说说为声卡更换运放吧～～以SQ200AT为例，，说一下

sd-iori

( E* x9 L; q* J7 i- F- H2 J
! @9 ^$ t# ?& I  G; oSQ200AT上面，，有一个运放插座，，
8 [% m8 {% D6 i这个插座，，能方便大家更换运放，，
1 o( ?! d& _! U0 I5 A" |
:charles: 水平菜，这里电子高手超级多，，，有错误的地方，，欢迎指正:charles:
# i/ G4 h" n* q& t
" G( ^& `* t2 E8 I7 x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，，
( e0 s5 }6 z; s$ L3 G4 ]% c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
) v' q+ a6 w8 m% ?3 Z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
3 T0 c3 [1 ?2 T所以我们要看这个运放在5V或者12V的性能，，这样才有价值
; X4 e$ E9 U4 ]7 M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

/ h( a% J7 ]( w1 |* P2 s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
3 Z2 V- A. Q1 V0 ~3 O2 q, aSlew 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

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
7 Z- F% R( \) ~% M/ h1 a, t9 t所以，，这里，，以SQ200AT为例:charles: 因为，，我正在用这个卡

+ O# ^1 j- i$ p' a, M[ 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，，
3 ]- t! t+ \% d- p
" W6 H6 Q6 e7 b9 ^- Q& o4 O* A* A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
. {. D2 q$ P" N( Z; S5 ~audio application.
1 l/ |' X: E* ?$ G" P9 KFeaturing noiseless, higher gain bandwidth, high output
+ I8 ?; y* E2 Z+ C" U. p' g  ^current and low distortion ratio, and it is most suitable not only
for acoustic electronic parts of audio pre-amp and active filter,
0 Q  c/ g6 p, _- N8 h0 w! Nbut also for the industrial measurement tools. It is also suitable
for the head phone amp at higher output current, and further
more, it can be applied for the handy type set operational
% K0 ~) v" _( pamplifier of general purpose in application of low voltage single
: F9 D4 z" |) q, o- |supply type which is properly biased of the low voltage source.
+ g# @& C% w$ m■ FEATURES
● Operating Voltage ( ±2V~±18V )
( K7 T9 [3 d9 P● Low Input Noise Voltage ( 0.8μVrms typ. )
& N  f. x7 K  u# ], @- _4 T' D& ^7 `● Wide Gain Bandwidth Product ( 15MHz typ. )
4 \8 m, t0 M0 I  N: z● Low Distortion ( 0.0005% typ. )
! N6 B- c5 U4 D: ?2 F● Slew Rate ( 5V/μs typ. )
: s1 V: d" v# I9 {$ P( w● Package Outline DIP8,SIP8,EMP8,SSOP8,DMP8


* w) w( s# H$ ~+ L6 q% ]
9 z* t  I6 _- e+ m这是4580的针脚定义，，
- b/ ]# t3 z7 m6 k3 k6 J( V
4 \0 y$ K3 J* y% Q% z4 d

7 e/ ~. Z. `& B( @. R

1 _/ I: ^5 g8 O/ ?/ j. Y. u从上图可以看出，，JRC4580在低压下，也就是5V下，
% N& e( Z+ b" f  `% c3 f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
, ~: v" p2 C% M/ K1 U: V
[ 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, ~* U' Z& h0 p# Z; O6 f" b转换速率（Slew Rate）只有5V/μs typ.
比较差劲，，会影响，，动态和解析度，，，

; i. Z. i0 i) Q! Z: E. d[ 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:
+ p" v1 L8 \5 W4 V6 \. b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:

这个，，，
6 [' k1 w$ T! y* h4 r+ P' T* k: s% ]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:
+ Z+ t( d- J8 w" s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。
* j5 Y2 m/ p0 I5 `8 N6 I
JRC 4580 适合输出2V 左右失真最小呢。
) a; j/ u& I" t5 w4 @5 U% y  k
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。
  E7 W, R+ k/ }) S" q8 t
JRC 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~
5 t3 c) Q( ~* @" u* X7 d( S干脆换个阿sa上去~

