review33.com:影音天地:單端胆機同好會

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[#3995] 單端胆機同好會多謝各位提供寶貴意見一於玩大啲，上淘宝買對6SJ7 轉EF37 插玩吓(小弟以前買落Mullard及GEC 各一對) 早幾日已經買咗對全新北京FU50$100亦改用U52 整流；啲膽放庶冇用費事留嚟陪葬：-（		Spong 正式會員 14.xxx.xxx.63	2024-04-15 11:37

[#3994] 單端胆機同好會
替代後微調工作點是必須的, 特性上兩個管子可以互換

最後修改時間: 2024-04-15 11:17:20

info2k

正式會員
180.xxx.xxx.240

2024-04-15 11:12

[#3993] 單端胆機同好會
Drop in replacement.??? No No la.

Different tube would have its own characteristic. Dropping another type of tube will give you sound but it won't be working in the right operating condition.

Better not unless you know how to fine tune it after replacement of the tube.

Johnny

johnnykmtang

會員
70.xxx.xxx.22

2024-04-15 10:49

[#3992] 單端胆機同好會
#3991

網上及 Copilot AI 等, 有海量相關信息提供, 只要花點時間查證

info2k

正式會員
180.xxx.xxx.240

2024-04-15 10:29

[#3991] 單端胆機同好會
多謝回覆
請問可否換上6sj7 直代？

Spong

正式會員
14.xxx.xxx.63

2024-04-15 09:34

[#3990] 單端胆機同好會
#3986

好可能係以下綫路

niceday009

正式會員
218.xxx.xxx.232

2024-04-15 09:01

[#3989] 單端胆機同好會
#3988

看似是 6J8P 或同類型管

最後修改時間: 2024-04-15 08:51:26

info2k

正式會員
180.xxx.xxx.240

2024-04-15 08:46

[#3988] 單端胆機同好會
另一角度
Thanks

Spong

正式會員
14.xxx.xxx.63

2024-04-15 08:19

[#3987] 單端胆機同好會
放大睇真啲

Spong

正式會員
14.xxx.xxx.63

2024-04-15 08:18

[#3986] 單端胆機同好會
Tube Identification
——————————-
各位師兄
小弟玩單端機座右銘有如相機
各施各法貴有貴玩平有平玩

最近*有幸*購入一座FU 50,音色尚可，
遺憾是推動膽未能確認型號（已甩x晒字）

各位大師經驗豐裕，可否指示明燈?
(或最有可能是xx管子亦妙啊，擄小弟有限度觀察所得，是一支雙三極管）

多謝。

最後修改時間: 2024-04-15 08:21:25

Spong

正式會員
14.xxx.xxx.63

2024-04-15 08:17

[#3985] 單端胆機同好會
TubeCAD balance phono amp

https://www.tubecad.com/july99/page9.html

I thought about this for some time. TubeCAD has an excellent article about it.

Johnny

johnnykmtang

會員
70.xxx.xxx.22

2024-04-13 18:53

[#3984] 單端胆機同好會
Yes, cascode would have much higher gain.

Using the J170 and ECC88 as per FVP5, the gain is approx 150 at the first cascode stage. The gain can be changed by adjusting the value of the source resistor to match with the output from the moving coil cartridge.

Pretty smart design.

Johnny

johnnykmtang

會員
70.xxx.xxx.22

2024-04-13 07:58

[#3983] 單端胆機同好會
Yes, I have two phono amps using cascode JFET to 6DJ8

Counterpoint SA5000

Audio Research SP15

niceday009

正式會員
182.xxx.xxx.162

2024-04-13 06:52

[#3982] 單端胆機同好會
Hi Niceday,

The Allen Wright FVP5 preamp design is great. Using JFET-6922 cascode would have very gain at the first stage. However, it is not as good as single triode stage in terms of linearity.

The K&K Audio phono amp kit also employs this cascode circuit.

Johnny

johnnykmtang

會員
70.xxx.xxx.22

2024-04-13 06:00

[#3981] 單端胆機同好會
Hi Johnny,

我見 Allen Wright 用FET 作輸入，不用MC 牛。

但我又見有一些人，一定要用MC 牛。又有一些喜愛 active pre-preamp.

當然也見過。有其他人，用類似的設計，例如英國EAR也是用FET 作輸入.

還有我見 LCR 的 Phono 嘅評價比較高. 比較貴價的設計才用。

最後修改時間: 2024-04-12 22:53:27

WilliamsonAudio

正式會員
182.xxx.xxx.178

2024-04-12 22:39

[#3980] 單端胆機同好會
Hi Niceday,

The transformer for the first stage need to be 4:1, 10 K: 600 ohm. The plate resistance of the D3a in triode mode is about 2K. So, 10K plate load would be good enough. The inductance should be 40H or higher to cover the low frequency response.

The second transformer is not critical and I prefer 2:1 for get higher gain.

BTW, a high gain step-up MC transformer is required because this LCR doesn't have much gain.

Johnny

最後修改時間: 2024-04-12 20:32:05

johnnykmtang

會員
70.xxx.xxx.22

2024-04-12 20:30

[#3979] 單端胆機同好會
Wow, phono stage with transformer

What is the requirements for the tranny

niceday009

正式會員
182.xxx.xxx.210

2024-04-12 18:55

[#3978] 單端胆機同好會
D3a LCR phono

Two of my friends built this phono amp and they like it so much.

I analyzed the RIAA EQ circuit by LTspice and found the input impedance is rather constant at 600 ohm. Therefore, I concluded that the first amplification stage need to be at least 4:1 in order to provide sufficient plate load impedance of the first D3a stage. Besides, the 600 ohm loading resistor at other end of the RIAA EQ network must be there. Otherwise, the impedance of the network will change significantly.

Johnny

最後修改時間: 2024-04-12 18:30:28

johnnykmtang

會員
70.xxx.xxx.22

2024-04-12 18:27

[#3977] 單端胆機同好會
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