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| [#5662] 單端胆機同好會 niceday 兄，很漂亮和用心製作的機器，讃！ |
Welborne 正式會員182.xxx.xxx.6 |
2026-01-16 14:20 | |
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| [#5661] 單端胆機同好會 Hi Wilson, 有些人覺得Glass Metal Nano太多高頻寧願要高牌號Hi B，看口味，實際上Hi B或鎳合金出超高頻仍十分清晰而且較平衡，Glass Metal就有强調高感，所以看口味 |
niceday009 正式會員 112.xxx.xxx.52 |
2026-01-16 13:39 |
| [#5660] 單端胆機同好會 Hi Eric, 我记得output 是Hi B interstage 牛最後统一用Nano? |
WilliamsonAudio 正式會員 103.xxx.xxx.132 |
2026-01-16 12:39 |
| [#5659] 單端胆機同好會 第三批蘭心，改用了强化玻璃 我心目中有個假設，市場上有邊部高級別單枝845 SE amp, 不論合併或是後級, 我都想去比較一下    最後修改時間: 2026-01-16 01:32:28 |
niceday009 正式會員 112.xxx.xxx.52 |
2026-01-16 01:16 |
| [#5658] 單端胆機同好會 I have the same thermal run away experience with the EH and Gold Lion 300B's too. The bias voltage is approximately 6~8 Volts lower than the WE and LinLai's. The EH and Gold Lion's are stable at around 350V B+ and 60mA. Once the idle current is higher, the current will get higher and higher. Of course I am using fixed bias for them. It is still safe using self bias. Johnny 最後修改時間: 2026-01-09 18:56:07 |
johnnykmtang 會員 70.xxx.xxx.22 |
2026-01-09 18:55 |
| [#5657] 單端胆機同好會 可能我都好彩，我買超過70隻大陸300B 包括林籟，曙光，Psvane ，金音萊，暫時未有一隻係DOA, 超過九成半Transconductance同电流係within specification. 剩餘那5%仍可用只不過特性高咗或低咗，而且全部冇Thermal runaway. 反而我用WE300B, 俄國300BEH 同 JJ 300B試過Thermal runaway 而我係用fixed bias同埋grid bias 电阻用220K. 我試過大陸某幾款300B事實比WE300B更有肉地同動態，如果怕萬一大陸胆短路而做成燒牛，就要立刻採取保護措施例如加Fuse. 我經驗係胆屏short入栅/陰/燈絲係好少機會但仍然見過，而且唔係淨係大陸胆會咁，欧美日俄都有聽聞過，但只要輸出牛次級接地，对喇叭唔會俾部300B SE amp整壞 最後修改時間: 2026-01-09 15:06:27 |
niceday009 正式會員 182.xxx.xxx.215 |
2026-01-09 14:39 |
| [#5656] 單端胆機同好會 曾經喺一位做機師傅度見到一盒曙光300B膽。就是圖中這款。隨手攞了兩隻返屋企試。一啲問題都冇，正常運作。可能我好彩。  最後修改時間: 2026-01-09 13:47:45 |
bambino 正式會員 61.xxx.xxx.40 |
2026-01-09 13:47 |
| [#5655] 單端胆機同好會 #5653 睇完你呢個經歷, 現在令到我有啲驚 :) |
Welborne 正式會員 182.xxx.xxx.92 |
2026-01-09 13:34 |
| [#5654] 單端胆機同好會 If you ask me about sound quality and sound quality only, I will tell you, 曙光 300B is a clear winner in my system. |
Thanatos 正式會員 42.xxx.xxx.92 |
2026-01-09 12:36 |
| [#5653] 單端胆機同好會 Hi Johnny, If safety is not a concern, I would actually choose 曙光 300B over my 1949 WE I really like 曙光's sweetness and warmth, and it sounds more "human" than WE. Microdynamics is more abundant too, you can hear the vibrato of strings more clearly than WE. But I really cannot rely on the stability of Chinese tubes. When I purchased my 曙光, I knew I had to bring my Amplitrex AT1000 tube tester in my backpack. Out of 12 tubes I tested, 4 had broken filaments, 2 had over current(internal short circuit or metallic gas poisoning), two had very low emissions (＜15%). I bought 2 with around 60% emissions and two with around 110% emissions. The two with around 110% emissions developed some very bright spots on the filaments after using for a few hours. (you know that's a sign of impending doom) Now only the two with ~60% emissions are still working. This means out of the 12 tubes that I tested, only 2 of them actually work. Sigh........ |
Thanatos 正式會員 42.xxx.xxx.92 |
2026-01-09 12:34 |
| [#5652] 單端胆機同好會 Got it, meaning the risk is Chinese 300B potentially having quality issues Again, nobody could predict when the tube would short it's plate to either filament or cathode. To protect the tube and OPT it is a good approach to use fuse in 300B cathode. Even Russian or European 300B could have such accident. I once tested a Tunsol USA 6550 also exhibited plate short filament. For the fuse adversely affecting the sound quality, I audition one with and without, I cannot say I hear a big difference 最後修改時間: 2026-01-09 00:43:12 |
niceday009 正式會員 112.xxx.xxx.52 |
2026-01-09 00:38 |
| [#5651] 單端胆機同好會 Hi Thanatos, You are absolutely right in choosing the Western Electric 300B. When I got my very first 300B SE amp built, I used the cheapest EH 300B's. I knew it is not best but something I can afford. No doubt that the WE 300B's are known with high reliability and good sounding. It would so nice having them fit in the system that people are so proud of. Anyway, all I would say I have some other 300B's I tried. I am so lucky that they don't kill my speakers so far. Cheers, Johnny |
