Harmonic Distortion is overrated.

Summary

このビデオでは、音響における歪みについて解説しています。歪みはハーモニック歪み、インターモジュレーテッド歪み、マルチトーン歪みの3つのタイプがあります。ビデオではリアルタイムでの測定と音声を組み合わせて説明し、スピーカーXを使用した測定セットアップとリスニングセットアップを紹介しています。また、測定マイクとボイスマイクを用いてテスト音を録音し、測定プロセスとその結果をスクリーンショットと共に分析しています。異なる音量レベルでテストトーンを再生し、その違いをヘッドホンで聴くことをお勧めします。歪みテストにはハーモニック歪み、インターモジュレーテッド歪み、マルチトーン歪みの3つのテストを行い、それぞれのテストで異なるトーンを再生します。歪みテストの結果をグラフィックに示し、スピーカーの性能を理解する上で重要な情報を提供します。

Takeaways

• 📊 この動画では、ディストーションの3つの主要なタイプ：ハーモニックディストーション、インターモジュレーションディストーション、マルチトーンディストーションについて説明しています。
• 🎵 動画では、リアルタイムでの測定とオーディオの同時再生を通じて、ディストーションの種類とそのサウンドについて理解を深めます。
• 🔍 測定セットアップには、スピーカー、測定用マイク、ボイスマイクが使用されており、これらのデバイスはクリッパー近場スキャナーとディストーションアナライザに接続されています。
• 📈 ディストーションテストでは、70dBから96dBまでの4つの音量レベルで、100Hzから6kHzまでの周波数範囲でテストが行われます。
• 🎧 ヘッドホンを推奨し、テスト前に音量を下げることをお勧めします。これにより、テストトーンが非常に大きな音量で再生されることを避けることができます。
• 📉 ハーモニックディストーションテストでは、1つのトーンが再生され、そのハーモニックが測定されます。しかし、人間の耳ではハーモニックディストーションを特定するのが難しいとされています。
• 🔁 インターモジュレーションディストーション（IMD）テストでは、2つのトーンが同時に再生され、音量が上がるにつれて奇妙なワブリングサウンドが聞こえます。
• 🎶 マルチトーンディストーションテストは、音楽そのものと似ています。複数のトーンが同時に再生され、スピーカーの非線形性を引き出すことで、より現実的なディストーションの理解が得られます。
• 🔊 バンドリミットを使用することで、ディストーションと圧力を減らすことができます。これは、低音をサブウーファーに譲る場合に、スピーカーのディストーションが減少することを示しています。
• ⚙️ ディストーションテストは、スピーカーの性能を理解するための重要なツールであり、リスナーがスピーカーをどの程度まで使用できるかを判断するのに役立ちます。
• ❗ ディストーションテストの結果は、測定された距離に基づいています。距離と音量は常に一緒に考えなければならず、片方だけでは意味がありません。

Q & A

ディストーションとは何ですか？

ディストーションとは、音の波形が元の形から変化することを指します。通常、音楽や音声が再生される際に、再生装置の性能不足や過剰な音量などによって生じます。

ディストーションの種類にはどのようなものがありますか？

ディストーションにはホーミックディストーション、インターモジュレーションディストーション、マルチトーンディストーションの3つの主要なタイプがあります。

ホーミックディストーションとは何ですか？

ホーミックディストーションは、基本周波数の倍数になる周波数の音が発生することを指します。例えば、100Hzの音が鳴らされた場合、200Hz、300Hz、400Hzなどのハーモニックが生成されます。

インターモジュレーションディストーションとは何ですか？

インターモジュレーションディストーションは、2つの異なる周波数の音が同時に鳴らされたときに生じるディストーションです。基本周波数と呼ばれる低い周波数の音と、高い周波数の音との相互作用によって、新しい周波数の音が生成されます。

マルチトーンディストーションの重要性は何ですか？

マルチトーンディストーションは、音楽そのものが多数の異なる周波数の音を一度に再生するため、実際の音楽再生におけるスピーカーのディストーションを再現するのに役立ちます。これにより、スピーカーがどのように歪むのか、そしてどの程度の音量まで安全に再生できるかを理解することができます。

ディストーションテストの際にリスナーにはどのようなアドバイスをするとのことですか？

ディストーションテストの際には、ヘッドホンを装着し、テスト前に音量を下げること、そしてテスト中には音量を上げすぎないこと、また最初の音が非常に大きいように聞こえる場合は音量を下げることなどをアドバイスしています。

スピーカーのテストで使用された測定装置は何ですか？

スピーカーのテストで使用された測定装置には、測定用マイク、ボイスマイク、クリップ_near field scanner、そしてクリップable distortion analyzerが接続されたコンピュータが使用されました。これらの装置は、クリップalソフトウェアと連携して動作し、テスト結果を報告します。

スピーカーのテストで使用された音楽の周波数帯は何ですか？

テストで使用された音楽の周波数帯は、400Hzから6kHzの範囲です。この範囲は、人の声の周波数帯をカバーし、ディストーションを検出しやすいです。

テストで使用された音量レベルは何db単位で、どのように変化しましたか？

テストで使用された音量レベルは70dbから開始し、4つの段階で96dbまで増加しました。具体的には、70db、78db、86db、96dbの4つのレベルが使用されました。

