Class D後級 Vs Class AB後級

天下第一刀

Class D後級 Vs Class AB後級
看了DiyAudio.com上對Class D後級 及 Class AB後級的爭論﹐
http://www.diyaudio.com/forums/c ... ss-d-amplifier.html
“Saturnus”講Class D後級跟Class AB後級的競爭與及超越大部份Class AB後級已
經是事實﹐ “The golden mean”不同意該說法及說用Class D後級已經令人頭痛﹔也是事實。

經實際檢測發現﹐市面大部份Class AB後級的靜態工作電流在100MA以下﹐就是技術上所謂的低偏置Class AB﹐其瞬態互調失真嚴重到難以忍受的地步﹐用于電分作高音放大時高音單元出現破裂聲﹐當將每個功率管靜態工作電流調整到１５０ＭＡ時破裂聲開始消失﹐到２５０ＭＡ時破裂聲完全消失﹐也是當前所謂的Class A後級每個功率管的實際靜態工作電流。

因此高偏置Class AB總的聽感上是秒殺Class D後級﹐因為Class D後級低音沒有彈性及高音損失嚴重。。。。。

odysseyhk

This type of argument is not going to add value.  It just simply cannot be generalized   that one is better than the other by referencing to the category of design.  It depends on the actual detail design of the specific amp.  

I used class A/AB and class D amp and they could all perform well.  The argument of one is better than the other would mostly base on personal preference indeed.

ma73

Class D後級 及 Class AB 後級的爭論, it is forever

天下第一刀

odysseyhk 發表於 2013-10-13 10:08
This type of argument is not going to add value.  It just simply cannot be generalized   that one is ...

大部份人用class D amp作80HZ以下的超低音後級﹐後果比class Ｂ amp及低偏置Class
AB好很多。盡管每個人愛好吾同﹐但作監聽實在無法還原大提琴等音樂實際的自然聲音。

天下第一刀

ma73 發表於 2013-10-13 10:30
Class D後級 及 Class AB 後級的爭論, it is forever

如果是汽車那種Class AB 後級﹐Class D後級可能好些

odysseyhk

You just missed the point , there are many different class d design and implementations, and therefore conclusion  of 聽感 could not be drawn by simply theory and generalization.

i.e. You cannot draw conclusion of "無法還原大提琴等音樂實際的自然聲音"  with theory and generalization .  "自然聲音" is subjective 聽感 and need to be supported by audition .

You made a lot of technical judgement here. But there are many steps missing before you could draw conclusion. End to end system detail design and execution are going to impact the end results .  

What u are saying is unfair to all the engineers who work hard to continue innovate and make a class-d design sound better and better . Cos you just pick one disadvantage of class-d , amplified it's impact and made solid judgement by your theory .  You ignored all the refinement and innovation of the design.

I'd prefer more open mind compare of the end product of different designs to appreciate the end results achieved, understand the constraints and looking forward how to overcome them .

haha12

Very well said, Odyssey Hing,

20-30 years ago, the audiophile industry major focus is Class A and AB, and since then there has been endless arguments.

While Class A and AB are  mature technology know how, Class D has been getting quite a bit of traction in recent years due to technological advancements and the ability to deliver high power loading efficiently with superb transient responses.

A friend of mine running a professional hi-end audio studio is using a Class D gear for monitoring and the outcome  far exceeds my expectation. IMHO, it is an area that worth investigation in the coming years.

odysseyhk

haha12,

Fully agree. While we appreciate the legendary audio components which brought us enjoyment over years, audio industry needs innovation.

Like any changes, there are people resist to change and find argument why new things are not good or won't work. There are people try find out why new things are not good enough and make it better.

There are many examples.

CAS cannot beat CD
Digital camera cannot beat film
Man cannot land on moon   (Well there are still conspiracy theories saying that man never have landed on moon.)

I'm not trying to argue what is right or wrong. What I'm trying to say is better keep our mind young, open and full of curiosity, looking for way to beat the great oldies and enjoy better music quality and convenience.

Mamiya

How about Class TD ?

http://labgruppen.com/about/history/class_td_and_dsp/

天下第一刀

odysseyhk 發表於 2013-10-13 11:33
You just missed the point , there are many different class d design and implementations, and therefo ...

Class D放大器与傳統的模擬功放是兩种不同的工作原理，
它屬于開關型的音頻功放，
d類使用的是pwm技術，是一种開關頻率隨著時鐘脈沖周期而變化的放大器。在大功率應用場合，數字功放同時具有頻率響應寬，大動態范圍和良好的瞬態響應。他的优點是失真小、抗干擾能力強、散熱器面積小、體積小重量輕、電源功耗小、轉換效率高、具有甲乙類的音質。目前主要是成本較貴，雖著現在軟硬件技術的發展成本降低，數字功放的應用會越來越多。

Class D AMP是否適合發燒人士的要求也即HIEND的要求﹖
如果你也認為‘這种放大器直接從數字語音數据實現功率放大而不需要進行模擬轉
換，這樣的放大器通常稱作數字功率放大器或者D類放大器。 ’
http://www.ednchina.com/ART_3709 ... omead_1381661725492
在沒有了解Class D前我也想當然如此﹐如此方式真的秒殺所有ＤＡＣ＋ＣＬＡＳＳＡ後級﹔問題是所謂的‘不需要進行模擬轉換’根本上在擴音機輸入電路中插入一個ＤＡＣ。

