review33 - 影音天地: DIY見聞錄

#194 [CFT], 25-10-08 00:59
原來2025年是被聯合國訂定為國際量子科學技術年，是紀念量子力學誕生 100 週年。(由1925年Heisenberg 學說開始)

Nobel prizes: 1973的Esaki tunneling diode vs 2025 的 macro quantum tunneling:

The 1973 Nobel: Leo Esaki won the Nobel Prize for being the first to experimentally demonstrate this specific quantum phenomenon of electron tunneling within a solid material.

2025 Nobel Prize: Macroscopic quantum tunneling
The tunneling particle: In the work of Clarke, Devoret, and Martinis, the "tunneling particle" is not a single electron but rather a collective quantum state of an entire electrical circuit. This is a fundamentally different concept known as "macroscopic quantum tunneling" (MQT).

最後修改時間: 2025-10-08 01:35:02
#193 [CFT], 25-10-07 21:30
好呀，有興趣可discuss 吓 :)，不過我的程度去到好表面而以.. ^^"
#192 [binderclips], 25-10-07 21:05
等我硏究吓先

最後修改時間: 2025-10-07 21:24:03
#191 [CFT], 25-10-07 20:39
https://inews.hket.com/article/4019023/2025%E8%AB%BE%E8%B2%9D%E7%88%BE%E7%8D%8E%EF%BD%9C%E8%8B%B1%E7%BE%8E%E6%B3%95%E4%B8%89%E5%AD%B8%E8%80%85%E5%A5%AA%E7%89%A9%E7%90%86%E5%AD%B8%E7%8D%8E%20%E8%A1%A8%E6%8F%9A%E7%99%BC%E7%8F%BE%E5%AE%8F%E8%A7%80%E9%87%8F%E5%AD%90%E5%8A%9B%E5%AD%B8%E7%A9%BF%E9%9A%A7%E5%92%8C%E8%83%BD%E9%87%8F%E9%87%8F%E5%AD%90%E5%8C%96

2025年物理學諾貝爾獎又係關於 quantum tunneling 同 Josephson junction.. ( 從80年代做的實驗得獎)

又可睇返#186 有關 quantum tunneling 1950s Sony 在 "做壞咗嘅 "diode 上的最初發現的資訊, 而得當時諾貝爾獎 :)

最後修改時間: 2025-10-07 20:52:41
#190 [CFT], 25-08-26 12:21
photo from FB vacuum tube amplifier page
《DIY胆機歌》inspired by 《燕歌》 :)
#189 [CFT], 25-08-26 11:51
《DIY胆機歌》

最後修改時間: 2025-08-26 12:16:26
#188 [CFT], 25-08-23 11:50

最後修改時間: 2025-08-23 11:56:51
#187 [CFT], 25-08-17 15:21
此amp看來帶有獨特的dynamic feedback 來貺失真。

最後修改時間: 2025-08-17 15:22:29
#186 [CFT], 25-08-14 13:26
Zener diode, quantum tunneling diode 的故事同 Leo Esaki 先生100th 生日快樂!

最後修改時間: 2025-08-14 13:35:48
#185 [CFT], 25-08-10 15:30
2) 整這Hamptone preamp或可帶些玩harmonics的樂趣。
https://www.diyaudio.com/community/threads/hamptone.405097/

這preamp係包左上面Tubecad同 Pass講嘅嘢。佢基本上係一個simple嘅tube 線路, 但用咗半導體做 (如上述H2 + follower with ccs, +24v 可以用9V電池 x3)。

*特點係:*

A) 可轉不同 input Fet, 做到不同 FFT distortion profiles的音色 (H2 only, or water fall, etc), 這個係真的scientific，唔係roll opamps/tubes 咁估估下..

B) 當然更可將input Fet *加Schade feedback 變左triode玩*, 到時又可以侵埋其它mosfet 如SiC mosfet等入去。

C) 連output follower 的silicon BJT轉埋 *germanium* (hi hfe) 的玩下都有可能。
#184 [CFT], 25-08-10 15:20
1) 讓自己比啲高手點化吓, 佢哋點解都玩 harmonic distortion profile 呢?