ディストーションテストの結果をどのように読むことができますか？

ディストーションテストの結果は、総ホーミックディストーション、2番目のホーミックディストーション、3番目のホーミックディストーションなどのグラフで表示されます。また、マルチトーンディストーションテストでは、周波数ごとのディストーションレベルが示されます。これらのデータを元に、スピーカーの性能と制限を理解することができます。

スピーカーのテストで気をつけるべきポイントは何ですか？

スピーカーのテストで気をつけるべきポイントは、テストの距離、使用された音量レベル、再生された周波数帯、そしてディストーションテストの結果の解釈です。また、テスト結果は、特定の条件下でのスピーカーの性能を反映しているため、一般化しないでください。

Outlines

00:00

🔊 オーディオの歪みについて

このビデオではオーディオの歪みについて解説します。特に、3つの主要な歪みタイプ：ハーモニック歪み、インターモジュレーション歪み、マルチトーン歪みに焦点を当てます。ビデオではリアルタイムでの測定とそれと同期した音声を提供する予定です。測定と聴き取りのセットアップが紹介されており、様々なボリュームレベルでのテストが行われます。また、聴くためにヘッドホンの使用が推奨されており、テスト前にボリュームを低く設定するよう注意喚起されています。

05:02

📊 ハーモニック歪みの測定

ハーモニック歪みは、単一の音をテストし、その音によって生成されるハーモニクスを測定します。ビデオでは400Hzから6kHzまでの20ステップの単純な音を再生し、それぞれのステップでボリュームを70dBから96dBまで4つのレベルまで増やしていきます。歪み成分が記録されると、画面に表示されます。総ハーモニック歪みは約1％で、400Hzから1kHzまでの高アウトプットボリュームでは2番目のハーモニック歪みが目立つことがわかります。

10:03

🔁 インターモジュレーション歪み（IMD）のテスト

インターモジュレーション歪みは、2つの音を同時に再生し、それらが相互作用して新たな歪みを生成することをテストします。ここでは50Hzの基本トーンと400Hzから6kHzまでのVOICEトーンのスweepを行います。ボリュームが上がるにつれて、音の変化が聞こえ始め、特に2kHz周辺で顕著な歪みが発生します。歪みは振幅変調とドップラー歪みに分けられており、ここでは振幅変調が主な要因とされています。

15:04

🎵 マルチトーン歪みの重要性

マルチトーン歪みは、音楽のような複数の音を同時に再生し、スピーカーシステムの非線形性をテストします。これはハーモニック歪みやインターモジュレーション歪みとは異なり、実際の音楽再生における歪みを再現するのに役立ちます。ビデオではマルチトーン歪みのテストを再開し、その重要性と実際の音楽再生における歪みの理解を深めることを目的としています。

20:06

📉 マルチトーン歪みテストの結果と分析

マルチトーン歪みテストでは、フルバンド幅、100Hzからカットオフ、200Hzからカットオフの3つの異なるテストを行います。それぞれのテストでは、スピーカーが異なる周波数帯でどの程度歪みが発生するかを比較します。結果は歪みと圧力損失を示しており、バンドリミットをかけることで歪みと圧力損失の両方を減らすことができることがわかります。

25:07

👂 マルチトーン歪みと圧力損失の比較

フルバンドからのテスト結果とバンドリミット後のテスト結果を比較することで、スピーカーの歪みと圧力損失を理解することができます。フルバンド再生では歪みが高く、周波数帯を狭めることで歪みと圧力損失の両方が減少することが示されています。これはスピーカーを極端なレベルまで再生しないようにするべきという教訓も提供しています。

30:08

🔊 音響テストの意義とリスニングテスト

ビデオの最終部では、スピーカーの歪みとリスニング体験について話します。スピーカーを近距離で聴くことの重要性と、距離と音量の関係について説明します。また、スピーカーの評価指標として音量と距離を組み合わせる必要性を強調しています。さらに、リスニングテストを行い、スピーカーの歪みを実感することを促します。

35:09

📚 オーディオテストの複雑性と学びのコミュニティ

ビデオの締めくくりでは、オーディオテストの複雑性と学びの重要性について触れています。スピーカーの歪みを理解することの難しさと、コミュニティを通じて学びを深めることを提案しています。また、今後のライブストリームやゲストを招待する可能性についても言及し、オーディオ専門家の知識を共有し、より深い理解を目指す意向を示しています。

🔧 スピーカーのテストと評価

ビデオでは、スピーカーのテストと評価に関する洞察を提供しています。スピーカーを極端なレベルまで再生することの意義と、リスニング距離が音の音量と質に与える影響について解説しています。また、スピーカーの性能を正確に測るためには、リスニング距離と音量の両方を考慮する必要性を強調しています。

