悅聲音響 REFERENCE AUDIO

Tamura in Japan just announced that they will not receive any order on the production of transformers after 31st December 2025. The reason is due to the aging of testing and filling machines which already became too old and therefore not giving good results on the final products.

SUNAUDIO said they has already made orders that will fulfill the requirements on the next two years, but what will happen afterwards we do not have any clue.

It may be your last chance to get their amplifiers now at affordable prices. Get it now before they were gone forever.

The unit was assembled in Japan by SUNAUDIO. It works on 100V but within upgrades on volume pots, capacitors and resistors. The transformers have square corners and it is the therefore the lastest version. Demo unit in excellent condition.

This unit is also the latest version of SV-300BE working on 220V. The components are of high quality parts supplied by SUNAUDIO. The bonnet is an extra bonus to protect your precious tubes. Demo unit in excellent condition.

This unit used one pair of NOGUCHI PMF-30WS-3.5 output transformers which have bigger iron core and power capacity of 20W. They provide a deeper base without sacrifice on the mid and high frequencies. Self made silver panel.

Another piece of SV-300BE using SWOTER output transformers which have even a bigger size iron core than the above item. It has a larger size chassis in order to accommodate these high quality transformers. Professional grade parts employ throughout the unit to ensure good performance.

This is a SUNAUDIO SV-2A3 having a nice gold top plate. It has NOGUCHI output transformers and Hammond choke. The bigger size transformers gives better and deeper bass. Good quality parts are being used to ensure good overall performance.

This is another piece of SV-2A3 using ISO Tango FC-12 output transformers. It gives more extended high range and transparent sound. The casing is made in Japan having a beautiful good top plate.

This unit is specially modified to use 845 power tubes to give output power more than 10W. Switching power supply supply the filament of the 845 tubes enable the use of such a small casing. The hum level is very low and there is no need for adjustment.

This pair of mono power amplifier require special attention due to the its design. 310A tube is being used to drive the 300B tubes to give warm and smooth sound which is unique for pentode tubes. The unit has high qualityTango U-808 output transformer which has wide frequency response and large reserve power capacity to ensure excellent performance. The power transformer is made by HP in USA.

Here is another pair of power amplifier with the same configuration as the above item. The same transformers are being used but the chassis is smaller in size. Very affordable price and small size to fit any where.

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 ……

We have recently acquired quite a lot of Cello equipments for restoration and repair. These jobs have become quite a common practice since Cello equipments appeared since 1980s and most of them are nearly thirty years old. The capacitors are the most vulnerable component that are going into trouble. Most of them start to fail due to leakage of electrolyte fluid or getting dry, losing the capacitance or simply short circuit.
We believe that these equipments can be restored to the original performance level with the renewal  of all the electrolyte capacitors and other components which may find to be defective. Most of them will be replaced with caps having the same capacitance and same makers as well in order to ensure a successful restoration. Caps of other makers have their own characteristics which may affect the sound quality of your precious equipments. It may still work alright but it is just not all right. Something is missing that anyone can sense the difference.
Cost of our work depends on the parts that need to be renewed and we cannot give you a precise amount unless the equipments are examined and tested. We are confident that you will be satisfy with our work since it will be done with utmost care and good workmanship as well, and the parts are mostly original (we have large stock on parts which are specially ordered two decades ago). 

 

 

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

 

Updated  2-2025

Got from my good friend some brand new and use transformers made by Tango and Tamura transformers. They are on sale at special price. Don’t miss the chance!

TANGO X-8P old version not ISO new in box $20000/pair
TANGO  ISO  LCPF-100-150D 100H 150mA Plate Choke for 212, 833A, 845 etc (matching with output transformer below)

TANGO  ISO  FCPF-100-5S  100W 5K  output transformer parallel feed (match with the above choke)           total 4 pieces    $28000

TANGO ISO FC-40-3.5  for 300B, PX-5 etc. new in box.                         Sold

TANGO ISO NC-20F II  interstage (the best you can find) new in box.    Sold

TANGO ISO LC-10-20  choke. 10H 200mA new in box                            Sold

TANGO  ISO FX-40-5  new in box                                                              $4500/pair

TANGO  FX-40-10  new in box                                                                   $4500/ pair

TANGO  #11792  2K 120W  for parallel push pull 4×6550 etc new in box      $15000/pair

TANGO  XE-65-1 , #11250 , #11251 one complete set of used irons for 6C33C push pull stereo power amplifier in very good condition.          $10000/set

TANGO  EQ-600P (LRC-TYPE)  best for DIY phono amplifier  used but in very good condition  $6000/pair

TANGO   MS-UVD 220V  for 845, 211 stereo amp excellent condition      $6500

TANGO  #10697  specially ordered new in box   primary: 0-220V     Secondary : 500-450-0-450-500V 0.26A, 0-6V 6A, 0-6V 6A, 0-6.3V 3A, 0-6.3V 3A, 0-5V 4A  for any suitable tubes    Sold

TANGO  MS-400H NOS with box   primary : 220V secondary:  0-115V-125V 1.4A, 320V 100mA, 70V 100mA, 6.3V 7A, 6.3V 7A, 6.3V 3A    for 6C33C         $3500/pc   2 in stock

Oversea buyers are welcome. $1US= $7.8HK You can pay through PAYPAL. Please contact me at: refaudiohk@gmail.com