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| [#5023] 單端胆機同好會 图，左及右300B燈絲焊接時正負对調  最後修改時間: 2025-04-05 21:28:51 |
niceday009 正式會員182.xxx.xxx.214 |
2025-04-05 21:26 | |
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| [#5024] 單端胆機同好會 另外我相信用SMPS 燈絲係效果唔錯，如果唔係日本CS PORT 4212 由高压至燈絲都用上SMPS，可能仲好過Rod Coleman Gyrator，不過SMPS lifespan可能冇linear PS咁耐用，特別係用IRON Choke PS 我認為胆係硬淨過原子粒好多好多，原子粒电压或电流過荷或靜电問題一瞬就釘蓋，300B就算你冇做高压延遲好多都冇事(唔知有冇99.999%)，就算211,845本身都冇事但輸出牛初級就唔敢包 最後修改時間: 2025-04-05 22:00:17 |
niceday009 正式會員 182.xxx.xxx.214 |
2025-04-05 21:40 |
| [#5025] 單端胆機同好會 #5020 Grid current 重點如下。方便理解。 • This current generates a voltage across the grid leak resistor. • This voltage makes the grid more positive which SUBTRACTS from the bias and results in increase tube current. • This effect is proportional to tube (anode) current and ＞＞so is worse in power tubes＜＜ • This effect also is worse in old “gassy” tubes. • This is why there are always 2 specifications for maximum Rg1 values. One value for cathode (auto) bias where the increased current is opposed by an increased bias due to increased voltage drop across the cathode resistor, and another smaller value for fixed bias where there is no action to oppose the current increase. The mechanism of NEGATIVE grid current, reducing the bias, increasing the current, increasing the negative grid current, reducing the bias etc. etc. round and round, then boom is called thermal run away and is what causes a lot of power tubes to self destruct. 最後修改時間: 2025-04-06 08:25:18 |
WilliamsonAudio 正式會員 182.xxx.xxx.92 |
2025-04-06 08:25 |
| [#5026] 單端胆機同好會 分享 Cathode Stripping 資料。845,211,805,212,833更加需要軟體啟動。 Cathode stripping refers to the physical damage or degradation of a tube's cathode surface due to ion bombardment. In a vacuum tube like a DHT, the cathode is heated directly by a filament to emit electrons. If high voltage is applied between the anode and cathode before the cathode is fully heated, residual gas molecules inside the tube can become ionized. These positively charged ions are attracted to the negatively charged cathode and can strike its surface with enough force to dislodge material from the emissive coating (typically oxides in indirectly heated tubes, but pure or thoriated tungsten in many DHTs).For DHTs, such as the 300B or 2A3, which often use thoriated tungsten filaments, cathode stripping is less of a concern at typical operating voltages (hundreds of volts) compared to high-voltage tubes (e.g., those operating at 10,000 volts or more, like in old radio transmitters). Experts generally agree that in audio applications, the voltages are too low for significant stripping to occur. However, it’s still good practice to allow the filament to warm up before applying full anode voltage to minimize any risk. 最後修改時間: 2025-04-06 08:47:29 |
WilliamsonAudio 正式會員 182.xxx.xxx.92 |
2025-04-06 08:35 |
| [#5027] 單端胆機同好會 Good info by WilliamsonAudio....... thank you. The Cary CAD-805RS has a STANDBY/OPERATE switch. This switch is used for turning the 211/845 power tube filament on/off. Then, cathode stripping would be a BIG problem because the 1000V B+ is once the Power switch is ON. Also, the 1KV supply is using diodes for rectification. Johnny |
johnnykmtang 會員 70.xxx.xxx.22 |
2025-04-06 17:35 |
