说说为声卡更换运放吧～～以SQ200AT为例，，说一下

sd-iori

  L" K9 @  w' ]- r% LSQ200AT上面，，有一个运放插座，，
8 U( ?8 i+ p6 k( Y/ ~, X这个插座，，能方便大家更换运放，，
" a$ T% j( n* F8 e; Z
:charles: 水平菜，这里电子高手超级多，，，有错误的地方，，欢迎指正:charles:
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; ~% r8 f$ c/ v  S! V$ l我说说选择打磨声卡运放的方法，，这是自己YY出来的
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
所以我们要看这个运放在5V或者12V的性能，，这样才有价值
! f$ u- r  G/ J- X1 I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
, B/ Z7 t0 t- J8 ZSlew 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
& u' ]1 w1 \* I2 o" a
0 I# R( g8 }" r% Z$ k: R2 f当然，这些是前期资料选择
4 y- o/ V6 q+ ^+ }( g$ h& _1 c& U具体，还要放到声卡上试听，，才能作准
) H$ F4 {; P" Y# R8 A8 I+ j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，，

/ c! Q8 x) N) i, D: V+ j3 T要二奶前，，应该先了解原配，，，

■ GENERAL DESCRIPTION ■ PACKAGE OUTLINE
NJM4580 is the dual operational amplifier, specially designed
for improving the tone control, which is most suitable for the
! ^+ f' Z" b( g/ paudio application.
Featuring noiseless, higher gain bandwidth, high output
current and low distortion ratio, and it is most suitable not only
' Y  V! W( t1 B' j3 b. F" M2 w# afor acoustic electronic parts of audio pre-amp and active filter,
8 a3 x7 f* j8 p% kbut also for the industrial measurement tools. It is also suitable
for the head phone amp at higher output current, and further
( H% W+ o  v, ^. p; M; emore, it can be applied for the handy type set operational
5 e0 {( P1 z& a9 k! S  Uamplifier of general purpose in application of low voltage single
+ Q6 A: T8 L/ }/ B( fsupply type which is properly biased of the low voltage source.
0 m: ~  O9 s3 d6 m# G/ q- V■ FEATURES
● Operating Voltage ( ±2V~±18V )
/ I9 b  J8 O/ I+ S● Low Input Noise Voltage ( 0.8μVrms typ. )
● Wide Gain Bandwidth Product ( 15MHz typ. )
1 \  T  I' E4 X! u+ k● Low Distortion ( 0.0005% typ. )
● Slew Rate ( 5V/μs typ. )
+ B% p0 b! b0 \1 S● Package Outline DIP8,SIP8,EMP8,SSOP8,DMP8
- Z; o+ A3 y1 N9 d
3 ?& ]( T' o& i( O( C

4 m, f) i- q: Q. K" D# X这是4580的针脚定义，，
$ O1 M3 Y2 ]: w) D
7 d# F( K4 A; i9 ]+ p% ?



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

: ], x4 @( I) g$ x1 y6 @8 Y[ 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，，

8 o" t7 ~/ n# x' X  H转换速率（Slew Rate）只有5V/μs typ.
  A  K( u) n8 F* H# k# }* U比较差劲，，会影响，，动态和解析度，，，
% g! a) E/ H5 ~# A8 k+ g
3 Z" A$ y* ^& N) Z% G" Q[ 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:
+ g/ V: U2 r) E( k, A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
0 G; ?$ `7 h1 a, G6 r. }: f0 S发贴有点结巴:funk:

3 L1 ?' x1 i  B- k这个，，，
: X% w8 P  {; B9 I2 l( x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:
  e9 }( e4 v( w9 s  e& S: s9 I% M+ w# O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。

. S* ^/ U4 l( O/ @6 Q; @JRC 4580 适合输出2V 左右失真最小呢。
# n4 ^1 X4 D, j2 m' Q8 V. d
9 U, |5 H) ?# i" K' u7 i' J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
& K+ q7 B; U! @7 q% U' [看这个THD N 图。

JRC 4580 适合输出2V 左右失真最小呢。
, y9 K  X. k) ]" I, D
8 {: Q, h) s" L4 x# y+ @$ \" j另外最好有FFT 分析  TH D 成份:lol:

) [9 y2 ]/ i- a7 |: S: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~
& m/ B! Q" s9 m干脆换个阿sa上去~

鲁爾

原帖由 nocturne 于 2008-3-4 10:29 发表
/ N& }0 L1 q- M
这个，，，
其实呢，，，
0 t6 i( X8 O& I. I# Y是阿娇的一贯风格啦。。

& P- Q; Y8 Q6 C5 }6 b
:lol: :lol:

sd-iori

OP275，，，这个运放，，适合SQ200AT，，
" k# R6 ?1 o/ z$ @% C- D; E
1 O! r' D1 y  a: j6 h: i' E先从引脚方面看，，和JRC4580是一样的


