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原帖由 ljm_ljm 于 2007-8-22 14:51 发表 ![]() * T0 X! @ [) U9 F, W
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。, d( @, ]3 v+ q. F9 ?! I
w00t) 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。
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$ D6 s# t# m) k Q至 ...
查了一下介质损耗的资料。好像就是ESR除以容抗。
8 f2 d, u/ Y, q6 @# X( Y. r# n; h1 q7 U d
Dissipation factor is measured at 120 Hz, up to
( |; t; Y( {$ j7 u/ L7 A1.0 volt rms maximum, and up to 2.0 volts DC5 P4 k1 g1 l, ?' h# o. J
maximum at +25°C. The application of DC bias
! _2 f* `# P" G3 Ccauses a small reduction in DF, about 0.2% when2 o5 Y( [% k7 g, A- C
full rated voltage is applied. DF increases with$ f3 Z3 w. v3 z d/ G6 J
increasing frequency.& `+ E1 e5 A. \4 K s
9 ~; T: X8 G* l( q# ~4 w1 T+ e8 ]Dissipation factor is a very useful low frequency6 F# y5 Z; C: D3 [! R
(120 Hz) measurement of the resistive component+ X2 P! z/ m3 V/ Z6 ] \, R; D, E6 v
of a capacitor. It is the ratio of the equivalent series {$ I; \' K G$ i: \0 r# k# U
resistance (ESR) to the capacitive reactance, (XC)
( w Y/ R7 B J' o. }1 |& o+ _and is usually expressed as a percentage. It is
4 _8 H7 ^6 j) Jdirectly proportional to both capacitance and frequency.2 e2 E( l8 E! E" t8 O
Dissipation factor loses its importance at
, f; N0 s# s: M$ ehigher frequencies, (above about 1 kHz), where0 l& B3 L7 E$ s' k8 h
impedance (Z) and equivalent series resistance2 _' ]3 e4 E4 s5 ?5 P1 ^1 ^# p T
(ESR) are the normal parameters of concern.
1 g: p: G8 `/ ^, h! y2 W3 c* D# d% Y9 g
DF = R/XC = 2pifCR/ h* m- }1 }+ K9 f
DF = Dissipation Factor
0 q/ p8 \( j0 t. H) gR = Equivalent Series Resistance (Ohms)
# o" T9 U; B9 i" g* J& x) ~+ JXC = Capacitive Reactance(Ohms)
. F* e& h& x0 e) f0 K, f2 G( Df = Frequency (Hertz)
1 w$ u+ N3 N2 t- X7 EC = Series Capacitance(Farads)
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DF is also referred to as tan or “loss tangent.”, g: Q9 }( G9 L8 h" \) H
The “Quality Factor,” “Q,” is the reciprocal of DF.
" i, R1 j$ I0 Z; y1 @3 h* ADF decreases with temperature above +25°C and% Q" Q$ L0 U4 b3 x$ s4 n: @: J m
may also increase at lower temperatures.
, P5 k' P: g' ~; F: h+ s) lUnfortunately, one general limit for DF cannot be3 ?: K# p* D5 e( \* j
specified for all capacitance/voltage combinations,7 s" j3 y; b3 m! g4 `
nor can response to temperature be simply stated.5 d, M: _" v! {% S) h6 L
DC bias is not commonly used at room temperature,
4 a L8 P( O |6 Q2 U6 ~' ^, ?but 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
