DIY tube guitar amplifier

Many musicians use sound-amplifying equipment to record their playing and performances at concert venues, especially those who play musical instruments that have a relatively weak and short sound. These include all, with rare exceptions, string players, especially electric guitarists, whose instruments without an amplifier at all, one might say, do not reproduce any sound. Musicians of other profiles who play electronic or electric musical instruments are in the same position.

Insufficiently strong sound is observed in small wind instruments (flute, harmonica, pipe and other pipes). In large concert halls, even the button accordion and accordion will be quite faintly audible. There is, of course, the electric piano, created not only for additional effects, but also in order to compete with other instruments, even on such concert venues as stadiums and airfields.

Consider in this article the features of tube guitar amplifiers for the home and their own installation.

For guitarists, especially those performing live or playing electric guitar, it is very important to find a good amplifier that produces quality guitar sounds. However, not all novice musicians have the opportunity to purchase expensive equipment from well-known companies that produce such audio equipment.

It has long been known that The most natural sound can be produced by tube guitar amplifiers (amps). This sound cannot be compared with modern amplifiers on microcircuits and transistors - only a lamp can produce sounds with absolutely clean, uniform and captivating bass or melodic high frequencies. But the cost of even non-professional tube amplifiers produced by world brands is an order of magnitude higher than any semiconductor amplifier with a similar power.

True, tube amplifiers have some drawbacks that are absent in analog devices. These include:

• bulkiness and large mass of the finished product;
• insufficient reliability of lamps in comparison with transistors;
• strong heating of parts, which can lead to damage to the electrical circuit and failure of some components;
• a natural shortage of necessary lamps due to the widespread use of electronic devices and the gradual curtailment of the production of parts for outdated audio equipment and technology.

but these difficulties do not stop musicians on the way to getting the quality sound of their guitars. Therefore, guitarists often try to find a home-made version of a tube amplifier suitable for the house, and then assemble it with their own hands, which, undoubtedly, is much cheaper than a factory device.

For home lessons on playing the guitar or recording individual pieces, a simple guitar amplifier with tubes and other parts is quite suitable, providing a sound output power in the range of 1.5-3.0 watts. This will be enough to successfully practice your playing technique, make a high-quality recording of a piece or song you just learned to your own accompaniment on an acoustic guitar and, of course, slightly irritate your nearest neighbors. Therefore, you can choose the option of a homemade amplifier with the following details for the electrical circuit:

• 6N1P triode lamp (or its analogs: 6N3P, 6N2P, 6N23P), required for the preliminary (input) stage of the entire circuit;
• 6P14P lamp (pentode), participating in the final (output) stage of the circuit;
• output sound transformer TVZ-1-1, designed for a current load within 8 ohms and a power of 3 W will not be able to qualitatively suppress the distortion of sounds);
• input resistor 560 kOhm;
• a resistor at the cathode of the triode lamp for 0.5 W, at the anode - 0.5-1.0 W;
• a capacitor in a shunt with a cathode resistor of a triode lamp with a maximum capacity and a voltage of about 10 V;
• the capacitor on the communication line between the stages must have a voltage of 300 V, and the variable resistor on the same line can be with parameters from 100 kOhm to 1000 kOhm;
• the resistor on the cathode of the pentode lamp should be more powerful than on the input lamp (about 2 W), with a resistance of 120 ohms, and the shunt capacitor should have a lower capacity compared to the shunt in the triode circuit;
• speaker for 8 ohms.

For the platform, you can use a thick duralumin sheet as a material, bending it into a compact shape resembling a box without a bottom side, or you can buy a finished product. Some users use an old computer case for a platform for an amplifier, sawing off a part of the cover from it to the desired size.

From the installation tools, you should prepare soldering equipment and solder, a hacksaw for metal, an electric drill with a set of drills for metal, needle files and sandpaper, taps, screws and screwdrivers, drapery material for the subsequent finishing of the finished product, glue, measuring rulers and markers for markings.

The proposed scheme for manufacturing a low-power guitar amplifier is a two-stage system, which can include a phase inverter stage. Its function is to split the signal at the input to the amplifier into two half-waves, which are opposite in phase. The bass reflex circuit is quite simple and gives good results in improving the amplifier's performance, but it is not always applicable, especially for high-quality equipment, since it greatly distorts the sound. But for low-power amplifiers, this device will certainly be useful.

First, assemble the pentode part of the circuit with a transformer, speaker, lamp and shunt, and then connect the transformer and the cathode part of the circuit to the electrical network. If everything is normal, then in the speaker you can hear a crack or background when you touch the lamp with your hands. After such a test, you can continue to work. Otherwise, you will need to look for a malfunction and fix it. After collecting the first stage, you should also check the operation of the circuit. Such a division of the installation into stages will allow you to determine in which part of the circuit the malfunction lurks, if an unwanted background appears in the dynamics.

Sometimes it is necessary, through experiments, to make the final adjustment of the amplifier in order to get a better output sound of a musical instrument. To do this, you may have to change some parts for analogs with other parameters (the value of the capacitance of the capacitors, a different power of the resistors, and so on). It happens that the lamps have to be changed at the stage of adjusting the sound.

How to make a tube guitar amplifier with your own hands, see the video below.