Rub & Buzz以及其他不規則揚聲器缺陷 - Klippel · Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 22 峰值&正負rms值 Peak

Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 1

Rub & Buzz以及其他不規則揚聲器缺陷Rub & Buzz and Other Irregular Loudspeaker Defects

ISEAT 2013

by Prof. Wolfgang Klippel,

University of Technology Dresden

Klippel GmbH


揚聲器信號失真的產生Generation of Signal Distortion in Loudspeakers

StimulusMeasured

Signal

Input

Signal

Output

Signal

H(s)-1

Regular

Nonlinearities

Defects

Noise

Parasitic

vibration

線性失真linear distortion

驅動系統和支撐系統產生的失真

Distortion caused by motor and suspension

過量失真Excessivedistortion

• 磁鐵Magnet•音圈Coil•彈波 Spider•懸邊Surround

• 異常聲 Rub&Buzz,• 鬆散部件/微粒/螺絲釘 Loose Particles / Parts / Screws

• 空氣雜訊 Air Noise (from Leakages)

• 環境雜訊•Ambient Noise

麥克風雜訊Mic Noise

箱體、房間或其他物體Enclosure, room, other objects


在328 Hz 处可能产生摇摆

Rocking mode may cause at 328 Hz

扬声器缺陷:音圈碰撞Loudspeaker Defect: voice coil rubbing

时间 time一个周期 one period

失真信号 distortion signal

音圈 Voice coil

缝隙 gap 音圈碰撞 voice coil rubbing


扬声器缺陷: 嗡嗡声问题Loudspeaker Defect: Buzz problem

大多数缺陷表现为非线性振荡器Most defects behave as a nonlinear oscillator•在一定的幅度以上起效用active above a critical amplitude•新的振动模式new mode of vibration• 由激励信号驱动并同步powered and synchronized by stimulus• 恒定的输出功率constant output power

Loose joint

(Nonlinearity)

parasitic resonator

Externally excited

spring

mass

Loose joint

(Nonlinearity)

parasitic resonator

Externally excited

spring

mass

时间 time一个周期 one period

振动 vibration

失真信号 distortion signal


揚聲器缺陷:鬆散微粒Loudspeaker Defect: Loose Particles

•隨機過程 stochastic process

•微粒由音圈的位移控制加速 particles are accelerated by cone

displacement

•與激發信號不同步 not synchronized with stimulus

•恒定的輸出功率 constant output power

時間time一個週期one period

音圈cone

dust cap

音圈筒Voice coil former

縫隙gap

失真信號distortion signal

鬆散微粒Loose Particle

跳躍bouncing

跳躍bouncing


揚聲器缺陷:音圈撞擊背板Loudspeaker Defect: voice coil hits the backplate

背板backplate 背板backplate 背板backplate 背板backplate

音圈Voice coil 音圈Voice coil

音圈Voice coil

音圈Voice coil

一個週期one period時間time

失真信號distortion signal

Klippel: Sound Quality of Audio Systems, part 7, rub and buzz, defects 11

揚聲器缺陷:空氣洩漏和嘈雜雜訊Loudspeaker Defect: Air Noise

•空氣壓力隨音圈位移改變air pressure is changed by coil displacement

•隨機過程 stochastic process

•與激發信號同步 synchronized with stimulus

音圈cone

縫隙gap

防塵蓋dust cap

洩漏leakage

空氣雜訊Air noise

一個週期one period

時間time


尋找一個最佳的激發信號-可聽見的音圈撞擊聲Searching for an optimal Stimulus-Audibility of Voice Coil Rubbing

Signal Stimulus Output

1V

Output

2V

Output

3V

Music

Multi-Tone

20 Hz – 20 kHz

Multi-Tone

20 Hz – 1 kHz

Sinussoidal Sweep

1 s

Most sensitive Stimulus

This Experiment investigates the influence of the stimuli and the input voltage

clear audible

Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 13

Hearing Threshold

Air LeakMasking Threshold

PassedFailed

揚聲器缺陷的遮蔽Masking of Loudspeaker Defects

•不規則失真產生高頻的成份irregular distortion produce high frequency components

•低頻處基頻成份不會遮蔽no masking from fundamental component at low frequencies

•接近人耳聽覺閥值close to the hearing threshold


在產線環境中人耳聽不到的揚聲器的缺陷是可接受的嗎?

