The first describes a common cathode amplification, as shown in Figure 1 1/2 6DJ8 tube. Experimental relationship, just to understand the characteristics and advantages and disadvantages of each line, but also for the sake of simple and easy system, apart from the machine, the whole does not have the voltage regulator circuit, especially the high-pressure, I believe in the general listening environment, the difference is not too significant, of course, set the voltage regulator circuit better. The aspects of parts, in addition to cross-connect capacitance better varieties such as VitaminQ, Rel the Cap the Wima outside; resistance addition 6DJ8SRPP use a light tone, Tokyo, were 0.5 yuan a stuff; rectifier with Mur1100E; power transformer low-voltage with one, each about 10-20 yuan, the effect is also considered. In addition, the following test of conclusions to the 300B single-ended tube amp and KEF's IS 3/5A match equipment, the conclusion of course, has its limitations. The route is simple and easy system may well be the choice of beginner, the success rate is extremely high, school sound fun can also try to change the output capacitor value, change the load resistor value, or increase the set of negative feedback. Cross-connect capacitance brand, once 300B after class last pay even Xeon put the position of the tube, listen, try Mitppmfx RelCappp, Kimber, and of Vitamin Q, the result is the Mit sound fine transparent but owed dynamic; Rel Cap thick, powerful sound; Kimber, sound transparent noble; SpragueVita-rain Q mellow smooth mix of rich harmonics and dynamic best performance of the most comprehensive. I like to use some the old Vitamin0, not pot value is also very accurate. Sound area, the machine background Masters quiet, transparent sound quality, high analytical power, full-frequency performance of the average operator, strength and control in general, but less thickness and smooth tone, tend to sound the end of the dry and clear. Once the trial 1.8mA and 4.5mA for bias, the sound in the high bias in greater detail. I tried not to join the negative feedback, readers can try to listen to the sound in line with their own sound. Should pay attention to the feedback resistor should be connected to the gate rather than the cathode, due to a common cathode to enlarge the output waveform is inverted, such as access cathode will be the cathode potential drop relative to the gate potential to improve the formation of positive feedback this differs from the bipolar common-cathode amplifier circuit feedback resistor back to the first level of the cathode.
6DJ8 a common cathode amplification, the output capacitor and the only Wima capacitors
Sessions with the 6SN7 's SRPP circuit
The second paragraph of is 6SN7SRPP lines, I believe that many readers trial this line, see Figure ② The. Adjust the push-pull line called shunt (Shunt regulated the push-pull), most people believe that the line has the following advantages: low distortion and excellent linearity, amplification rate, over-charge the amount of width and output impedance low. Principle is subordinate tube for common cathode, the gain depends on the plate impedance, most of the tube body at a higher level, higher tube for a constant current source as active load to the lower tube, but also as a cathode follower, the signal transported to the lower tube screen very superior tube gate. R1 and R2 are of equal value. Superior tube is definitely not to achieve 100% constant current purpose of therefore late have Mufollower line of the invention, at a later date to discuss with the reader. In any case, this machine is also easily create a successful, but I have some reservations, to speak, this line does not have a special place, a sense of permeability, smooth, and the intensity of both the general. Although the intensity, thickness and musical than a 6DJ8 good, but I still take the 6DJ8 one line.
Sessions with the 6SN7 's SRPP output capacitance Vitamin Q 0.22μ1000V and Wima Black Box, 0.01μ
6DJ8 's SRPP plus bufier line
The third is 6DJ8SRPP plus buffer, buffer tube can be used 6DJ8, 6922,6 FQ7, 12AU7, 12AX7, the circuit shown in Figure ③. It is the recent Canary and Taurus brand - level in the paragraph before the line, this line is also refreshing than the 6DJ8 smooth plant, control the sound of the end of thick, ample amount of overload. More favorable than in a line, I believe better than the single line using 6DJ8 SRPP without buffer. But to mention the buffer tube is required 12AU7 6DJ8 transistor audio features, as it can to reconcile, but also to maintain a hearty mellowness of tone, a bit like the sound of the XLO line. The author of the products put on the RCA put buffer and Canary machine buffer l2AU7 do Amperex gold pin 6922 for comparison (originally 6FQ7), and always still 12AU7 for the buffer more positive. Have Canary friends before class, as long as the change - the factory intermediate tube filament power supply pin, followed by 4,5 feet shorted positively charged, 9 pin negatively charged, and other parts do not change, can be replaced by the 12AU7 tube . In addition, I have the trial of two pairs of (and access) are said the commutator C25P40F/FR of the world wonderful product, the commutator can be as transistor grade specifications for 25A 400V. The audition using two pairs, separated by a pair of the Forte lA level for Bi-amp, and Reference3A Baccarat speakers with a pair of the most obvious is the more powerful bass and clear, the degree of separation of music devices and sound the end of hearty a; then the next level. I also read on an electronic tubes 1/2 6DJ8, a tube 1/2 12AU7 and up and down the other two are used 12AU7 SRPP line, I do not know how. Come back to say this machine, sound bright and crisp transistor machine also has the soft sound of the point tube machine, good analytical and got used to the sound of the Marantz 7, scheduled for a fresh feeling, might fall in love with it. I was more greedy that the fans the best is the cake and eat it.