A) Tubecad: Harmonic Restorers

https://www.tubecad.com/2013/06/blog0265.htm

https://www.tubecad.com/2020/12/blog0523.htm

B) Nelson Pass: H2 Harmonic Generator

https://positive-feedback.com/audio-discourse/the-pass-h2-harmonic-generator/

Thomas Mayer : UX201A DHT Sound Processor (圖)

最後修改時間: 2025-08-10 15:31:40
#183 [CFT], 25-08-07 14:11
Marantz amps designer- *Sid Smith*
相信是第一次網上面有佢嘅相片出現。
對，就是他! ✌

我學生哥嘅時候喺一個AES meeting 上見過他，有人介紹我 : 呢位就係Sid Smith! 同佢握過手say過 hello，佢有d shy, 其實我當時唔知佢係邊個，只識得marantz呢個牌子嘅原子粒擴音機。

當晚 discussion meeting喺某一個NY radio station嘅auditorium 舉辦, topic 係 "Tube vs transistor sound".. 個host係Harvey Rosenberg, 他買咗Futterman OTL amps 間公司而自己開咗 NYAL 做production，不過搞咗幾年就關門了

最後修改時間: 2025-08-07 14:12:53
#182 [CFT], 25-08-04 00:01
GaN HEMT?
Please report your results later. :)
#181 [mcc_2001], 25-08-03 15:33
#180,

聽過幾款用這類半導體既Amp.，初聽令人覺得舒服，音場闊度，深及分析力也正常，但聽耐一點就覺得有點黏黏糊糊令人不耐煩的感覺，可能是心理作用，也可能是這類管子因減少Schottky barrier之後，令本來已偏高的結電容更加大的結果，有時間訂幾對呢類管DIY測試一下先！
#180 [CFT], 25-08-03 13:53
#177

Good info! 請問失係邊方面呀？

如果揀埋啲用low voltage更linear嘅就正，有d名廠機前级全用high voltage mosfet 做放大有佢原因!!

最後修改時間: 2025-08-03 13:55:14
#179 [CFT], 25-08-03 13:49
#178
淘寶仲有好多germanium preamp kits賣有埋JLH 1969全germanium version 呀!

最後修改時間: 2025-08-03 13:50:23
#178 [WilliamsonAudio], 25-08-03 08:44
剛剛看到，分享一下
Hi , Parkerdiy ! I see that this topic was started a year ago. And if you haven 't decided to build a germanium preamp , I want to say this . Don 't listen to the skeptics . Germanium preamps sound good and their construction even now still makes sense . I say this as a person who built 6 phonopreamps on germanium transistors . I have preamps on JFET and silicon bipolar transistors . But I really like to listen to records through germanium preamps . The result by sound - justified all efforts .
#177 [mcc_2001], 25-08-03 07:21
現代用於音响的半導體會用特別的doping去降低Schottky barrier，從而加大ohmic region (下圖的Linear region）.但這一得也變成另外一失！
#176 [CFT], 25-08-02 14:00
以下係 silicon, germanium , selenium 同tube 的IV curves, 留意下佢哋個slope, 除咗silicon其他三種都相似..

最後修改時間: 2025-08-02 14:04:44
#175 [CFT], 25-08-02 13:55
可能可以咁解釋到

這圖係exponential curve 同埋square curve 個樣嘅分別。

*Square curve math formula可被拆散出的是 'second harmonic'*,

而 exponential 就雜不甩,乜harmonics都有d..

#175 係不同材料做出嚟嘅rectifier的IV curves, 看來 silicon 係exponential形 ( 個slope好斜, 看上面d圖)，

*而 selenium,germanium 同tube 都係靠近square curve嘅slope或許這同好聲有關係。

最後修改時間: 2025-08-02 14:12:11
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