说说为声卡更换运放吧～～以SQ200AT为例，，说一下

sd-iori

SQ200AT上面，，有一个运放插座，，
9 [9 v& H" [$ Y8 r1 F; V1 H这个插座，，能方便大家更换运放，，
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# C7 C- x7 d$ k! S6 A( J: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
! R! Y9 D# f8 V! f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，，
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
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
1 _( D- @0 q7 m: A) c+ C" }$ P, F所以我们要看这个运放在5V或者12V的性能，，这样才有价值
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

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

5 w0 u, h6 o5 P) o! |+ g当然，这些是前期资料选择
8 m: b: n/ d! G2 R) v具体，还要放到声卡上试听，，才能作准
" W9 d3 S. B- ]8 n7 f( c2 J所以，，这里，，以SQ200AT为例:charles: 因为，，我正在用这个卡

& a! ^2 i) r9 I4 {. |% E[ 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，，
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要二奶前，，应该先了解原配，，，
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/ A9 T& q( f* X3 ?■ GENERAL DESCRIPTION ■ PACKAGE OUTLINE
NJM4580 is the dual operational amplifier, specially designed
) i8 e. K4 a' j& Z" Ofor improving the tone control, which is most suitable for the
audio application.
4 V& X5 M2 e  [: G" e4 tFeaturing noiseless, higher gain bandwidth, high output
current and low distortion ratio, and it is most suitable not only
; c: G( E7 A' ]- \5 w; n; ]for acoustic electronic parts of audio pre-amp and active filter,
/ H: O$ B, R" f1 x, d2 ~but also for the industrial measurement tools. It is also suitable
for the head phone amp at higher output current, and further
8 e* O0 j  d/ s0 a8 ~" x" gmore, it can be applied for the handy type set operational
/ W, o! u# ^) [, P8 b  d6 s' j2 g+ iamplifier of general purpose in application of low voltage single
9 [; t: Z" r2 |6 Q& Psupply type which is properly biased of the low voltage source.
: D5 n2 ]" L+ C# n9 V■ FEATURES
● Operating Voltage ( ±2V~±18V )
$ T' t1 f0 @! X  W; l5 I: ]● Low Input Noise Voltage ( 0.8μVrms typ. )
; n; g) x2 I* S/ j7 b● Wide Gain Bandwidth Product ( 15MHz typ. )
+ x1 ~6 ?& I- f* E0 ~/ _; Z● Low Distortion ( 0.0005% typ. )
- j% g: X" e/ z/ d  G0 g! l6 S) g  g● Slew Rate ( 5V/μs typ. )
5 e+ F$ B/ [8 P5 c● Package Outline DIP8,SIP8,EMP8,SSOP8,DMP8



这是4580的针脚定义，，

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从上图可以看出，，JRC4580在低压下，也就是5V下，
/ Y+ B3 {  {" K( v! q有较好的音质，，总谐波失（THD）真最小，，
  Z8 ?& o3 t9 v6 K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，，

) }0 U% A* h5 P转换速率（Slew Rate）只有5V/μs typ.
) q* Y- i- b/ M6 H: ]比较差劲，，会影响，，动态和解析度，，，
- L5 U; ]9 q- j6 {+ T" P
[ 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
发贴有点结巴:funk:

1 j% U; _5 s, j1 U9 B* M这个，，，
其实呢，，，
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:
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。
+ T  x+ R3 X8 ^6 L% o2 _/ Z2 R
JRC 4580 适合输出2V 左右失真最小呢。

( L6 e0 g5 N5 |* ^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。

' G5 W2 H, J1 I2 [) C/ X2 X4 [另外最好有FFT 分析  TH D 成份:lol:

: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~
干脆换个阿sa上去~

鲁爾

原帖由 nocturne 于 2008-3-4 10:29 发表
# L9 p  i) N# Z: g. m$ d
这个，，，
7 u; @  N: _* _/ k其实呢，，，
) l0 Q+ o; H% ?是阿娇的一贯风格啦。。