Are loudspeaker defects are acceptable which are inaudible for a human ear in a production environment ?

NO !

• 某些揚聲器的缺陷會隨時間越嚴重(在懸邊分裂後)

some loudspeaker defects become worse over time (after break-in of the suspension)

• 某些揚聲器缺陷產生隨機症狀(鬆散粒子)

some loudspeaker defects generate random symptoms (loose particles)

• 產線的噪音將會遮蔽缺陷的症狀(空氣洩漏)

the production noise masks the symptoms of the defect (air leakage)

• 末端使用者可以利用更嚴格的激發型式(低頻)

the end user may use a more critical stimulus (low frequency bass)

• 倘若客戶檢測到聲音品質明顯損失的症狀

Significant loss of sound quality if symptoms detected by customer


整線上主觀聽測的結果Consequences of Subjective Testing at the Assembling Line

• 需要訓練操作員使之比使用者更敏感]

Need for trained operators more sensitive than the end user

• 避免人耳疲勞(規則分裂,低SPL)

Avoiding fatigue of the human ears (regular breaks, low SPL)

• 在相似的條件下操作揚聲器,就像最後的應用端條件一樣(聆聽距離,振幅,大小)

Operating the loudspeaker under similar condition as in the final application (listening

distance, amplitude, load)

• 有足夠的時間進行人耳的檢測(柔軟度以及長時間周期)

Sufficient time for human inspection (flexible and long cycle times)

人耳測試是相當昂貴,不可靠,太主觀Human testing is expensive, not reliable and highly subjective !


好與壞兩個不同揚聲器產生的60Hz的信號60 Hz Tone reproduced by a good and bad speaker

Passed

Failed

基波 fundamental

2nd 3rd

高通滤波High Pass Filtering

减小基波和低阶谐波required to suppress

fundamental and low order

harmonics环境噪声ambient noise


時域分析Time Domain Analysis

解決方法:返回到時域Solution: back to the time domain

高次諧波的峰值振幅和相位Peak exploits amplitude and phase of higher-order

distortion

峰值顯示短暫的瞬間peak value reveals small transients (clicks)

峰值和有效值的比值給出失真的峰值因數Ratio between peak and rms value gives crest factor of distortion

常規失真產生很低的峰值因數regular distortion generates low crest factor

大多數缺陷產生有很高峰值因數的徵兆most defects generate symptoms with high crest factor

SPL

frequency

fundamental

Regular distortion

SPL fundamental

SPL fundamental fundamental

Regular distortion Regular distortion higher order

harmonics

amplitude spectrum

SPL

frequency

fundamental

Regular distortion

SPL fundamental


Regular distortion Regular distortion

phase spectrum

higher order

harmonics

360 deg

180 deg

0 deg

amplitude spectrum

SPL

frequency

fundamental

Regular distortion

SPL fundamental


Regular distortion Regular distortion

FFT-1

rms-value

time

peak-value

phase spectrum

higher order distortion

360 deg

180 deg

0 deg

amplitude spectrum

RMS value

有效值

Crest factor

波峰因数

Peak value

峰值


峰值&正負rms值Peak value Contra rms-Value

sinusoidal

generator

Drive

Unit

~ tracking

filter

microphone

high-passcut-off frequency fc > 10f

instantaneous frequency f

squarer

integrator

peak

detector

electro-acoustical

system

Ratio

Single tone with varying

frequency f (chirp)

High-pass filtered

Distortion

60

70

80

90

100

110

120

130

100 1000 10000

Sound P

ressure

[d

B]

Frequency [Hz]

Frequency Response峰值(PHD)對於大部分不規則缺線來說是一個敏感的量測(如rub and buzz鬆散粒子)Peak value (PHD) is a sensitive measure for most irregular defects such as „rub and buzz“, loose particles !!

peak value

(PHD)

peak value (PHD)

rms value

(MHD)

rms value (MHD)

crest factor

(CHD)


諧波失真的峰值因數Crest factor of harmonic distortion (CHD)

諧波失真峰值因數可以在絕對尺度上被解釋說明！CHD can be interpreted on an absolute scale !