鲁爾

原帖由 nocturne 于 2008-3-4 10:29 发表

6 D, R; H' M! p6 x6 I5 i/ Z8 p这个，，，
其实呢，，，
是阿娇的一贯风格啦。。

0 h$ o- \1 g1 e+ }8 j) }+ O
:lol: :lol:

sd-iori

OP275，，，这个运放，，适合SQ200AT，，

/ E. g/ d1 G$ q% Y+ O" ?先从引脚方面看，，和JRC4580是一样的



8 P2 E* W* S9 Q# J$ q我们来看看，，，OP275的介绍

8 Q7 i1 Y& E3 |8 F: M% EExcellent Sonic Characteristics
Low Noise: 6 nV/ÖHz
4 Y- ]! e( W/ E* i; `Low Distortion: 0.0006%
High Slew Rate: 22 V/ms
Wide Bandwidth: 9 MHz
9 |1 S- b9 C. P6 aLow Supply Current: 5 mA
4 H' b2 e% B& ]- G  M: i8 ?: ALow Offset Voltage: 1 mV
' d0 w9 d! D5 ^$ E! GLow Offset Current: 2 nA
3 M( O9 x0 m; H7 j! R$ N5 nUnity Gain Stable
! ^0 D" Q/ s& ^' Y3 YSOIC-8 Package
  k5 y7 z9 r8 G& o' ]) E6 K
1 `6 r8 v/ X( q8 z0 ]. l  PPower Supply Rejection Ratio（PSRR）V = ±4.5 V to ±18 V
, `5 U6 ~- S+ l7 A5 D
Common-Mode Rejection Ratio（CMRR）VCM = ±10.5 V


- G4 Y  R2 X1 LImproved dc performance is also provided with bias and offset
: n9 `8 g  I  F) @; Icurrents 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
/ R8 z8 j7 y, q2 X) ?) Z+ E) p* Dor summing applications without the need for special selections
  ^; Z# a5 L; n' [or the added noise of additional offset adjustment circuitry.
: E2 I4 E; d" [% i8 H1 z! o' I" _The output is capable of driving 600 W loads to 10 V rms while
# w; W( }+ z* [( D+ Qmaintaining low distortion. THD + Noise at 3 V rms is a low
0.0006%.

从这些参数来看，，
OP275在SQ200AT的12V的电压下，，性能比JRC4580好
. _5 j: v4 J& tHigh Slew Rate也比JRC4580好很多，，
所以解析度和动态方面，，OP275都比较好
  P7 z% Q6 V$ G1 x3 ]# ]
( F; Z8 S2 f) s. F0 X: F[ 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
Total Harmonic Distortion + Noise (THD + N) of the OP275
is well below 0.001% with any load down to 600 W. However,
6 \# H3 c4 M3 a: b" b& ~* g! Rthis 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
+ W& h9 s& `$ g  w8 ]0.001% 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
2 m' ^0 j, L" M4 l3 u: F% iswing 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.
1 Q; F  n; h) V3 Q/ T; Z- SThis performance is similar to competitive products.

$ l: k% A! {) D# ]The output of the OP275 is designed to maintain low harmonic
distortion while driving 600 W loads. However, driving 600 W
loads with very high output swings results in higher distortion if
  p1 ~2 Z3 H3 U. jclipping 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,
9 B/ R- S8 E, osupply voltages may be increased. Figure 5 shows the performance
4 Z$ T- `9 J" `5 \( n* R( ^% Kof the OP275 driving 600ÊW loads with supply voltages
! B$ [$ |+ I3 S7 Rvarying from ±18 volts to ±20 volts. Notice that with ±18 volt
4 c3 |: `+ {$ W0 b4 U1 usupplies the distortion is fairly high, while with ±20 volt supplies
it is a very low 0.0007%.

; U9 E# Q5 J9 v7 y. \; u/ m1 I
' y8 y! ^+ z) }4 m这是OP275 THD的说明，，
1 ~% r$ u% j( E  l4 y大概意思是说，，3V，，THD为0.001，，，
$ A: e4 L, S. w& u1 k; R, L/ A. q失真最少，，是20V以上，，，0.0007
( v5 J+ b# S  F; a* ?% V5 W7 H0 O, D0 r' I
:charles: 不知，，有没有理解错误

4 z- B% D$ e2 U% t9 Q$ }




:sweatingbullets: 找不到12V下的，，数据，，
( X7 [/ O+ Q0 @) U9 }9 w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，，
* g9 [- t2 u+ f% s" O. T从15V和18V的曲线看，，区别不大
# S) l1 U9 i) N7 B& |" \' `OP275对电压不敏感
8 X, C9 x0 q/ }! y6 C+ r
5 p' l+ v+ p: b5 V6 c- T8 U[ 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
( i' h: R/ L. I8 O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
- p% ?; S9 I9 T, p2 p- L9 r& Z" x) f
/ k3 C- Z" u; U7 Y5 i3 y0 K2 ]另外为什么他们要叫你"阿娇"呢?