Just completed the building of 808 single end amplifier. It was built using the chassis of the former 805 tube amplifier. The aim is to simplify the construction of the mentioned unit as all I need was to mount the power and output transformers for the 808 tube without further modification on the other parts. The internal circuit reconstruction was also much simplified since the configuration was quite similar. There was no need to built another bias board, only a resistor was put on both regulator IC and the bias voltage can be adjusted between 30-50V which is what needed for the job.
I am using HATT AUDIO interstage transformer which gives very good result. The performance of the 808 tube amplifier is remarkable. The sound is full of energy and alive. It really sings. You can fell that the singer is performing with passion and you just want to continue playing your favorite CDs.
I think that there is not much 808 tube amplifiers appearing on the market today though there must be hundreds of these amps being made by DIYs in Japan in the 80s or 90s. At least I knew one nice gentleman from Japan who had owned one unit in around 1995. He said that its performance was excellent and now I learnt that it is honestly quite true.
This unit was modified to use the 808 tube. The one with all TANGO transformers looks and sounds better and therefore there is no need to keep another similar unit. The HATT AUDIO output transformers on these unit was designed for the WE-212 tubes, and I shall start the project if one pair of 212 tubes is available at reasonable price. The price of STC-4212 tubes is now double since 1995. The power, output and interstage transformers are taken off and reserved for another project. I had once seen one pair used Tango 10887 output transformers on the second hand market, and therefore it may be possible to built another piece of 805 amplifier in the future. Let’s wait and see.
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.
just completed another headphone amp using the famous 300B as the power tube. The client is a very young and nice guy. He is studying and working part-time. But he wants to get the best and affordable headphone amp, and it is my job to fulfil his dream.
All the transformers are Tango ISO since the may be the best but still reasonably priced items that we can get from Japan. The design of circuit is simple and no interstage transformers are used due to limited budget and size of the unit. High quality parts such as Elna and Jensen copper film caps are used to ensure best attainable performance.
He has special concern on the appearance of his toy and we had a lot of discussion on the planning of this project. The position of transformers and tubes are finalised and the drilling and cutting began. It took one week to get it completed and the operation test proved to be outstanding. All the measured readings are within the designed value, and the residue hum is very low. I was quite worry about that too much hum may induce due to the positioning of transformers and tubes but it turns out okay.
To hear is to believe. His AGK headphone sings and there is black silent while no music is playing. He loves it.
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.
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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.
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 had recently completed two orders on triode preamp with input and output transformers. The outcome was very encouraging and three similar preamps are under construction with different triodes. We expect they will perform well , though with difference in sound character.
The following preamps are newly made with the same configuration – parallel feed output stage. Plate choke made by SILK audio (Thailand) are used on these preamps. It has 200H 10mA capacity and excellent frequency response.
We had selected suitable combination of plate choke and output transformers, and also caps to give the best result. Regulated filament supply and a series of CLCRCRC filter on high voltage to ensure low hum level on the output. The working point of the tubes are carefully chosen so as to get optimal performance.
VT-25 preamp using UTC input and Tamura output transformers. Tamura power transformer and choke. Price is $16800 hk.
Vintage 26 tube preamp using Tamura input and output transformers. Toroidal power transformer and Tamura choke. Price is $14800 hk.
Vintage 01A or 112A tubes can be used here. UTC input and output transformers. Toroidal power transformer and Tamura choke. Price is $14800 hk.
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).
剛從日本運來幾件新款的SV-300BE，所有火牛外殼都改變為方角，高度增加近壹寸而銘牌亦變大了，整體來說覺得外觀更加好看更有吸引力。我懷疑輸出牛除外型上有所改變外其他分別應該不大，但電源牛及握流圈明顯變容量比以前的有所增加，預期長時間工作這些火牛不會像舊型號那些那麽燙手，對於準買家來說是一個喜訊。
We have just received a few pieces of SV-300BE (new version) from SUNAUDIO JAPAN. All the transformers have been upgraded to new version having square top corners. These transformers are taller in height with larger logo plates on top giving a more attractive appearance. I suspect that there is not much difference in the output transformer SOT-525A comparing to the old one though it has increased in height, but the power transformer and choke are replaced with the PC-1035E and CH-515A which have bigger capacity than the old one ( PT-150B and CH-515). In fact these power transformers runs much cooler than the former (the old version become quite hot in time running. It is a good news for the buyers.
十分抱歉，價格現在提升至$23800元。廠家解釋因為材料價格升高及火牛容量增大以致成本急劇成比例變高，再無法維持以往的售價了。目下只有兩件存貨，下壹批次有可能在數月後，或者更久也不一定。
price is now $23800HK. Sorry for the increase in price but the increase in the cost of material and upgrade in transformer makes it impossible to keep the old price. Only two units are available for the time being. Next shipment may take up to 3-4 months or even longer.
No upgrade in parts but still sounds wonderful. SOLD
Totally ungraded with Jensen capacitors. Really sounds great and nice looking. SOLD
Last piece of modified unit lighting up. No upgrade in parts. Amazing sound quality and good looking. SOLD
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.
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.
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.
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
I have just completed a project on one of the BEST and possibly the BIGGEST headphone amplifier on the Planet. It is huge (600mm wide x 300mm depth) and weight around 70 lbs.
It was tailor made for a young guy who has the rare passion on the sound of vacuum tubes. I had built a couple of headphone amplifier for him using different types of direct heat triode tubes, and this is the final and ultimate construction of the series.
Tamura ISO transformers are employed for the construction to ensure un-surpass sound quality. We follow the golden rule – SIMPLE IS THE BEST. Top grade iron plus best quality parts, simple and straight forward circuit design.
Here we use Western Electric 275A as the output tube. Compare to WE 300B, it is not well known, but considered by some audiophiles to be better or at least as good as the big brother. The useful output power of this tube is merely 4 watt, but it is already more than we need. The miniature western electric 417A is the driver tube. It will be coupled to the 275A through a interstage transformer. The design is extremely simple and effective as there is no capacitor in the signal path, and therefore no colouration or delay of any sort. The input is connected direct to the CD player or any signal source, and the level controlled by a high quality volume pot.
I am not going into detail of the construction and choice of parts etc. You may have other design and preference on parts. Hope you enjoy.
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
