Tube power amplifiers are an element of the equipment control system. These devices are currently actively used for acoustics. You can make a model for headphones yourself. However, there are complex amplifiers based on output transformers. They are intended mainly for speakers of various capacities.
Important parameters of the models include the frequency, as well as the sensitivity of the equipment. Depending on the power of the power supplies, the output voltage indicator changes. In order to understand this issue in more detail, you need to consider the device of a simple amplifier.
Amplifier circuit
A simple tube amplifier consists of a capacitor, a power supply and resistors. Transistors in devices are often used orthogonal type. The lamps themselves are applied at 6 watts. Regulators for models are selected both push-button and rotary type. Modulators in amplifiers are mainly pulsed, but code modifications also exist. To increase the frequency of the device, elements such as arresters are used. Some models have thyristors. They lower the output voltage quite strongly. In this case, capacitors do not experience large overloads. Cartridge regulators are rarely used in this type of model.
Single-cycle models
A single-cycle tube amplifier is used for speakers whose power does not exceed 20 watts. In this case, transformers are usually used output type. Capacitors themselves are often used field. At the same time, lamps can be safely selected for 15 watts. The sensitivity of such devices is highly dependent on resistors. As a rule, they are mounted on a single-cycle tube amplifier at the beginning of the circuit orthogonal type.
Thyristors are never used in such models. This is due to the fact that the resistance in the circuit is quite variable. It is also important to note that the voltage should be regulated using the controller. The acoustics for the tube amplifier are connected via a two-wire port. The modulator in models is most often used precisely pin. On average, the negative resistance parameter is at the level of 50 ohms. It is also important to note that sensitivity is greatly reduced in amplifiers when using copper conductors.
Push-pull modifications
It is very difficult to make a push-pull tube amplifier with your own hands. Step-by-step instructions in this regard will be very useful. For assembly, a transformer will need an output type. Resistors for push-pull tube amplifiers are easiest to install single-pole. Two capacitors are required at the input. Negative resistance in the circuit they must withstand at least 60 Ohms. In this case, the sensitivity of the devices can reach up to 3 microns.
Trimmer resistors are used to minimize glitches in the modulators. Conventional field capacitors are installed at the system output. Power supplies for push-pull tube amplifiers are suitable even at 30 V. Cassette regulators in such devices are almost never used. The input voltage parameter in the amplifiers is on average 15 V. The oscillation amplitude in this case depends on the signal frequency.
Hybrid Modifications
Hybrid tube sound amplifiers are a set of output transformer and half duplex resistors. In order to assemble the model yourself, you need a 40 V power supply. Orthogonal type resistors are used directly at the circuit input. They must withstand negative resistance at 55 ohms. In this case, it is more advisable to install thyristors behind the output transformer.
The lamps are soldered in sequential order. The frequency of the model depends on the amplitude of the magnetic oscillations. The output voltage parameter in the devices can be easily adjusted using the controller. After installing orthogonal resistors, a power supply is placed on the tube sound amplifiers. In this case, the throttle must be directly connected to the controller. The acoustics for the tube amplifier must be connected through a two-wire port. At the last stage of assembly, the output voltage of the transformer should be checked. For normal operation of the system, this indicator should not exceed 15 V.
Features of low-frequency modifications
It is quite difficult to make a low-frequency tube amplifier with your own hands. Step-by-step instructions can greatly help. Many experts recommend starting with the installation of a transformer. In this case, field resistors will be required. Their conductivity is good, and they are able to serve for quite some time. At the input of the circuit, it is important to solder the capacitor. In this case, an orthogonal type model works well. In the next step, it is more advisable to deal directly with the controller to adjust the device.
In some cases, it is selected rotary type. The minimum frequency should be set at 500 Hz. The lamps in this case are soldered in sequential order. It is better to use a coaxial cable to connect the transformer to the controller. To test the equipment, the output voltage parameter is measured first. In this case, it is important to consider the power of the power supply. Most often it is selected at 20 V. In this situation, the negative resistance parameter should not exceed 45 Ohms.
High frequency models
High-frequency tube power amplifiers belong to the class of push-pull modifications. Their difference lies in the presence of power transformers. All this is necessary to increase the conductivity of the signal. The parameter of the maximum frequency of devices is capable of reaching up to 500 Hz. In this situation, it is more advisable to start assembling the model with the installation of a transformer.
The panel for this can be selected wooden. In this case, the controller must be installed on a lining. In this case, the output voltage can always be checked using a tester. Directly the unit is used in a circuit of 30 V. In this situation, the transistors are soldered beam. They must withstand negative resistance in the system at least 43 ohms. All this will allow you to easily adjust the frequency of the equipment.
The lamps in this case are soldered in sequential order. Capacitors are used in both orthogonal and capacitive types. In this situation, a lot depends on the type of controller. If we consider push-button modifications, then you can not do without a thyristor. With rotary controls, you can use a conventional modulator.
