SUNAUDIO SV-300BE 並沒得到如同門兄弟 SV-2A3一樣的口碑,實在令人惋惜。我有很多擁有這件精品的朋友一致都認為它是同價泛圍內表現最好的300B放大噐,也許它提供的能量及震撼不若其他對手,但它能發掘出300B內在所包涵的甜美與幼細的音色,是無可比喩的事實,使用高效率音箱時音量也著實令人滿意的。況且因為此機的300B管子工作屏壓不高(300V左右),玩家真的一生都不用更换灯胆,要試用不同牌子的300B不計。
It is a pity that Sunaudio SV-300BE did not receice much good reviews as compared to its little brother – the SV-2A3. However most of my friends who own the SV-300B consider it to be one of the best 300B tube amplifier in that price range. Though it may not be as powerful and punchy as the other competitor, the sweetness and smoothness that it digs out from the 300B tube is hard to beat, and it gives a respectul sound pressure on higher efficient spakers. Owing to the lower working plate voltage (about 300V) in this baby you will never need to replace the 300B tubes unless you desire to try other tube makers as well.
SV-300BE的線路結構與SV-2A3十分相似,因為大家都用同款的電源牛和輸出牛,不同處如下:
- 輸出牛初級接去3.5K
- 陰極電阻300B用1kohm
- 300B灯絲用5V直流燃点,這才可以把hum減到不可聞程度,這裹用6.3VAC組經整流及濾波再經一支10ohm電阻降壓才接往給300B灯胆。
The circuit of the SV-300BE looks more or less the same as the SV-2A3 since they are using the same type of power and output transformers. The differences are:
- The primary of the output transformer is connected to the tapping of 3.5K.
- The cathode resistor is changed to 1Kohm to set the bias for 300B tube.
- The filment circuit is more complicated as the 300B tubes run on 5V DC in order to minimize hum. The 6.3VAC is rectified and regulated and connected to the 300B tube through a 10 ohm resistor.