Keywords

💡ディストーション（Distortion）

ディストーションとは音響において、音の波形が変形し本来の音と異なる状態に変化する現象を指します。ビデオでは、ディストーションがどのような音を産み出し、どのように測定されるかが解説されています。例えば、和音ディストーション（Harmonic Distortion）やインターモジュレーションディストーション（Intermodulated Distortion）など、様々なタイプのディストーションが存在し、スピーカーの性能評価に重要な役割を果たします。

💡ハーモニックディストーション（Harmonic Distortion）

ハーモニックディストーションは、基本周波数の整数倍周波数が生じることで発生するディストーションです。ビデオでは、100Hzの音が鳴ると200Hz、300Hzなどのハーモニックが生じることでディストーションが測定される様子が紹介されています。このディストーションは、スピーカーが楽音を再生する際に発生し、聴覚的にはある程度まで覆い隠されることがあると説明されています。

💡インターモジュレーションディストーション（Intermodulated Distortion）

インターモジュレーションディストーションは、2つの異なる周波数の音を同時に鳴らせることで発生するディストーションです。ビデオでは、50Hzの基本周波数と400Hzから6kHzまでの声音を同時に鳴らせることで、音量を上げていくと不規則な音が聞こえる様子が示されています。この現象は振動の相位の違いによって生じるドップラー歪（Doppler Distortion）や振幅変調による歪みと関連しています。

💡マルチトーンディストーション（Multi-tone Distortion）

マルチトーンディストーションは、複数の周波数を同時に鳴らせることでスピーカーシステムの非線形性を引き出し、より実際の音楽再生状況をシミュレートするディストーションです。ビデオでは、このテストが楽器の異なる音や楽曲の複雑さを再現し、スピーカーがどの程度の歪みを起こしうかを評価する上で最も重要なテストであると主張しています。

💡スピーカー（Speaker）

スピーカーとは、電気信号を音に変換するデバイスです。ビデオではスピーカーXを使用し、ディストーションの測定と聴き比べのために使用されています。スピーカーの性能はディストーションのレベルによって評価され、スピーカーが楽音を再生する際の質に大きな影響を与えます。

💡周波数（Frequency）

周波数は、1秒間に繰り返される波のサイクル数を表す単位Hz（ヘルツ）で測られます。ビデオでは、ハーモニックディストーションテストやインターモジュレーションディストーションテストで400Hzから6kHzまでの周波数の範囲が取り上げられています。周波数は音の高さを決定し、スピーカーが再生する音の質に直接関係します。

💡音量（Volume）

音量は音の大さを指し、ビデオではデシベル（dB）で測られます。ビデオでは、70dBから96dBまでの4つのレベルでテストが行われ、音量がどのようにディストーションに影響を与えるかが解説されています。また、聴覚に与える影響やスピーカーの性能評価においても音量は重要な要素です。

💡圧縮（Compression）

圧縮とは、音の振幅が一定を超えた場合に生じる音の削減現象です。ビデオでは、スピーカーが音量を上げるときの出力が低下する様子が圧縮と呼ばれ、ディストーションと同様スピーカーの性能を評価する上で重要な指標となります。

💡測定マイク（Measurement Microphone）

測定マイクとは、音圧や周波数特性を正確に測定するための特別なマイクです。ビデオでは、測定マイクを使用してスピーカーからの音を捕捉し、ディストーションの測定を行います。測定マイクはスピーカーの性能を客観的に評価する上で不可欠な工具です。

💡マルチバンド制限（Band Limiting）

マルチバンド制限は、スピーカーの再生周波数帯域を特定の範囲に限定する処理です。ビデオでは、スピーカーを20Hzから20kHzまでの全バンドでテストするだけでなく、100Hzから20kHzや200Hzから20kHzの範囲に制限してテストすることで、スピーカーの性能を評価しています。バンド制限はスピーカーの歪みを減らし、効率を向上させる効果があります。

Highlights

介绍了三种主要的失真类型：谐波失真、互调失真和多音调失真。

视频将通过实时测量和音频展示来解释失真类型。

展示了整个测量和听音设置，包括扬声器、测量麦克风和声音麦克风。

解释了测试麦克风通过Clipper近场扫描仪连接到Clippable失真分析仪的过程。

将测试音频和测量过程的截图同步，以展示整个测试过程。

测试将从70分贝逐步增加到96分贝，以展示不同音量下的失真情况。

建议使用耳机进行测试，以便更容易区分不同的失真。

在播放测试音之前，提醒观众降低音量以保护听力。

谐波失真测试是通过播放单一音调并捕捉其产生的谐波来进行的。

在400赫兹到6千赫兹的范围内进行谐波失真测试，重点关注声音区域。

总谐波失真在70分贝到87或88分贝之间大约为1%。

第二谐波失真在高输出音量下显著增加，可能导致听到失真。

互调失真(IMD)测试通过同时播放两个音调来揭示非线性失真。

多音调失真测试通过播放多个音调来模拟音乐中的复杂声波。

多音调失真测试结果表明，限制频率范围可以减少失真和压缩。

视频最后强调了在测量中考虑音量和距离的重要性。

提出了未来可能进行直播讨论失真主题的想法。

Transcripts

distortion i know you've heard that term

before but what does it mean what does

it sound like that's what we're going to

talk about in today's video

[Music]

