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| [#4805] 單端胆機同好會 十字型  |
johnnykmtang 會員70.xxx.xxx.22 |
2025-01-17 23:30 | |
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| [#4804] 單端胆機同好會 Jonny, Is this 845 having a cross head(十字型而唔係王字型) by looking from the top 最後修改時間: 2025-01-17 23:28:28 |
niceday009 正式會員 218.xxx.xxx.220 |
2025-01-17 23:25 |
| [#4803] 單端胆機同好會 Received a pair of new LinLai 845 tubes yesterday. The price is about same as the LinLai 300B's. The bias idle current is same as the cheaper LinLai 845 ones that I have. That means there quality control is very consistent. Sounds good too.  |
johnnykmtang 會員 70.xxx.xxx.22 |
2025-01-17 23:14 |
| [#4802] 單端胆機同好會 題外話 Mcintosh 都做咗經典275, 點解Mcintosh 要出部胆機前面用原子粒放大？ 效果好D定成本平D 最後修改時間: 2025-01-17 16:50:58 |
niceday009 正式會員 218.xxx.xxx.220 |
2025-01-17 16:50 |
| [#4801] 單端胆機同好會 大家的電壓工作點是一樣，可能是用同一款輸出變壓器   最後修改時間: 2025-01-17 10:40:37 |
tom55 正式會員 118.xxx.xxx.6 |
2025-01-17 10:37 |
| [#4800] 單端胆機同好會 我當時用275推Klipsch LA Scala, 其低音之震撼係而家D家用低效率喇叭難以企及. 套Drum Set直程好似在現場，但講像真以及中高音之details，前面对三極單端零負回輸係高班好多  最後修改時間: 2025-01-16 23:17:10 |
niceday009 正式會員 182.xxx.xxx.36 |
2025-01-16 22:50 |
| [#4799] 單端胆機同好會 Mcintosh MC275我買過兩部，一原裝1965年，一部新版，新版高頻清晰過舊版，兩部低音都算好(同類4/5極加負回輸計)，低音表現絕對好過粒機同等功率，相反MC2275原子粒加胆唔係同級數 一樣事係肯定，MC275外型係經典級，買嚟擺已經值 但係講声音表現，KT88, EL34 果D 4，5極胆，像真度(包括速度及音準)冇得同無負回輸三極胆比，如果唔係都唔使係度開個單端胆機同好會 最後修改時間: 2025-01-16 22:58:28 |
niceday009 正式會員 182.xxx.xxx.36 |
2025-01-16 22:45 |
| [#4798] 單端胆機同好會 之前覺得好奇怪。為什麼國內的人/書叫Unity Coupled 為單端推挽。 原来早期SEPP( 单端推挽)是叫 unity couple。 麦景图的Unity coupling circuit 也是同名。 所以会混淆在一起  |
WilliamsonAudio 正式會員 182.xxx.xxx.1 |
2025-01-16 22:08 |
| [#4797] 單端胆機同好會 如果有興趣瞭解Unity Coupled。可以看這一篇文章。網上可以找到的。  |
WilliamsonAudio 正式會員 182.xxx.xxx.1 |
2025-01-16 22:05 |
| [#4796] 單端胆機同好會 之前在國內群組同人討論McIntosh的資料。也分享出來。 MC275 根据搜索结果,McIntosh 的 Unity Coupling 电路(1949年的專利設計,)是一种独特的输出级电路设计,具有以下特点: A) 50-50 反馈安排: 在传统电路中,负载全部连接在输出管的阳极。而在 Unity Coupling 电路中,50%的负载连接在阳极,另外 50%连接在阴极。 这种 50-50 的分配方式构成了总的输出阻抗。 B) 屏极电压稳定: 由于阴极电压会随着功率输出的增加而上升,这会导致屏极-阴极电压下降,从而限制最大功率输出。 McIntosh 的解决方案是将屏极连接到另一只输出管的阳极。这样可以保持屏极电压基本不变,即使功率输出增加。 C) 负反馈和偏置: Unity Coupling 电路使用了大量的负反馈(约 100%)。这使得偏置电压的精确设置并不重要,可以采用较宽松的偏置电流设置。 D) 输出变压器的设计: 为了实现这种 50-50 的反馈安排,输出变压器需要采用特殊的双绕组或三绕组的紧密耦合技术。这种设计更加复杂和昂贵,但可以带来出色的性能。 总的来说,McIntosh 的 Unity Coupling 电路是一种创新的输出级设计,通过特殊的反馈和变压器耦合方式,实现了出色的音质和功率输出性能。这种设计在当时是非常先进的。  |
WilliamsonAudio 正式會員 182.xxx.xxx.1 |
2025-01-16 21:46 |
| [#4795] 單端胆機同好會 在推挽的電路上面。其實都會有不同的接法。 而有一些是比較後期才有的。 下圖就是一個比較有系統的接法示意圖。 Mcintosh 是第四種接法。叫 Unity Coupled  最後修改時間: 2025-01-16 21:27:37 |
WilliamsonAudio 正式會員 160.xxx.xxx.90 |
2025-01-16 21:25 |
| [#4794] 單端胆機同好會 Hi tom55, The complete service manual of the McIntosh can be downloaded from this link. https://elektrotanya.com/mcintosh_ma-2275_sm.pdf/download.html#google_vignette The newer products of McIntosh inclined employs more solid state components of transistors, IC's, and op-amps. I don't really like their design as they still having high gain amplification stages and the good old global NFB. So, Tom, what is your opinion on the MA-2275??? Johnny 最後修改時間: 2025-01-16 16:35:48 |
