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[TRON] DSH 438 Determination of voltage at loudspeaker terminals

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发表于 2012-11-8 18:50 | 显示全部楼层 |阅读模式
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DSH 438. Q( U, B. u% v* @7 o: ~" d8 W2 e

6 s& a$ f5 I/ u! `& l; \$ \( b4 L
Determination of voltage at loudspeaker terminals: w7 R1 f/ \( R/ h8 Y% h
4.2.4/ P. I7 w& ^6 s1 y7 G! {( k; r. z
60065(ed.6)
9 N  `; }- ^; {9 @

1 f8 e8 P; D& Q8 rStandard(s):
" @+ P6 }1 F6 W& DIEC 60065:1998 6th edition.
0 Y  s. X! d2 C6 E9 I5 TSub clause(s):. b! d, V: q- x; h+ Y
4.2.4: J/ q# t" D$ G, A0 }, J* N
Sheet No.3 K; _; E$ d) O' `5 E' a
438/ r* `- M, z/ A0 l/ H4 n$ O& {
Subject:5 p7 Z& @& R" e& z
Determination of voltage at& X" e4 H* @6 N/ W. g
loudspeaker terminals) i( \" k6 e) X, h% q
Key words:0 U) A3 R1 U  H
- Terminals  u0 y3 ?8 T7 z* L5 y' H: N
- Loudspeakers9 A1 a% M' s' M  N, k9 Y, ~
- Non-clipped output power
. k  F5 X$ s, j; R8 U6 kDecision taken at the 39th! ?: v# U# u- F; \7 z0 j
meeting 2002
. Z5 T! u9 B) B8 @2 Y- U  [Question:
4 N) m  c1 i& U) U& _6 h2 dIs the apparatus to be operated in a way as to deliver one-eighth of the NON-CLIPPED OUTPUT* X; k) b+ H+ ?% P* Q% X6 ~& Y
POWER to the RATED LOAD IMPEDANCE also for the alternative test method described in
  R( i* G# S: z# kparagraph 3 of clause 4.2.4(a)?! }! a9 F. {+ T
Rationale:) z8 }0 C  o! Y: E+ z  q1 E
The first paragraph of clause 4.2.4(a) requires the apparatus to be operated as to deliver one-eighth of the- O/ c- L2 H1 d: M1 r7 U, U; n
NON-CLIPPED OUTPUT POWER to the RATED LOAD IMPEDANCE.
# J9 U* W$ v, E8 o- V% fWHEN determining whether a part or terminal contact is hazardous live acc. to 9.1.1 and 11.1, at the
" r/ R& S# R  X9 N$ G9 gmanufacturer's option the apparatus may also be operated in such a way as to deliver the NON-CLIPPED
+ H& Z. ~0 ]- i7 v9 d9 EOUTPUT POWER to the RATED LOAD IMPEDANCE using a 1 kHz signal
3 b0 v# J6 T+ l5 ~. ]5 G. WIn the 6th edition, the use of sine waves as an alternative for noise signals was introduced, for the purpose8 S* P. c6 Q2 z  o) `2 L
of output voltage measurement, because the NON-CLIPPED output power was already defined in terms of" Y  y. \. y. \1 X! _& \
a 1 kHz sine wave. The intent was to permit easy and reproducible measurement of the output voltage ,
; e) ?& R  E' Z) p9 Z4 ]without switching to the noise signal.
5 R% X- }$ G, ~& ZAlso, it was intended to permit use of the sine wave for the Heating Test, where results would be equivalent7 k4 `* d& ^! p
to use of noise.7 P" Q/ p! ]9 \/ V, H4 A" p
However, in case of doubt, the noise signal was to be used as the reference method.7 y3 o* w0 _* }' u4 A# Z+ z
The TC introduced the sine wave alternative in the 4th paragraph for measuring the output voltage, but did( i: t0 ^! l- [  Z
not intend to change the voltage limit from! b9 T# m, n# _* M0 ]
a) 35V pk (25Vrms) at 1/8 max output in the 5th edition, to
9 l) ?7 ?0 t! U& Z  P* s) mb) 35V pk at max output.
. b1 q/ Z, x6 H# m" [9 ?3 rTherefore, it is quite sure that the 4th paragraph should have included the 1/8 factor which was omitted by
5 ?- i" N4 g/ Terror. If we follow the 6th edition as written, it means that any amplifier with 25Vrms output must have
) l/ w, I4 _* `" j! ^" Z, V% m* L) o0 xinsulated output terminals marked with the "lightning flash" symbol. Clearly, this has not happened in the. |  C" H2 V$ M: ]4 f$ e! ]4 P7 G
audio industry.: N, A3 u. H2 A
Because of the confusion introduced in the 6th edition text, this clause together with 9.1.1.1a) was rewritten# {4 m: M, n, o; O; k5 Z8 i9 _
in the 7th edition to permit 71Vrms output on uninsulated terminals in household amplifiers at maximum' t8 r' ]; |* M4 ~: r
output (equivalent to 35Vpk or 25Vrms at 1/8 max output in the 5th edition). Also, Cl. 11.1 was rewritten to3 b' A4 G1 |% u* H
not permit higher audio output voltages under fault conditions.. C( _5 @; T0 u
Decision:2 K& t& M/ X/ J+ O
When determining whether a part or terminal is hazardous live acc. to 9.1.1 and 11.1 at the
% S. Q6 ]. w; ], H% D+ T5 V4 e% Y+ ^manufacturer's option the apparatus may also be operated in such a way as to deliver one-eight of
1 [1 [9 b( y0 ?the NON-CLIPPED OUTPUT POWER for requirements of 9.1.1 and the maximum NON-CLIPPED
& x0 I* `1 Z! O; G, Q, W4 |OUTPUT POWER for requirements of 11.1 to the RATED LOAD IMPEDANCE using a 1 kHz
, d/ ?) h: j; o* a# _- xsignal.. b/ v$ G2 [* X

7 b9 J2 v% z8 H1 G; D
& |6 `9 `4 Y7 R

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