johnnykmtang 會員 70.xxx.xxx.22 |
2026-01-09 00:33 |
| [#5650] 單端胆機同好會 The only risk we had talked about so far was a catastrophic meltdown of Chinese 300B |
Thanatos 正式會員 146.xxx.xxx.12 |
2026-01-09 00:10 |
| [#5649] 單端胆機同好會 Hi Thanatos, Maybe I got the meaning incorrectly because you pop up"Why risk?"，I re read your post only found you recommending WE300B being much safer. So I thought your risk indicated was not to use WE300B So Why risk is referring what item? 最後修改時間: 2026-01-08 23:58:58 |
niceday009 正式會員 112.xxx.xxx.52 |
2026-01-08 23:57 |
| [#5648] 單端胆機同好會 Johnny was talking about the comparisons between Chinese 300B and WE300B. I was just sticking to his context. No other tubes were mentioned in the above discussions. I have not excluded other well-made tubes as far as safety and stability. Saying that WE300B is safer and more stable than Chinese 300B doesn't imply that the only safe tube on earth is WE300B. There are tubes other than the above two. |
Thanatos 正式會員 104.xxx.xxx.130 |
2026-01-08 23:50 |
| [#5647] 單端胆機同好會 Hi Thanatos, Your previous advise was to use WE300B which is much safer. However most of the 300B users in the world may not really use WE300B, probably because of cost issue. It is always good to put a 200mA fuse in cathode such that protection on tube and output transformer are guaranteed. 最後修改時間: 2026-01-08 23:43:36 |
niceday009 正式會員 112.xxx.xxx.52 |
2026-01-08 23:37 |
| [#5646] 單端胆機同好會 Why risk? |
Thanatos 正式會員 104.xxx.xxx.134 |
2026-01-08 23:12 |
| [#5645] 單端胆機同好會 Hi Thanatos, I would say no one can predict that a tube short it's plate to cathode while in use. The best approach is to put a fuse in cathode. (Which is normally what I do) If the amp is tube OTL say 8W output, when a surge comes in due to the tube short circuit, as a result the output can reach to power supply threshold which lead to intermittent(resonance)DC or permanent DC energy causing the diaphragm of the speaker unit not able to move as to convert electrical energy to kinetic energy，meaning the driver unit coil in this case need to withstand all the heat energy. This particular case can harm the speaker unit. However, if the 300B SE amp has output transformer. Aforementioned case would not lead to DC output (permanent or intermittent). A big sinwave generated due to a surge, through the OPT, the speaker unit is able to convert the AC energy to movement(kinetic) energy. One may hear a pop(which is good thing because the electrical energy now converted) but maximum is 8W to 14W(distorted sinewave)RMS for very short time. It shouldn't have caused obvious damage. Alinco speaker driver is known for the deguass issue after a period of high level LOW frequency signal. A 50 years old driver could only maintain 50% of original magnetism but it has gone through many year of high level of low frequency impact. The article said that one big stroke can cause immediate 2% of deguass. Not sure how big the article was talking about. For this extreme case I do not know but for sure 300B SE through an output transformer cannot generate a high stroke such as 200W RMS AC. 最後修改時間: 2026-01-08 23:09:44 |
niceday009 正式會員 112.xxx.xxx.52 |
2026-01-08 22:52 |
| [#5644] 單端胆機同好會 I would never subject the tweeters of my loudspeakers to loud clashing sound (which is created when tube innards short circuit). A loud pop is guaranteed regardless of the presence of output transformers. People had damaged tweeters when they accidentally unplugged interconnects. Woofers may survive since their coils have thicker copper wires. Believe it or not, very loud clashing sound can demagnetize loudspeaker magnets without necessarily damaging coil wires. https://www.vancouveraudiospeakerclinic.ca/alnico-magnet-issues Quote from the above article, "A single high power 'pop' can reduce sensitivity by 2dB, and repeated pulses, such as loud cracks from a faulty connection will cause additional (smaller) losses." |
Thanatos 正式會員 104.xxx.xxx.129 |
2026-01-08 21:26 |
| [#5643] 單端胆機同好會 胆機有輸出牛，而次級係連接去地，就算隻胆爆炸，或輸出牛初級和次級擊穿造成短路只會令电源牛初級fuse斷開，对喇叭係永遠冇事 最後修改時間: 2026-01-08 17:51:10 |
niceday009 正式會員 182.xxx.xxx.207 |
2026-01-08 17:46 |