KLIPPEL

50 100 200 500

[dB]

Frequency [Hz]

2,5

5,0

7,5

10,0

12,5

15,0

17,5

20,0CHD

常規失真regular distortion

驅動信號: 正弦掃頻 Stimulus: Sinusoidal sweep

rub & buzz,其他異聲other disturbances

10 dB


高通濾波失真ICHD(f,x)的瞬時峰值因數Instantaneous crest factor of high-pass filtered distortion ICHD(f,x)

Frequency of sine sweep

ICHD

12 dBgood bad

time


揚聲器缺陷或雜訊?Loudspeaker Defect or Noise ?

50

60

70

80

90

100

110

120

130

dB

Fundamental

THD

2nd3rd

PHD

Fund. mean

PHD limit

MHD

4010 20 50 100 200 500 1k 2k 5k 10k

Frequency [Hz]

(-40dB)

CHD

Symptoms of a significant defect:1. Sufficient amplitude: peak value PHD > FUNDmean - 40dB

2. Impulsive: crest factor CHD > 12dB

Check for coincidence !(microphone noise is not impulsive)

並非可聽聞聲的起始閥值is not an audibility threshold !


KLIPPEL

40

50

60

70

80

90

100

110

120

10 20 50 100 200 500 1k 2k 5k 10k

Fundamental + Harmonic distortion components (SHAPED STIMULUS)Signal at IN1

dB

- [

V]

(rm

s)

Frequency [Hz]

Fundamental THD 2nd Harmonic 3rd Harmonic

Absolute PHD Fund. mean (100 to 500 Hz) PHD limit (-40dB)

特性診斷-從PHD&CHD的單值參數

Characteristics for Diagnostics Single-valued parameter derived from PHD and CHD

Conditions:Rms Voltage Ur&b = 12 V Peak displacement Xr&b= 4mmFrequency fr&b = 65 HzInst. Displacement xin, r&b = 3.8 mm

Batch of TRF measurements

voltage

6V

8V

10V

12V

KLIPPEL

40

50

60

70

80

90

100

110

120

130

10 20 50 100 200 500 1k 2k 5k 10k


dB

- [

V]

(rm

s)

Frequency [Hz]



50

60

70

80

90

100

110

120

130

10 20 50 100 200 500 1k 2k 5k 10k


dB

- [

V]

(rm

s)

Frequency [Hz]



Significant defect (R&B)

50

60

70

80

90

100

110

120

130

10 20 50 100 200 500 1k 2k 5k 10k


dB

- [

V]

(rm

s)

Frequency [Hz]



12V

-40 dB

fr&b

PHD > FUNDmean - 40dB

CHD > 12dBimpulsive

high amplitude


診斷不規則缺陷(1st範例)Diagnostics on Irregular Defect (1st example)

條件 Conditions:

•低於共振頻率的正向的峰值位移為0.5mmPositive peak displacement at 0.5 mm below fs

•大於端子電壓0.9Vabove a terminal voltage of 0.9 V

問題來源：底部Root Cause: Bottoming


診斷不規則缺陷(2nd範例)Diagnostics on Irregular Defect (2nd example)

Conditions:• Negative turning point of voice coil excursion above fs

• maximal acceleration Tilting of voice coil former• independent of displacement

根本原因：音圈磨擦Root Cause: Voice coil Rubbing


隨機雜訊是個有價值的表徵Random Noise is a valuable Symptom

time

one period

Air noise

平均方法來抑制隨機成分 Averaging suppresses the random component

成倍的表現 Multiple realizations

time

平均的表現 Averaged realizations


空氣洩漏產生信號的調變Air Leakage generates a modulated signal

one period

Air noise

Envelope

•包絡是具有確定性的 Envelope is deterministic

•包絡跟氣壓和音圈位置相一致 Envelope corresponds with air pressure and coil displacement

•干擾產生隨機的雜訊信號 Turbulences generate a random noise signal

空氣洩漏產生調變的雜訊信號 A air leakage generate a modulated noise signal

time

Random noise


Noise

Detection

聽診器Stethoscope

Test

microphone

Power amplifier

EingangAusgang

Speaker 2Amplifier Speaker 1

OUT2OUT1 MIC1 LINE1 LINE2 MIC2

0

Production Analyzer

Ambient

microphone

FireWire

USB

Loudspeaker

Leak

USB FireWire

PCAuralization

目標 Objectives:

• 非常規失真的可聽化Auralization of Irregular Distortion

• 聽覺保護Ear Protection

• 信號轉化Signal Transformation

• 缺陷定位Defect Localization

• 診斷Diagnostics

主觀評價和客觀測量相結合Combining Objective and Subjective Assesment


漏氣的定位Localization of Air Leaks

用麥克風手動偵測Manual inspection with ONE microphone

漏氣Air Leak

Good Bad


相當快速的測量Ultra Fast Measurement

THD SPL

Rub Buzz Butzz

T/S parameters

impedance

2nd –5th harmonics

measured with a 200 ms chirp 200ms

KLIPPEL

-1,0

-0,5

0,0

0,5

1,0

0 25 50 75 100 125 150 175 200Time [ms]

Curve 2


利用不同的時間頻率映射進行多種激發訊號方式產生諧波Various Stimuli for Harmonics with different Time Frequency Mapping

Step Sine

Log. Sweep with Profile

Log. Sweep

0.0 0.9 1.0

log(fmin)

log(fmax) Linear Sweep

t / t total

log(f

)

0.5


高速輪廓的對數掃頻Log. Sweep with Speed Profile

時間Time

頻率 Frequency

時間Time

頻率 Frequency


KLIPPEL

50

60

70

80

90

100

110

120

130

140

102 103 104

So

un

d P

ress

ure

[d

B]

Frequency [Hz]

Response Max

Response Min

THD Max

Rub+Buzz Max

KLIPPEL

60

70

80

90

100

110

120

130

140

102 103 104

So

un

d P

ress

ure

[d

B]

Frequency [Hz]

Response Max

Response Min

THD

THD Max

Rub+Buzz Max

非常快速的Rub & Buzz測量Ultra-fast testing of Rub & Buzz

Input

Signal

Measured

Signal

Frequency Response

Rub+Buzz

Frequency Response

THD

Rub+Buzz

0.2 s

KLIPPEL

-1,0

-0,5

0,0

0,5

1,0

0 25 50 75 100 125 150 175 200Time [ms]

Curve 2

1 s

KLIPPEL

-1,0

-0,5

0,0

0,5

1,0

0 100 200 300 400 500 600 700 800 900 1000

[V]

Time [ms]

Stimulus (t)


KLIPPEL

85

90

95

100

105

110

115

120

125

102 103 104

Fundamental SPL

[dB]

Frequency [Hz]

0.2 s 0.5 s 1 s 2 s

測量時間的影響--掃描時間(time2s, 1s,500ms and200ms)Influence of measurement time -- sweep time2s, 1s,500ms and200ms

SPL fundamental

KLIPPEL

60

65

70

75

80

85

90

95

100

105

102 103 104

THD

[dB]

Frequency [Hz]

0.2 s 0.5 s 1 s 2 s

THD

KLIPPEL

60

65

70

75

80

85

90

95

100

102 103 104

2nd order harmonic

[dB]

Frequency [Hz]

0.2 s 0.5 s 1 s 2 s

2nd-order harmonicsKLIPPEL

40

45

50

55

60

65

70

75

80

102 103 104

R & B

[dB]

Frequency [Hz]

1 s 0.5 s 0.2 s 2 s

rub & buzz


130 dB終端電壓Voltage at Terminals

線性系統

Linear System

SPL at Mic

90 dB常規諧波Regular

Harmonics

50 dB不規則諧波

Irregular Harmonics (Defects)

40 - 60 dB

Noise

訊號成分的大小Level of the Signal Components

問題Problems:

• 缺陷的表徵非常小(但仍可聽見) symptoms of defects are very small (but still audible)

• 生產線的環境雜訊(強大的,寬頻的)ambient noise in a production environment (impulsive, wideband)

• 影響是什麼?缺陷Rub&Buzz),諧波,沒有基頻成分!!What is affected? Defects (Rub&Buzz), Harmonics, no fundamental!


最佳的SPL測試-環境雜訊檢測Optimizing SPL tests -Ambient Noise Detection

- Use test box- 每個箱體都是獨立的 each box is individual

- 測試箱體的衰減係數 measure test box attenuation.

