数，，也可以
: v4 a& G* G! R# v. c到了声卡，，情况就不一样了，，由于声卡的供电，，一般就是5V或者12V
所以我们要看这个运放在5V或者12V的性能，，这样才有价值
6 Z+ u/ x% V3 @! E: u7 y正是由于这个原因，，网上很多对运放的主观测评，，放在声卡，，不一定适用，，甚至完全相反
, Z" ^9 f: A; N$ E
至于性能嘛，，我就看THD和Slew Rate，，:charles: 因为这是最重要的，，而且，，，，其他的，，我也不懂，，咔咔
Slew Rate对电压不敏感，，
所以我选择运放，，就看Slew Rate和声卡供电电压下的THD
7 ?& E1 A/ g" p1 a8 n
9 f$ g" T, Y2 u+ O/ C, b/ I0 J8 m当然，这些是前期资料选择
具体，还要放到声卡上试听，，才能作准
! ^1 f7 F" ~& Z5 }  i/ a所以，，这里，，以SQ200AT为例:charles: 因为，，我正在用这个卡

' z! S7 H% C% @# m( R& V: @# G1 ?. U[ 本帖最后由 sd-iori 于 2008-3-4 23:11 编辑 ]

sd-iori

向来说说原配的JRC4580，，

要二奶前，，应该先了解原配，，，

0 ~5 ]# B, ~. D; A■ GENERAL DESCRIPTION ■ PACKAGE OUTLINE
5 x0 H- v1 [/ `; G" d/ XNJM4580 is the dual operational amplifier, specially designed
for improving the tone control, which is most suitable for the
audio application.
Featuring noiseless, higher gain bandwidth, high output
# ^1 }9 r: O$ Mcurrent and low distortion ratio, and it is most suitable not only
for acoustic electronic parts of audio pre-amp and active filter,
but also for the industrial measurement tools. It is also suitable
4 u% U% d3 v: zfor the head phone amp at higher output current, and further
more, it can be applied for the handy type set operational
0 ~- f  n9 W5 a, tamplifier of general purpose in application of low voltage single
. H) ?1 k1 N' i7 w- m9 F, X# `supply type which is properly biased of the low voltage source.
2 I* ~7 g* b  f! F1 Q4 T% n! z. S■ FEATURES
$ [( p6 v( P2 F* y- M● Operating Voltage ( ±2V~±18V )
● Low Input Noise Voltage ( 0.8μVrms typ. )
; R) J/ Y/ ]9 `● Wide Gain Bandwidth Product ( 15MHz typ. )
1 A+ p0 y& u- ?, w● Low Distortion ( 0.0005% typ. )
( ]: L) r; `) s( @9 B" C● Slew Rate ( 5V/μs typ. )
● Package Outline DIP8,SIP8,EMP8,SSOP8,DMP8
5 N% B: {. r+ r( O
3 O/ }. d4 l4 _- U+ y, g9 t

这是4580的针脚定义，，

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6 I4 o- j; J6 q从上图可以看出，，JRC4580在低压下，也就是5V下，
有较好的音质，，总谐波失（THD）真最小，，
这应该是众多声卡选择JRC4580作为运放的原因吧

[ 本帖最后由 sd-iori 于 2008-3-4 23:13 编辑 ]

sd-iori

:sweatingbullets:JRC4580，，是低压的双运放，，

转换速率（Slew Rate）只有5V/μs typ.
! B; o7 C6 U5 ]5 d9 j比较差劲，，会影响，，动态和解析度，，，

[ 本帖最后由 sd-iori 于 2008-3-4 00:28 编辑 ]

flygg2006

继续哎~~~:loveliness:

bill_max

图看不懂，术语听不懂:whistling:
有没有基础教材介绍啊

luckytowns

发贴有点结巴:funk:

nocturne

原帖由 luckytowns 于 2008-3-4 09:59 发表
% v8 O$ Q" J+ f- d9 M$ o- X发贴有点结巴:funk:

7 m  m0 l  s4 I, n" _这个，，，
其实呢，，，
6 S& a) w. U4 J& M" s. a0 Q是阿娇的一贯风格啦。。

一生相随

等我的功放，，弄到手后，，就找吖娇，，弄个SQ200AT，，玩玩:lol:
) R; U. s; C, X8 U- \/ i5 K+ G这东西的，，兼容性，，驱动，，做的如何？:p

语蓝

继续:lol:

ljm_ljm

看这个THD N 图。
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JRC 4580 适合输出2V 左右失真最小呢。
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另外最好有FFT 分析  TH D 成份:lol:

sd-iori

原帖由 ljm_ljm 于 2008-3-4 15:11 发表
看这个THD N 图。

JRC 4580 适合输出2V 左右失真最小呢。
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7 }# ]5 e( M* Y4 u% g, b& O9 {另外最好有FFT 分析  TH D 成份:lol:

6 \; D) ^+ V1 o:charles: 新头像，，不错啊，，，，

agrantleung

换了头像都没有反应过来是阿娇呢，呵呵~
: l1 e* r- _$ I8 |% G干脆换个阿sa上去~

鲁爾

原帖由 nocturne 于 2008-3-4 10:29 发表

& A1 Y# b9 F5 f2 p( E1 y2 o这个，，，
其实呢，，，
是阿娇的一贯风格啦。。

4 h/ j# ~( V' L5 u5 p( f! r:lol: :lol:

sd-iori

OP275，，，这个运放，，适合SQ200AT，，
( ^7 B, t. p; P
+ y; Q6 r2 k1 c; U先从引脚方面看，，和JRC4580是一样的
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我们来看看，，，OP275的介绍
5 T0 q# o4 w. F5 [# W/ V
+ `/ \1 S3 F7 `, pExcellent Sonic Characteristics
6 @# \, w1 \9 o( |: JLow Noise: 6 nV/ÖHz
- B0 a. U/ ^3 Q; i4 V& xLow Distortion: 0.0006%
High Slew Rate: 22 V/ms
$ R7 O  ]: C  c- P6 `Wide Bandwidth: 9 MHz
6 \5 N0 z- e2 D  HLow Supply Current: 5 mA
Low Offset Voltage: 1 mV
Low Offset Current: 2 nA
  n3 G" \% J$ ~2 v1 D! c3 U0 yUnity Gain Stable
SOIC-8 Package

+ ]4 I. `$ d1 QPower Supply Rejection Ratio（PSRR）V = ±4.5 V to ±18 V
! ?5 d, @/ I/ m6 N4 K
Common-Mode Rejection Ratio（CMRR）VCM = ±10.5 V


Improved dc performance is also provided with bias and offset
* A3 _1 ?; Z- ?9 l/ g0 \currents greatly reduced over purely bipolar designs. Input offset
voltage is guaranteed at 1 mV and is typically less than
200 mV. This allows the OP275 to be used in many dc coupled
0 s; Y) t8 \+ u. u; v. k9 Yor summing applications without the need for special selections
or the added noise of additional offset adjustment circuitry.
The output is capable of driving 600 W loads to 10 V rms while
maintaining low distortion. THD + Noise at 3 V rms is a low
7 i6 J2 a; j$ M4 t0 ~4 s0.0006%.
; I( [0 M, C7 C+ N& V2 f
$ ^0 ?, I4 R/ N2 N7 W5 A) j从这些参数来看，，
OP275在SQ200AT的12V的电压下，，性能比JRC4580好
9 @& c. G$ L2 ^9 Y+ O! sHigh Slew Rate也比JRC4580好很多，，
所以解析度和动态方面，，OP275都比较好

1 z1 ?9 K, l* z  Q[ 本帖最后由 sd-iori 于 2008-3-4 17:51 编辑 ]

luckytowns

SQ210W也同理么？:lol:

ChrisVinyard

大学里面学了2年数电和模电。。。。。结果全还给老师了。。。。。。:w00t):

sd-iori

原帖由 sd-iori 于 2008-3-4 17:34 发表
Total Harmonic Distortion
- L# ?/ D2 j- p; ?. a0 @Total Harmonic Distortion + Noise (THD + N) of the OP275
is well below 0.001% with any load down to 600 W. However,
this is dependent upon the peak output swing. In Figure 2 it is
8 |3 w0 {# ]4 w+ `9 ~' cseen that the THD + Noise with 3 V rms output is below
0.001%. In the following Figure 3, THD + Noise is below
0.001% for the 10 kW and 2 kW loads but increases to above
- X% e) X0 [' [7 X" R  b+ v0.1% for the 600ÊW load condition. This is a result of the output
swing capability of the OP275. Notice the results in Figure 4,
9 I0 t( [: Y! }showing THD vs. VIN (V rms). This figure shows that the THD
; U, W9 Z7 J$ S" w+ Noise remains very low until the output reaches 9.5 volts rms.
+ b$ j6 M. t& Q: |3 v3 i+ r0 T0 mThis performance is similar to competitive products.
( x5 ]3 o2 E/ ~- B8 u1 k5 y6 q
The output of the OP275 is designed to maintain low harmonic
distortion while driving 600 W loads. However, driving 600 W
2 V- V0 r1 W" i, L% g; ^- Z2 zloads with very high output swings results in higher distortion if
" a: t2 q- K( j" nclipping occurs. A common example of this is in attempting to
drive 10 V rms into any load with ±15 volt supplies. Clipping
will occur and distortion will be very high.
To attain low harmonic distortion with large output swings,
+ z9 Z1 L7 C) h/ p  ksupply voltages may be increased. Figure 5 shows the performance
of the OP275 driving 600ÊW loads with supply voltages
varying from ±18 volts to ±20 volts. Notice that with ±18 volt
supplies the distortion is fairly high, while with ±20 volt supplies
% d" g9 J7 @( j' Y" yit is a very low 0.0007%.

6 w1 M! V& I# S4 {" a这是OP275 THD的说明，，
大概意思是说，，3V，，THD为0.001，，，
失真最少，，是20V以上，，，0.0007

:charles: 不知，，有没有理解错误

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:sweatingbullets: 找不到12V下的，，数据，，
- _! y7 s% r" V8 _不过PDF，，里面，，也没有说列出电压对THD影响，，只是一味强调温度，，
从15V和18V的曲线看，，区别不大
OP275对电压不敏感
3 W  Z' N' T; ~/ Z
[ 本帖最后由 sd-iori 于 2008-3-4 22:46 编辑 ]

flygg2006

那2132呢~~~:loveliness:

MrGlass

我上学时的<脉冲与数字电路>这门课是和老师拉关系才过关的
<电子线路>这门课最后补考不及格...发毕业证前被拉回去考试
很惨的说

MrGlass

看其它的帖子里有朋友说那个2132是很配SQ210W的
/ w1 t( u! b* _: K! o  {阿娇大姐能不能给来点形象些的对比啊,这些数据和图表虽然高手喜欢,但是确实很让人头痛啊
+ ?9 N3 v; a/ I- B- Z& u% g
) l, \) Q$ ?: {" a另外为什么他们要叫你"阿娇"呢?