review33.com: 影音天地: 單端胆機同好會

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[#5383] 單端胆機同好會 Hi Niceday009, My believe is that if we can keep each stage with minimum distortion, minimum number of stages and no NFB, the Intermodulation distortion IMD will be kept minimal as well. Johnny 最後修改時間: 2025-11-04 05:45:58		johnnykmtang 會員 70.xxx.xxx.22	2025-11-04 05:45

[#5384] 單端胆機同好會
＞#5382, The author；John Atkinson claimed that they used AP in the measurement. If so, the measurement is trustable.

mcc2018

會員
116.xxx.xxx.134

2025-11-04 08:33

[#5385] 單端胆機同好會
From AP's 2722 specification, the lowest signal distortion limits is down to -120dB.

mcc2018

會員
116.xxx.xxx.134

2025-11-04 08:36

[#5386] 單端胆機同好會
＞#5383 & #5375, The frequency domain nonlinearity and time domain nonlinearity should be properly addressed before all kind of distortions are said to be minimal.

mcc2018

會員
116.xxx.xxx.134

2025-11-04 09:49

[#5387] 單端胆機同好會
#5384

Although the AP could generate extremely low THD sinewave signal, but the Gryphon amp itself shows obvious harmonics as depicted in upper screenshot.

The different order harmonic products shown in bottom screenshoot based on dual tone signal, I do have a doubt that only capacitor coupling could produce those harmonic products while the direct coupling could eliminate the similar harmonic products. With the FFT shown below for Gryphon amp, without coupling cap could highly possibly possess the same result

最後修改時間: 2025-11-04 13:45:41

niceday009

正式會員
182.xxx.xxx.138

2025-11-04 13:30

[#5388] 單端胆機同好會
#5387,

The by-products of dual tone measurement is not harmonic based, it's called beat-frequency or non-harmonic based distortion. Below is a measurement of a film type capacitor by coupling the loopback path of the analyzer. Note the +35dB beat distortion.

mcc2018

會員
116.xxx.xxx.134

2025-11-04 16:28

[#5389] 單端胆機同好會
#5375 has mentioned the key word "SRF”；and that is the root cause of such behaviour. Anyway, it is the basic physic of capacitor. No matter how expensive the capacitor is, the world has to oblige the law of physics.

mcc2018

會員
116.xxx.xxx.134

2025-11-04 16:47

[#5390] 單端胆機同好會
#5388

Interesting, seldom see dual tone measurement in audio domain, but it is a fact that actual music has carriers involving several frequencies at the same time, here comes 2 questions

1. What would happen if coupling device is transformer not capacitor

2. Does it still maintain the high level beat distortion when NFB employed in the loop. I ask because it seems the most fundamental device for coupling for the past century in fact create high intensity of non linearity, meaning an amp with coupling capacitor can not be called as high fidelity

最後修改時間: 2025-11-04 18:23:28

niceday009

正式會員
61.xxx.xxx.130

2025-11-04 18:19

[#5391] 單端胆機同好會
-85dB(0.005％)係好低既失真數字，其實係咪可以忽略。。。

mark1

正式會員
202.xxx.xxx.34

2025-11-04 18:57

[#5392] 單端胆機同好會
Mark師兄冇錯，冇留意reference 係-120dB, 聽到+35dB下意識以為好大

不過John Crul 曾經講過Harmonic Order 7 係0.01%都可以人耳detect 到

最後修改時間: 2025-11-04 19:13:22

niceday009

正式會員
61.xxx.xxx.130

2025-11-04 19:10

[#5393] 單端胆機同好會
但是如果signal source background noise floor 係-90dB, 情況就不一樣

最後修改時間: 2025-11-04 19:58:35

niceday009

正式會員
61.xxx.xxx.130

2025-11-04 19:49

[#5394] 單端胆機同好會
#5391, -85dB(0.056%}的確是非常低的數字，但不要忘記這只是一颗電容在analyzer的lookback path 中做成的beat frequency distortion, 如果整個amplifier系統計算、每個電容都加進beat distortion,再加上其他電子零件的harmonic distortion，更如果落入電容的SRF, 那麼overall measurement一定比Gryphon那部差得多，但好多人都認為這種beat distortion是善意的失真，令音樂更好聽，頗像even harmonics的感覺云云，所以這種measurement在報告之後，作者大多不會再加任何評論的。

最後修改時間: 2025-11-04 19:54:27

mcc2018

會員
116.xxx.xxx.134

2025-11-04 19:52

[#5395] 單端胆機同好會
＞...但是如果signal source background noise 係-90dB, 情況就不一樣...

Backgroung noise 如果是white noise -90dB(0.0032%）更加聽不到，但如果是dual tone就不一樣，因19/20KHz是一定聽不到，但所有beat frequencies都會落入人耳最靈敏的audio band,聽感上不言而喻！

mcc2018

會員
116.xxx.xxx.134

2025-11-04 20:04

[#5396] 單端胆機同好會
We have discussed a lot about distortions THD and Intermodulation. What could be a good sample of the design with tube SE amp with low distortion?

Johnny

johnnykmtang

會員
70.xxx.xxx.22

2025-11-04 22:48

[#5397] 單端胆機同好會
Today, absolute low distortion is no longer the main objective of an audio system. Instead, "Harmonic dissonance & consonance" become the most critical factor:

https://testhifi.com/2019/08/09/flaws-in-audio-systems-aurally-weighted-intermodulation-disconsonance/

最後修改時間: 2025-11-05 07:13:16

mcc2018

會員
116.xxx.xxx.134

2025-11-05 07:06

[#5398] 單端胆機同好會
Re : 5379
Hi Johnny
我有eTracer你需要那一項目測試
可以做we300B
或5U4G
可以upload以下報告不知是否你耍的資料
E.H新膽 (反而noise 多)聽感
K.R (超静)聽感
舊G.E (静音色最鐘意)聽感
以上测試report都唔同晚上post 上去嚟
謝謝

waitobuy

正式會員
119.xxx.xxx.201

2025-11-05 07:44

[#5399] 單端胆機同好會
etracer

waitobuy

正式會員
119.xxx.xxx.201

2025-11-05 07:51

[#5400] 單端胆機同好會
Hi waitobuy,

It's great! Thank you for your help.

It would be very helpful to get the test data for various 300B's. There are just so many different ones available in the market especially from Psvane and LinLai.

I downloaded the eTracer program that I can find the distortion/harmonics with the test data.

Please try to run the tests. Then, you can PM them to me.

Thank you,
Johnny

johnnykmtang

會員
70.xxx.xxx.22

2025-11-05 16:41

[#5401] 單端胆機同好會
有朋友攞咗对金音萊9845, 係特種845屏耗有130W比普通845大3成，係部Ultimate 845推A2 甲類出到45W RMS 不削波，9845低頻動力及速度，相信5隻300B做並聯都出唔到9845咁强勁及結實