Lanzar amplifier for home use. Setting up a Lanzar power amplifier - circuit diagram of a power amplifier, description of the circuit diagram, recommendations for assembly and adjustment. Other useful information and possible troubleshooting options

This amplifier differs from the original circuit in both the element base and the operating modes of the elements in the amplifier, which made it possible not only to significantly increase the output power, but also to reduce THD. The schematic diagram of the amplifier is shown in Figure 1, brief technical characteristics are summarized in the table. It should be noted right away that the intrinsic gain is quite high (31 dB) and if you want to reduce the THD level, you need to increase the value of resistor R9 to 680 Ohms.

In this case, the intrinsic gain will be 26 dB, since the ratio of the values of resistors R9-R14 determines the amplifier’s own gain. The THD level when using a 680 Ohm resistor will decrease to 0.04% for the fully bipolar version and to 0.02% for the option with field effect transistors in the penultimate stage at a 4 Ohm load and an output power of 100 W.

The amplifier's circuitry is almost completely symmetrical, which allows for minimal distortion and fairly high thermal stability. The signal from the audio signal source is fed to a composite pass capacitor C1-C3. This decision to make a pass-through capacitor is due to the fact that electrolytic capacitors have leakage currents when reverse polarity is applied.

In this case, two series-connected capacitors C2-C3 make it possible to completely get rid of this effect. In addition, electrolytic capacitors at frequencies above 10 kHz already increase their reactance quite significantly and capacitor C1 compensates for this change in parameters.

Next, the input alternating signal is divided into two, almost identical, amplification paths - for positive and negative half-waves. After the differential amplifier on transistors TV1, VT3 (VT2, VT4), the signal enters the amplifier stage on a transistor connected in a circuit with a common emitter (VT5 and VT6) and finally acquires the required amplitude.

In fact, the amplification of the input signal has already been completed - it has already acquired a sufficiently large amplitude and all that remains is to amplify the signal by current, for which emitter followers made of powerful transistors are usually used. However, the base currents of powerful transistors are quite large, and sending a signal without an intermediate repeater means getting huge nonlinear distortions.

In this amplifier, both bipolar transistors and field-effect transistors (VT8, VT9) can be used as an “intermediate” current amplifier. The purpose of this cascade is to relieve the load on the previous cascade as much as possible, the load capacity of which is not large. The use of field-effect transistors as VT8, VT9 quite significantly relieves the cascade on VT5, VT6, which reduces the THD level by almost 2 times.

However, the overall efficiency of the amplifier also decreases - at the same supply voltage, an amplifier with field-effect transistors will produce less power of a signal not distorted by Kipling (limitation of the output signal from above and below) than a completely bipolar version.

It would also be unfair to keep silent about the fact that these amplifiers sound slightly different, although the devices do not record this, but still each option has its own sound color, so it would be recommended to use the completely bipolar version or with field-effect transistors stupid - taste and color...

After the current pre-amplifier loaded onto resistor R22 (the load of this stage is not tied to either the common wire or the load, i.e. it is a floating load, which allows the current flowing through this stage to change minimally and leads to an additional reduction in THD) and already supplied to the base of the final stage.

In this embodiment, two transistors are used in parallel. However, the number of these transistors can be reduced if it is necessary to create an amplifier with a power of up to 150 W and increased to three pairs if it is necessary to build an amplifier with a power of 450 W.

Parallel connection of terminal transistors allows you to obtain greater total power, but you should pay attention to some features of this solution. Transistors connected in parallel must be not only of the same type, but also of another batch, i.e. produced in one shift of production at the manufacturing plant.

This will allow you to get rid of the selection of transistors according to parameters, since the spread of parameters between transistors of the same batch is guaranteed by the manufacturer to be less than 2%, which is actually true. In other words, transistors for the final stage should be purchased in one place and all the required quantity at once.

You should also pay attention to the markings of transistors - on transistors actually from Toshiba the markings are made with a laser, i.e. The inscription has an ocher tint and is not very visible. The font of the inscriptions has some peculiarities; some letters and numbers are cut (Figure 2).

And finally - in this case, the inscription 547 and the oval icon located just to the left of these numbers is the batch number, therefore all transistors connected in parallel should have the same markings and the same numbers and signs. By the way, instead of an oval there can be a letter, a number or a number with a letter.

The selection of parameters between transistors of n-p-n and p-n-p structures is desirable, but not at all mandatory - as a rule, using high-quality equipment, such a spread is compensated by the action of negative feedback.

Figure 3 shows a drawing of the amplifier printed circuit board (view from the track side, board size 127x88 mm), Figure 4 shows the location of the parts and connection diagram (view from the parts side).

The values of resistors R3, R6 depend on the supply voltage used and can range from 1.8 kOhm to 3 kOhm. Inductance L1 is wound on a mandrel with a diameter of 10 mm and contains 10 turns of wire with a diameter of 1.2...1.3 mm.

The quiescent current of the final stage should be in the range from 30 to 60 mA - adjustment is made by adjusting resistor R15. There is no need to raise it higher - when the amplifier warms up, sub-excitement may occur inside the case, i.e. excitation of the amplifier at the tops of the sinusoid. This is not noticeable by ear, but causes additional heating of the final stage.

The quiescent current is set to the minimum before the first switching on (the slider of the adjusted resistor is placed in the upper position according to the diagram). After switching on, the required quiescent current is set and after the amplifier warms up (about 2...3 minutes), an additional adjustment is made - transistors TV5, VT6 will reach their operating temperature and the temperature will not rise any further.

The transistors of the final and penultimate stages are attached to a common heat sink together with the thermal compensation transistor VT7 through heat-conducting spacers (mica). On transistors VT5, VT6 it is also necessary to install a heat sink, which can be made from aluminum sheet with a thickness of 1...1.5 mm and a size of 20x40 mm for each transistor.

This heat sink can be installed on both transistors at once, i.e. The transistors are clamped between aluminum plates with a screw, which is inserted into the hole just between the transistors.

Frankly speaking, we never expected that this scheme would cause so many difficulties when repeating it, and that the thread on the Soldering Iron forum would cross the 100-page threshold. So we decided to put an end to this topic. Of course, when preparing materials, material from this thread will be used, since it is simply not realistic to foresee some things - they are too paradoxical.
The Lanzar power amplifier has two basic circuits - the first is entirely based on bipolar transistors (Fig. 1), the second using field ones in the penultimate stage (Fig. 2). Figure 3 shows a circuit of the same amplifier, but executed in the MS-8 simulator. The position numbers of the elements are almost the same, so you can look at any of the diagrams.

Figure 1 Circuit of the LANZAR power amplifier entirely based on bipolar transistors.
INCREASE

Figure 2 Circuit of the LANZAR power amplifier using field-effect transistors in the penultimate stage.
INCREASE

Figure 3 Circuit of the LANZAR power amplifier from the MS-8 simulator.

INCREASE

LIST OF ELEMENTS INSTALLED IN THE LANZAR AMPLIFIER

FOR BIPOLAR OPTION

FOR THE OPTION WITH FIELDS
C3,C2 = 2 x 22µ0
C4 = 1 x 470p
C6,C7 = 2 x 470µ0 x 25V
C5,C8 = 2 x 0µ33
C11,C9 = 2 x 47µ0
C12,C13,C18 = 3 x 47p
C15,C17,C1,C10 = 4 x 1µ0
C21 = 1 x 0µ15
C19,C20 = 2 x 470µ0 x 100V

C14,C16 = 2 x 220µ0 x 100V
R1 = 1 x 27k
R2,R16 = 2 x 100
R8,R11,R9,R12 = 4 x 33
R7,R10 = 2 x 820
R5,R6 = 2 x 6k8
R3,R4 = 2 x 2k2
R14,R17 = 2 x 10
R15 = 1 x 3k3
R26,R23 = 2 x 0R33
R25 = 1 x 10k
R28,R29 = 2 x 3R9
R27,R24 = 2 x 0.33
R18 = 1 x 47
R19,R20,R22
R21 = 4 x 2R2

R13 = 1 x 470
VD1,VD2 = 2 x 15V

VD3,VD4 = 2 x 1N4007
VT2,VT4 = 2 x 2N5401
VT3,VT1 = 2 x 2N5551
VT5 = 1 x KSE350
VT6 = 1 x KSE340
VT7 = 1 x BD135
VT8 = 1 x 2SC5171
VT9 = 1 x 2SA1930
VT10,VT12 = 2 x 2SC5200

