说说为声卡更换运放吧～～以SQ200AT为例，，说一下

sd-iori

7 o7 F) A7 e9 ^
+ c1 R0 Z$ X! c2 q- s' n6 E$ w0 zSQ200AT上面，，有一个运放插座，，
这个插座，，能方便大家更换运放，，

/ L, m* y5 ]' v  {:charles: 水平菜，这里电子高手超级多，，，有错误的地方，，欢迎指正:charles:

* M$ }" u! G/ x! J我说说选择打磨声卡运放的方法，，这是自己YY出来的
/ F( _6 |$ @1 A+ h6 j- a; C. b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，，
1 a3 b, C$ O" ]. w: A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
所以我们要看这个运放在5V或者12V的性能，，这样才有价值
+ k, `- O1 T+ J7 i. j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
* @5 }8 H0 R/ w( Z+ ^$ v4 ~7 R' G* M
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
* R+ n- x8 N1 d) ^! wSlew Rate对电压不敏感，，
5 T6 {0 d) [* w$ H, Z: s4 o所以我选择运放，，就看Slew Rate和声卡供电电压下的THD

+ k5 h' q. N6 ]7 c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
所以，，这里，，以SQ200AT为例:charles: 因为，，我正在用这个卡

[ 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 m9 S  |3 I■ GENERAL DESCRIPTION ■ PACKAGE OUTLINE
NJM4580 is the dual operational amplifier, specially designed
for improving the tone control, which is most suitable for the
) O1 g. I: i  E. @6 P# yaudio application.
+ w" q$ y: \/ \6 j/ j+ zFeaturing noiseless, higher gain bandwidth, high output
current 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
for the head phone amp at higher output current, and further
- @' ?+ m% @5 B! X2 C- I/ S" rmore, it can be applied for the handy type set operational
; \+ i& }& W* C7 U& \/ K% Hamplifier of general purpose in application of low voltage single
- v9 \* n* J$ i1 E3 H& O" |supply type which is properly biased of the low voltage source.
■ FEATURES
● Operating Voltage ( ±2V~±18V )
3 T8 c( e- Q% s9 O4 I; E0 z1 H: O● Low Input Noise Voltage ( 0.8μVrms typ. )
- B9 B; F/ S: h# g0 {● Wide Gain Bandwidth Product ( 15MHz typ. )
● Low Distortion ( 0.0005% typ. )
  o+ ]" Q) z8 n" S2 m; K! t2 C● Slew Rate ( 5V/μs typ. )
● Package Outline DIP8,SIP8,EMP8,SSOP8,DMP8



这是4580的针脚定义，，
9 N* B* F! c3 c" s


& T. l5 v4 n1 P( |" y

9 p, G3 M% H. \; b/ _从上图可以看出，，JRC4580在低压下，也就是5V下，
' x, Y2 u6 ?; j/ z$ t: @有较好的音质，，总谐波失（THD）真最小，，
0 B& @9 N' X+ J9 d这应该是众多声卡选择JRC4580作为运放的原因吧

! `$ Z/ K. `, v' U[ 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.
9 t7 x, m( e* S( s+ ?# J比较差劲，，会影响，，动态和解析度，，，

% I# o2 W- N) }( V' M[ 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
6 U  i  `# L5 l$ p% l) m+ w发贴有点结巴:funk:

, ?8 n2 e0 t0 ~- d: a这个，，，
其实呢，，，
0 F2 X! `/ f8 t9 C/ H, s7 o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:
5 ]/ S: {4 ~* C9 R5 ?, 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。
. p( ^/ |6 K( _7 m; g
; A& A4 B. x% [' ^7 jJRC 4580 适合输出2V 左右失真最小呢。
" }: W2 u4 K8 g; Q
- q% O. E5 v! o. ?9 t# Y8 [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
$ q1 n% {! E1 S  R2 h看这个THD N 图。

$ d* L/ d7 d" M7 J  }. fJRC 4580 适合输出2V 左右失真最小呢。

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~
2 Y- ~9 `8 \% g, t* O. w- M! \7 Q& ^干脆换个阿sa上去~

