In the article you will learn how to make tube amplifiers with your own hands from improvised materials. It is no secret that the tube sound is the most beautiful, its fans will exist at all times, despite the fact that the market is replete with a large number of offers of small-sized equipment based on transistors and microcircuits. Take a closer look at what you should consider when building a tube amp.
Food is the main difficulty
Yes, it is with the power that problems can arise, since you will need two values of AC voltage: 6.3 V to power the filaments and 150 V for the anodes of the lamps. The very first thing you need to find out for yourself is the power of the future design. The power of the transformer for the power supply depends on this. Please note that the transformer must have three windings. Without such power, you can’t make tube amplifiers with your own hands.
In addition to the above-mentioned secondary ones, there must also be a network (primary) one. It must containso many turns for the transformer to work normally. And even with a significant load (and power surges up to 250 V), the winding should not overheat. Of course, the dimensions of the power supply will be rather big due to the large size of the transformer.
Rectifier
You will need to make a rectifier to get at least +150 volts DC output. To do this, you need to use a bridge circuit for connecting diodes. Diodes D226 can be used in the design of the power supply. If you need to make high reliability, then use D219 (they have a maximum operating current of 10 amperes). If you make tube amplifiers with your own hands, then follow the safety rules.
Diode assemblies work well in power supplies. It is only necessary to choose those that are able to function normally at voltages up to 300 volts. Pay special attention to filtering the output DC voltage - install 3-4 electrolytic capacitors connected in parallel. The capacitance of each must be at least 50 microfarads, the supply voltage must be over 300 V.
Vamp pre-amp circuit
So, now closer to the scheme itself. If you are making a tube guitar amplifier with your own hands, or for playing music, you need to understand that the most important thing is safety and reliability. The most common circuits contain one or two pre-amplifier stages and one final amplifier. Preliminaries are built on triodes. Since there aretubes that have two triodes in the same base, you can save some space when installing.
And now about what elements contain tube amplifiers. With your own hands you will have to assemble everything into a single structure. For a lamp in a preamplifier, it is best to use 6N2P, 6N23P, 6N1P. Moreover, despite the fact that all these lamps are analogues to each other, 6N23P sounds much more pleasant. This lamp can be found in the PTK unit (television channel switch) of old black-and-white TVs such as Record, Vesna-308, etc.
Final amplifier stage
As an output lamp, 6P14P, 6P3S, G-807 are usually used. Moreover, the first will be the smallest, but the last two are very impressive in size. And for the G-807, the anode is completely in the upper part of the cylinder. Please note that in tube ULFs, it is imperative to use a transformer to connect acoustics. Without such a matching transformer, you cannot make a tube amplifier with your own hands.
Excellent work as output transformers TVK used in the vertical scan. Its primary winding is connected between the plus of the power supply and the anode of the output lamp. A capacitor is connected in parallel to the windings. And it is very important to choose the right one! Firstly, it must be paper (such as MBM). Secondly, its capacitance must be at least 3300 pF. Do not use electrolytic or ceramic.
Adjustments and stereo sound
Make stereo sound will be very simple. It is enough just to make two identical amplifiers. You can find a stereo tube amplifier in old Soviet technology. You can repeat the design with your own hands. But you need to take into account some features:
- The volume control is connected directly to the input of the amplifier. The variable resistor that is used for it must be chosen such that there are two elements on the axis in one housing. In other words, so that when the knob is rotated, the resistance of two resistors changes at once.
- Similar requirements for the frequency controller. It is included in the anode circuit of the first triode of the preamplifier.
Amplifier housing
If you make a tube guitar amplifier with your own hands, then using a metal case makes sense. He will not be afraid of blows and other minor shocks. But if you are making an amplifier for use at home, for example, for connecting to a player, computer, then it is wiser to use a wooden case. But you need to take into account that it is desirable to attach the power transformer to the case using rubber gaskets. They reduce vibrations.
Much depends on what the tube amplifier case will be. With their own hands, many craftsmen make cases from sheet aluminum. If even small vibrations affect the lamp, its grid will begin to oscillate. And these fluctuations will begin to intensify, and the result is a buzz in the speakers. You also need to make a common bus, which should pass near all the lamps included inconstruction. All wires carrying the signal should be shielded as much as possible - this will get rid of various kinds of interference.
Circuits with transistors
And another interesting design is tube-transistor amplifiers. You can make these with your own hands literally in the evening. But lamp structures, as a rule, are made by hanging installation. It turns out to be the most convenient and simple. And if transistors are used, printed wiring must be used. In addition, a voltage of 9 or 12 volts will be required to power the transistor stages. Moreover, transistors are used only to build a preliminary amplification stage. In other words, you will have only one tube left - in the output stage (or two, if we are talking about a stereo version).