FOR THE OPTION WITH FIELDS
C3,C2 = 2 x 22µ0
C4 = 1 x 470p
C6,C7 = 2 x 470µ0 x 25V
VT11,VT13 = 2 x 2SA1943
C11,C9 = 2 x 47µ0
C11,C10 = 2 x 47µ0
C15,C17,C1,C10 = 4 x 1µ0
C21 = 1 x 0µ15
C19,C20 = 2 x 470µ0 x 100V

C14,C16 = 2 x 220µ0 x 100V
R1 = 1 x 27k
R2,R16 = 2 x 100
R8,R11,R9,R12 = 4 x 33
R7,R10 = 2 x 820
C15,C17,C1,C9 = 4 x 1µ0
R3,R4 = 2 x 2k2
R14,R17 = 2 x 10
R15 = 1 x 3k3
R26,R23 = 2 x 0R33
R4,R3 = 2 x 2k2
R28,R29 = 2 x 3R9
R27,R24 = 2 x 0.33
R18 = 1 x 47
R19,R20,R22
R21 = 4 x 2R2

R13 = 1 x 470
VD1,VD2 = 2 x 15V

R29,R28 = 2 x 3R9
VT8 = 1 x IRF640
VT9 = 1 x IRF9640
VT2,VT3 = 2 x 2N5401
VT3,VT1 = 2 x 2N5551
VT5 = 1 x KSE350
VT6 = 1 x KSE340
VT9 = 1 x 2SA1930
VT10,VT12 = 2 x 2SC5200

The printed circuit board drawing in LAY format has two types - one developed by us and used for assembling and selling power amplifier boards, as well as an alternative version developed by one of the SOLDERING IRON forum participants. The boards differ quite a lot. Figure 4 shows a sketch of our power amplifier board, and Figure 5 shows an alternative option.

Figure 5 Sketch of the printed circuit board of the LANZAR power amplifier.

DOWNLOAD

Figure 6 Sketch of an alternative printed circuit board for the LANZAR power amplifier. DOWNLOAD

ATTENTION! THERE IS AN ERROR ON THE BOARD - CHECK IT AGAIN!

The power amplifier parameters are summarized in the table:

PARAMETER

power amplifier circuit diagram of the Lanzar power amplifier operation description recommendations for assembly and adjustment

PER LOAD
2 Ohm

(4 ohm bridge)

Maximum supply voltage, ± V
Maximum output power, W

at distortion up to 1% and supply voltage:

±30 V

±35 V

±40 V

±45 V

±55 V

240

±65 V For example, let's take the supply voltage equal to ±60 V. If the installation is done correctly and there are no faulty parts, then we get the voltage map shown in Figure 7. The currents flowing through the elements of the power amplifier are shown in Figure 8. The power dissipation of each element is shown in Figure 9).

(about 990 mW is dissipated on transistors VT5, VT6, therefore the TO-126 case requires a heat sink

Figure 7. LANZAR power amplifier voltage map ENLARGE

Figure 8. Power amplifier current map ENLARGE

Figure 9. Amplifier power dissipation map ENLARGE
A few words about details and installation: First of all, you should pay attention to the correct installation of parts, since the circuit is symmetrical, errors are quite common. Figure 10 shows the arrangement of parts. Regulation of the quiescent current (current flowing through the terminal transistors when the input is closed to a common wire and compensating the current-voltage characteristic of the transistors) is carried out by resistor X1.

When turned on for the first time, the resistor slider should be in the highest position according to the diagram, i.e. have maximum resistance.

The quiescent current should be 30...60 mA. There is no thought to setting it higher - there are no noticeable changes in either instruments or audibly. To set the quiescent current, the voltage is measured on any of the emitter resistors of the final stage and set in accordance with the table: VOLTAGE AT THE TERMINALS OF THE EMITTER RESISTOR, V THE STILL CURRENT IS HIGH - EXCESSIVE HEATING, IF THIS IS NOT AN ATTEMPT TO CREATE CLASS "A", THEN THIS IS AN EMERGENCY CURRENT.

REST CURRENT OF ONE PAIR OF TERMINAL TRANSISTORS, mA

Figure 10 Location of parts on the power amplifier board.

The places where installation errors most often occur are shown.
The question was raised about the advisability of using ceramic resistors in the emitter circuits of terminal transistors. You can also use MLT-2, two of each, connected in parallel with a nominal value of 0.47...0.68 Ohm. However, the distortion introduced by ceramic resistors is too small, but the fact that they are breakable - when overloaded they break, i.e. their resistance becomes infinite, which quite often leads to the salvation of the final transistors in critical situations. The radiator area depends on the cooling conditions; Figure 11 shows one of the options,

it is necessary to attach power transistors to the heat sink through insulating gaskets

. It is better to use mica, since it has a fairly low thermal resistance. One of the options for mounting transistors is shown in Figure 12.
Figure 11 One of the radiator options for a power of 300 W, subject to good ventilation

Figure 12 One of the options for attaching power amplifier transistors to a radiator.

Insulating gaskets must be used.

Before installing power transistors, as well as in case of suspected breakdown, the power transistors are checked with a tester. The limit on the tester is set to test diodes (Figure 13). There are quite a lot of disputes on this topic and the idea of selecting elements dates back to the late seventies, when the quality of the element base left much to be desired.

Today, the manufacturer guarantees a spread of parameters between transistors of the same batch of no more than 2%, which in itself indicates the good quality of the elements. In addition, given that the terminal transistors 2SA1943 - 2SC5200 are firmly established in audio engineering, the manufacturer began producing paired transistors, i.e. transistors of both direct and reverse conduction already have the same parameters, i.e. the difference is no more than 2% (Figure 14). Unfortunately, such pairs are not always found on sale, however, we have had the opportunity to buy “twins” several times. However, even having sorted out the coffee code. gain between forward and reverse transistors, you just need to make sure that transistors of the same structure are of the same batch, since they are connected in parallel and the spread in h21 can cause an overload of one of the transistors (which has this parameter higher) and, as a result, overheating and failure building. Well, the spread between the transistors for the positive and negative half-waves is fully compensated by the negative feedback.

Figure 14 Transistors of different structures, but from the same batch.
However, this amplifier is also assembled using domestic components. This is quite realistic, but let’s make allowance for the fact that the parameters of the KT817 purchased and those found on the shelves in your workshop, purchased back in the 90s, will differ quite significantly. Therefore, here it is better to use the h21 meter available in almost all digital test rooms.
True, this gadget in the tester shows the truth only for low-power transistors. Using it to select transistors for the final stage will not be entirely correct, since h21 also depends on the current flowing. This is why separate testing stands are already being made to reject power transistors. from the adjustable collector current of the transistor being tested (Figure 15). The calibration of a permanent device for rejecting transistors is carried out in such a way that the microammeter at a collector current of 1 A deviates by half the scale, and at a current of 2 A - completely. When assembling an amplifier, you don’t have to make a stand for yourself; two multimeters with a current measurement limit of at least 5 A are enough..

Such screening will first of all allow you to select transistors with a really similar gain factor, and checking powerful transistors with a digital multimeter is only a check to ease the conscience - in microcurrent mode, powerful transistors have a gain factor of more than 500, and even a small spread when checking with a multimeter in real current modes can turn out to be huge . In other words, when checking the gain coefficient of a powerful transistor, the multimeter reading is nothing more than an abstract value that has nothing in common with the gain coefficient of the transistor, at least 0.5 A flows through the collector-emitter junction.

