No upgrade in parts but still sounds wonderful. Price is $14800HK

Totally ungraded with Jensen capacitors. Really sounds great and nice looking. Price is $18000HK

Last piece of modified unit lighting up. No upgrade in parts. Amazing sound quality and good looking. Price is $15800HK

Two modules (switching power supply mounted on the bottom cover plate. Easy access for doing upgrade.

Bottom plate put on and secured. Just enough space thanks for the small size of modules.They stay warm only after several hours of operation.

I always wonder why Sunaudio did not produce any kind of 845 or 211 single end amplifier in their series. At closer study it was found that the same power transformer (PT-150) is used on all their amps (except the top model SV-300BSM). There is no 10V windings ( filament of 845 tube needs 10V) on the transformer, and two 10V AC 5A windings are required because the big tubes need DC on their filament in order to get reasonable low hum at the speaker output terminal.

很久以前已經有這個疑問，為什麼SUNAUDIO沒有生產使用大型燈膽如211或845等的管子作為輸出功率管呢？細心的觀察一下不難發覺差不多在所有型上使用的電源牛（PT-150)是沒有10V燈𢇁用的繞組，而若果用這類大管時必須有2組10V5A的燈𢇁繞組用以提供2組10V直流給燈𢇁用才成，否則喇叭會聽到相當大的交流聲。

I have tried to fit (barely sufficient space) and use Tango or Hatsimoto power transformers on a few units but they becomes alarmingly hot during prolong usage (not more than 4 hours). Though I learn for a long time that switching power supply is used on some big power tubes (212 and 833A) filament supply, I have no idea how these items can be fitted on Sunaudio amps.

我亦嘗試過用TANGO或橋本火牛（體積可以勉強放下）放在一些實驗機上使用．但長時間使用時熱量大高（四小時後）。雖然很久以前已經知道有些設計是使用開關式電源組件作大管子如212或833A等燈𢇁供電，但我並不知道這些是否可以用在SUNAUDIO的機種上。

Recently I have bought two 12V 50W switching power supply and commence my experiment. It proved to be a success and it is also possible to squeeze two of such unit inside the casing.

I am very pleased with the finished product. The sound quality is better and the hum is even lower than the previous version, and the power transformer runs warm only after a few hours operation.

最近買了2個12V50W的開關式電源組件做實驗，實驗是成功的，2件組件都可以擠入機箱內。對於件成品我十分滿意，跟以前的制成品相比，它音色更好噪音更低，並且火牛在數小時工作後只是暖手而已。

Three units are modified. There are difference on the use of parts and therefore not are the same price. Hope you like and enjoy their performance.

改做了三件成品，因為三件機內零件畧有不同，所以售價不一樣。希望你們會喜歡它們的表現。

Oversea buyers are welcome. But please be noted that the amplifiers works on 230-240V AC only. Free packing but SHIPPING  and other charges are hot included in the price. YOU can pay through PAYPAL. $1US=$7.8HK.  Please contact me at : refaudiohk@gmail.com