- #4255 [johnnykmtang], 24-06-29 16:31
- #4254 [WilliamsonAudio], 24-06-28 23:40佐久間的設計理念。分成幾點方便閱讀。
Design Concept
1 use the same (直熱膽)tube for driver and output.
2 Their tones are clear and powerful.
3 the driver's tone contributes the greater part of the amplifi-er's voice.
4 Few driver tubes can sing along in beautiful harmony with a good power tube.
他設計的 4212 poweramp, 當然也是用 4212
做推動膽。直熱推直熱,是“”全直熱設計理念“”。
我對佐久間的理解是。
在他的文章中,提到一個例子。就是WE300B, 當他用300B 推300B,就感受到真正西電300B 的聲音。因為整個信號就祇有300B,並沒有加上其他膽的聲音。
膽本身就有分層次。例如。小九腳膽,大8腳膽,直熱膽。五極,三極等。當然最好就是直熱三極。現代的設計主流都是應用高跨度膽和直熱三極膽。當中直熱三極更是貴價機中的主流。
由於推動膽。影響聲音的比例更加重要。所以在直熱膽前面用比直熱膽低級的膽,只會聽到驅動膽的失真和音色。down grade 了直熱輸出膽的純真度。所以好多時直熱膽機,我們是在聽前面推動膽的聲音。例如12AX7, 五極管。
想像一下。4212 用 12AX7 去推KT88 再推4212. 你就知道兩者之間的設計理念區別有多大。膽成本相差也好遠。
最後修改時間: 2024-06-28 23:44:40 - #4253 [niceday009], 24-06-28 00:11I also believe a good sounding amp must be equipped with reasonably low distortion but tuning to low distortion must not involve loop type NFB.
Wilson made a point that driving stage linearity before the DHT output power tube is crucial
最後修改時間: 2024-06-28 00:13:04 -
- #4252 [johnnykmtang], 24-06-27 21:1315 years ago, I built a single ended 45 tube amplifier for a friend with Sun Audio's schematic. I used expensive high quality components. After it was done, the amp was tested at my friend's place. He was so delighted with the wonderful sound from it. His wife came in and she asked if we can play an old Chinese CD album by Teresa Tang. After we played a song, she said it doesn't sound like Teresa. I just blamed it on the poor recording of the CD.
After I found my way in minimizing the distortion in my amplifiers, I played couple of the old Chinese CD albums including the ones by Teresa. I realized that the sound quality is real good indeed and I could recognize it is the real voice of Teresa that I familiar with.
I think this is a good way testing of the HiFi system with some old CD albums and see if it can reproduce the lively sound that you like and familiar with. - #4251 [johnnykmtang], 24-06-27 06:47So, how to determine the best idle current of the SE output power tube?
It is better to use the plate V-I curve graph, draw the load line, try out the lower distortion region you can get for say half power. Most of the time we just listen to 1 or 2 watts max (depending on the efficiency of your speaker).
Here is a good online program you may try.
https://trioda.com/tools/triode.html
My idea is getting low distortion at low power. High power??? No no.... I don't need that.
Johnny - #4250 [johnnykmtang], 24-06-27 06:41Regarding using 211 to drive 211, I believe the concept is providing ultra low distortion signal driving the output power tube. With use of smaller tubes to drive, usually its output signal has higher distortion than the large power tubes.
Therefore, if we can find a small tube with higher gain and low distortion, this would be the best solution. That's why I experimented using 6DJ8 differential PP IT drives the 300B SE.
Johnny
最後修改時間: 2024-06-27 06:41:59 - #4249 [niceday009], 24-06-27 00:02
- #4248 [niceday009], 24-06-26 23:43若果用理性分析,845 燈絲3.25A 10V 直熱,做phono amp hum會好大
而211 IT drive 211, 211 Miller capacitance 算幾大,可能用300B 仲實際因為211 input swing 要求較少
但211作第一級放大(用#4240例子),可能有好多小型直熱管更好唔使用隻75W 屏耗胆做 - #4247 [WilliamsonAudio], 24-06-26 23:29當時Thomas Mayer 的211推211后級。
Sound Practices Issue 16
其後他的產品也有這種概念。,例如46推46 - #4246 [WilliamsonAudio], 24-06-26 23:16佐久用 845 做 Phono amp
- #4245 [niceday009], 24-06-26 23:09
- #4244 [WilliamsonAudio], 24-06-26 23:08Thomas Mayer
推動膽也是喜歡用直熱膽,也提到他受到佐久啟發。
""""""
I stayed with the 211 since that very first decision, while I tried out numerous input/driver stages. The first attempts used 6SN7/6SL7 stages in SRPP and mu-follow- er configuration. I finally dropped these to go for an all directly heated amp with transformer coupled DHT driver stages. I tried the 26, 71A 45 and 46, the 46 being the best solution of all of these. At that stage my amp design was already heavily inspired by Sakuma's artwork. So I decided to go "whole hog" and see what it's all about with his amps using big triodes as drivers
But there was one problem. The Tango NC-20 which was my choice for the inter- stage transformer would not handle the DC required by the 211, although the pri mary impedance would be a good fit.
