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原帖由 ljm_ljm 于 2007-8-22 14:51 发表 ![]() % C2 |) F0 J: Q5 w8 u
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。9 {. |& T0 V* D* z
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。+ K ?9 B5 ?3 T$ R
9 J; q: d4 ^7 {! Q1 i
至 ...
$ z+ S/ \$ L! o/ f; s查了一下介质损耗的资料。好像就是ESR除以容抗。
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Dissipation factor is measured at 120 Hz, up to. v& u- Z T$ g& V: B' E
1.0 volt rms maximum, and up to 2.0 volts DC$ Z! U+ V0 O( O: U! {8 V# E
maximum at +25°C. The application of DC bias, K( l$ G3 M* y* @6 w
causes a small reduction in DF, about 0.2% when0 u3 U, @0 N: @, g
full rated voltage is applied. DF increases with5 f2 T8 d. b T' Q7 W3 R2 s- \; w
increasing frequency.
! {, z, c4 M; w1 F* o" @7 ^6 @- n
3 [& X; D7 n9 R. pDissipation factor is a very useful low frequency) z% u4 _ Q8 z, U% z
(120 Hz) measurement of the resistive component
) A) n% t! ^( q, \' B5 Pof a capacitor. It is the ratio of the equivalent series
4 c/ @% w- g* y3 {resistance (ESR) to the capacitive reactance, (XC)- Y/ b# B8 [' C0 i
and is usually expressed as a percentage. It is* C1 p2 L. A$ l' h" P) _1 M# R$ `2 d( F
directly proportional to both capacitance and frequency.
& Y: Z# ~, m# B+ V0 IDissipation factor loses its importance at
4 t) P6 Q$ T# p# rhigher frequencies, (above about 1 kHz), where
9 w* G3 V. l1 e( ~5 g( nimpedance (Z) and equivalent series resistance
% a4 c6 \2 N' E' @(ESR) are the normal parameters of concern.
% k3 A; Z8 W/ }( a+ c- O* y& D& n
6 ~3 T4 V( m0 U8 }; w8 Q9 dDF = R/XC = 2pifCR
5 ^+ X/ V: s0 mDF = Dissipation Factor
4 s0 |1 d/ B8 `7 YR = Equivalent Series Resistance (Ohms)
h5 ]+ n, S( }; G% a4 pXC = Capacitive Reactance(Ohms)
: p1 g& ?1 l: u" v n# Wf = Frequency (Hertz)
2 z- f# g8 n9 cC = Series Capacitance(Farads)& R/ q$ j" h/ o' G A
' c6 _1 W* ~0 r. U+ L. p1 eDF is also referred to as tan or “loss tangent.”
9 d7 a u# A+ K' [) c8 Y+ \The “Quality Factor,” “Q,” is the reciprocal of DF.1 \$ C3 Y r; z' x) C Y
DF decreases with temperature above +25°C and
+ K6 B) t1 k! ?+ }1 v6 T' n3 omay also increase at lower temperatures.( g) s" y$ s3 _) Z, {/ S4 K
Unfortunately, one general limit for DF cannot be3 E2 f" }! {! b' H- z& h
specified for all capacitance/voltage combinations,
( @) X" o) j3 \0 G$ z+ n5 h# anor can response to temperature be simply stated.
& X- S0 [( I! LDC bias is not commonly used at room temperature,1 j; F+ s4 \1 o7 t3 j6 x
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