! I, r& n4 [! w/ S1 e8 g+ \0 |:lol: :lol:

sd-iori

OP275，，，这个运放，，适合SQ200AT，，

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

Excellent Sonic Characteristics
Low Noise: 6 nV/ÖHz
( f0 t5 c+ @6 ?0 j5 L2 NLow Distortion: 0.0006%
& [& i6 ]/ {3 x  wHigh Slew Rate: 22 V/ms
% t0 w* N- Y+ Y+ P. yWide Bandwidth: 9 MHz
Low Supply Current: 5 mA
1 l) D& X3 f7 S3 V5 A, h3 MLow Offset Voltage: 1 mV
& v$ J( @- }; w+ ILow Offset Current: 2 nA
5 X) `% m7 g: K2 h  N% B- cUnity Gain Stable
SOIC-8 Package
, P' D- E1 S5 k* a; u' ]: E
' D4 x" [5 M# i4 XPower Supply Rejection Ratio（PSRR）V = ±4.5 V to ±18 V
  L5 b. {$ Y3 \# X0 L' c5 O
Common-Mode Rejection Ratio（CMRR）VCM = ±10.5 V
, e8 u" ?5 U% y3 ~

Improved dc performance is also provided with bias and offset
7 X! v) R) t9 O) acurrents greatly reduced over purely bipolar designs. Input offset
6 V# |+ x$ a% e" \* w! {# hvoltage is guaranteed at 1 mV and is typically less than
+ E' G# O" A/ r! `200 mV. This allows the OP275 to be used in many dc coupled
6 X' ^' a8 I0 E1 D+ k6 ^7 eor summing applications without the need for special selections
6 u  a. d. O  J0 J$ G% d* bor the added noise of additional offset adjustment circuitry.
The output is capable of driving 600 W loads to 10 V rms while
% Z9 v' d' T4 J, @* Jmaintaining low distortion. THD + Noise at 3 V rms is a low
% L% z! V) @5 _" }1 w0.0006%.
  r+ v- u/ g: l7 Q) t
5 Q8 W# P$ M& |3 ^! M7 S从这些参数来看，，
. s( v3 I$ ^0 t$ e9 c" SOP275在SQ200AT的12V的电压下，，性能比JRC4580好
1 C4 o# W, O& u2 fHigh Slew Rate也比JRC4580好很多，，
所以解析度和动态方面，，OP275都比较好

4 \2 Q  T# w  C1 a6 c% X; R[ 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
' o6 v) @: z* W0 z  X' QTotal Harmonic Distortion
. L& O+ B- j; S( C& W1 rTotal Harmonic Distortion + Noise (THD + N) of the OP275
0 @+ ~% ?1 L- Q; x! u9 J% |2 I+ Yis well below 0.001% with any load down to 600 W. However,
6 C+ Q) U/ G. m: r: fthis is dependent upon the peak output swing. In Figure 2 it is
4 t6 H' o' ]& `" D7 Hseen 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
, z' e& X9 z& s* i8 u4 ~0.1% for the 600ÊW load condition. This is a result of the output
. r* C1 H% |2 F' F# sswing capability of the OP275. Notice the results in Figure 4,
showing THD vs. VIN (V rms). This figure shows that the THD
+ Noise remains very low until the output reaches 9.5 volts rms.
% [. Y  [9 b, }$ NThis performance is similar to competitive products.
+ _5 d8 x; U% V% B. ^
: N* a" Q* ?0 X; }+ i; X, q$ VThe output of the OP275 is designed to maintain low harmonic
  B" ^( V# G9 Z' z% j$ n$ Odistortion while driving 600 W loads. However, driving 600 W
loads with very high output swings results in higher distortion if
, f1 y& n$ e3 ^. K- S3 c$ G% |clipping occurs. A common example of this is in attempting to
9 ]% e, N* y, w, Vdrive 10 V rms into any load with ±15 volt supplies. Clipping
- H, j8 n3 V- w8 y- m% qwill occur and distortion will be very high.
To attain low harmonic distortion with large output swings,
supply voltages may be increased. Figure 5 shows the performance
+ s7 i, g/ j7 Q$ N1 ]  f4 E- U* Xof the OP275 driving 600ÊW loads with supply voltages
, a; y. b0 [$ u: z9 x6 T* `: jvarying from ±18 volts to ±20 volts. Notice that with ±18 volt
) i6 G* e# T) g9 m/ V' q7 N) nsupplies the distortion is fairly high, while with ±20 volt supplies
it is a very low 0.0007%.

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
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; F& T. W* Y+ \:charles: 不知，，有没有理解错误



9 K& h: L! x% L8 I; ^4 @8 p
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:sweatingbullets: 找不到12V下的，，数据，，
0 ~% g4 l  f; P( N9 W9 [( i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，，
8 F# ]4 {5 e. c: z从15V和18V的曲线看，，区别不大
OP275对电压不敏感
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. @) c; u; J3 N3 K1 K[ 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
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
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; l$ s3 @. c6 {& P; A5 p; v另外为什么他们要叫你"阿娇"呢?