鲁爾

原帖由 nocturne 于 2008-3-4 10:29 发表

这个，，，
其实呢，，，
是阿娇的一贯风格啦。。

* w" A( A0 ]# J2 m
:lol: :lol:

sd-iori

OP275，，，这个运放，，适合SQ200AT，，
2 l5 \1 K7 P0 _7 E& q% w
先从引脚方面看，，和JRC4580是一样的



我们来看看，，，OP275的介绍

Excellent Sonic Characteristics
Low Noise: 6 nV/ÖHz
Low Distortion: 0.0006%
High Slew Rate: 22 V/ms
Wide Bandwidth: 9 MHz
Low Supply Current: 5 mA
Low Offset Voltage: 1 mV
Low Offset Current: 2 nA
7 n+ q& N' P" oUnity Gain Stable
0 ]5 F8 U8 Y' `9 `$ ^SOIC-8 Package
" Q6 r2 W9 z0 P/ i
Power Supply Rejection Ratio（PSRR）V = ±4.5 V to ±18 V
$ e( E' S: c5 M, w/ B
, M, x, B. k5 ^9 h: \% b7 \  UCommon-Mode Rejection Ratio（CMRR）VCM = ±10.5 V

0 u1 B1 C7 \* ]. b1 l3 N9 r
+ w4 i: u2 k9 J& D; XImproved dc performance is also provided with bias and offset
0 g% x" l, N; Ocurrents greatly reduced over purely bipolar designs. Input offset
1 p& O' `* s1 Nvoltage is guaranteed at 1 mV and is typically less than
200 mV. This allows the OP275 to be used in many dc coupled
$ P8 t, @3 J1 vor 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
. |0 n; v, I7 e: l7 F1 }maintaining low distortion. THD + Noise at 3 V rms is a low
. y' x/ V( D* p6 R7 `0.0006%.

4 v/ C5 T0 D/ |% b# i! N3 G从这些参数来看，，
/ H* S/ e8 Q8 A1 dOP275在SQ200AT的12V的电压下，，性能比JRC4580好
High Slew Rate也比JRC4580好很多，，
) z6 l# ?, n3 H) v- w+ ^所以解析度和动态方面，，OP275都比较好

[ 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
1 u: }& h6 L& r+ v8 F% d5 W) OTotal Harmonic Distortion + Noise (THD + N) of the OP275
is well below 0.001% with any load down to 600 W. However,
# u# `  R4 w8 B1 B6 S, @* Dthis is dependent upon the peak output swing. In Figure 2 it is
seen that the THD + Noise with 3 V rms output is below
* v2 g! H6 U5 K3 h- [: n  t8 L( ]' ^0.001%. In the following Figure 3, THD + Noise is below
8 a( ~1 w5 M; g! l6 n" L0.001% for the 10 kW and 2 kW loads but increases to above
+ c; K2 P& ~+ m% t( g% n$ f0.1% for the 600ÊW load condition. This is a result of the output
4 l- U% y1 D/ }, Mswing capability of the OP275. Notice the results in Figure 4,
showing THD vs. VIN (V rms). This figure shows that the THD
+ w: S% g5 d/ Q+ Noise remains very low until the output reaches 9.5 volts rms.
This performance is similar to competitive products.
1 c3 p" I, v: C1 v3 s; _+ [2 |, T
The output of the OP275 is designed to maintain low harmonic
distortion while driving 600 W loads. However, driving 600 W
4 K9 r% q8 k# q, s, Ploads with very high output swings results in higher distortion if
0 U5 N4 [# s5 Z$ E+ Q! nclipping occurs. A common example of this is in attempting to
drive 10 V rms into any load with ±15 volt supplies. Clipping
- X! T; r- }& s& Gwill occur and distortion will be very high.
To attain low harmonic distortion with large output swings,
- y& \% G8 y. A2 I! m+ Usupply voltages may be increased. Figure 5 shows the performance
of the OP275 driving 600ÊW loads with supply voltages
. O+ ]0 V4 x8 Qvarying from ±18 volts to ±20 volts. Notice that with ±18 volt
supplies 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，，，
; P5 x7 s7 e! @7 s6 `* A失真最少，，是20V以上，，，0.0007
! a4 j9 w0 b, g$ q
:charles: 不知，，有没有理解错误
6 h# S& c9 L* i: _, y5 a& f- ]

# R$ T- X( p8 @

; U* L) L; o. p% b% I
+ X( ^9 K2 T/ w6 a# u  W( j
:sweatingbullets: 找不到12V下的，，数据，，
* n% A. H3 n/ I; {: T; T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，，
+ }9 V: ]: \, F! \3 S. ]) ~) n1 N从15V和18V的曲线看，，区别不大
8 a4 ~/ }2 [8 y" M' X2 @+ LOP275对电压不敏感

9 M  Q& K2 K' i0 v, O& m[ 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
8 L1 L  G% b0 O! |+ m<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
  \7 X' v/ m; [. f5 W+ c# t很惨的说

MrGlass

看其它的帖子里有朋友说那个2132是很配SQ210W的
; R2 z8 ^+ h) z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
2 n7 N7 }$ t1 `  L0 X( S1 m
另外为什么他们要叫你"阿娇"呢?