review33.com: 影音天地: 單端胆機同好會

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[#5343] 單端胆機同好會 Agree,cathode bypass capacitor's impedance appear down slope vs frequency, however shunt regulator is basically flat across the audio band. But shunt regulator lost self control bias current, will it be better to create a dc cathode current feedback to auto control the regulated cathode voltage?		LaLaLam 會員 42.xxx.xxx.123	2025-10-25 08:56

[#5344] 單端胆機同好會
BTW, when considering capacitor impedance, the down slop way really is not the best design for cathode bypass.

LaLaLam

會員
42.xxx.xxx.123

2025-10-25 09:01

[#5345] 單端胆機同好會
Hi LaLaLam,

I agree with you that it is better having circuit to maintain the required amount of idle current. On the otherhand, it makes the circuit more complicated and stablility would be an issue too.

I prefer something simple.

Johnny

johnnykmtang

會員
70.xxx.xxx.22

2025-10-25 09:43

[#5346] 單端胆機同好會
剛看到這這一篇文章。有參考價值。

https://www.reliablecapacitors.com/information/the-rel-multicap-in-power-supplies-filter-circuits.html

WilliamsonAudio

正式會員
182.xxx.xxx.240

2025-10-30 07:28

[#5347] 單端胆機同好會
Audio Myth: We don't need high-quality capacitors except in the direct signal path.
Audio Reality: The secondary signal paths are also sonically signifcant - a better capacitor in these non-coupling applications will improve the sonic performance of the component.

The increased sonic performance of high-quality capacitors in coupling applications has been well established in recent years. Few devotees of transistor amplifiers or digital components, however, recall that the sonic differences in audio capacitors were noted first (in late 1970s) in power supplies. Because these devices, and others, such as filter networks, are not in the direct signal path, many designers have avoided the use of fine capacitors in these applications.
However these networks do form a secondary path and the sonic qualities of capacitors in these applications are significant and greatly influence overall performance

POWER SUPPLIES

A power supply, whether regulated or unregulated, must perform two basic functions in audio components:

Provide low impedance over a wide frequency range
Provide energy for the circuit as fast as, or faster than, the audio signal
Capacitors aid in both functions. The ideal capacitor would serve both purposes: smoothing the rectified current and providing fast energy to accommodate the fast changes of the music signal.

Unfortunately there is no ideal capacitor. Audio designers use electrolytic capacitors in the power supply because they are efficient in size vs. capacitance - they are excellent in providing DC. But electrolytics are not fast, and therefore lag in responding to changes demanded by audio

最後修改時間: 2025-10-30 07:40:05

WilliamsonAudio

正式會員
182.xxx.xxx.240

2025-10-30 07:30

[#5348] 單端胆機同好會
BY-PASSING ELECTROLYTICS WITH MULTI CAPS - FOR SMOOTHNESS & SPEED

The REL MultiCapTM provides the lowest ESR ESL and dielectric absorption available in an audio capacitor today and therefore can supply the speed the circuit needs By-passing the electolytic capacitor with a MultiCapTM will give the circuit the required smooth DC and the speed to accommodate the music

The REL MultiCapTM makes an excellent by-pass cap in power supplies. REL recommends a by-pass that is at least 1 to 10 microfarads.

FILTER NETWORKS

A filter acts upon the signal to discriminate against some frequencies, for example, boosting certain frequencies in amplitude or reducing certain frequencies as opposed to others - in short, controlling or modifying the magnitude of a frequency - which they must do, in audio components, without adding distortions. Filter networks are found in many applications in audio. DC servo circuits and equalization networks are two important examples.

EQUALIZATION NETWORKS - or EQ - can be applied to many circuits: RIAA circuits, speaker crossovers, multi-band equaliz.ers, and digital filter circuits - S/H, A/D, and D/A converters. These will all benefit from increased performance in the areas of inductance, capacitance, resistance, and dielectric absorption. The RIAA filter, for example, compensates for the high-frequency boost at the cutter head. Better caps in this filter will result in better sonics on the LP (so, incidentally, would better caps at the cutter head), because of decreased distortion. The excellent qualities of the REL MultiCapTM will provide better performance of any equalization filter - better L, C, and R equals lower distortion.

THE DC SERVO CIRCUIT is a filter in the amplifier that removes all AC in the music signal at the output and leaves only the DC components, which it then feeds back to the amp' s input. This DC feedback is used to correct for or null DC offset voltage at the amp' s output.

You may hear that capacitor performance is not significant in some ofthese networks - especially in filters not in the direct signal path. But this is not the case. A high-quality filter should produce a signal with low noise and distortion - and to do this, a high-quality capacitor is necessary.

The MultiCap'sTM qualities of low ESR, ESL, and dielectric absorption make it an ideal choice for all these applications because it will prevent the introduction of distortion.