6DJ8 's SRPP with buffer (12AU7): left and right tube by Philips 6 922, the intermediate tube is the RCA 12AU7.
Output capacitor Rel Cap 0.22μ in Wima 0.22μ,
6SN7 stage amplifier negative feedback circuit
Fourth paragraph introduces a 6SN7 two amplification negative feedback circuit, as shown in Figure ④. I used the CV 181 tube, this line can easily be produced, the thickness and smoothness of the midrange is the highest of all the machines, the power of ordinary, but unfortunately it is the high and low frequency were not considered special, a little convergence, I do not know whether the IF too good but so that high-low-frequency appear pale, a bit like the old days I have another 3/5A. However, even if the sound is not comprehensive, but also very flattering, especially to play the violin and female voice. I do not know the addition of a buffer, can improve the low and high frequency, this machine is more comprehensive, I will try, if good results, targeted report that. In any case, I will vote for it and homes 6SN7SRPP, because it at least a very strong project.
Pre-line and Tian Mao
The Di Wukuan line for a 12AX7 bipolar amplification plus a 12AU7 white cathode fo11ower recommended by the Japanese name for Tianmao Shi preamp, before the two with the Marantz 7 is similar to, and finally a similar white cathode and SRPP follower circuit shown in Figure 5,6. The Marantz 7 line, in addition to the next pole of the input impedance of the load, as well as the feedback network, resulting in the third tube of the AC load is quite heavy, especially for high frequency. Follow the circuit, and Tian Maoshi the SRPP seems specifically to join, and the general voltage amplification, voltage gain, only for reducing the output impedance and the steady flow effect, making it with a load capacity than the total screen extremely connection follow is much larger, high-frequency response and signal to noise ratio than the screen connection.
Output stage cross-connect capacitance by 3μ to 10μ, depending on the level after the input impedance, using 10μ think the sound end of the heavy intensity of, but a little real feeling, you owe 1μ low frequency results and 1μ, 2.2μ and 0.22μ, whichever is the middle value, the better.
The sound quality, that is, maintaining the mellow sound of the Marantz 7 line, full of musical taste, but dynamic and high-frequency response can win, analytical, high signal to noise ratio. This line above the line performance in the most average and comprehensive, the sound score, I recommend readers trial.
12AU7 cathode operating voltage of 148V, over a hundred volts above the filament voltage, compared with manual cathode filament limit is 90V high, of course, can also work, but will be reduced by the short tube life, the partial pressure resistance filament floating about 90V.
And Tian Maoshi part of the circuit, the output capacitor and then Solen 2.2μ the Wima 1μ Vitamin Q-0.22μ, and Sprague, 0.02μ
And Tian Maoshi pre-map, the power is extremely high signal to noise ratio
Finally, I stress again that this is the conclusion of a test, only to match the 300B single-ended after the level LS3/5A speaker is not the most comprehensive and absolute, although we know that sound is the combination of all aspects of the listening environment is more important, without a conclusion which The former is the best match properly, the self can come up with good sound. Depends on the personal accomplishment and preferences, that is, to hear the kind of music and sound effects, such as lively and hearty, optional 6DJ8SRPP; such as alcohol and transparent, optional the Marantz 7; to be more mellow, optional ECC 32 (sessions with the 6SN7 ) two amplification. I am very loyal supporter of the value combinations of equipment, tube machine, and want to share with you the reasons that look like vacuum tube machine. For a long time to have the battle of the tubes and transistors, transistor machines help to criticize the high distortion rate of the vacuum tube machine, down caused said he would reduce the transparency of the music and lines, but we can listen to listen to the 300B or 845 single-ended types of audio, I believe No one can say that it is transparent lack of music, the lack of lines or texture.
I think the sound is also a way to enjoy life, to switch the change room to improve the sound is a pleasure and art, but also reflects the people (fans) love the change and the pursuit of the perfect features, it can not be confined to the Who comprehensive than who . Members transistor friend, who can guarantee that you will never change to listen to the tube machine? I certainly can not guarantee that they will never switch to transistors machine. However, subjective terms, the dense living environment in Hong Kong, the average family less likely to have an independent sound absorption and sound insulation, sound room, the walls are limestone walls of home, tube machine as listen to the tool, and set more appropriate, especially for the lower audio equipment.
Members Friends of the transistor, would like to broaden the ear vision, willing to spend money, then, may wish to buy Jadis, Conrad-Johnson, AudioResearch tube before and after the class: If only to hold the test - test the mood, but also can be purchased in Hong Kong products such as Houston, Allegro tube before and after class, etc., varieties (can try a variety of tube sound), three or four thousand dollars has been trading, sound machine should have the same price to a large extent and multi-faceted than transistor.