in order to keep this video short i'm

going to try to keep things very concise

and to the point there are three main

types of distortion harmonic distortion

intermodulated distortion multi-tone

distortion and in this video what i'm

going to try to do my best at is to

provide you with

real time measurements

synced up with

audio of those measurements so what

we've got here is the entire measurement

setup and listening setup

we've got the speaker which is speaker x

now i may block this out because i don't

want people focusing on the speaker i

want them focusing on the content of

this video

we've got my measurement microphone

and then we've got my voice microphone

now normally the voice microphone would

not be out here it's only out here for

my testing

we normally have the test microphone

only which runs through the clipper near

field scanner out the bottom

and then runs into the clippable

distortion analyzer which is tied into

my computer which is tied into the

clipal software and depending on what

module or what test i'm trying to run at

the time the software knows what to do

with the stimulus collected from the

microphone and then it will report that

to me on the screen

what i'm going to do in this video is

i'm going to actually be recording the

stimulus sent out from the speaker

captured by the measurement microphone

as well as captured by the voice

microphone now this voice microphone is

connected to my computer that's inside

so what i'm going to be doing is

collecting audio from the test while i'm

also grabbing a screenshot of the

measurement process and for each one i'm

going to talk to you about what the

measurements are showing you as it's

being conducted or maybe after depending

on how hard this whole video is to put

together

as part of all of this testing

you're going to be listening to a tone

or a series of tones depending on what

the test is which i'm going to cover in

a second now that tone or series of

tones is going to be

swept at different volumes

first volume is going to be 70 db at 1

meter and then the last volume is going

to be 96 db at 1 meter and we're going

to step in four increments so we're

going to go

roughly 70 to 78 to 86 to 96 and yes i

know 86 to 96 isn't the same step but

it's like eight and a half db in between

i'm not going to do that math in my head

and look like a fool in real time

because i can't math

but

regardless of that that's what the video

is going to be showing you and that's

what you're going to hear now for each

test so the harmonic distortion imd

multi-tone test

i'm going to play different tones right

and i'll explain to you what those tones

are going to be before i start each test

but just understand up front that you're

going to hear four different volume

levels for each test that i'm doing

i also suggest that you wear headphones

for this test because while you can hear

the differences to your phone through

your pc speakers through your

loudspeakers in your listening room tv

speakers whatever you can hear the

difference hearing the difference on

headphones is much much easier and also

with that said

since i'm going to be playing test tones

what i'd suggest you do is before i play

each test before i start each test

turn the volume down so start at a low

volume now

the flip side of that is when the first

tone plays it's going to be at that 7 db

volume so it's not going to sound as

loud but you can play around with the

volume you can restart the test when you

figure out what's too loud what i don't

want you to do is to have headphones on

and have your volume cranked up and then

that first tone comes in or that last

tone comes in and it just blows your

ears off so i warn you again

start with the volume low before each

test i'll throw up a graphic to warn you

i'll give you five seconds to turn the

volume down make sure you do that and

then you can go back and listen to

different volumes as you need to now for

what it's worth

i did all this testing one round earlier

to make sure that i'm not going to run

into distortion for the voice microphone

where it is and on my motu m2

the volume bars that give me an idea

where the signal level is it's always

green so it never even hits yellow so no

issues with the voice microphone at all

and then this measurement microphone can

take a lot of spl before it runs into

issues but at the same time i don't want

it too far away because if i have it

much further away then i'm going to

capture a lot of the room environment

and you're going to hear some of the

room from the voice microphone but just

understand that normally this isn't how

i conduct my tests this is just set up

for this video i want to state that

right up front

the first test is going to be the

harmonic distortion test the harmonic

distortion test is just a test of one

tone at a time and then it picks up the

harmonics created by that tone

so you can have a tone of 100 hertz and

then the next harmonic of that is 200

hertz and then 300 hertz 400 hertz 500

hertz so on and so forth meaning that

the fundamental tone 100 hertz has a

second order harmonic two times 100 200

hertz has a third order harmonic three

times 100 the fundamental 300 hertz okay

i don't know why i just did that either

that was really weird um the fourth

order harmonic is going to be four times

the fundamental which is 100 so that's

going to be 400 hertz then 500 600 hertz

so on and so forth that's how you get

the harmonics of the fundamental test

tone now in my opinion hearing harmonic

distortion

i just don't think that we have the ear

for that now i know some people say that

they can hear harmonic distortion and i

think to a degree they can hear

distortion or they can i should say i

think they can hear distortion but i

don't think that they can singularly say

it's harmonic distortion because when

you listen to music you're listening to

a lot of different tones at one time

you're not listening to one tone which

again remember harmonic distortion and

we're going to touch on that in a

subsequent set of

sweeps and you'll see what i mean when

we get to that point but for right now

let's focus on the harmonic distortion

so what i'm going to do is i'm going to

play one tone at a time from 400 hertz

to 6 kilohertz and the reason i chose

that band is because i wanted to focus

on the voice region because it's easier

to pick up

distortions through that region and plus

it'll save us some time

normally we also will typically run the

harmonic distortion as a sweep so it'll

sound like

and you probably heard that before but

for the purpose of this video it's going

to be harder to

pick out the individual tones so that's

why i'm doing individual tones there's

going to be 20 steps from 400 hertz to 6

kilohertz it's going to take a little

bit of time give it time

remember wear your headphones but also

remember go ahead and turn your volume

down you can always turn it back up and

start this section over again if you

want to

play it safe turn the volume down don't

blast your ears off and here we go

first of all i want to state that up

here are the different voltage levels

that represent the output volume

1.13 volts is fed to the speaker that

results in about 70 db at one meter

3.06 volts is about 78 db

this is about 86 87 db and then this is

about 96 db all again at one meter when

the tones play you're going to hear

this voltage this voltage this voltage

then this voltage in that order so it's

going to sound like

it's just going to keep ramping up in

volume when those distortion components

are recorded they'll be displayed on the

screen so it's going to take a little

bit of a second for them to display

there's a little bit of a lag up here in

the top left is the total harmonic

distortion

y-axis is zero to ten percent this is in

percent

second harmonic distortion is over here

third harmonic distortion is down here

and then this is going to show you in

real time the tone that's playing

and the voltage that is playing

and then once i get through playing all

these

we'll come back we'll discuss this a

little bit

[Music]

[Music]