Figure 15 Rejection of powerful transistors based on gain.
Feed-through capacitors C1-C3, C9-C11 have a non-typical connection compared to factory analogue amplifiers. This is due to the fact that with this connection, the result is not a polar capacitor of a rather large capacity, but the use of a 1 µF film capacitor compensates for the not entirely correct operation of electrolytes at high frequencies. In other words, this implementation made it possible to obtain a more pleasant amplifier sound, compared to one electrolyte or one film capacitor.
In older versions of Lanzar, instead of diodes VD3, VD4, 10 Ohm resistors were used. Changing the element base allowed for slightly improved performance at signal peaks. For a more detailed look at this issue, let's look at Figure 3. The circuit does not model an ideal power source, but one closer to a real one, which has its own resistance (R30, R31). When playing a sinusoidal signal, the voltage on the power rails will have the form shown in Figure 16. In this case, the capacitance of the power filter capacitors is 4700 μF, which is somewhat low., more is possible, but a significant difference is no longer noticeable. But let's return to Figure 16. The blue line shows the voltage directly at the collectors of the final stage transistors, and the red line shows the supply voltage of the voltage amplifier in the case of using resistors instead of VD3, VD4. As can be seen from the figure, the supply voltage of the final stage has dropped from 60 V and is located between 58.3 V in the pause and 55.7 V at the peak of the sinusoidal signal.

Due to the fact that capacitor C14 is not only charged through the decoupling diode, but also discharged at signal peaks, the amplifier supply voltage takes the form of a red line in Figure 16 and ranges from 56 V to 57.5 V, i.e. has a swing of about 1.5 IN.

Figure 16 voltage waveform when using decoupling resistors.

Figure 17 Shape of supply voltages on the final transistors and voltage amplifier
By replacing the resistors with diodes VD3 and VD4, we obtain the voltages shown in Figure 17. As can be seen from the figure, the ripple amplitude on the collectors of the terminal transistors has remained almost unchanged, but the supply voltage of the voltage amplifier has taken on a completely different form. First of all, the amplitude decreased from 1.5 V to 1 V, and also at the moment when the peak of the signal passes, the supply voltage of the UA sags only to half the amplitude, i.e. by about 0.5 V, while when using a resistor, the voltage at the peak of the signal sags by 1.2 V. In other words, by simply replacing resistors with diodes, it was possible to reduce the power ripple in the voltage amplifier by more than 2 times.
However, these are theoretical calculations. In practice, this replacement allows you to get a “free” 4-5 watts, since the amplifier operates at a higher output voltage and reduces distortion at signal peaks.

After assembling the amplifier and adjusting the quiescent current, you should make sure that there is no constant voltage at the output of the power amplifier. If it is higher than 0.1 V, then this clearly requires adjustment of the operating modes of the amplifier. In this case, the simplest way is to select a “supporting” resistor R1. For clarity, we present several options for this rating and show the DC voltage measurements at the output of the amplifier in Figure 18.

Despite the fact that on the simulator the optimal constant voltage was obtained only with R1 equal to 8.2 kOhm, in real amplifiers this rating is 15 kOhm...27 kOhm, depending on which manufacturer the differential stage transistors VT1-VT4 are used.
Perhaps it’s worth saying a few words about the differences between power amplifiers using bipolar transistors and those using field devices in the penultimate stage. First of all, when using field-effect transistors, the output stage of the voltage amplifier is VERY heavily unloaded, since the gates of field-effect transistors have practically no active resistance - only the gate capacitance is a load.

In this embodiment, the amplifier circuitry begins to step on the heels of class A amplifiers, since over the entire range of output powers the current flowing through the output stage of the voltage amplifier remains almost unchanged. The increase in the quiescent current of the penultimate stage operating on the floating load R18 and the base of the emitter followers of powerful transistors also varies within small limits, which ultimately led to a rather noticeable decrease in THD. However, there is also a fly in the ointment in this barrel of honey - the efficiency of the amplifier has decreased and the output power of the amplifier has decreased, due to the need to apply a voltage of more than 4 V to the field gates to open them (for a bipolar transistor this parameter is 0.6...0.7 V ). Figure 19 shows the peak of the sinusoidal signal of an amplifier made on bipolar transistors (blue line) and field-field switches (red line) at the maximum amplitude of the output signal.

Figure 19 Change in the amplitude of the output signal when using different elements in the amplifier.
In other words, reducing THD by replacing field-effect transistors leads to a “shortage” of about 30 W, and a decrease in the THD level by about 2 times, so it’s up to each individual to decide what to set. It should also be remembered that the THD level also depends on the amplifier’s own gain. In this amplifier The gain coefficient depends on the values of resistors R25 and R13 (at the nominal values used, the gain is almost 27 dB). Calculate, where R13 and R25 are the resistance in Ohms, 20 is the multiplier, lg is the decimal logarithm.
If it is necessary to calculate the gain coefficient in times, then the formula takes the form Ku = R25 / (R13 + 1).

This calculation is sometimes necessary when making a pre-amplifier and calculating the amplitude of the output signal in volts in order to prevent the power amplifier from operating in hard clipping mode.
Reducing your own coffee rate. gain up to 21 dB (R13 = 910 Ohm) leads to a decrease in the THD level by approximately 1.7 times at the same output signal amplitude (the input voltage amplitude is increased). Well, now a few words about the most popular mistakes when assembling an amplifier yourself. One of the most popular mistakes is

installation of 15 V zener diodes with incorrect polarity

, i.e. These elements do not operate in voltage stabilization mode, but like ordinary diodes. As a rule, such an error causes a constant voltage to appear at the output, and the polarity can be either positive or negative (usually negative). The voltage value is based between 15 and 30 V. In this case, not a single element heats up. Figure 20 shows the voltage map for incorrect installation of zener diodes, which was produced by the simulator.

Invalid elements are highlighted in green.

Figure 20 Voltage map of a power amplifier with improperly soldered zener diodes. The next popular mistake is mounting transistors upside down

, i.e.

when the collector and emitter are confused. In this case, there is also constant tension and the absence of any signs of life. True, switching the transistors of the differential cascade back on can lead to their failure, but then depending on your luck.

If the transistors are swapped, and the emitter-collector is soldered correctly, then a small constant voltage is observed at the output of the amplifier, the quiescent current of the window transistors is regulated, but the sound is either completely absent or at the level “it seems to be playing.” Before installing transistors sealed in this way on the board, they should be checked for functionality. If the transistors are swapped, and even the emitter-collector places are swapped, then the situation is already quite critical, since in this embodiment, for the transistors of the differential stage, the polarity of the applied voltage is correct, but the operating modes are violated.
In this option, there is strong heating of the terminal transistors (the current flowing through them is 2-4 A), a small constant voltage at the output and a barely audible sound. Confusing the pinout of the transistors of the last stage of the voltage amplifier is quite problematic when using transistors in the TO-220 housing, but transistors in the TO-126 package are often soldered upside down, swapping the collector and emitter

. In this option, there is a highly distorted output signal, poor regulation of the quiescent current, and lack of heating of the transistors of the last stage of the voltage amplifier. A more detailed voltage map for this power amplifier mounting option is shown in Figure 24.

Figure 24 The transistors of the last stage of the voltage amplifier are soldered upside down.

Sometimes the transistors of the last stage of the voltage amplifier are confused. In this case, there is a small constant voltage at the output of the amplifier; if there is any sound, it is very weak and with huge distortions; the quiescent current is regulated only in the direction of increase. The voltage map of an amplifier with such an error is shown in Figure 25.

Figure 25 Incorrect installation of transistors of the last stage of the voltage amplifier.
Sometimes an amplifier fails; the most common reasons for this are overheating of the terminal transistors or overload.
For example, let's look at several options for failure of terminal transistors. Figure 26 shows the voltage map if the reverse end-of-line transistors (2SC5200) go to open, i.e. The transitions are burnt out and have the maximum possible resistance. In this case, the amplifier maintains operating modes, the output voltage remains close to zero, but the sound quality is definitely better, since only one half-wave of the sine wave is reproduced - negative (Fig. 27). The same thing will happen if the direct terminal transistors (2SA1943) break, only a positive half-wave will be reproduced.

Figure 26 The reverse end-of-line transistors burned out to the point of breaking.

Figure 27 Signal at the amplifier output in the case when the 2SC5200 transistors are completely burned out

Figure 27 shows a voltage map in a situation where the terminals have failed and have the lowest possible resistance, i.e. shorted. This type of malfunction drives the amplifier into VERY harsh conditions and further burning of the amplifier is limited only by the power supply, since the current consumed at this moment can exceed 40 A. The surviving parts instantly gain temperature, in the arm where the transistors are still working, the voltage is slightly greater than where the short circuit to the power bus actually occurred.

