I bought this book in 1990 from Hong Kong Bush. The circuits on making amplifiers with big transmitter tubes amaze me up to the present moment. I was lucky enough to purchase some of the transformers in the following years but never had the time to really complete one single projects. I aware that my time is running short and decided to commence my long awaited journey right now.

Now with the help of new software available I can translate all the words on the book in Chinese or English. I was delighted to understand the true meaning of its contents which was quite impossible in the last 25 years. I wanted to learn Japan language in the pass but it took too much time and soon I lose the will to proceed. Last week I finished reading some chapters within an hour and find it amazing. Thank you for the advance in technology which make it possible.

For those guys who are interested in the knowledge of this book I think you can still find it somewhere in Japan or simply get a copy on the web. May be I can quote some of the main points here but a total translation posted may not be practical or un-respectful.

I

I had finished the project on two amps on the 805 tube with different output transformers and interstage transformers as well. One with the original Tango transformers, and the other one with transformers made by HATT AUDIO in Japan. They use the same power transformers (I intend to built the projects on two mono amps).

The output power and frequency response of the two amps are practically the same, but there are slight difference in sound character between them due to the use of two separate brands of transformers.

805 amplifier with Tango transfomers (The first tube was changed to use WE437A now with upgraded clarity and dynamic, unbelievable). The amplifier was constructed on a large chassis measuring 600 mm x 350mm with top plated 4mm thick. I began building the amplifier on a smaller chassis but the heat was unbearable. The big tubes generates a lot of heat and a good ventilation is essential for long term operation. It occupies a lot of space but that is the only way to ensure safety. I use Elna 200mfdx2/500V caps which was attained 15 years ago. The blackgate caps may be better but their price had become unrealistic now. The total weight is around 35kg and I cannot move it around easily.

之後的改良：這款擴大機蘊含著巨大的可能性，但完成後我一直焦慮於尚未充分發揮其潛力。我知道原因似乎在於初段管，因此在決定使用12AU7並聯作為初段管後，我仍在尋找更適合這款擴大機的初段管。

我偶然從松並先生的文章中得知Western Electric 的WE-437A 電子管。

我去了進口商Trial Electric （03-3351-6556） 調查其特性，發現它是一個介於MT 管和GT 管之間、可愛大小的9腳Magnoval 管，具有7W 屏耗、45mA 最大屏流，即使作為輸出管也能輸出1-2W 的三極管。而且，它的內阻低於1k02， 為41。12AU7 的內阻約7KQ2，並聯後也有3.5kQ。對於喜歡低內阻的我來說，這是一個不可多得的管子。表2-11-3 顯示了其規格和引腳連接圖。

將初段管更換為該管後，我感到驚訝。正如我預料的那樣，聲音品質在各方面都確實提升了一個等級。音質和平衡性甚至超越了之前被一些人讚譽為「極致真空管擴大機」的808擴大機。雖然之前也曾做出過在某些方面（例如弦樂）優於808擴大機，或在鋼琴和貝斯方面超越808擴大機的放大器，但從未有過在所有方面都超越808 擴大機的放大器。

WE-437A 初段的805 放大器，聽感上的音域上下延伸很多，因此原本具有的規模感得到了充分發揮，聲音的鮮活度也更上一層樓。最重要的是，它不挑音源，這一點優於其他任何放大器。一般來說，每種放大器都有其優點和缺點，有的更適合弦樂，有的更適合鍵盤樂器（也有很多兩種都不適合的），而且隨著重播設備等級的提高，這種傾向會變得越來越明顯。改良後的805 單端放大器從這個意義上來說，堪稱非常稀有的放大器，適合弦樂、適合鍵盤樂器，尤其適合聲樂，管弦樂、室內樂等所有音源都能以與以往被認為專門適合該類型音樂的放大器同等或更高的音質進行重播，讓人無可挑剔。

The final version used the WE437A in the first stage. It has a very low output impedance and high gain which gives a big improvement in sound quality. There is a wider soundstage and more lively presentation. The modified 805 amplifier suits every type of music and the performance is unbeatable in every sense.

The photo below shows another unit of 805 power amplifier with HATT AUDIO transformers (picture is not updated using tango transformers instead) The amplifier was made on a smaller chassis (600mm x300mm) as smaller Mcaps 200mfd/500V are used. It is lighter in weight due to the smaller size output transformers and caps. This amplifier uses 12AU7 in the first stage. Its performance is remarkable though may be less perfect than the above unit. But the cost and size will be more acceptable by most user.

I am going to start the projects on other transmitter tubes such as 808 and 800 tubes. It will take some time, but it is better now or ……