let's talk about the results what we can

see is the total harmonic distortion

is about one percent for the most part

from 70 db to about 87 or 88 db

except for

400 hertz to 1 kilohertz at the high

output volume 96 db

relatively high i mean it's above 3

so that's interesting we can see that

something certainly breaks down between

about 88 to 96 db

what makes that distortion component so

high well we can see if we look over

here at the second order harmonic

distortion it's right here so when 400

hertz is played it's going to sound more

like 800 hertz and when one kilohertz is

played it's going to sound more like 2

kilohertz

at this output level than it does at the

lower output levels

as compared to the third order harmonic

distortion where all this is below

roughly half a percent

so more than likely if you do hear

distortion artifacts it's going to be

born from the second order distortion

and given that the second order

distortion is so close to the

fundamental

it is likely to be masked meaning that

it's going to be covered up by the

fundamental tone because it's still

relatively low in level at 3 percent

it's about 30 db down now depending on

the muse that you're listening to and

depending on how good your ear is

you may or may not hear this distortion

and i'll be honest with you in this

particular test i didn't hear this

distortion if harmonic distortion is one

tone at a time

then intermodular distortion which is

what we're talking about right now

is two tones at a time

meaning that

normally what you do is you fix a base

tone and in this particular case i'm

going to be playing 50 hertz

what i'm also going to do is play

a sweep of voice tones those voice tones

are going to be 400 hertz to 6 kilohertz

and 20 different steps just the same as

it was for the harmonic distortion so

the difference here between imd and hd

testing is going to be now with imd

testing i'm adding that 50 hertz

fundamental tone now what you're going

to hear is that lower volumes it'll

probably sound okay you're going to hear

basically just the two tones playing at

one time

but as i increase the volume higher and

higher through those four different

steps

you're going to hear some weirdness

you're going to hear probably what

sounds like

maybe best described as a warble sound

it's going to sound weird that's

intermodulated distortion and that's

created by playing a fundamental tone at

a lower frequency and then higher

frequencies now you can also do this the

other way around

intermodular distortion can be any set

of two tones but that's what i'm playing

right now 50 hertz and then sweeping a

bunch of different tones through the

voice region

listen for how those tones

sound different as i increase the volume

and what you're going to be picking up

on most likely is going to be the

amplitude modulation there is doppler

distortion which is caused by phase or

timing differences

when you have a small driver and it's

moving a lot of excursion like one way

then that creates doppler distortion but

you're not going to hear doppler storage

and you're going to be hearing amplitude

modulation and for what it's worth i

made a post on my facebook group

overnight last night

and then lars riesbo from purify replied

back now my understanding of what i was

hearing i thought it was doppler

distortion this is just me being

completely candid because i don't know

everything i try to do the best i can

with trying to help people understand

and trying to teach i'm still learning

continually and i think this is a great

opportunity for us all to learn so

that's why i'm telling you this okay

so lars posted a link basically saying

hey aaron you think it's doppler but

it's really amplitude modulation and it

turns out that

you hear amplitude modulation klipple

has a white paper on this i'll try to

link it in the description below

so in the particular case of this

speaker yes indeed i'm hearing amplitude

modulation and in the data that we're

going to see in real time you're going

to see that it's dominated by amplitude

modulated distortion there's also a lot

of doppler distortion but you're not

going to be hearing that you're going to

be hearing the amplitude modulation

because it is much more dominant than

doppler distortion and i'll put the link

below because they have a really good

link on the purify website to show you

the difference of those two bottom cells

because there's no way for me to

separate those two different

contributions amplitude modulation and

frequency modulation aka doppler

distortion i can't separate that in this

particular test but they've done a

really good job of doing that on their

website i'll link that below you can

follow that so yes put your headphones

on turn your volume down let's kick off

the imd test

before i let this play all the way

through i want to point out a couple

things real fast the second order

distortion is up here and the third

order distortion is down here

but mainly note that i've had to change

the scale from zero percent to 100

percent

rather than zero to ten percent like you

saw with the harmonic distortion the

reason for that is you're about to see

some of these numbers jump drastically

especially when you get to around two

kilohertz

listen for how that third voltage and

that fourth voltage sound it'll almost

sound like

to me it reminds me of like a bird

whistling the pitch of the frequency

changes so much and remember what we're

doing in this test is we're playing

a 50 hertz tone down here but we're

recording

the voice tones up here so we're

basically just trying to see how much a

base tone affects the higher frequency

in the mid frequency tones and this test

clearly shows you

just how

close excursion is tied to amplitude and

doppler distortion in the mid to high

frequencies this graphic up here shows

the amplitude distortion in red and then

it's also going to show the doppler

distortion and that's covered by the

blue gray and black the black and the

gray are the components that make up the

doppler distortion now if you go back to

that screenshot that i provided briefly

a second ago or follow the link to

clipple's i said white paper it's it's

actually a presentation

if you look at this screenshot from

clipple's presentation i'm basically

paraphrasing but essentially what it

says to me

is that amplitude modulation is

detectable at about three percent three

percent would be negative 30 db down in

amplitude they state that doppler

distortion is at about 20 db higher than

that so about negative 10 db down

and that's where those thresholds of

distortion are going to come into play

now at this particular voltage because

i'm only showing one voltage in this

actual pane those all run together so

it's really hard to tell what's

contributing to what other than the fact

that we know based on what i said

earlier that amplitude modulation is

easier to detect so more than likely

what you're hearing

is from amplitude modulation and then

some of course influence from the

doppler distortion

[Music]

foreign

[Music]

[Music]