麥克風Microphone

環境雜訊信號Ambient NoiseSignal

» 1m

測試箱Test Box

KLIPPEL

70

75

80

85

90

95

100

105

110

102 103 104

Box Attenuation

Inside Box Outside Box

attenuation -20 dB

Inside Box

outside Box

測量信號Measurement Signal

NearfieldMicrophone


在嘈雜的生產環境進行可靠的測試Reliable Measurement in a noisy production environment

Solution: 第二支麥克風測遠場噪音 Second microphone in the far field

預測待測物處的噪音 Predict noise at DUT

有效檢測測量是否被環境雜訊干擾 Detect corrupted measurements reliably

自動重複測試 Repeats measurement automatically

Stimulus

Device under Test

Noise

Detection

Fail/Pass

Repeat


環境雜訊免疫Noise Immunity

合併有效的部分

生產線上的環境雜訊可以由置於遠場的第二個麥克風來監測。被環境雜訊干擾的測量結果會自動重複測量，每個測量結果都會保存並整合，最後提供有效的測量結果。儘管每個單一的測量都被環境雜訊干擾，也確保了完全的生產線環境雜訊免疫


汽車內部的聲音品質-汽車產線的雜訊免疫Sound Quality in the Car Interior Noise immunity at a car assembling line

ambient noise source

test microphone inside the car

Progress in Data Acquisition

fundamental

rub and buzz

../../../../audiofiles/videos for demo/QC car/ni pass.wmv

../../../../audiofiles/videos for demo/QC car/ni pass.wmv


門唧唧聲的模擬Simulation of Door Buzzing

reliable detection of the defect

tambourine


揚聲器缺陷的根源Root Causes of Loudspeaker Defects

鬆散部件Loose particle

音圈摩擦Coil Rubbing

漏氣Air Leak

vibration

嗡嗡作響Buzzing

打底Bottoming

打膠的問題Glue dispenserProblem

儲藏環境差dirty storage condition

螺絲脫落Missing screw

錐盆品質分佈mass distribution on the cone

懸掛系統不對稱Asymmetrical Suspension

設計Design

來料品質檢測Qualtiy Inspectionof Incoming Parrts

生產（工藝程序控制）Manufacturing(Process Control)

供應商Supplier


Human

inspection

Measurement

FAIL

Feature

Extraction

PASS/FAIL

Detection

Fuzzy

Classification

Limits

Expertise

Knowledge

Base

Selection

PASS

Learning

Measurement

Defect

Class

Defective unit

Off-Line DiagnosticsAutomatic

End-of-Line Testing

缺陷自動分類Automatic Classification of Defects

2nd source: practical experience in manufacturing (dynamic)

1st source: theoretical knowledge in engineering (static)

Measurement

FAIL

PASS/FAIL

Detection

Limits

Expertise

Selection

PASS

Automatic

End-of-Line Testing

Measurement

FAIL

Feature

Extraction

PASS/FAIL

Detection

Fuzzy

Classification

Limits

Expertise

Knowledge

Base

Selection

PASS

Defect

Class

Automatic

End-of-Line Testing


總結Summary

揚聲器非常規失真Irregular Loudspeaker Distortions

• 由揚聲器的缺陷產生are generated by loudspeaker defects

• 被認可的模型和黃金樣品中不存在非常規失真not found in approved prototypes, golden reference unit

• 難以預測或建模are difficult to predict or model

• 由製造過程、超載工作、材料老化和環境變化導致arecaused by manufacturing, overload, ageing and ambient conditions

• 隨時間變化且與工作環境（如鬆散粒子）有關are time variant and depend on the operation condition (e.g. loose particle)

• 與成本、大小和重量沒有直接的聯繫not directly related to cost, size, weight

• 若非常規失真可聞，顧客是無法接受的inacceptable by customer if become audible


結論Conclusions

• 缺陷經過運輸，在最終使用場合會更嚴重

Defects may become worse after shipping and in final application

• 有缺陷的揚聲器不應該出貨給用戶

Defective loudspeakers should not be shipped to the customer

• 需要靈敏測量系統，它會比使用者的耳朵更加靈敏

SensitiveMeasurementtechniques are required more sensitive than the ear of the customer

• 可靠的測量應考慮環境雜訊的影響

Reliable measurements require automatic detection of invalid tests corrupted by ambient noise

• 揚聲器診斷表明了缺陷最根本的原因

Loudspeaker diagnostic shows the root cause of the defect

• 生產中需要控制工藝，動作迅速以保證高產量

Process control and fast action is required to ensure high yield rate in production

Documents

Rub & Buzz以及其他不規則揚聲器缺陷 - Klippel · Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 22 峰值&正負rms值 Peak