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原帖由 ljm_ljm 于 2007-8-22 14:51 发表 ![]()
% Z Y: ~ [' I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。
) q- S+ }7 l! k; y% H5 B1 vw00t) 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。0 L+ B" a; R4 {$ {6 {
" Y$ q" _! j& Y. r- {7 }" c
至 ...
+ ^4 a9 {- }1 ?6 M) Y$ ?, r3 p$ Y8 f查了一下介质损耗的资料。好像就是ESR除以容抗。# V/ f- j" z! Q% ]6 T+ c
, X6 {1 F+ [. ~. w1 s# wDissipation factor is measured at 120 Hz, up to
. @$ E' l5 s5 X u1 s1.0 volt rms maximum, and up to 2.0 volts DC
+ V( `* M' o/ M2 _8 Omaximum at +25°C. The application of DC bias
; m! a/ m3 H5 _5 o9 dcauses a small reduction in DF, about 0.2% when' a8 h( B8 P6 |. N! H+ m$ c6 p
full rated voltage is applied. DF increases with2 Y4 `6 ~2 T3 p+ D9 J2 t
increasing frequency." j! W2 v3 D0 d i( G
& W6 c9 F' ~5 U5 a- g2 q( L7 X8 {
Dissipation factor is a very useful low frequency
" P& A6 p0 O; E1 b/ t# { E) k+ I, H(120 Hz) measurement of the resistive component3 Z6 e( @" c, f& n
of a capacitor. It is the ratio of the equivalent series$ x- Q- n* d3 O- q' x3 g* `9 J
resistance (ESR) to the capacitive reactance, (XC)
; g( @/ J+ M8 Z) h _# y3 i/ cand is usually expressed as a percentage. It is
" ~% C) R. |& Y/ J9 W1 Udirectly proportional to both capacitance and frequency.% c, x) _7 o* D
Dissipation factor loses its importance at7 ~0 @" \4 x- q: {
higher frequencies, (above about 1 kHz), where1 V- N1 z C$ ?* }! B) q
impedance (Z) and equivalent series resistance
- `, r3 ^! W5 W/ P" o(ESR) are the normal parameters of concern.
4 H$ Y* k; K, k( Z) l1 T4 F: U1 ~ e6 o8 h1 F' Y" Z+ ^: Y, F0 U7 _# B( m1 S( q
DF = R/XC = 2pifCR
- l$ F. z$ G' o# VDF = Dissipation Factor$ _' o1 j K9 f. r0 w" w! Y3 j7 b
R = Equivalent Series Resistance (Ohms)% }( l3 ^4 S# q) H2 L
XC = Capacitive Reactance(Ohms)
" h( F# k. z2 y/ e5 Lf = Frequency (Hertz)7 j L& e' b# Z3 c
C = Series Capacitance(Farads)
& f. a) W4 }' L9 `7 c/ S
( }4 Z P# d' @4 EDF is also referred to as tan or “loss tangent.”2 {. { i7 S/ Q' v+ ?
The “Quality Factor,” “Q,” is the reciprocal of DF.
: ?0 X& D. J6 l ~ [1 bDF decreases with temperature above +25°C and
8 r4 V4 ~* x1 T3 T& P# s/ l) y0 hmay also increase at lower temperatures.% \/ G. f" [* ~; a( e; A3 N+ t
Unfortunately, one general limit for DF cannot be
- P5 y7 I8 |, A2 n: o( Aspecified for all capacitance/voltage combinations,
& g4 O/ b% c |. e! D, o# inor can response to temperature be simply stated./ [ g+ ^9 M0 d
DC bias is not commonly used at room temperature,
( s: f. T3 d& x2 }# n6 c8 j, Zbut is more commonly used at elevated temperatures. |
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IP卡
狗仔卡
楼主
显身卡
发表于 2007-8-22 01:31