um

okay now that imd testing is done let's

talk about multi-tone distortion

harmonic distortion was one tone

imd distortion that's redundant was two

tones multi-tone distortion is multiple

tones multiple times multiple turns like

see i just did those are three different

tones that i just did

when you played multiple tones you enact

a lot of non-linearities in the speaker

system or the drivers themselves

and in doing so you're able to highlight

distortions that you wouldn't otherwise

hear with just a harmonic distortion

sweep or just intermodulated distortion

and in my opinion if you're going to

present one bit of evidence for

distortion data that actually makes

sense

then it's multi-tone distortion and

here i am being a hypocrite

i used to provide that up until about a

year and a half ago

and i kind of just

nobody was looking at it nobody was ever

commenting on it i don't think people

understood how to read it and i didn't

really do a good enough job of

explaining it i guess so some of that's

on me and i just quit providing it but

with this most recent speaker test when

i hooked this thing up and was listening

even in the near field

not very high volume you can hear all

sorts of graininess

now that graininess isn't from harmonic

distortion and it's not from imd at

least not singularly

it's from multiple tones being played at

the same time multiple tones

is what music is made up of music is a

whole bunch of sound waves a whole bunch

of tones played at one time and i guess

you could play square waves if you

wanted to synth i love scent music but

understand what i'm saying when i say

that music is just tones it's all it's

what it is it's just made up of tones

different frequencies different

harmonics an instrument has a

fundamental frequency and it has its own

harmonic profile that's why

that's why a bassoon sounds different

than a bass that's why a flute sounds

different than a clarinet you could play

the same fundamental tone

but the harmonics are different

and when you play back music you're

playing vocals you're playing

instruments you're playing synthesized

stuff you're playing a lot of different

things at one time and that's what makes

things get more distorted from a real

speaker and so because of this listening

test that i did last night i decided you

know what ma'am

i need to start doing that again and i

thought if i'm going to do that again i

need to make a video explaining why i'm

doing that and that's this video

basically this entire video is

predicated on me providing multi-tone

distortion testing again because in my

opinion that is the quintessential

testing that needs to be provided for a

loudspeaker harmonic distortion is good

for some reasons intermod distortion is

good for some reasons

but multi-tone distortion simulates

music it provides you with complex

series of tones

and it gives you a more real-world

understanding of

how the speaker is going to react in

terms of distortion and in terms of

compression

now keep in mind the compression that

you're going to see in this data test is

going to be different than the

compression that i already provided and

if i need to i'll make a separate video

for that but hopefully for right now

that's good enough

so what i'm going to do is i'm actually

going to run this multi-tone distortion

testing three different times the first

time is going to be full bandwidth

20 hertz to 20 kilohertz the second time

is going to be 100 hertz to 20 kilohertz

and then the third time is going to be

200 hertz to 20 kilohertz now you may be

thinking aaron why are you doing this

three different times think about it

like this

you know that when you high pass a

bookshelf speaker to a subwoofer you

release the stream from that bookshelf

speaker it doesn't have to play low

frequencies anymore and you probably

know from experience that when you do

that you can increase the volume and

have

more

output from that speaker with less

distortion that's basically what i'm

trying to emulate in this test is a high

pass filter

depending on what i'm testing i'll

probably change the filter i may stick

it 80 hertz i don't know but for this

particular speaker being a full range

speaker three inch

surface area i'll let you try to figure

out what it is if i'm not here showing

it here

i wanted to see what happens if i let it

play full band cut it off at 100 hertz

and then do another test cutting it off

at 200 hertz so what i want you to do

and what i expect you're going to need

to do

is listen to each of these three

different tests but then go back and

forth between them try to compare the

highest output which is going to be

around 22 volts

between the three different tests and

i'll screenshot at the end

the difference in all of those so i'll

show you what the distortion looks like

and what the compression looks like

