标题: DSH 438 Determination of voltage at loudspeaker terminals [打印本页] 作者: 小米 时间: 2012-11-8 18:50 标题: DSH 438 Determination of voltage at loudspeaker terminals
Determination of voltage at loudspeaker terminals " y8 q0 V- Z7 X+ r# s* i
4.2.4 / {; I0 v4 r: t9 \6 |: r% ^$ X
60065(ed.6)! F0 K: r3 X: Q! F
7 }7 h, o) ~# sStandard(s): 3 y- q+ I C) R1 k- g6 k PIEC 60065:1998 6th edition.2 a P* D- ~7 o; P
Sub clause(s):, s# V/ v* z" S0 R+ {$ [ u, Q4 I
4.2.4 9 W( g7 D7 }+ ~4 n$ [Sheet No. 9 [9 E- D5 n" }% A2 B: c438# ]9 X% L% J7 ^
Subject:7 O/ Y% \1 Q( J) }1 @2 S9 Y
Determination of voltage at " e8 U7 A1 R. U( E# ploudspeaker terminals 6 c3 L. o1 p& U# \7 pKey words:5 T9 s5 t" N9 z9 O, r6 B
- Terminals6 \" T5 U8 t! A# \
- Loudspeakers: Y, H' Z! l6 w6 P1 i, _( H
- Non-clipped output power# `3 W$ V. F. B$ I& s# b
Decision taken at the 39th4 a( f' E4 g2 C+ D" S
meeting 2002 0 p/ d/ k1 ~" X' hQuestion: & l* V+ I; H3 [ SIs the apparatus to be operated in a way as to deliver one-eighth of the NON-CLIPPED OUTPUT : h3 O) R- X) EPOWER to the RATED LOAD IMPEDANCE also for the alternative test method described in 7 O" q! ^9 w. w5 l% vparagraph 3 of clause 4.2.4(a)?' c% k) p8 s5 D8 s( a
Rationale:, e8 P1 {( g9 x0 S. e+ N
The first paragraph of clause 4.2.4(a) requires the apparatus to be operated as to deliver one-eighth of the: O6 y1 b6 @. F2 W( E
NON-CLIPPED OUTPUT POWER to the RATED LOAD IMPEDANCE.8 ~5 \0 t& s1 _; d; Y6 { v% J
WHEN determining whether a part or terminal contact is hazardous live acc. to 9.1.1 and 11.1, at the) U8 {% B: f/ o0 o
manufacturer's option the apparatus may also be operated in such a way as to deliver the NON-CLIPPED9 u) q4 E& h# t8 v
OUTPUT POWER to the RATED LOAD IMPEDANCE using a 1 kHz signal " m/ p$ m4 `+ WIn the 6th edition, the use of sine waves as an alternative for noise signals was introduced, for the purpose % j1 O6 B3 S7 x& x" Yof output voltage measurement, because the NON-CLIPPED output power was already defined in terms of) b/ j. p3 X. O* |5 S
a 1 kHz sine wave. The intent was to permit easy and reproducible measurement of the output voltage , ! Q" [( o/ j' O! N& _9 J9 J4 bwithout switching to the noise signal.+ g! s( O3 K: G0 U* J
Also, it was intended to permit use of the sine wave for the Heating Test, where results would be equivalent . m( k1 c1 _1 u+ P$ jto use of noise. ; p& Z2 }& j F. THowever, in case of doubt, the noise signal was to be used as the reference method. - n) C/ ^2 m. j5 \' |The TC introduced the sine wave alternative in the 4th paragraph for measuring the output voltage, but did 9 \6 E. ~1 A: l- R5 q3 W# onot intend to change the voltage limit from4 L, M u: x8 ?( [( K
a) 35V pk (25Vrms) at 1/8 max output in the 5th edition, to ' c: o3 O# X, `b) 35V pk at max output./ X! a+ t' A$ n* n" f& u
Therefore, it is quite sure that the 4th paragraph should have included the 1/8 factor which was omitted by% O6 r* b0 a. ?* [! l" G, J
error. If we follow the 6th edition as written, it means that any amplifier with 25Vrms output must have $ i$ x9 p7 x2 i5 Xinsulated output terminals marked with the "lightning flash" symbol. Clearly, this has not happened in the / K4 P- E$ N* j: `& n& W4 oaudio industry.6 k3 Q6 m9 j" ~, C$ z0 w7 u
Because of the confusion introduced in the 6th edition text, this clause together with 9.1.1.1a) was rewritten ' q* Y5 k& i& f, g4 iin the 7th edition to permit 71Vrms output on uninsulated terminals in household amplifiers at maximum# X( v' N: Q4 j, |, n( g
output (equivalent to 35Vpk or 25Vrms at 1/8 max output in the 5th edition). Also, Cl. 11.1 was rewritten to 7 F+ q; F* v3 |/ u. |not permit higher audio output voltages under fault conditions. % C5 E. Z* j4 W( g3 g gDecision:# p4 H% X, \$ E
When determining whether a part or terminal is hazardous live acc. to 9.1.1 and 11.1 at the6 Q- z4 {2 F* h
manufacturer's option the apparatus may also be operated in such a way as to deliver one-eight of - o( j) R( S7 n$ e1 D, ]: P3 G- I$ P6 ethe NON-CLIPPED OUTPUT POWER for requirements of 9.1.1 and the maximum NON-CLIPPED/ A9 w0 P4 s6 }% |/ T) x
OUTPUT POWER for requirements of 11.1 to the RATED LOAD IMPEDANCE using a 1 kHz) J: l; i* X1 R/ X) i0 v
signal.# `$ \# B" }3 n" ^& n6 Z, C4 W" Y u
+ S% e/ m5 Y0 h( @
[attach]77296[/attach] . m2 Q( {+ G$ x5 @5 p! n& _) |
DSH 4381 m, @ @: C' R; m