In sum - the better the capacitor in any power supply or filter network, the better the sonic results. We must not overlook secondary signal paths in fine audio designs.

WilliamsonAudio

正式會員
182.xxx.xxx.240

2025-10-30 07:42

[#5349] 單端胆機同好會
電容器是一個非常有趣的零件，無論e-cap,film type....等，好多人都以為是一個linear component, 其實佢既線性度受下圖的ESL,ESR,EPR等的影響變成非線性concave curve. 圖下是實測一個film type電容，linearity 也是呈現concave type non-linearity. 這種非線性對人類耳朵也有著非一般的聽覺反應和感受，尤其當年紀漸長時，聽覺大多只能到8KHz, 但上述電容器的非線性部份卻能將人耳聽不到的部分利用互調（IMD）差拍到人耳可聞的範圍，在發燒友而言，的確是聽多好多音樂的細節。

mcc2018

會員
42.xxx.xxx.123

2025-10-30 08:48

[#5350] 單端胆機同好會
於是電容交連和直接交連放大器，誰家好也成了熱論的話題，不過在測試上兩者的確存在非常大的分別：下圖是ccif 19+20KHz的dual tone measurement, 電容交連的互調諧波非常豐富,諧波也是可聞的，直接交連則是原汁原味，但高頻細節完全聽不到，變了平淡無味！

最後修改時間: 2025-10-30 09:01:05

mcc2018

會員
42.xxx.xxx.123

2025-10-30 08:58

[#5351] 單端胆機同好會
#5347

Audio Myth: We don't need high-quality capacitors except in the direct signal path.
Audio Reality: The secondary signal paths are also sonically signifcant - a better capacitor in these non-coupling applications will improve the sonic performance of the component.
-----------------------------------------------------------------------------------------------

哩兩句說話其實喺#5255張圖已經有解説. 圖如下

C1 (psu bypass cap) 有output signal+psu noise經過
C2 (cathode bypass cap) 有input signal + output signal + psu residual noise經過

除左coupling cap有signal經過(direct signal path), psu 同 cathode bypass caps都會對音質有明顯影響(secondary signal path). 好多人都忽略了psu bypass cap......

最後修改時間: 2025-10-30 09:42:01

bambino

正式會員
61.xxx.xxx.40

2025-10-30 09:41

[#5352] 單端胆機同好會
我以前都對比過PSU用Black Gate豎琴 vs Mundorf TubeCap polypropylene大水塘

論電子聲學特性，薄膜電容一定全面勝過電解電容。但係理論歸理論，實際試聽各有千秋

Mundorf通透啲、分析力高啲，但係質感、厚度同埋低頻能量感輸俾Black Gate

曾經有段時間，我整咗兩個power supply俾我部前級，一個用Black Gate，另一個用Mundorf TubeCap，睇心情睇音樂類型而揀邊一隻power supply

最後兩樣都落啲-----近電源牛嗰邊用Black Gate豎琴，上到前級用Black Gate non-polar super e-cap, 過晒regulators之後去到膽附近就用Mundorf TubeCap

以我當年嘅性格，如果我覺得TubeCap全面贏晒，我一定義無反顧全套系統用晒，唔會各樣用一啲

Thanatos

正式會員
104.xxx.xxx.129

2025-10-30 11:03

[#5353] 單端胆機同好會
#5349 [這種非線性對人類耳朵也有著非一般的聽覺反應和感受，尤其當年紀漸長時，聽覺大多只能到8KHz, 但上述電容器的非線性部份卻能將人耳聽不到的部分利用互調（IMD）差拍到人耳可聞的範圍，在發燒友而言，的確是聽多好多音樂的細節]

1. 差拍到人耳可聞的範圍...所指的是8kHz以下的中高頻段？還是8kHz以上的高頻？如果因年長，已聽不到8kHz以上，那無論是原來的音樂訊號還是差拍失真，又如何能聽到呢？
2. 既是差拍而得來的，即並非原來的音樂訊號，只能算是失真。就算真能聽到，聽失真有意義嗎？如果失真好聽的話，那發燒友為何不一窩蜂去聽結他amp呢？
3. 製造一台只針對年紀漸長的顧客的音響器材，那對十多二十歲的顧客而言，高頻(無論是原來的訊號，還是差拍的失真成分)豈不是會過多？為何自有音響器材以來，未嘗見有產品以此作為推銷賣點！？(助聽器除外)
4. 若非理想電容non-ideal capacitor能有此奇效，那是否愈非理想(即ESR愈大，ESL愈大，EPR愈小)，那電容音效就會愈好？垃圾電容特性很不理想，音效比發燒電容更好嗎？它倆中間有分界線嗎？買天價的發燒電容來造/摩機，豈非本末倒置？