compared between the three different

sets at the highest output volume and

you'll see that it is different and

you'll think to yourself why is it

different right because

if you're only concerning yourself with

the distortion in the vocal region

what you would expect then is that

that's not going to change

regardless of whether or not i play low

frequencies or not but remember this

isn't one tone distortion testing this

is multi-tone so if i'm not asking the

speaker to play down to 20 hertz or 50

hertz

then there's going to be less distortion

in the mid-range and the high frequency

and i know that may sound weird but

you'll see the data and you'll

understand what i mean and then you'll

understand why multi-tone distortion

testing is like in my opinion it's light

years beyond harmonic distortion and

that's why i'm going to start doing that

testing again because it's important to

do

and

anyway that's kind of enough rambling

for me let me run those three tests and

then we'll talk about the results and

then we'll go on

i've already skipped to the end of this

first test result because i want to show

you what you're looking at here

on the bottom is the distortion

okay and this is relative to the

fundamental when something says relative

to the fundamental that's why you have

negative values rather than percent

i like using

relative to the fundamental because

percent sometimes can jump off the scale

pretty quickly and it's hard to tell the

difference between one percent fifty

percent so when you use relative to the

fundamental it's easier to tell these

differences and this is a good case for

where relative

is easier to show than percentage scale

okay

the black line represents the noise

floor in the room and this is important

because as you get lower in frequency

the output of this speaker is low its

roll-off is is around 150 hertz or so

and so that means that the output of the

speaker is

not easily able to overcome the just

regular old ambient noise of a static

room even if there's nothing going on in

the room itself

the room has a noise floor and the lower

frequency you go

the higher that noise floor is

so at some point on the lower end the

results are kind of

i would say they're basically inaccurate

if i'm being honest

but as long as you understand that then

you can still know how to use the data

and i would say generally speaking above

about 50 hertz you're okay to use that

data

okay

so then the gray lines represent each

voltage that has been tested

and then the green line represents the

last voltage that's been tested so when

it gets to this final 22.47 right here

that's this right there and this is

showing us that the last voltage tested

22.47 so that's 96 db out output i

should say at 1 meter

is about negative 10 db down

in terms of distortion well that's

really really high you're definitely

going to hear that

this one is 8.32 volts

3.07 volts 1.13 volts so 70 db

78 db 86 87 something like that db and

then 96 db

now if we go up here this is compression

and this shows us

how much output we are losing as we

increase the volume and this is all

relative to the initial

output

voltage or output spl

so

notice you only have three lines here

right you have the green one and then

two grays why don't you have four grays

like you did down here because the first

gray is your baseline

that's basically this flat gray bar

right through here so the other voltages

are referenced to

this initial voltage right there

everything is referenced to 70 db

as you increase from 70 db

to

96 db well according to this data

you've

lost 3 db in compression i know that the

results right here say negative down

here but the way that this particular

data is represented a positive is a loss

in output so you have lost

about three actually to four db of

output as you've increased the volume so

you wanted to be at 96 db well it turns

out you were actually at around 93 to

92 db because you've lost

output due to some kind of compression

issue probably like heating of the voice

coil or something along those lines and

again i mentioned earlier that i think

when i hear the graininess of sound that

that's due to compression and i recall

reading that somewhere but if i'm being

honest i don't recall where so take that

maybe for now with a grain of salt but

keep this information in mind i'm about

to play back the stimulus starting from

the beginning i'm going to speed it up

so it doesn't quite take as long but

listen for how grainy the sound is as

you get to this 3 volts 8 volts 22 volts

i'm telling you you're going to be like

whoa and it's going to be way more

eye-opening than the harmonic distortion

and certainly even more eye-opening than

the intermodulated distortion so put

your headphones on turn the volume down

a little bit and let's go

[Music]