Resistive Load Models
It is very difficult to make this type of tube amplifier with your own hands. Step-by-step instructions in this regard will be very useful. Many experts advise folding an amplifier based on electrolytic capacitors. It is important to start assembling the model directly with the installation of a transformer. The lamps in this case are soldered in sequential order.
Resistors in the models use the beam type. However, orthogonal analogs are installed at the input of the circuit. Zener diodes in this situation are used if the power supply is available at 30 V. Otherwise, the modulator copes with overloads in the network. The controller is connected in the amplifier behind the transformer. To increase the sensitivity of the model, comparators are used. The minimum frequency element must be 300 Hz. In turn, the negative resistance should not exceed 50 Ohms.
Resonant Load Amplifiers
Models of this type are today very common. The transformer for a tube amplifier needs to be selected power. It should also be borne in mind that the controllers should be used only cassette type. Modulators themselves are installed with expanders. All this gives a significant increase to the signal conductivity.
The sensitivity of the model in amplifiers depends on the types of resistors. If we talk about the power supply at 20 V, then it should be selected orthogonal type. Otherwise, preference can be safely given to single-contact analogs. At the same time, field resistors will not be able to provide high frequency. The oscillations in the network are most easily regulated through thyristors. In this case, the output voltage in the system should not exceed 15 V.
Step-down Transformer Model
It is quite difficult to make a tube amplifier with your own hands on a step-down transformer. Step-by-step instructions can greatly help. It is best to use orthogonal resistors for the amplifier in this situation. However, it is important to build the model by installing the power supply. Then, the lamps should be connected to the panel. In this case, capacitors can be used capacitive. They must keep negative resistance at 33 ohms. All this will stabilize the frequency at low overloads. Thyristors are used very rarely in this type of circuit. However, if we talk about high-frequency models, then they will be appropriate.
Use of power transformers
You can create an amplifier with a power transformer only if you find a high-quality comparator. Also in this situation, you can not do without tuning resistors. It is recommended to start assembling the model from the panel. Lamps should be installed in sequential order. The power supply in this situation is required to connect directly to the inductor.
The negative resistance in the circuit should not exceed 55 ohms. In this case, the output voltage depends on the power of the power supply. Modulators in such devices are available with switches. All this allows you to quickly lower the frequency when the load on the capacitors increases sharply. Beam transistors in the models must be installed behind the transformer. In this case, the comparator is soldered at the beginning of the chain.
Application of pulse transformers
To make an amplifier with a pulse transformer, the panel is first procured. The easiest way to pick it up is plastic. Lamps in this situation must be connected in sequential order. The transformer must be located on a lining. In this case, the capacitor at the beginning of the circuit will require a capacitive type. Power supplies for the models are selected at 30 V. All this, ultimately, ensures good signal conductivity. An integral element of the amplifier is considered a modulator.
Behind a pulse transformer, it should not be installed. In this case, the load on the capacitors will be large. To avoid circuit failures, use a thyristor to reduce sensitivity. He must withstand negative resistance at the level of 35 Ohms. Transistors in the system are installed behind the transformer. Modulators can be used directly code. In stores, they are most often sold labeled PP20. Their distinctive feature is the presence of a broadband head. Thus, it is possible to regulate the frequency of the device more smoothly.
Headphone Model
For computer headphones, electrolytic capacitors can be used. In this case, high sensitivity is not required from the model. To suppress interference in systems, various kinds of thyristors are used. Modulators are more appropriate to use the tuning type. The output voltage in the circuit should not exceed 12 V.
In order to adjust the frequency of the amplifier, compact controllers are soldered. In this case, the lamps should be installed in sequential order. The power supply is connected via a choke. Duplex resistors are rarely used in such circuits.
Guitar Amplifier
A set for a tube amplifier should be selected only in specialized radio stores. First of all, beam transistors will be required. In this case, the modulator is important to install on the panel. Capacitors are used small capacity. Particular attention during assembly should be given to the selection of the controller. Two-pin models are ideal for such systems. However, devices with comparators should not be considered.
Lastly, the power supply is fixed directly. The bandwidth of such systems is usually low. However, it should be borne in mind that problems with increased sensitivity are quite common. This happens in most cases due to burnout of the capacitors. The problem can be solved very simply by installing an auxiliary fuse.
Transistor Amplifier 2SA872
A homemade tube amplifier on transistors of this type is capable of an average frequency output of 550 Hz. In order to assemble a model, a conventional power transformer is quite suitable. Capacitors in this case can be used orthogonal. Immediately at the beginning of the circuit, resistors are used with low resistance.
Due to this, sudden jumps in the system are rare. The modulator must be installed behind the transformer. The lining in this situation must be used. The tube amplifier must be powered through a 20 V power supply.
To increase the output voltage, a comparator is used. Most often, it is selected network type. On average, he is able to keep negative resistance at 45 ohms. After installing the comparator, you can screw the lamp. In order to avoid the feedback effect, it is more advisable to use electrolytic capacitors.