羅密歐

正式會員
219.xxx.xxx.65

2025-10-30 11:05

[#5354] 單端胆機同好會
再記清楚啲，經過咁多對比及實測，當年我比例上用Black Gate多過TubeCap好多

要知道當年(2000年左右)Black Gate仲未絕版，唔係特別珍貴，所以冇特別嘅情意結或者偏愛，純粹係從聲音角度考慮

Thanatos

正式會員
104.xxx.xxx.129

2025-10-30 11:06

[#5355] 單端胆機同好會
#5350 [電容交連的互調諧波非常豐富,諧波也是可聞的，直接交連則是原汁原味，但高頻細節完全聽不到，變了平淡無味！]

1. 互調諧波就是互調失真，[失真]穿上了一件[諧波]外衣，等於狼披上羊皮，狼的本質沒有改變。什麼高次低次，奇次偶次...諧波，如果豐富就等同於音效好，那要[豐富]到何等程度才會不好，越豐富就越好？中間有分界線嗎？
2. [高頻細節]，指的是原來音樂訊號中的高頻？還是諧波失真中的高頻失真？
3. 如果原汁原味就等同平淡無味，那什麼叫做high fidelity呢？

羅密歐

正式會員
219.xxx.xxx.65

2025-10-30 11:18

[#5356] 單端胆機同好會
8kHz以下約-120dB至-80dB，真的可以聽到嗎。。。

mark1

正式會員
124.xxx.xxx.129

2025-10-30 11:24

[#5357] 單端胆機同好會
#5354

TubeCap我都有. 用左個零月,俾足時間佢就換走咗. BG低頻同能量感係有佢優勢. 喺PSU放一隻冇問題,我而家部機都有一隻. PSU尾(即每支膽B+前)嗰隻電容可以用film cap. 即係#5351圖中C1. 可以考慮Mundorf EVO Oil 18uf 或 22uf (大約HKD300). 如果可以用更細數值又吾影響noise的話更好. 聲音更快. HKD200左右就得.

俾多啲可以選擇Supreme EVO Oil 18/22uF (大約HKD700). 吾使用SGO. Oil cap俾到多些低頻同能量感. 現代oil cap吾會好似舊裝咁慢同㕸

最後修改時間: 2025-10-30 11:30:52

bambino

正式會員
61.xxx.xxx.40

2025-10-30 11:30

[#5358] 單端胆機同好會
#5356, 根據耳科醫學的聽力圖測試(下圖)，令人聽力産生痛楚感覺的最大聲壓是120dB SPL, 而正常年輕人的最低可聽到的threshold是0dB SPL, 如果以最大音壓是0dB, 那麽正常人是應該可以聽到-120dB (2-8KHz），我自己身體檢查時亦測試過，醫生說正常但遠遠不及年輕人了。

mcc2018

會員
42.xxx.xxx.123

2025-10-30 16:16

[#5359] 單端胆機同好會
人類可以聽到的最低音壓是0dB SPL，如果失真是-80dB(0.01%)，當音壓達到80dB SPL的時候，失真的音壓就是0dB，音壓達到100dB的時候，失真的音壓就是20dB，理論上，音樂開得很大聲的時候，的確是會有可能聽到失真的，但是我們的房間也存在環境噪音，實際上是否能聽到失真，真的不知曉了

mark1

正式會員
124.xxx.xxx.129

2025-10-30 16:42

[#5360] 單端胆機同好會
#5355 ”High Fidelity”呢個term的定義十分虛無縹緲，也沒有一個確實的指標,只概括地指出應包括：Minimal distortion, Accurate frequency response, Faithful reproduction and High-quality components...等等, 於是一部超貴價的Amp.可以包含上述的所有形容詞,另外一些超平價的器材也毫無疑問也達標，#5349/5350, 提及的ccif imd測試並非一個常用的指標，但一些第三方的測試則可以顯示出一件器材的添加劑成份，例如這個：（留意最後的ccif 19+20測試)

https://www.stereophile.com/content/gryphon-essence-mono-power-amplifier-measurements

mcc2018

會員
42.xxx.xxx.123

2025-10-30 16:42

[#5361] 單端胆機同好會
音響啲嘢，好似煮餸咁，唔會話一樣嘢好食就樣樣都用晒佢

龍蝦鮑魚好食，會唔會用嚟做甜品？

每樣嘢都有佢嘅優點缺點，全部用晒同一樣嘢，缺點就會出晒嚟

Thanatos

正式會員
220.xxx.xxx.180

2025-10-30 16:56

[#5362] 單端胆機同好會
在耳科醫生處測量hearing threshold是用ー個特製的耳機(如下圖）進行的，可以避開所有環境噪音，如用揚聲器則可能需要在anechoic chamber或類似房間進行。