D類(數字音頻功率)放大器是一种將輸入模擬音頻信號或PCM數字信息ＤＡＣ後變換成PWM(脈沖亮度調制)或PDM(脈沖密度調制)的脈沖信號,然后用PWM或PDM的脈沖信號去控制大功率開關器件通/斷音頻功率放大器，也稱為開關放大器。具有效率高的突出优點.數字音頻功率放大器也看上去成是一個一比特的功率數模變換器.放大器由輸入信號處理電路、開關信號形成電路、大功率開關電路(半橋式和全橋式)和低通濾波器(LC)等四部分組成.D類放大或數字式放大器。系利用極高頻率的轉換開關電路來放大音頻信號的。
（現在的開關穩壓電源分PWM脈沖調寬及FM調頻的方式﹐PWM由于頻率固定﹐因而濾波易一些﹔FM由于頻率不固定因而濾波難一些﹐但用于音響的反應高速很多。）
FM收音機調制頻段是88MHZ到108MHZ﹐因此﹐D類後級不論是用PWM or PDM 或者FM調制﹐要跟上FM收音機的音質就必須工作在88MHZ到108MHZ。但以目前技術及成本的限制而無法實施﹐現在實施的結果是效率及音質不如Class A.

我也想買一個真正的‘直接從數字語音數据實現功率放大而不需要進行模擬轉換’的音頻功率放大器﹐你有嗎﹖

天下第一刀

odysseyhk 發表於 2013-10-13 13:22
haha12,

Fully agree. While we appreciate the legendary audio components which brought us enjoyment ...

音響技術已經在不斷創新﹐但在此是講ＨＩＥＮＤ﹐ＣＡＳ我可以簡單地用一塊專業
Sound Card做到CD的音質﹐所有我接受ＣＡＳ﹔但CLASS D後級我只接受其人聲部份﹐
超低音喇叭的功率放大也可以考慮﹐做個ＫＡＬＡＯＫ房用CLASS D後級是首選。

以銷售後沒有那麼多麻煩的角度﹐CLASS D後級是最好的﹗

‘CAS cannot beat CD’無論從任何角度分析都不正確。

但‘Digital camera cannot beat film’在以像素的角度來看是正確的﹐但人眼的分辨能力比耳朵低很多﹐因此在以印小照片及專業解碼支持下做大型廣告的角度來看該說法是不正確的。

PS.
ＣＬＡＳＳ　Ｄ‘無法還原大提琴等音樂實際的自然聲音’在于阻尼問題﹐喇叭的反電動勢沒法消耗盡而引起的聽感問題﹐加大鐵牛可以改善﹐但不實際。

odysseyhk

As I said, I'm not arguing something is right or wrong and in fact it is probably not  conclusive anyway.

My issue is premature and biased judgement based on mainly theory and generalization, not taking consideration of detail design refinement and end-to-end engineering execution to build the product.

My feedback of your posts is about「以偏概全」的謬誤.  Let me borrow some good description of 「以偏概全」from the web.  

你推理的那個結論未必是錯的，但是，在這整個推論中，我要說的是，一個全稱結論無法簡單的被一些個別的例子所證成，我們稱此為「以偏概全」的謬誤.   "企圖使用一些個別證據來證明一個全面的宣告".

While I highly respect your deep technical knowledge but I'm not able to accept your stated conclusion.   That's is exactly the reason why I do not intend to argue on the individual item as that is the not the point.

多多得罪

CKL

乜 class 都有好聲和衰聲，全在乎設計！

FCKC

想請教class I 又如何，youtube話佢係最好，是不？

odysseyhk

FCKC 發表於 2013-10-13 21:17
想請教class I 又如何，youtube話佢係最好，是不？

Appreciate if you include link to the material.

Interesting, you mean youtube now hire hifi reviewers and publishing review on audiophile products?  New to me.

chowchowchow

CKL 發表於 2013-10-13 21:09
乜 class 都有好聲和衰聲，全在乎設計！

絕對認同 呢個時候仲話冰個class 好啲，真係井底之蛙

FCKC

odysseyhk 發表於 2013-10-13 21:27
Appreciate if you include link to the material.

Interesting, you mean youtube now hire hifi revie ...

http://www.youtube.com/watch?v=9vxZcLhNfXA
搵5返果條片，上面條片只廣告，但主要都係講個波弦，
先申報，我也識電學，只係當時要買后級至看一下。

odysseyhk

It is marketing video by Crown Audio. Not much useful reference information yet.

天下第一刀

odysseyhk 發表於 2013-10-13 20:55
As I said, I'm not arguing something is right or wrong and in fact it is probably not  conclusive an ...

以FM收音機的音質來比較目前的Class D後級的音質不能說是‘「以偏概全」的謬誤’﹐
因為目前晶片的技術及干擾問題不可能如此做。

當前市面的Class D後級開關工作頻率在10MHZ以下﹐離88MHZFM收音機的頻段還差很遠。

天下第一刀

FCKC 發表於 2013-10-13 21:17
想請教class I 又如何，youtube話佢係最好，是不？

class I聽說原理同CLASS TD，浮動電源部分為開關形式。goole都沒法查到有Class I後級