However, this particular situation is the easiest to diagnose - just before turning on the amplifier, check the resistance of the transitions with a multimeter, without even removing them from the amplifier. The measurement limit set on the multimeter is DIODE TEST or AUDIO TEST. As a rule, burnt-out transistors show a resistance between junctions in the range from 3 to 10 ohms.

Figure 27 Power amplifier voltage map in the event of a short circuit burnout of the final transistors (2SC5200)
If there is overheating, when it is believed that the radiator for the transistors of the last stage of the voltage amplifier is not needed (transistors VT5, VT6), they can also fail, both due to an open circuit and a short circuit. In the case of burnout of the VT5 transitions and an infinitely high resistance of the transitions, a situation arises when there is nothing to maintain zero at the output of the amplifier, and slightly open 2SA1943 end-of-line transistors will pull the voltage at the amplifier output to minus the supply voltage.

If the load is connected, then the value of the constant voltage will depend on the set quiescent current - the higher it is, the greater the value of the negative voltage at the output of the amplifier. If the load is not connected, then the output voltage will be very close in value to the negative power bus (Figure 28).

Figure 28 Voltage amplifier transistor VT5 has broken.

If the transistor in the last stage of the voltage amplifier VT5 fails and its transitions are short-circuited, then with a connected load at the output there will be a fairly large constant voltage and a direct current flowing through the load, about 2-4 A. If the load is disconnected, then the voltage at the output amplifier will be almost equal to the positive power bus (Fig. 29).

Figure 29 Voltage amplifier transistor VT5 has “shorted”.

Finally, all that remains is to offer a few oscillograms at the most coordinate points of the amplifier:

Voltage at the bases of the differential cascade transistors at an input voltage of 2.2 V. Blue line - bases VT1-VT2, red line - bases VT3-VT4.

As can be seen from the figure, both the amplitude and phase of the signal practically coincide.

Voltage at the connection point of resistors R8 and R11 (blue line) and at the connection point of resistors R9 and R12 (red line).

All that remains is to explain about the power supply. First of all, the power of the network transformer for a 300 W power amplifier should be at least 220-250 W and this will be enough to play even very hard compositions. You can learn more about the power of the power amplifier power supply. In other words, if you have a transformer from a tube color TV, then this is an IDEAL TRANSFORMER for one amplifier channel that allows you to easily reproduce musical compositions with a power of up to 300-320 W.
The capacitance of the power supply filter capacitors must be at least 10,000 μF per arm, optimally 15,000 μF.
When using capacities higher than the specified rating, you simply increase the cost of the design without any noticeable improvement in sound quality. It should not be forgotten that when using such large capacitances and supply voltages above 50 V per arm, the instantaneous currents are already critically enormous, so it is strongly recommended to use soft start systems.

.
First of all, it is strongly recommended that before assembling any amplifier, you download manufacturers’ plant descriptions (datasheets) for ALL semiconductor elements. This will give you the opportunity to take a closer look at the element base and, if any element is unavailable for sale, find a replacement for it.

In addition, you will have the correct pinout of transistors at hand, which will significantly increase the chances of correct installation. Those who are especially lazy are encouraged to VERY carefully at least familiarize themselves with the location of the terminals of the transistors used in the amplifier:

Finally, it remains to add that not everyone requires a power of 200-300 W, so the printed circuit board was redesigned for one pair of terminal transistors. This file was made by one of the visitors to the forum of the site "SOLDERING IRON" in the SPRINT-LAYOUT-5 program (DOWNLOAD BOARD). Details about this program can be found.

As can be seen from the photo, the horn has nothing in common with electronics, however, search queries for POWER AMPLIFIER are increasingly being replaced by SOUND AMPLIFIER, and the full name of this device, AUDITORY FREQUENCY POWER AMPLIFIER, is entered only 29 times a month versus 67,000 searches for SOUND AMPLIFIER.
I’m just curious what this is connected with... But that was a prologue, and now the fairy tale itself:

The schematic diagram of the LANZAR power amplifier is shown in Figure 1. This is an almost standard symmetrical circuit, which has made it possible to seriously reduce nonlinear distortions to a very low level.
This circuit has been known for quite a long time; back in the eighties, Bolotnikov and Ataev presented a similar circuit on a domestic element base in the book “Practical circuits for high-quality sound reproduction.”
However, work with this circuitry did not begin with this amplifier.

It all started with the PPI 4240 car amplifier circuit, which was successfully repeated:

Schematic diagram of the PPI 4240 car amplifier
Next was the article “Opening Amplifier -2” from Iron Shikhman (the article has unfortunately been removed from the author’s website). It dealt with the circuitry of the Lanzar RK1200C car amplifier, where the same symmetrical circuitry was used as an amplifier.

It is clear that it is better to see once than to hear a hundred times, so delving into my hundred-year-old recorded discs, I found the original article and present it as a quote:

OPENING THE AMPLIFIER - 2

A.I. Shikhatov 2002
A new approach to the design of amplifiers involves the creation of a line of devices using similar circuit solutions, common components and style. This allows, on the one hand, to reduce design and manufacturing costs, and on the other hand, it expands the choice of equipment when creating an audio system.
The radiators are located on the side surface of the amplifier, which allows you to stack several devices in a rack without interfering with their cooling. This is an undoubted convenience when creating extensive audio systems. However, when installing in a closed rack, you need to worry about air circulation - install supply and exhaust fans, temperature sensors. In short, professional equipment requires a professional approach in everything.
The line includes six two-channel and two four-channel amplifiers, differing only in output power and cabinet length.

The block diagram of the crossover of the Lanzar RK series amplifiers is shown in Figure 1. A detailed diagram is not given, since there is nothing original in it, and it is not this unit that determines the main characteristics of the amplifier. The same or similar structure is used in most modern mid-priced amplifiers. The range of functions and characteristics are optimized taking into account many factors:
On the one hand, the crossover capabilities should allow the construction of standard audio system options (front plus subwoofer) without additional components. On the other hand, there is little point in introducing a full set of functions into a built-in crossover: This will significantly increase the cost, but in many cases it will remain unclaimed. It is more convenient to delegate complex tasks to external crossovers and equalizers, and to disable the built-in ones.

The design uses dual KIA4558S operational amplifiers. These are low-noise, low-distortion amplifiers designed with "audio" applications in mind. As a result, they are widely used in preamp stages and crossovers.
The first stage is a linear amplifier with variable gain. It matches the output voltage of the signal source with the sensitivity of the power amplifier, since the gain of all other stages is equal to unity.
The next stage is the bass boost control. In amplifiers of this series, it allows you to increase the signal level at a frequency of 50 Hz by 18 dB. In products from other companies, the rise is usually less (6-12 dB), and the tuning frequency can be in the region of 35-60 Hz. By the way, such a regulator requires a good power reserve of the amplifier: an increase in gain by 3 dB corresponds to doubling the power, by 6 dB - quadrupling, and so on.
This is reminiscent of the legend about the inventor of chess, who asked the Raja for one grain for the first square of the board, and for each subsequent one - twice as many grains as for the previous one. The frivolous Raja could not fulfill his promise: there were no such quantity of grains on the entire Earth... We are in a more advantageous position: an increase in the level by 18 dB will increase the signal power “only” 64 times. In our case, 300 W are available, but not every amplifier can boast such a reserve.
The signal can then be fed directly to a power amplifier, or the required frequency band can be selected using filters. The crossover part consists of two independent filters. The low-pass filter is tunable in the range of 40-120 Hz and is designed to work exclusively with a subwoofer. The tuning range of the high-pass filter is noticeably wider: from 150 Hz to 1.5 kHz. In this form, it can be used to work with a broadband front or for the MF-HF band in a system with channel amplification. The tuning limits, by the way, were chosen for a reason: in the range from 120 to 150 Hz there is a “hole” in which the acoustic resonance of the cabin can be hidden. It is also noteworthy that the bass booster is not turned off in any of the modes. Using this cascade simultaneously with a high-pass filter allows you to adjust the frequency response in the interior resonance region no worse than using an equalizer.
The last cascade has a secret. Its task is to invert the signal in one of the channels. This will allow you to use the amplifier in a bridge connection without additional devices.
Structurally, the crossover is made on a separate printed circuit board, which is connected to the amplifier board using a connector. This solution allows the entire line of amplifiers to use only two crossover options: two-channel and four-channel. The latter, by the way, is simply a “double” version of the two-channel one and its sections are completely independent. The main difference is the changed layout of the printed circuit board.