""""""""
最後修改時間: 2024-06-26 23:22:37 - #4243 [niceday009], 24-06-26 23:05
佐久間最喜歡845製作,而佢任何放大級最喜歡interstage load
You tube 有不少佐久間生前訪問
https://youtu.be/fxb-7ARBYQQ?si=0mEC4mmZHs3ANByK
最後修改時間: 2024-06-26 23:12:36 - #4242 [WilliamsonAudio], 24-06-26 22:59他有自己的一套理念。可以參考。
設計過DHT後級的人也知道。最難設計就是推動級。
Design Concept
The schematics show you my concept in power amplifier design. I use the same tube for driver and output.
I made PX4/PX4 SE power amplifier, RCA50/RCA50 SE power amplifier. Their tones are clear and powerful. Through lis- tening, I discovered that the driver's tone contributes the greater part of the amplifi- er's voice. An excellent power tube demands a similar level of quality from its driver. Few driver tubes can sing along in beautiful harmony with a good power tube.
I also made 300B push-pull/300B push- pull power amplifier. Before this, I didn't have the impression that the 300B tone was very elegant. But the special tone of the 300B push-pull driver/300B push-pull output power amplifier taught me the true Western Electric sound.
Issue 13 - SOUND PRACTICES - #4241 [WilliamsonAudio], 24-06-26 22:52日本有一位大師叫 佐久間駿(Sakuma).
他提倡用直熱膽(DHT)推直熱膽(DHT)的設計.
例如 845 推 845,300B 推 300B.
由於他有出過書(直熱管放浪記)。也在日本雜誌發表文章。美國膽機地下雜誌Sound Practice Issue 13 也發表過文章。
他的影響力甚大。德國Thomas Mayer, Thrax Audio,也受到他的設計理念。而得到啟發。Lynn Olson 在他的網站也有提及他。
相信日本人受""佐久大師""。設計理念影響更加深遠。
所以在日本。211推845也變成相對合理。
最後修改時間: 2024-06-26 23:00:46 - #4240 [niceday009], 24-06-26 17:39日本人都有些係慕名去制直熱3極單端机,咁講等於係有D唔實際
以下呢部用211做初級放大,845做driver, 833A做輸出功率管
845做推動可能係有必要,因為833A一般bias 正偏压栅內阻較低,interstage可以做3:1出400 ohm output內阻,但211做初級放大就有D過火
最後修改時間: 2024-06-26 17:44:06 - #4239 [niceday009], 24-06-26 13:15#4237
833 push pull 零回輸,原子粒电子分音,果位70歲伯伯不時提及無㷌還(無負回輸),應該对三極胆机好有經驗 - #4238 [mcc2018], 24-06-26 08:09This is so called "Craftsman spirit 匠人精神", salute! BTW, parallel multiple tubes,transistors or dac's to lower SNR can be applied to non-correlated (random) noise only.
- #4237 [WilliamsonAudio], 24-06-25 21:35
- #4236 [WilliamsonAudio], 24-06-25 19:35例如,
12AX7 並聯, S/N 會好 3dB
CJ ART 6DJ8 X10, S/N 會好 10dB
CJ ACT 6H30 X 4, S/N 會好 6dB
是以單一支膽(沒有並聯)去對比。
我自己也測試過。CJ ART前級, Noise 真係好低
最後修改時間: 2024-06-25 19:38:04 - 下一頁 (1 of 213)
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The 6SN7 driver stage use the Lundahl LL1667 push pull plate choke and capacitor output to the KT66. This maximize the frequency response at both low and high ends. Also, it provides better balance and low distortion drive signal.
Complete constant current in both driver and power stages. Therefore, the power supply can be very simple one.
最後修改時間: 2024-06-29 16:35:57