now let's compare the 96 db

output for each of the three multi-tone

distortion tests

again those three are going to be

full band 20 hertz to 20 kilohertz in

red

100 hertz to 20 kilohertz in blue

and 200 hertz to 20 kilohertz in black

and what you notice right off the top is

in red the full band has higher

distortion throughout and if you band

pass this speaker from 200 hertz in

black and above

then you have about

negative 10 db which is about 33

i believe

down to about negative 30 db and maybe

negative 25 db so i'm ballparking that

at around

three percent to about maybe five

percent thd

so you lose a ton

of distortion

going from

full band to band limited if you were to

put a subwoofer with this system then

you could see that you would save

yourself a lot of distortion but what

happens when you talk about compression

here we are

0db references the

lowest output anything above this is

output that is lost same thing as before

20 hertz 220 kilohertz is in red and

then the other colors represent the

other tests

in red you lose about four three to four

db depending on what frequency you're

talking about but if you band limit this

speaker you save some output so you

actually only lose about

2 db to 3 db and when i say only lose

well

that's not

a little bit but you do see that you

save some compression by band limiting

the speaker so you save compression you

save distortion by band limiting the

speaker but more importantly i think

this data tells us don't play the

speaker that loud and i think anybody

realistically already knows that now

just to recap i'm going to play

these three sound clips

back to back so you can hear what they

sound like all in a row and save you

some time from having to scroll all the

way to the back

[Music]

that's it for this video

what i hope is that you've learned

something from it now what i encourage

you to do is to ask any questions if you

have them i'm going to try to drop a

bunch of links

in the description below to various

sources from clipple the one i mentioned

from purify as well

and what i may do if i have enough

interest is i may just do a live stream

sometime soon and we can talk in real

time about this video because

i understand that it's complex and trust

me it gets a lot more complex because

the stuff that i've learned in the last

decade i don't even remember half of it

i'd be lucky if i remember like 1 20th

of it and a lot of that goes a long way

toward explaining

the different distortion elements the

non-linearity so

if the

suspension isn't uniform in versus out

if the motor force isn't uniform

inverses out

through excursion

that creeps up in different forms and at

different frequencies

depending on the speaker itself so a

large woofer may behave differently than

a small mid-range and all of this stuff

matters the devil really is in the

details but my hope is

between just a basic harmonic distortion

sweep to give you an idea of how low you

can take a driver

and

the multi-tone distortion which will

give you an idea of the contributing

factors toward maybe high distortion and

when you can expect the speaker to start

sounding really grainy and have an idea

of how loud you can turn it up

between all of that you'll be better

informed and you'll better understand

this topic itself rather than just

saying yeah it's high distortion like i

said if you have any questions please

ask in the comments below i apologize if

you feel like this video has taken too

long but if you want to learn that's

what i'm trying to do is i'm trying to

help you learn trying to help teach and

i'm trying to teach myself at the same

time and as a community we will all grow

in our learning and our understanding

and these won't be just numbers that

somebody put up on a website these will

actually make sense and mean something

to us and that's important because the

data is important

i don't do this stuff trivially and i

truly believe that having more

information is much better than just

having me say

it doesn't get loud

that's useless so with that all said yes

i appreciate you watching if you have

any questions let me know and if you're

interested in a live stream sometime let

me know try to do that sometime soon

talk about this stuff and maybe i can

try to have some guests on that are well

more versed in these different

distortion types and the reasons for

them at some point the future

but for now hopefully this is good

enough gives you a good idea of what the

distortion sound like and how to track

it in the measurements and i will talk

to you all later take care

peace

it's really hot in this garage i gotta

turn the ac on

later y'all

if you're thinking to yourself

you chose the worst possible speaker to

do this with why would you push

this little speaker to such high levels

well that's actually the point

that's exactly why

i'm using this speaker

when i listened to it within like a

meter so like three feet just

a regular pair of speakers

i started to hear

compression i started to hear that

grainy sound that i often tribute to

compression and that's what triggered me

into thinking i need to do some

additional testing of the speaker and

then i need to do a video to explain

what that data means and then i thought

man i need to start doing this again for

future speakers

so while i don't think that i would

necessarily push such a speaker

to the limits that maybe i'm going to

show you in this video i can say that to

some degree i actually did

and that really matters when you're

talking about listening at different

distances so here's the thing

when somebody says

a certain volume level so they say 80db

that number is meaningless unless they

tell you how far away they are from the

speaker

80 db

at

a few feet away is going to sound a lot

louder to you than it would be if you

are

10 feet away because the further you get

away from that speaker the less loud

it's going to seem you already know this

every doubling of distance

drops the amplitude by about 6 db

and depending on which source you read

and depending on what frequency range

you're talking about

research shows that our perception of

output

doubles in terms of it sounds twice as

loud

between 6 to 10 db of volume increase

so

if i take the volume from 80 to 90 db

then it sounds twice as loud conversely

if i take it from 80 to 70 db then it

sounds half as loud

now if i move from maybe a foot away to

three feet away or a little bit further

well that's going to drop the volume

level or the spl level a lot so it could

sound half as loud

that's what matters

if you're listening close you don't have

to turn the volume as loud as you do

when you're listening further away so

when some person says i'll listen to

80db and you're saying well i do too but

i'm having these issues well you may be

listening to different distances number

one that that could be a problem

so when i talk about running these tests

at x volume i'll always specify at one

meter or however far away because that's

important if you're at one meter away

and then you go two meters away so

roughly six feet

then you drop the volume by six db so

it's almost not quite as loud or not

twice as loud anymore just keep that in

mind i see this come up a lot and i i

think a lot of people don't quite

understand the significance of not just

volume but volume and distance those

should always always always

be paired together because

one number is useless without the other