johnnykmtang 會員 70.xxx.xxx.22 |
2025-01-16 16:34 |
| [#4793] 單端胆機同好會 McIntosh MA2275 vs MC275 mk4 大家都是KT88輸出級及牛輸出，一樣是75W 分別在於推動KT88的電路不同 MA2275是膽放大加石buffer MC275是全膽   最後修改時間: 2025-01-16 11:05:47 |
tom55 正式會員 118.xxx.xxx.6 |
2025-01-16 10:58 |
| [#4792] 單端胆機同好會 #4790 Here's the original thread for discussion of "Single-ended OR push-pull?" https://www.diyaudio.com/community/threads/single-ended-or-push-pull.120358/ |
johnnykmtang 會員 70.xxx.xxx.22 |
2025-01-16 10:52 |
| [#4791] 單端胆機同好會 #4787 唔肯定，只可Assume兩部机係zero feedback |
niceday009 正式會員 218.xxx.xxx.220 |
2025-01-16 02:46 |
| [#4790] 單端胆機同好會 我只係睇到diyaudio https://www.diyaudio.com/community/threads/single-ended-or-push-pull.120358/ but for the observation provided by Jack, should we meditate what cause the missing 30% THD reduced by PP mechanism (while SE could maintain the original 80%)  最後修改時間: 2025-01-16 00:34:00 |
niceday009 正式會員 218.xxx.xxx.220 |
2025-01-16 00:14 |
| [#4789] 單端胆機同好會 #4786 Eric, 有否原來文章的出處? |
WilliamsonAudio 正式會員 103.xxx.xxx.16 |
2025-01-15 22:38 |
| [#4788] 單端胆機同好會 Hi Niceday009, I would say the THD measurement is quite confusing. The level of 2nd harmonics is most significant one generates from the SE amp. With a complex signal of 80% distortion (that means it contains large amount of harmonics) feed into the SE amp, it will further modulate the harmonics with its 2nd harmonic. The measured THD doesn't mean much as there's some sort cancellation among the harmonics. Unfortunately, the mixing of the harmonics through the SE would become much distorted which the THD doesn't show. Johnny 最後修改時間: 2025-01-15 17:42:41 |
johnnykmtang 會員 70.xxx.xxx.22 |
2025-01-15 17:39 |
| [#4787] 單端胆機同好會 我反而想問一個問題，嗰部測試嘅p-p amp係咪都係class A機，兩部都係冇負回輸定係有負回輸。 最後修改時間: 2025-01-15 17:38:18 |
DY2036 正式會員 182.xxx.xxx.14 |
2025-01-15 17:36 |
| [#4786] 單端胆機同好會 一個有啟發性post, DRD 300B 設計者Jack Eillano 做了個實驗，看來Single Ended 才是更faithful in reproduction. Jack create一個基本訊號mixed with another frequency 做成80%THD測試訊號，經過SE amp出嚟都係大約80%THD, 但經過PP amp就得返50%THD, 等於PP將原有某原訊號删減咗 True, perhaps, if you listen to sin waves, but I'm not sure this is quite as much of a fact as stated here. From Jack Elliano: P-P will cancel even order harmonics but will add or emphasize the odd order. To illustrate this, one experiment that still intrigues me is when we took two audio frequencies and mixed them to one waveform which measured as 80% distortion. It then passed through a very good quality commercial P-P amp where the output waveform measured about 50% hmm! But when we then passed it through a SET amp and its output measured 80% just like the original. What Happened to the other 30% within the P-P amp? It appears that there are occasions that some audio signal complexities may also cancel or change structure from the original as well as the P-P tube transfer characteristics on even order harmonics. 最後修改時間: 2025-01-15 16:26:59 |
niceday009 正式會員 182.xxx.xxx.106 |
2025-01-15 16:19 |
