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原帖由 ljm_ljm 于 2007-8-22 14:51 发表 ![]() ! V: V5 f% k3 F1 J% }+ E
我从来不觉得胆机失真大会好听。说夸张点，可以说我从来没觉得电子管好听过。
0 h" Z" S. @+ G; c) A9 e' ew00t) 也许是我比较喜欢新的科技技术，说电子管好听的。有机会去听听140DB 动态的大录音制作室就知道。电子管原来是XXX。$ h# {. P* P3 z8 m, r- C( X: h
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至 ...
: e9 P7 N% z0 N7 @, ?* L1 s查了一下介质损耗的资料。好像就是ESR除以容抗。5 I$ E E# ^* \' m7 E- W& v
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Dissipation factor is measured at 120 Hz, up to7 T: g! n L. S" o+ C
1.0 volt rms maximum, and up to 2.0 volts DC
* V. @& o2 g$ emaximum at +25°C. The application of DC bias
' D- L) t% n1 c% f4 Dcauses a small reduction in DF, about 0.2% when
: \0 \$ S3 }/ j; s. m) L" y bfull rated voltage is applied. DF increases with( c; h7 o6 V" Q1 e0 ?8 {! @
increasing frequency.' V; r- X2 V/ o, H1 N, I( `
- _( z' D4 m5 `Dissipation factor is a very useful low frequency4 ]' F; I1 Z t; u
(120 Hz) measurement of the resistive component! m0 R. h* \4 e' P; u
of a capacitor. It is the ratio of the equivalent series3 `2 D ^5 V8 A- D; D
resistance (ESR) to the capacitive reactance, (XC)
" E% D6 j6 L" ?% D" c/ M, Mand is usually expressed as a percentage. It is/ X+ P% c% ^6 Y; S% }
directly proportional to both capacitance and frequency.; q4 r u* R/ M1 |3 N o# G% k
Dissipation factor loses its importance at0 ~+ s1 g+ A; X1 F. [4 ~3 {
higher frequencies, (above about 1 kHz), where' B! R- b' j4 S4 o4 J
impedance (Z) and equivalent series resistance
& v9 {& P. y/ T(ESR) are the normal parameters of concern./ ~" X! B7 R$ x9 F! P
+ d9 ~) m; l7 @& c+ B9 A4 E: cDF = R/XC = 2pifCR
; G$ D6 @9 {7 n- M: p, S5 M( YDF = Dissipation Factor. p3 P, y: V, H) n! v9 E0 a
R = Equivalent Series Resistance (Ohms) W7 `9 o6 R' M3 F2 @: |
XC = Capacitive Reactance(Ohms)7 M) `( |2 d6 i2 J
f = Frequency (Hertz): O3 p/ X9 z7 f; I; W- _. N
C = Series Capacitance(Farads)
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& {. V \' ?; G m$ ADF is also referred to as tan or “loss tangent.”
# r% s E S8 ?2 P7 ^The “Quality Factor,” “Q,” is the reciprocal of DF.3 m% Z, v* J9 M* {' [/ K6 v1 q
DF decreases with temperature above +25°C and/ S! P. S0 V* U1 Z- K7 {/ P8 y% D
may also increase at lower temperatures.
& F4 N9 c1 _% ^5 i* r' V6 {Unfortunately, one general limit for DF cannot be/ w& V! U0 X2 Z2 K! _
specified for all capacitance/voltage combinations,) V- }: Y, v1 ]# |: R6 Z( @' O
nor can response to temperature be simply stated.+ j Q6 h8 |: S) ^" S! w* m
DC bias is not commonly used at room temperature,
$ a& P% ~9 o* tbut is more commonly used at elevated temperatures. |
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IP卡
狗仔卡
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显身卡
发表于 2007-8-22 01:31
