The Wonderful Sound from the Terrace of Changing Tubes
Making Comment on
The Focus-836 Single-ended Tube Power Amplifier of Music Space Time

All the HiFi lovers who have used tube amplifiers know a phenomenon clearly that the color of sound will be changed if the electric tubes are changed to the other brands¡¯ or being made in different periods in the same amplifier. If the different types of the same kind of tubes are changed, the sound colour will change more differently. And changing tubes is very easy that you just need to plug in after taking off the original tubes. Because of this, a group of HiFi lovers are always looking for different tubes to have a try. It has changed to another kind of hobby of playing out of listening to the music. But in normally, the tubes can only be changed to the same kind of different types¡¯ or brands¡¯. It has a limit because of the different voltage using of the different kinds of tubes. If one tries to change evey kinds of different voltage using tubes on the same tube socket and the tube will still work correctly, he needs to get a perfect solution on many kinds of technological problems. Of course it is not so easy. That¡¯s why for having a long period of time there are few of this kind of tube power amplifiers to be made.
The Music Space Time Tube Power Amplifier Manufacturing corperation has always being tried to make first class of products on reasonable prices. I have tested many lines of products for ?years so I know the products of this corperation are acturally satisfactory. The product of Focus-836 single-ended tube power amplifier is a revolution which is based on the model of Focus-88A to creation. This amplifier can be changed directly from dozens of electric tubes as KT88/6550, EL34/6CA7, 6L6, 6v6, etc. It needn¡¯t be adjusted but the output power is different.
Focus-836 is a single-ended construction AMP. Because of the unsymmetrical specialization, it has more second harmonic waves. So it has a very special sound. For the need of high fidelity of power output, the powerful concentritive radiation tube KT100 is used as the amplification. For reducing the inter-resistance, the negative feedback is led to the first class output. The HiFi output power is over 16w. The tube 1252¡¯s pentode part is used for voltage magnifying and excite the power magnifier when its triode part is used for special circle negative feedback. The whole amplifier uses the MLF technology, multi layer negative feedback, for surmounting the difficulty that circle negative feedback could not be too deep. The AMP works steadily and it also has got very high standard. Especially the inter-resistance is very low so that the amortization can get twelve. The special construction of output power transformer provides the insurance of the quality. The design of the electric power is optimized. The preamplification part is surpplied by the steady voltage of power. The amplification part is supported fastly and abundantly. The electric circuit is adopted special measures tp inprove the work, so the different kinds of tubes can be changed.
The actural testing frequency response of Focus-836 is 28-23kHz,0dB and 16-48kHz,¡À3dB. The difference of 0dB and 3dB indicates that its low and high frequency reduction is very flat and its twinkling reaction is better, so it has very small distortion. The 100Hz and 1kHz square wave output detects very well. Only the 10kHz square wave has small difference. But it¡¯s better than the other same class of AMPs. Thus the winkling reaction of this AMP is pretty well. Because of the amortization 12, it can control the woofer easier and better. The woof sounds clear and bloomy.
We organized a group to comment the Focus-836. we all admitted that it had high density and more details. It¡¯s very balanced, transparent and active, fine and wide. Lingering charm and speed is coexistent. When the large dynamic sound comes, no phnomenon of compression. The extension of high frequency is good. Air sense is rich and bright. Medium frequency is liquid, sweet and natural. Low frequency is punchy and clear. Background is silent. Basicly, it was very pleasing the ear even you had listened for a long time. It can play every kinds of music well.
We used three pairs of speakers to listen. First was JBL4311, it sounded powerful. Then was Rogers 5/9 50years anniversary, it souned classical, thick medium frequency. The last was Triangle XS which was the champion accompanying the Focus-836. it sounded great. Though all three pairs of the speakers sounded different, no one was bad. It indicates the amp¡¯s fitness is good except for the lower sensitivity speakers. In the second stage, we started changing the tubes to listen. When the EL34 were working, the sound was flesh and beautiful. The power output was 9w. Then they were changed to 6L6G, this time the power output was 6w. We felt dense and strong medium frequency. It souned like old classical style. When the tubes were changed again to 6V6, the sound color is more like EL34, but output power was only about 4w. After a round of listening, we all thought that KT100 was the best champion of this time though every kinds of tubes had its own specialization. It¡¯s a wonderful experience of listen. What a pity could we change more tubes to listen due to the time.
Comparing to its price of the sound, I can say the Focus-836 is the bestbuy. For the 300B single-ended amplifier lovers, it¡¯s worth to have a try to listen. Except the power is more strong, you will find more exciting elements in it. With the exception of the brightness and beauty, there is something more elegant and noble you might never have experienced before. For the HiFi lovers who have many good tubes to play, the Focus-836 is more recommended. It provides you a good terrace to change and play the tubes.

Digested from¡¶overview of consumer appliance¡·2007.7¡¡Writer: Tang Dao Ji