Amplifier

The Lanzar power amplifier is made according to a typical scheme for modern designs, shown in Figure 2. With minor variations, it can be found in most amplifiers of the middle and lower price category. The only difference is in the types of parts used, the number of output transistors and supply voltage. The diagram of the right channel of the amplifier is shown. The left channel circuit is exactly the same, only the part numbers start with a one instead of a two.

A filter R242-R243-C241 is installed at the amplifier input, eliminating radio frequency interference from the power supply. Capacitor C240 does not allow the DC component of the signal to enter the power amplifier input. These circuits do not affect the frequency response of the amplifier in the audio frequency range.
To avoid clicks when turning on and off, the amplifier input is connected to a common wire with a transistor switch (this unit is discussed below, together with the power supply). Resistor R11A eliminates the possibility of self-excitation of the amplifier when the input is closed.
The amplifier circuit is completely symmetrical from input to output. A double differential stage (Q201-Q204) at the input and a stage on transistors Q205, Q206 provide voltage amplification, the remaining stages provide current amplification. The cascade on transistor Q207 stabilizes the quiescent current of the amplifier. To eliminate its "unbalance" at high frequencies, it is bypassed with a mylar capacitor C253.
The driver stage on transistors Q208, Q209, as befits a preliminary stage, operates in class A. A “floating” load is connected to its output - resistor R263, from which the signal is removed to excite the transistors of the output stage.
The output stage uses two pairs of transistors, which made it possible to extract 300 W of rated power and up to 600 W of peak power. Resistors in the base and emitter circuits eliminate the consequences of technological variation in the characteristics of transistors. In addition, resistors in the emitter circuit serve as current sensors for the overload protection system. It is made on transistor Q230 and controls the current of each of the four transistors in the output stage. When the current through an individual transistor increases to 6 A or the current of the entire output stage to 20 A, the transistor opens, issuing a command to the blocking circuit of the supply voltage converter.
The gain is set by the negative feedback circuit R280-R258-C250 and is equal to 16. Correction capacitors C251, C252, C280 ensure the stability of the amplifier covered by OOS. The circuit R249, C249 connected at the output compensates for the increase in load impedance at ultrasonic frequencies and also prevents self-excitation. In the audio circuits of the amplifier, only two electrolytic non-polar capacitors are used: C240 at the input and C250 in the OOS circuit. Due to their large capacity, it is extremely difficult to replace them with other types of capacitors.

Power supply The high-power power supply is made of field-effect transistors. A special feature of the power supply is the separate output stages of the converter for powering the power amplifiers of the left and right channels. This structure is typical for high-power amplifiers and makes it possible to reduce transient interference between channels. For each converter there is a separate LC filter in the power supply circuit (Figure 3). Diodes D501, D501A protect the amplifier from erroneous switching on in the wrong polarity.

Each converter uses three pairs of field-effect transistors and a transformer wound on a ferrite ring. The output voltage of the converters is rectified by diode assemblies D511, D512, D514, D515 and smoothed by filter capacitors with a capacity of 3300 μF. The output voltage of the converter is not stabilized, so the power of the amplifier depends on the voltage of the on-board network. From the negative voltage of the right and positive voltage of the left channel, parametric stabilizers generate voltages of +15 and -15 volts to power the crossover and differential stages of power amplifiers.
The master oscillator uses the KIA494 (TL494) microcircuit. Transistors Q503, Q504 increase the output of the microcircuit and speed up the closing of the key transistors of the output stage. The supply voltage is supplied to the master oscillator constantly, the switching is controlled directly from the Remote circuit of the signal source. This solution simplifies the design, but when turned off, the amplifier consumes insignificant quiescent current (several milliamps).
The protection device is made on a KIA358S chip containing two comparators. The supply voltage is supplied to it directly from the Remote circuit of the signal source. Resistors R518-R519-R520 and a temperature sensor form a bridge, the signal from which is fed to one of the comparators. A signal from the overload sensor is supplied to another comparator through a driver on transistor Q501.
When the amplifier overheats, a high voltage level appears at pin 2 of the microcircuit, and the same level appears at pin 8 when the amplifier is overloaded. In any emergency case, signals from the output of the comparators through the OR diode circuit (D505, D506, R603) block the operation of the master oscillator at pin 16. Operation is restored after eliminating the causes of the overload or cooling the amplifier below the temperature sensor response threshold.
The overload indicator is designed in an original way: the LED is connected between the +15 V voltage source and the on-board network voltage. During normal operation, voltage is applied to the LED in reverse polarity and it does not light. When the converter is blocked, the +15 V voltage disappears, the overload indicator LED turns on between the on-board voltage source and the common wire in the forward direction and begins to glow.
Transistors Q504, Q93, Q94 are used to block the input of the power amplifier during transient processes when turning on and off. When the amplifier is turned on, capacitor C514 is slowly charged, transistor Q504 is in the open state at this time. The signal from the collector of this transistor opens the keys Q94,Q95. After charging the capacitor, transistor Q504 closes, and the -15 V voltage from the output of the power supply reliably blocks the keys. When the amplifier is turned off, transistor Q504 instantly opens through diode D509, the capacitor quickly discharges and the process is repeated in the reverse order.

Design

The amplifier is mounted on two printed circuit boards. On one of them there is an amplifier and a voltage converter, on the other there are crossover elements and turn-on and overload indicators (not shown in the diagrams). The boards are made of high-quality fiberglass with a protective coating for the tracks and are mounted in a housing made of an aluminum U-shaped profile. Powerful transistors of the amplifier and power supply are pressed with pads to the side shelves of the case. Profiled radiators are attached to the outside of the sides. The front and rear panels of the amplifier are made of anodized aluminum profile. The entire structure is secured with self-tapping screws with hexagon heads. That's all, actually - the rest can be seen in the photographs.

As you can see from the article, the original LANZAR amplifier itself is not bad at all, but I wanted it to be better...
I searched the forums, of course, Vegalab, but didn’t find much support - only one person responded. Perhaps it’s for the better - there aren’t a ton of co-authors. Well, in general, this particular appeal can be considered Lanzar’s birthday - at the time of writing the comment, the board was already etched and soldered almost completely.

So Lanzar is already ten years old...
After several months of experiments, the first version of this amplifier, called "LANZAR", was born, although of course it would be fairer to call it "PIPIAY" - it all started with him. However, the word LANZAR sounds much more pleasant to the ear.
If someone SUDDENLY considers the name an attempt to play on a brand name, then I dare to assure him that there was nothing like that in mind and the amplifier could have received absolutely any name. However, it became LANAZR in honor of the LANZAR company, since this particular automotive equipment is included in that small list of those who are personally respected by the team that worked on fine-tuning this amplifier.
A wide range of supply voltages makes it possible to build an amplifier with a power from 50 to 350 W, and at powers up to 300 W for UMZCH coffee. nonlinear distortion does not exceed 0.08% throughout the entire audio range, which allows the amplifier to be classified as Hi-Fi.
The figure shows the appearance of the amplifier.
The amplifier circuit is completely symmetrical from input to output. A double differential stage (VT1-VT4) at the input and a stage on transistors VT5, VT6 provide voltage amplification, the remaining stages provide current amplification. The cascade on transistor VT7 stabilizes the quiescent current of the amplifier. To eliminate its “asymmetry” at high frequencies, it is bypassed with capacitor C12.
The driver stage on transistors VT8, VT9, as befits a preliminary stage, operates in class A. A “floating” load is connected to its output - resistor R21, from which the signal is removed to excite the transistors of the output stage. The output stage uses two pairs of transistors, which made it possible to extract up to 300 W of rated power from it.
Resistors in the base and emitter circuits eliminate the consequences of technological variation in the characteristics of transistors, which made it possible to abandon the selection of transistors by parameters.
We remind you that when using transistors from the same batch, the spread in parameters between transistors does not exceed 2% - this is the manufacturer’s data. In reality, it is extremely rare that parameters go beyond the three percent zone. The amplifier uses only “one-party” terminal transistors, which, together with balance resistors, made it possible to maximally align the operating modes of the transistors with each other. However, if the amplifier is being made for a loved one, then it will not be useless to assemble the test stand given at the end of THIS ARTICLE.

