Amazing relay board

最後修改時間: 2026-02-13 22:18:58

417A/5842 line amp with Monolith nano core output transformer and Khozmo auto-transformer Volume Control. Power supply :- HP711A tube regulated power supply and 5Vdc linear power supply. Lastly, using transistor shunt regulator circuit for cathode bias of the 417A tube.

This is a wonderful project that my young neighbor worked on for few months. I helped him to finish off the bug fixes and adding few improvements.

With use of the transformer volume, it helps to reduce the background noises substantially. I believe it is because of the low resistance right to the grid of the 417A tube.

On the other hand, we asked quidance from ChatGPT on the arrangement on RCA and XLR outputs. There are different arrangement and I isn't sure which one is better.

Anyway, I am so proud having the opportunity involve the work on this great project.

Johnny



最後修改時間: 2026-02-13 22:18:24

冇錯，玩黑膠要靚聱，除咗財力雄厚，盤臂頭的調較經驗比數碼音响係講究很多，熱愛黑膠係要長時間接觸不斷嘗試才慢慢get addicted, 買得三百幾萬個盤都應該唔係玩咗短時間，除非富二代，聽到人地話黑膠靚，自己打個电話就乜都有但係完全新手，都有呢個可能

最後修改時間: 2026-02-12 11:27:25

黑膠盤嘅位置正正處於右邊嘅一個角落頭，嗰個角落正正形成一個兜型兜住啲聲音

嗰兩塊吸音板唔似會吸到幾多嘢，尤其係兜住嘅聲音一定好強大

其實只要做一個實驗就得：用數碼音源播歌，唱針落在靜止不旋轉黑膠碟上，量度phono amp output就可以知道嗰個角落頭駐波有幾強？有幾影響黑膠重播？

其實香港而家好多人都有幾億身家，攞一二千萬出嚟買心頭好唔係太難

難就難在下下只用錢搞掂晒啲嘢，買人哋嘅心血結晶，自己就錯過咗好多學習機會

我唔太相信呢啲所謂一步到位買超貴價器材嘅人會好似呢度嘅師兄識得咁多電子、電聲學問。

你冇呢一啲學問，我只能夠講，俾錢只係買個牌子、買個信任，被人牽着鼻子走

呢一類人未必太介意最後結果音效，佢哋介意牌子、信仰、同埋最重要嘅二手價

單純睇佈局，左邊嘅CD架吸音吸得勁，右邊嘅黑膠盆好容易被喇叭發出嘅聲音震盪到而引致共鳴強化音效，左邊吸得勁、右邊被強化，好大機會會左右失衡

離題一下

見到附图即刻感受到有好多錢係幾咁美好，雖然对Magico同Kondo PSE不是所愛，但個TechDAS zero係世界唯一最好唱盤

睇图就知，VFET已經係原子粒之中最線性，但比起Direct Heated Triode 仲差一大截

Triode will never disappear. 300B ,2A3, 211, 845, 212呢D胆已經有接近100年，現在仍生產，我諗去到個孫果代仲有生產





最後修改時間: 2026-02-08 23:49:28

最線性放大元件。

直熱三極 排第一
旁熱三極 排第二
VFET 排第三

wcw12師兄，確實直熱胆推直熱胆可保存更高綫性，一百多年前之擴音機都是全直熱胆

而直熱三極管係人類到現在唯止最高綫性之主動放大零件，不嫌麻煩，呢句說話最少係度講過五次

最後修改時間: 2026-02-08 16:15:16

靚仔！直熱管推動直熱管係德國人發現的好好方法！日本人左久間駿將這方法實踐並傳揚。

RELCAP RT 英文字作方向性焊接





最後修改時間: 2026-02-07 00:47:50

＞＞ we really got into identifying the outside foil, and listening to them either way, seeing which we preferred.
They do sound different, depending on how you put them in the circuit.

確是可以聽到分別，而按电容表面印字作方向性焊接是聲音比較中性，一般我會按交連電容的英文字作方向性焊接，入→英文字→出

最後修改時間: 2026-02-07 00:41:48

原文

電容的方向。對聲音的影響。

What about capacitors? How did you go about selecting capacitors and resistors for your circuits?

You have to listen to them. As far as capacitors go, we really got into identifying the outside foil, and listening to them either way, seeing which we preferred.
They do sound different, depending on how you put them in the circuit.

Capacitors used to be marked with a band on one side indicating the outside foil. Now, most caps don't have the band, so you don't know which is the outside foil. If the cap doesn't have a band you can use test equipment to find the outside foil.

What is the preferable way to wire a coupling cap, from the plate of your driver tube to the grid of your output tube?

If your outside foil is connected to the plate of the driver tube, using your example, that is what I call the slow way. That is the way I put them in, because I prefer transients are a little slower. Another advantage to this way is that it is fuller sounding. If you put them in the other way, it's a little faster sounding, but it's thinner sounding. And it works the same way for bypass capacitors and power supplies. I'm sure it does the same thing.

Did you have any specific brand of capacitors? Back in the 1970s, there weren't as many choices of gourmet capacitors.

Well, back in the mid-70s, we didn't really know the difference between capacitors. We used the Electrocubes, just the straight Mylars. I also used Vitamin Qs because they were available at electronics surplus stores. Vitamin Qs, however, give a soft and sometimes smeared sound.

What kind of capacitors are you using in the signal path of your new designs?

I use Rel-Cap polystyrenes.

昨晚重看了這一篇文章。

Hi Johnny, It would be much cheaper If we buy from China. My friend bought a pair 2 years ago. It is real bargain !!

It would be much better If the output transformers could have been bigger

The price is too good to be true. Just wondering if anyone got this pair of 300B mono's?

Johnny

Western Electric claims the type 100 capable of producing 125W RMS. They employed MOSFET in the power stage working together with 308 Triode. WE claim their proprietary current source circuitry help to gain the output power


TubeCAD explains that WE type 100 in fact is push pull operation but it uses a single-ended parafeed output transformer

最後修改時間: 2026-01-28 14:22:08

The Western Electric WE type 100 power amp employ WE308B power tube. With 1KV B+ 210mA idle current, and 3K ohm plate load, its output power is 35 watts.

From the plate curve from the datasheet, it seems the 308Bs operating in a very linear region under the above condition.

Johnny



最後修改時間: 2026-01-28 06:46:35

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