| [#5028] 單端胆機同好會 原來211,845等牛奶樽胆開機一刹cause stripping, 又知多件事因乜原因，我量度過在845燈絲未熱屏上HV, cathode 條保護fast blow 250mA Fuse可以断，211,845燈絲主要係鎢合金並非表面coating可能唔會有cathode物質脱落問題，但刹那高电流可以整断初級線組 按以下文章描述300B 係冇大問題，試過300B cathode 未熱上HV都唔會將條120mA fast blow 衝断 最後修改時間: 2025-04-06 18:38:40 |
niceday009 正式會員 182.xxx.xxx.214 |
2025-04-06 18:26 |
| [#5029] 單端胆機同好會 A friend got his 2A3 Stereo SE amp built. Here's his words:- Just finished building a 2A3 single-ended amp for my AER open baffle setup, using Johnny’s schematic. Over the years, I’ve tried various amps, but none of them could truly unlock the AER’s potential. Honestly, it got to a point where I lost passion for the hobby — I didn’t even feel like turning on my system anymore. This amp completely changed that. It brought the system to life in a way I didn’t think was possible. Now I can’t stop listening, and I actually don’t want to turn it off.  |
johnnykmtang 會員 70.xxx.xxx.22 |
2025-04-27 17:44 |
| [#5030] 單端胆機同好會 今日執書找到出來。Kondo 除了單端，也有PP 設計的（右手面那一台）。而且更貴 左面是Ongaku SE  |
WilliamsonAudio 正式會員 182.xxx.xxx.8 |
2025-05-01 15:53 |
| [#5031] 單端胆機同好會 極早期日本 Audio Note. 應該是之前早期MJ雜誌的其中一頁。  |
WilliamsonAudio 正式會員 182.xxx.xxx.8 |
2025-05-01 15:58 |
| [#5032] 單端胆機同好會 日本Audionote出機其實土炮味好重，但這樣形容並非負面，因為有經驗有技術土炮友係做機時永遠放音質第一，例如綫路計算設計，排位及用料等等排第一，外觀或內觀係排第二 最後修改時間: 2025-05-01 22:58:30 |
niceday009 正式會員 218.xxx.xxx.220 |
2025-05-01 22:42 |
| [#5033] 單端胆機同好會 今天找了出来。分享一下。中間那支膽應該係5687 這張圖嘅資料來源係。當年英國Audio note 賣膽機電路圖紙(好似係10-20英鎊)。給那些DIY 人參考。方便他們賣出更加多的零件。 output膽應該係用211  |
WilliamsonAudio 正式會員 182.xxx.xxx.8 |
2025-05-01 23:05 |
| [#5034] 單端胆機同好會 #5032 那個年代CNC 的機器非常昂貴。所以加工費也會非常之高。 隨著CNC 的普遍性以及廣泛應用。 Kondo 現在的機殼設計也有用到CNC 。  |
WilliamsonAudio 正式會員 101.xxx.xxx.131 |
2025-05-02 08:28 |
| [#5035] 單端胆機同好會 Kondo EL34 PP amp, 也應用了新的技術。用constant current source 做 EL34 的bias. CCS 應該是用原子粒。他現在的設計也融入了原子粒， 因為他只用了6072+12BH7膽(這部分只足夠做EL34前面的推動)。 https://www.audionote.co.jp/en/products/power_amplifier/melius.html ""Push-pull circuit further refined from Overture"" The first stage and driver stage are direct coupled, and a new generation pure silver foil capacitors with vibration suppression are used for coupling with the output stage. Moreover, the low impedance design of the whole circuit is aimed the direct sound performance. The output stage continue to employ ""CCB (constant current bias circuit)"". The music signal is prevented from flowing into the bias adjustment VR, enabling pure signal transmission. |
WilliamsonAudio 正式會員 101.xxx.xxx.131 |
2025-05-02 08:37 |
| [#5036] 單端胆機同好會 Wilson, 佢咁介紹係乜意思？ ＞＞The output stage continue to employ ""CCB (constant current bias circuit)"". The music signal is prevented from flowing into the bias adjustment VR 見到佢用咗兩粒黑豆，电流應該好低唔似係EL34 做differential 係 cathode 做CCS  最後修改時間: 2025-05-02 11:56:18 |
niceday009 正式會員 182.xxx.xxx.162 |
2025-05-02 11:41 |
| [#5037] 單端胆機同好會 如果訊號係經VR, 相信就係這種設計。  |
WilliamsonAudio 正式會員 182.xxx.xxx.8 |
2025-05-02 13:14 |
| [#5038] 單端胆機同好會 #5037, The schematic shown is the one used in KT66 triode strapped PP. I like the bias arrangement because it can easily adjust the DC balance between the power tubes. Also, the 250 ohm resistor which is common to both KT66 forms a differential circuit. This will further improve the linearity. I used the same circuit but replace the 250 ohm resistor with a MOSFET CCS. Details of the Williamson KT66 PP :- http://www.r-type.org/articles/art-107b.htm Johnny |
johnnykmtang 會員 70.xxx.xxx.22 |
2025-05-03 17:13 |
