Post on 21-Mar-2020
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 5
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 7
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 8
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 9
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 10
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 12
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
Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 14
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
Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 15
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 !
Klippel: Sound Quality of Audio Systems, part 7, rub and buzz, defects 18
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 21
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
SPL fundamental 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
SPL fundamental 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
Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 22
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)
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 24
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
Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 26
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
Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 27
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, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 28
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
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)
50
60
70
80
90
100
110
120
130
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)
Significant defect (R&B)
50
60
70
80
90
100
110
120
130
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)
12V
-40 dB
fr&b
PHD > FUNDmean - 40dB
CHD > 12dBimpulsive
high amplitude
Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 29
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
Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 30
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
Klippel: Sound Quality of Audio Systems, part 7, rub and buzz, defects 40
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
Klippel: Sound Quality of Audio Systems, part 7, rub and buzz, defects 41
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
Klippel: Sound Quality of Audio Systems, part 7, rub and buzz, defects 43
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 44
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 49
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 50
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 51
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:Rub & Buzz以及其他不規則揚聲器缺陷, 57
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:Rub & Buzz以及其他不規則揚聲器缺陷, 58
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 60
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!
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 65
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 66
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 67
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 68
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 69
門唧唧聲的模擬Simulation of Door Buzzing
reliable detection of the defect
tambourine
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 72
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
Klippel, Sound Quality of Audio Systems, Part 10 Diagnostics on Irregular Loudspeaker Defects, 76
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 80
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
Klippel:Rub & Buzz以及其他不規則揚聲器缺陷, 81
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