2 N. C: N1 v  [/ K- N3 G
9 G7 t; Q7 s' k1 O2 h2 T& i$ j+ i. ?我们来看看，，，OP275的介绍

Excellent Sonic Characteristics
, H( }: ?, d$ i) [! qLow Noise: 6 nV/ÖHz
Low Distortion: 0.0006%
* z1 ~; C  n# M. uHigh Slew Rate: 22 V/ms
2 W- c2 i" q% hWide Bandwidth: 9 MHz
4 G! U% I5 g+ v2 @Low Supply Current: 5 mA
Low Offset Voltage: 1 mV
Low Offset Current: 2 nA
Unity Gain Stable
3 v! A/ F! g$ K" iSOIC-8 Package
) d1 b! k  C- e  M
Power Supply Rejection Ratio（PSRR）V = ±4.5 V to ±18 V

Common-Mode Rejection Ratio（CMRR）VCM = ±10.5 V
) ]4 W! N) F5 v. o! t6 V
2 l! C  ]6 j. w" V: O5 k
, Y: G0 V/ l/ Z9 A* V! d2 W8 b% y& FImproved dc performance is also provided with bias and offset
9 w3 Q2 u* ~) g4 Scurrents 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
or summing applications without the need for special selections
5 s; {# y+ M) m; Z) v( @" For the added noise of additional offset adjustment circuitry.
: P, z" o" `; i4 B) eThe 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
0.0006%.
: Z2 K: S& a6 w2 i
从这些参数来看，，
$ m: V+ v( Z. }9 D( i: J7 _1 v7 {OP275在SQ200AT的12V的电压下，，性能比JRC4580好
& v, n1 x, G  W) d  y: lHigh Slew Rate也比JRC4580好很多，，
- g3 V/ l' W/ E: r( h. F. D所以解析度和动态方面，，OP275都比较好
8 @, C/ N3 l4 ^8 `9 D' w1 n% ]. P
5 }8 e1 ]7 ?- N6 w( Q. y. 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
+ I" m+ T+ z8 Y% k7 u4 t0 eTotal Harmonic Distortion
Total Harmonic Distortion + Noise (THD + N) of the OP275
5 ^! `. f1 ^% c" M/ d, fis 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
seen that the THD + Noise with 3 V rms output is below
0.001%. In the following Figure 3, THD + Noise is below
! ~3 Y# o+ t* ]' q' x0.001% for the 10 kW and 2 kW loads but increases to above
0.1% for the 600ÊW load condition. This is a result of the output
, N* ]6 D. a0 S5 e2 q) j- a( wswing capability of the OP275. Notice the results in Figure 4,
# N, w# n$ R6 p) g/ t' Vshowing THD vs. VIN (V rms). This figure shows that the THD
! W/ w* v2 l" G: j' I+ Noise remains very low until the output reaches 9.5 volts rms.
- l9 m+ v: [2 V+ w' ^& LThis performance is similar to competitive products.

The output of the OP275 is designed to maintain low harmonic
- L) Q7 m& V2 W1 w2 D& Y4 C1 l* Adistortion while driving 600 W loads. However, driving 600 W
6 R9 Q0 \$ ?. A0 h! ]* K: _loads with very high output swings results in higher distortion if
clipping occurs. A common example of this is in attempting to
drive 10 V rms into any load with ±15 volt supplies. Clipping
: z! L6 [: s" s7 e3 R) o9 t7 l; L% Ewill occur and distortion will be very high.
0 G% `3 L5 F% W4 QTo attain low harmonic distortion with large output swings,
supply voltages may be increased. Figure 5 shows the performance
of the OP275 driving 600ÊW loads with supply voltages
5 _% I8 e# V5 a+ mvarying 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%.

9 F  k# P4 w9 U0 w4 a这是OP275 THD的说明，，
* l6 |/ Y/ s+ L大概意思是说，，3V，，THD为0.001，，，
4 E: Q- D5 H! N8 i/ m( s4 m( |3 u. T, |失真最少，，是20V以上，，，0.0007
& k* D. k, |& |% ?- ~. H$ h9 t6 e6 y
:charles: 不知，，有没有理解错误

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3 f& |6 \9 B# w/ a) t  ^
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, S( i5 U; A! a" _:sweatingbullets: 找不到12V下的，，数据，，
+ `5 o) N; C( B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，，
; B2 X; {3 H9 \* l6 ^从15V和18V的曲线看，，区别不大
OP275对电压不敏感

[ 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
$ Z9 g6 I$ q* ~* w3 E% C<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
8 e- s8 V2 A) s' s: S1 V# y8 d5 V
另外为什么他们要叫你"阿娇"呢?