Focus-836 36 Kinds of Models of Electronic Tubes in one Amplifier
36 Kinds of Models of Electronic Tubes in one Amplifier
By Music Space Time
There is a common hobby for audiophiles in playing tube amp. That is changing tubes in the tube amp. If someone doesn¡¯t have three or five pairs of tubes, it cannot be called playing tubes. Some experienced players have dozens of or even dozens of dozens of different brands of tubes for his tube amps. It is hard to think about if one amp has 10 or 30 different models of tubes, how many tubes shoud we prepare to change?
There is another common consciousness for tube players. It is as if changing machine after changing tubes. And it is just changing the same model of different brands of tubes. One EL34 tube amp can be used Russia EH tube or Americ GE tube, but the amp¡¯s sound is totally different. The difference of different models of tubes could be more greatly. For example, the sound of KT88 is totally different from 6L6. Normally, one model of tube could not be changed directly to the other model of the tube. There is different technical design in different models of the amps. So, it is seldom to see one amp can be used different kinds of models of tubes.
36 models of tubes could be used in an amp
The Focus-836 tube amp which was based on the design of Focus-88A was manufactured by Music Space Time recently. It¡¯s a single-ended intergrated tube amplifier could be used 36 kinds of models of electronic tubes includes KT88/6550, EL34/6CA7, 6L6, 6V6 etc. All these tubes could be changed directly and you don¡¯t need to think about bias adjusting. ( of course you should cut the power first before change.) It is satisfactory for the tube players who have the hobby of changing tubes.
How about the sound quality of the Focus-836? After a round of testing, I think it¡¯s a successful design for listening to the music. Changing different models of tubes repeatedly to listen many kinds of music before long time of warming up and run-in. I found it had a wonderful sound reproduction. Balance, transparency, wide dynamic and strong control is its main advantage. Of course the sound colour is different from using different tubes. For the best performance, the power of control is not less than some 80w to 100w transistor amps. On the side of sound colour, a not successful design class A transistor amp could not be compared to it.
Focus-836 uses a kind of special atructure of self-fitting output power transformer which can fit many kinds of models of tubes. Every channel of the preamp part uses a tri-pentode tube 1252. the pentode part is used to voltage amp, the triode part is used to special negative circle feed. The amp part uses single-ended output. For reducing the resistence and impedence, it uses a kind of technology called MLF to ensure better dynamic and phase property. Thus, working condition is steady and output impedence is greatly reduced. The DAMP is 12, so it could control many kinds of speakers. When using it to push the Nine loudspeakers, the natural expressive force is more like the Mark Levinson No. 383. The Nine is the new model of floor-stand refrence loudspeakers of the Eggleston. It uses one Dynaudio T330D tweeter and two Morel 6.5 inches mid-range which are working on the condition of no crossover circuit. The woofer uses a special made Morel 9 inches speaker. The sensitivity of the Nine higher, but all I know if the amp doesn¡¯t have actural power atrength. It could not speak out good sound.
The shape of the Focus-836 is small, exquisite and very succinct. There is only a volume knob in the face board. The power switch is on the left side board and the input selector is on the right. All the covers are made by thick aluminium board with silk-push handle process. The transformers are covered by 1mm thick iron boxes. The handle bars beside the tubes can also protect the tubes and provide decoration. All the machine looks steady and modern though its dimension is just half of a standard amp.
How strong is the fitness? Could it show the characteristics of different models of the tubes? Which loudspeakers could be pushed by so limited output power? With these doubt we took the test in our magazine publisher listening room. The reference speakers were the Nine of Eggleston. The CD player was Meridian 588. Once the Nine was singing, all my doubt was gone. Because the power was not a problem to the Focus-836. Only when I changed to 6v6(4w), the sound density changed thinner. But when I changed to KT100(18w), the power was almost as the same as the Mark Levinson No.383. In this meaning, the Focus-836 has very strong fitness. If took it to push floor stand speakers like the Nine or even lower sensitivity speakers, you could use KT100. But if you had higher sensitivity bookshelf loudspeakers, you could use 6v6 to enjoy the extreme clearest and transparent sound colour.
Changing tube is like changing machine
How was the effect when changing different kinds of models of tubes in the Focus-836? I know what is our readers would care. The original power tubes were KT100 and three pairs of EL34, 6L6 and 6V6 were as the attatchments by the manufacturer. Next I took these four tubes as this test.
First was the KT100. This was the most powerful tube in the test. The output power was 18w. When playing LIGHT CAVALRY OVERTURE, the brass spoke out with extremely rough air stream. The percussion was deep and rich of elasticity. The sound field was widely and full of dynamic. It¡¯s hard to believe that the amp just had 18w to output. Though the high frequency was less a little mild and roundabout, the trumpet and the violin were still vivid and smooth.
Next was the EL34. the output was 9w. the pushing power was little down so as the low frequency. But the sound colour was more of moist and musical. When playing Naihe Huang Hongyng, the vocal expression and sound colour of piano were full of aesthetic feeling. The change obviously better compared to KT100 was the sound colour of high frequency. It was more air and moist.
And the next was 6L6. the output power was 6w. This was the most exciting tube I¡¯v ever heard in this test. The pushing power was little down than the the pairs of tubes. The volume clock should be adjust 11 to 12. after adjust, I had found the sound pressure was as the same as the EL34 and KT100. But compare to them, the 6L6 was obviously more full of medium frequency, more details, more loos and comfortable. The low frequency¡¯s quality was the most exquisite of all the test tubes. Smooth, soft, transparent, moist, every word was belong to the tube. No matter the detail of the Pipa in White Snow in Early Spring, or the roudish feeling of piano in Naihe, all was exciting, vivid, noble and elegant. Especially the female vocal was very alluring.
At last was the 6V6. the output power was 4w. The characteristic of the tube was extreme clear and transparent. But using it to push the Nine, it was obviously short of power. In fact, the density and setail could still remain on the lighter volume. String music and vocal sound was performed innocent like spring wind to the face.
Focus-836 is an amplifier with strong fitness. To the experenced tube amp players, it¡¯s a fitted tool to appraise the majourity of your colectings. To the normal audiophiles and music lovers, it¡¯s a high grade tube amp to listen to the music. The price of the amp is only RMB3980yuan. I cannot find another same quality and more cheaper audio product at the present.
Extracted from¡¶HIGH FIDELITY¡·2008-6 Author£ºMa Longhui