DSH 438 Determination of voltage at loudspeaker terminals

小米

广东安规检测
有限公司提供：

小型摆管淋雨试验机

IPX5X6X7喷水试验机

1000L恒温恒湿箱

各种试验指现货

可程式恒温恒湿试验箱

水平垂直燃烧机

自动卷线器试验机

耐划痕试验机

各种灯头量规现货

灼热丝试验机现货

GB1002插头量规

IPX1-X7淋雨现货

IEC61347/UL935镇流器热试验箱

灯具防风罩

IK冲击试验机

UL498插头插座量规

VDE0620插头插座量规

稳定性试验台

家电温升测试角

针焰试验机现货

热电偶焊机现货

家电125mm试验指

E12灯头量规

无绳壶无绳电熨斗插拔寿命试验机

IEC60335试验指甲

DSH 438 1 m# W+ f6 A4 _3 k$ q * ?, ?! d# E% U3 L6 R" ?' @( _

Determination of voltage at loudspeaker terminals 5 B: t# \' z5 j( S1 M

4.2.4 6 w; E2 A! B. {4 C. U4 j0 x# S

60065(ed.6)

: S- J2 {, L7 m; yStandard(s):
IEC 60065:1998 6th edition.
$ y. A" m* q9 t1 q* Y+ RSub clause(s):
. d* ?1 A, j3 e4.2.4
Sheet No.
438
Subject:
Determination of voltage at
8 ?, U% p  S* C' ?loudspeaker terminals
Key words:
- Terminals
( J8 a# m( e& S3 i3 I- Loudspeakers
& p5 a. K% m# P% S& x- Non-clipped output power
5 N8 s8 p0 s9 yDecision taken at the 39th
meeting 2002
( }; f: G! G+ q9 S8 \Question:
" G* z% }2 B( H8 F+ tIs the apparatus to be operated in a way as to deliver one-eighth of the NON-CLIPPED OUTPUT
POWER to the RATED LOAD IMPEDANCE also for the alternative test method described in
paragraph 3 of clause 4.2.4(a)?
Rationale:
* Y. A7 c: |9 OThe first paragraph of clause 4.2.4(a) requires the apparatus to be operated as to deliver one-eighth of the
9 }! e' O* Y1 Y" X# tNON-CLIPPED OUTPUT POWER to the RATED LOAD IMPEDANCE.
WHEN determining whether a part or terminal contact is hazardous live acc. to 9.1.1 and 11.1, at the
9 f9 b. q% c& G0 e0 Q9 }  Omanufacturer's option the apparatus may also be operated in such a way as to deliver the NON-CLIPPED
OUTPUT POWER to the RATED LOAD IMPEDANCE using a 1 kHz signal
, Q' H8 T. Q5 u1 ^In the 6th edition, the use of sine waves as an alternative for noise signals was introduced, for the purpose
4 N; {5 b) |! dof output voltage measurement, because the NON-CLIPPED output power was already defined in terms of
8 _9 m+ D4 o+ B4 A( sa 1 kHz sine wave. The intent was to permit easy and reproducible measurement of the output voltage ,
without switching to the noise signal.
Also, it was intended to permit use of the sine wave for the Heating Test, where results would be equivalent
% O2 L1 u" V' z, R" O/ V1 w, V$ Mto use of noise.
' P# ?" G/ `& ^* |9 K1 ?7 P# ~- bHowever, in case of doubt, the noise signal was to be used as the reference method.
The TC introduced the sine wave alternative in the 4th paragraph for measuring the output voltage, but did
8 s. S7 q/ p( ]9 a! D5 q) [& Mnot intend to change the voltage limit from
/ ~! |( i1 j9 p& D+ M: fa) 35V pk (25Vrms) at 1/8 max output in the 5th edition, to
1 ~% T+ I; H+ ^2 f7 b0 N- I2 kb) 35V pk at max output.
Therefore, it is quite sure that the 4th paragraph should have included the 1/8 factor which was omitted by
: G  W6 P. _7 m: {3 j9 werror. If we follow the 6th edition as written, it means that any amplifier with 25Vrms output must have
% P: j. b0 ]* P7 K1 k) ^8 C- x4 ]insulated output terminals marked with the "lightning flash" symbol. Clearly, this has not happened in the
- X5 V. C$ }, V  Qaudio industry.
! o6 d) D' G; D( r3 e' _Because of the confusion introduced in the 6th edition text, this clause together with 9.1.1.1a) was rewritten
in the 7th edition to permit 71Vrms output on uninsulated terminals in household amplifiers at maximum
output (equivalent to 35Vpk or 25Vrms at 1/8 max output in the 5th edition). Also, Cl. 11.1 was rewritten to
not permit higher audio output voltages under fault conditions.
Decision:
When determining whether a part or terminal is hazardous live acc. to 9.1.1 and 11.1 at the
manufacturer's option the apparatus may also be operated in such a way as to deliver one-eight of
3 N' d. D. o" y+ A+ h& K& s4 ?the NON-CLIPPED OUTPUT POWER for requirements of 9.1.1 and the maximum NON-CLIPPED
) B, e" N8 p- v8 {2 S$ dOUTPUT POWER for requirements of 11.1 to the RATED LOAD IMPEDANCE using a 1 kHz
signal.