Figure 1 - schematic diagram of the LANZAR amplifier. INCREASE .

Figure 2 - appearance of the LANZAR V1 amplifier.

Figure 3 - appearance of the LANZAR MINI amplifier

Schematic diagram of a powerful stage power amplifier 200 W 300 W 400 W UMZCH on high quality transistors Hi-Fi UMZCH

Power amplifier specifications:

±50 V ±60 V

390

As can be seen from the characteristics, the Lanzar amplifier is very versatile and can be successfully used in any power amplifiers that require good UMZCH characteristics and high output power.
The operating modes were slightly adjusted, which required installing a radiator on transistors VT5-VT6. How to do this is shown in Figure 3; perhaps no explanation is required. This change significantly reduced the level of distortion compared to the original circuit and made the amplifier less capricious of the supply voltage.
Figure 4 shows a drawing of the location of parts on the printed circuit board and a connection diagram.

Figure 4

You can, of course, praise this amplifier for quite a long time, but it is somehow not modest to engage in self-praise. Therefore, we decided to look at the reviews of those who heard how it works. I didn’t have to search for long - this amplifier has been discussed on the Soldering Iron forum for a long time, so take a look for yourself:

There were, of course, negative ones, but the first was from an incorrectly assembled amplifier, the second from an unfinished version with a domestic configuration...
Quite often people ask how an amplifier sounds. We hope that there is no need to remind you that there are no comrades according to taste and color. Therefore, in order not to impose our opinion on you, we will not answer this question.

Let's note one thing - the amplifier really sounds. The sound is pleasant, not intrusive, good detail, with a good signal source.
The audio frequency power amplifier UM LANZAR based on powerful bipolar transistors will allow you to assemble a very high-quality audio frequency amplifier in a short period of time.
Structurally, the amplifier board is made in a monophonic version. However, nothing prevents you from purchasing 2 amplifier boards for assembling a stereo UMZCH, or 5 for assembling a 5.1 amplifier, although of course the high output power appeals more to a subwoofer, but it plays too well for a subwoofer...
The relatively low price of a ready-made 350 W power amplifier board will pleasantly surprise you.
Amplifier UM LANZAR has proven itself well both in automotive and stationary equipment.

It is especially popular among small amateur musical groups not burdened with large finances and allows you to increase power gradually - a pair of amplifiers + a pair of speaker systems. A little later, once again a pair of amplifiers + a pair of speaker systems and there is already a gain not only in power, but also in sound pressure, which also creates the effect of additional power. Even later, UM HOLTON 800 for a subwoofer and transfer of amplifiers to the mid-HF link and as a result, a total of 2 kW of VERY pleasant sound, which is quite enough for any assembly hall...
Power supply ±70 V - 3.3 kOhm...3.9 kOhm
Power supply ±60 V - 2.7 kOhm...3.3 kOhm
Power supply ±50 V - 2.2 kOhm...2.7 kOhm
Power supply ±40 V - 1.5 kOhm...2.2 kOhm
Power supply ±30 V - 1.0 kOhm...1.5 kOhm

Power supply ±20 V - CHANGE AMPLIFIER

Of course, ALL resistors are 1 W, zener diodes at 15V are preferably 1.3 W

Regarding heating VT5, V6 - in this case, you can increase the radiators on them or increase their emitter resistors from 10 to 20 Ohms.
About LANZAR amplifier power filter capacitors:
With a transformer power of 0.4...0.6 of the amplifier power in the arm of 22000...33000 µF, the capacitance in the power supply of the UA (which for some reason was forgotten) should be increased to 1000 µF
With a transformer power of 0.6...0.8 of the amplifier power in the arm of 15000...22000 µF, the capacitance in the power supply is 470...1000 µF
With a transformer power of 0.8...1 of the amplifier power in the arm of 10000...15000 µF, the capacitance in the power supply is 470 µF.

The indicated denominations are quite sufficient for high-quality reproduction of any musical fragments.
Since this amplifier is quite popular and questions about making it yourself quite often come up, the following articles were written:
Transistor amplifiers. Basics of circuit design
Transistor amplifiers. Building a balanced amplifier
Lanzar tuning and circuit design changes
Setting up the LANZAR power amplifier
Increasing the reliability of power amplifiers using the example of the LANZAR amplifier
The penultimate article quite intensively uses the results of parameter measurements using the MICROCAP-8 simulator.
How to use this program is described in detail in a trilogy of articles:
AMPovichok.

CHILDREN'S

And finally, I would like to give the impressions of one of the fans of this circuit, who assembled this amplifier on his own:
The amplifier sounds very good, the high damping factor represents a completely different level of low frequency reproduction, and the high slew rate does an excellent job of reproducing even the smallest sounds in the high and midrange ranges.
You can talk a lot about the delights of the sound, but the main advantage of this amplifier is that it does not add any color to the sound - it is neutral in this regard, and only repeats and amplifies the signal from the sound source.
Many who heard the sound of this amplifier (assembled according to this circuit) gave the highest rating to its sound as a home amplifier for high-quality speakers, and its endurance in *close to military action* conditions gives the chance to use it professionally for scoring various outdoor events , as well as in the halls.
For a simple comparison, I will give an example that will be most relevant among radio amateurs, as well as among those already *experienced with good sound*
in the soundtrack of Gregorian-Moment of Peace, the choir of monks sounds so realistic that the sound seems to pass right through, and the female vocals sound as if the singer is standing right in front of the listener.
When using time-tested speakers such as 35ac012 and others like them, the speakers get a new lease of life and sound just as clearly even at maximum volume.
For example, for fans of loud music, when listening to the music track Korn ft. Skrillex - Get Up
The speakers were able to play all the difficult moments with confidence and without noticeable distortion.
As a contrast to this amplifier, we took an amplifier based on the TDA7294, which, already at a power of less than 70 W per 1 channel, was able to overload the 35ac012 so that it was clearly audible how the woofer coil hit the core, which was fraught with damage to the speaker and, as a result, losses.
The same cannot be said about the *LANZAR* amplifier - even with about 150W of power supplied to these speakers, the speakers continued to work perfectly, and the woofer was so well controlled that there were simply no extraneous sounds.
In the musical composition Evanescence - What You Want
The scene is so elaborate that you can even hear the drumsticks hitting each other. And in the composition Evanescence - Lithium Official Music Video
The skipping part is replaced by an electric guitar, so that the hair on your head just begins to move, because there is simply no *longness* to the sound, and the quick transitions are perceived as if a painful form of 1 is flashing in front of you, in one moment and YOU are immersed in a new world. Not forgetting about the vocals, which throughout the entire composition bring generalization to these transitions, giving harmony.
In the composition Nightwish - Nemo
The drums sound like gunshots, clearly and without boom, and the rumble of thunder at the beginning of the composition simply makes you look around.
In the composition Armin van Buuren ft. Sharon den Adel - In and Out of Love
We are again immersed in the world of sounds that penetrate us through and through, giving us a feeling of presence (and this is without any equalizers or additional stereo expansions)
In the song Johnny Cash Hurt
We are again immersed in the world of harmonious sound, and the vocals and guitar sound so clearly that even the increasing tempo of the performance is perceived as if we are sitting behind the wheel of a powerful car and pressing the gas pedal to the floor, while not letting go but pressing harder and harder.
With a good source of sound signal and good acoustics, the amplifier *doesn't bother you* at all, even at the highest volume.
Once a friend was visiting me and he wanted to listen to what this amplifier was capable of, putting on a track in AAC format Eagles - Hotel California, he turned it up to full volume, while instruments began to fall from the table, his chest felt like well-placed punches of a boxer , the glass tinkled in the wall, and we were quite comfortable listening to music, while the room was 14.5 m2 with a ceiling of 2.4 m.
We installed ed_solo-age_of_dub, the glass in two doors cracked, the sound was felt by the whole body, but the head did not hurt.

The board on the basis of which video was made in LAY-5 format.

If you assemble two LANZAR amplifiers, can they be bridged?
You can, of course, but first, a little poetry:
For a typical amplifier, the output power depends on the supply voltage and load resistance. Since we know the load resistance and we already have power supplies, it remains to be seen how many pairs of output transistors to use.
Theoretically, the total output power of alternating voltage is the sum of the power supplied by the output stage, which consists of two transistors - one n-p-n, the second p-n-p, therefore each transistor is loaded with half the total power. For the sweet couple 2SA1943 and 2SC5200, the thermal power is 150 W, therefore, based on the above conclusion, 300 W can be removed from one pair of outputs.
But practice shows that in this mode the crystal simply does not have time to transfer heat to the radiator and thermal breakdown is guaranteed, because the transistors must be insulated, and the insulating spacers, no matter how thin they are, still increase the thermal resistance, and the surface of the radiator is unlikely to who polishes to micron precision...
So for normal operation, for normal reliability, quite a lot of people have adopted slightly different formulas for calculating the required number of output transistors - the output power of the amplifier should not exceed the thermal power of one transistor, and not the total power of the pair. In other words, if each transistor of the output stage can dissipate 150 W, then the output power of the amplifier should not exceed 150 W, if there are two pairs of output transistors, then the output power should not exceed 300 W, if three - 450, if four - 600.

Well, now the question is - if a typical amplifier can output 300W and we connect two such amplifiers in a bridge, then what will happen?
That's right, the output power will increase approximately twofold, but the thermal power dissipated by the transistors will increase by 4 times...
So it turns out that to build a bridge circuit you will no longer need 2 pairs of outputs, but 4 on each half of the bridge amplifier.
And then we ask ourselves the question - is it necessary to drive 8 pairs of expensive transistors to get 600 W, if you can get by with four pairs simply by increasing the supply voltage?

Well, of course, it’s the owner’s business....
Well, several options of PRINTED BOARDS for this amplifier will not be superfluous. There are also original versions, and some taken from the Internet, so it’s better to double-check the board - it will give you mental training and fewer problems when adjusting the assembled version. Some options have been corrected, so there may not be any errors, or maybe something has slipped through the cracks...
One more question remains unanswered - assembly of the LANZAR amplifier on a domestic element base.
Of course, I understand that crab sticks are made not from crabs, but from fish. So is Lanzar. The fact is that in all attempts to assemble on domestic transistors, the most popular ones are used - KT815, KT814, KT816, KT817, KT818, KT819. These transistors have a lower gain and a unity gain frequency, so you won’t hear Lanzarov’s sound. But there is always an alternative. At one time, Bolotnikov and Ataev proposed something similar in circuit design, which also sounded pretty good:

You can see more details about how much power a power supply is needed for a power amplifier in the video below. The STONECOLD amplifier is taken as an example, but this measurement makes it clear that the power of the network transformer may be less than the power of the amplifier by about 30%.

At the end of the article, I would like to note that this amplifier requires a BIPOLARY power supply, since the output voltage is formed from the positive side of the power supply and the negative one. The diagram of such a power supply is shown below:

You can draw conclusions about the overall power of the transformer by watching the video above, but I’ll give a short explanation about the other details.
The secondary winding must be wound with a wire whose cross-section is designed for the overall power of the transformer plus an adjustment for the shape of the core.
For example, we have two channels of 150 W each, therefore the overall power of the transformer must be at least 2/3 of the power of the amplifier, i.e. with an amplifier power of 300 W, the transformer power must be at least 200 W. With a power supply of ±40 V into a 4 Ohm load, the amplifier develops about 160 W per channel, therefore the current flowing through the wire is 200 W / 40 V = 5 A.
If the transformer has an W-shaped core, then the voltage in the wire should not exceed 2.5 A per square mm of cross-section - this way there is less heating of the wire, and the voltage drop is less. If the core is toroidal, then the voltage can be increased to 3...3.5 A per 1 square mm of wire cross-section.
Based on the above, for our example, the secondary must be wound with two wires and the beginning of one winding is connected to the ends of the second winding (the connection point is marked in red). The diameter of the wire is D = 2 x √S/π.
At a voltage of 2.5 A we get a diameter of 1.6 mm, at a voltage of 3.5 A we get a diameter of 1.3 mm.
The diode bridge VD1-VD4 not only must calmly withstand the resulting current of 5 A, it must withstand the current that occurs at the moment of switching on, when it is necessary to charge the power filter capacitors C3 and C4, and the higher the voltage, the greater the capacitance, the higher the value of this starting current. Therefore, the diodes must be at least 15 Amperes for our example, and in the case of increasing the supply voltage and using amplifiers with two pairs of transistors in the final stage, 30-40 Ampere diodes or a soft start system are needed.
The capacity of capacitors C3 and C4, based on Soviet circuit design, is 1000 μF for every 50 W of amplifier power. For our example, the total output power is 300 W, which is 6 times 50 W, therefore the capacitance of the power filter capacitors should be 6000 uF per arm. But 6000 is not a typical value, so we round up to the typical value and get 6800 µF.
Frankly speaking, such capacitors do not come across often, so we put 3 capacitors of 2200 μF in each arm and get 6600 μF, which is quite acceptable. The issue can be solved somewhat simpler - use one 10,000 µF capacitor

COLLECTING LANZAR

The repetition of the same questions on every page of discussion about this amplifier prompted me to write this short sketch. Everything written below is my idea of what you need to know. beginner to the radio amateur who decided to make this amplifier, and does not pretend to be the absolute truth.

Let's say you are looking for a good transistor amplifier circuit. Circuits such as “UM Zueva”, “VP”, “Natalie”, and others seem complicated to you, or you have little experience in assembling them, but you want good sound. Then you have found what you were looking for! Lanzar is an amplifier built according to a classical symmetrical circuit, with an output stage operating in class AB, and has a pretty good sound, in the absence of complex settings and scarce components.

Amplifier circuit:

I found it necessary to make some minor changes to the original circuit: the gain was slightly increased - up to 28 times (R14 was changed), the values of the input filter R1, R2 were changed, as well as according to the advice May Be I'm a Leo resistor values of the base divider of the thermal stabilization transistor (R15, R15’) for smoother adjustment of the quiescent current. The changes are not critical. The numbering of elements has been preserved.

Amplifier power

Amplifier power supply- the most expensive link in it, so you should start with it. Below are a few words about IP.

Based on the load resistance and the desired output power, the desired supply voltage is selected (Table 1). This table is taken from the source site (interlavka.narod.ru), however, I personally urgently I would not recommend operating this amplifier at powers exceeding 200-220 watts.

REMEMBER! This is not a computer, no super-cooling is needed, the design should not work at the limit of its capabilities, then you will get a reliable amplifier that will work for many years and delight you with sound. We decided to make a high-quality device, and not a bouquet of New Year’s fireworks, so let all sorts of “squeezers” go through the forest.

For supply voltages below ±45 V/8 Ohm and ±35 V/4 Ohm, the second pair of output transistors (VT12, VT13) can be omitted! At such supply voltages, we get an output power of about 100 W, which is more than enough for a home. I note that if you install 2 pairs at such voltages, the output power will increase by a very insignificant amount, on the order of 3-5 W. But if “the toad is not strangling,” then in order to increase reliability, you can install 2 pairs.

Transformer power can be calculated using the program "PowerSup". Calculation based on the fact that the approximate efficiency of the amplifier is 50-55%, which means the transformer power is equal to: Ptrans=(Pout*Nchannels*100%)/efficiency applicable only if you want to listen to a sine wave for a long time. In a real music signal, unlike a sine wave, the ratio of peak to average values is much smaller, so there is no point in spending money on extra transformer power that will never be used anyway.

In the calculation, I recommend choosing the “heaviest” peak factor (8 dB) so that your power supply does not bend if you suddenly decide to listen to music with such a p-f. By the way, I also recommend calculating the output power and supply voltage using this program. For Lanzar dU you can choose about 4-7 V.

More details about the program "PowerSup" and calculation methods are written in website author (AudioKiller).

All this is especially true if you decide to buy a new transformer. If you already have it in your bins, and suddenly it turns out to have more power than the calculated one, then you can safely use it, a reserve is a good thing, but there is no need for fanaticism. If you decide to make a transformer yourself, then on this page of Sergei Komarov there is a normal calculation method .

The circuit itself the simplest bipolar power supply looks like that:

The circuit itself and the details for its construction are well described by Mikhail (D-Evil) in FAKe according to TDA7294.

I will not repeat myself, I will only note the amendment about the power of the transformer, described above, and about diode bridge: since Lanzar’s supply voltage can be higher than that of the TDA729x, the bridge must “hold” a correspondingly higher reverse voltage, no less than:

Urev_min = 1.2*(1.4*2*Uhalf-winding_of the transformer) ,

where 1.2 is the safety factor (20%)

And with large transformer powers and capacitances in the filter, in order to protect the transformer and bridge from colossal inrush currents, the so-called. “soft start” or “soft start” scheme.

Amplifier parts

A list of parts for one channel is attached in the archive in

Some denominations require special explanation:

C1– coupling capacitor must be of good quality. There are different opinions on the types of capacitors used as isolation capacitors, so those experienced will be able to choose the best option for themselves. For the rest, I recommend using polypropylene film capacitors from well-known brands such as Rifa PHE426, etc., but in the absence of such, widely available lavsan K73-17 are quite suitable.

The lower limit frequency, which will be amplified, also depends on the capacitance of this capacitor.

In the printed circuit board from interlavka.narod.ru, as C1 there is a seat for a non-polar capacitor, composed of two electrolytes, connected with “minuses” to each other and “pluses” in the circuit and shunted by a 1 µF film capacitor:

Personally, I would throw out the electrolytes and leave one film capacitor of the above types, with a capacity of 1.5-3.3 μF - this capacity is enough to operate the amplifier at “wideband”. In the case of working with a subwoofer, more capacity is required. Here it would be possible to add electrolytes with capacities of 22-50 μF x 25 V. However, the printed circuit board imposes its own limitations, and a 2.2-3.3 μF film capacitor is unlikely to fit there. Therefore, we set 2x22 uF 25 V + 1 uF.

R3, R6– ballast. Although initially these resistors were chosen to be 2.7 kOhm, I would recalculate them to the required supply voltage of the amplifier using the formula:

R=(Ushoulder – 15V)/Ist (kOhm) ,

where Ist – stabilization current, mA (about 8-10 mA)

L1 – 10 turns of 0.8 mm wire on a 12 mm mandrel, everything is smeared with superglue, and after drying a resistor is placed inside R31.

Electrolytic capacitors S8, S11, S16, S17 The voltage must be calculated to be no lower than the supply voltage with a margin of 15-20%, for example, at ±35 V, 50 V capacitors are suitable, and at ±50 V, you need to select 63 Volts. The voltages of other electrolytic capacitors are indicated in the diagram.

Film capacitors (non-polar) are usually not made rated for less than 63 V, so this should not be a problem.

Trimmer resistor R15– multi-turn, type 3296.

Under emitter resistorsR26, R27, R29 and R30– the board has seats for ceramic wires S.Q.P. 5 W resistors. The range of acceptable values is 0.22-0.33 Ohm. Although SQP is far from the best option, it is affordable.

You can also use domestic resistors C5-16. I haven't tried it, but they might even be better than SQP.

Other resistors– C1-4 (carbon) or C2-23 (MLT) (metal film). All except those indicated separately - at 0.25 W.

Some possible replacements:

Paired transistors are replaced with other pairs. Composing a pair of transistors from two different pairs is unacceptable.
VT5/VT6 can be replaced with 2SB649/2SD669. It should be noted that the pinout of these transistors is mirrored relative to the 2SA1837/2SC4793, and when using them, they must be rotated 180 degrees relative to those drawn on the board.
VT8/VT9– on 2SC5171/2SA1930
VT7– on BD135, BD137
Transistors of differential stages ( VT1 andVT3), (VT2 andVT4) it is advisable to select pairs with the smallest beta spread (hFE) using a tester. An accuracy of 10-15% is quite enough. With a strong scatter, a slightly increased level of direct voltage at the output is possible. The process is described by Mikhail (D-Evil) in the FAK on the VP amplifier .

Another illustration of the beta measurement process:

Transistors 2SC5200/2SA1943 are the most expensive components in this circuit and are often counterfeited. Similar to the real 2SC5200/2SA1943 from Toshiba, they have two break marks on top and look like this:

It is advisable to take identical output transistors from the same batch (in Figure 512 is the batch number, i.e., say both 2SC5200 with number 512), then the quiescent current when installing two pairs will be distributed more evenly across each pair.

Printed circuit board

The printed circuit board was taken from interlavka.narod.ru. The corrections on my part were mainly of a cosmetic nature; some errors in the signed values were also corrected, such as mixed up resistors for the thermal stabilization transistor and other little things. The board is drawn from the parts side. There is no need to mirror to make LUTs!

IMPORTANT! Before soldering each the part must be checked for serviceability, the resistance of the resistors must be measured to avoid errors in the nominal value, the transistors must be checked with a continuity tester, and so on. It is much more difficult to look for such errors later on the assembled board, so it is better to take your time and check everything. Save A LOT time and nerves.
IMPORTANT! Before soldering the trimmer resistor R15, it must be “twisted” so that its total resistance is soldered into the gap in the track, i.e., if you look at the picture above, between the right and middle terminals. all the resistance of the trimmer.
Jumpers to avoid accidental short circuit. It is better to do it with insulated wires.
Transistors VT7-VT13 are installed on a common radiator through insulating gaskets - mica with thermal paste (for example, KPT-8) or Nomakon. Mica is more preferable. Indicated in the diagram VT8,VT9 in an insulated housing, so their flanges can simply be lubricated with thermal paste. After installation on the radiator, the tester checks the transistor collectors (middle legs) for the absence of short circuits. with radiator.
Transistors VT5, VT6 You also need to install it on small radiators - for example, 2 flat plates measuring about 7x3 cm, in general, install whatever you find in the bins, just don’t forget to coat it with thermal paste.
For better thermal contact, differential cascade transistors ( VT1 and VT3), (VT2 and VT4) you can also lubricate them with thermal paste and press them together with heat shrink.

First launch and setup

Once again, we carefully check everything, if everything looks normal, there are no errors, “snot”, short circuits to the radiator, etc., then you can proceed to the first start.

IMPORTANT! The first start-up and setup of any amplifier must be carried out with input shorted to ground, power supply current limited and no load . Then the chance of burning something is greatly reduced. The simplest solution that I use is incandescent lamp 60-150 W, connected in series with the primary winding of the transformer:

We run the amplifier through the lamp, measure the DC voltage at the output: normal values are no more than ±(50-70) mV. “Walking” constant within ±10 mV is considered normal. We control the presence of voltages of 15 V on both zener diodes. If everything is normal, nothing exploded or burned, then we proceed to the setup.

When starting a working amplifier with a quiescent current = 0, the lamp should flash briefly (due to the current when charging the capacitors in the power supply), and then go out. If the lamp is bright, it means something is faulty, turn it off and look for the error.

As already mentioned, the amplifier is easy to set up: you only need set the quiescent current (TC) output transistors.

It should be exhibited on "warm up" amplifier, i.e. Before installation, let it play for a while, 15-20 minutes. During installation of the TP, the input must be short-circuited to ground and the output suspended in the air.

The quiescent current can be found by measuring the voltage drop across a pair of emitter resistors, e.g. R26 And R27(set the multimeter to the limit of 200 mV, probes to the emitters VT10 And VT11):

Accordingly, Ipok = Uv/(R26+R26) .

Further SMOOTHLY, without jerking we turn the trimmer and look at the multimeter readings. Required to install 70-100 mA. For the resistor values indicated in the figure, this is equivalent to the multimeter reading (30-44) mV.

The light bulb may begin to glow a little. Let's check the DC voltage level at the output again, if everything is normal, you can connect the speakers and listen.

Photo of the assembled amplifier

Other useful information and possible troubleshooting options

Amplifier self-excitation: Indirectly determined by the heating of the resistor in the Zobel circuit - R28. Reliably determined using an oscilloscope. To eliminate this, try increasing the ratings of the correction capacitors C9 And C10.

High level of DC component at the output: select differential cascade transistors ( VT1 and VT3), (VT2 and VT4) by "Betta". If it doesn’t help, or there is no way to choose more precisely, then you can try changing the value of one of the resistors R4 And R5. But this solution is not the best; it is still better to choose transistors.

Option to slightly increase sensitivity: You can increase the sensitivity of the amplifier (gain) by increasing the resistor value R14. Coef. gain can be calculated by the formula:

Ku = 1+R14/R11, (once)

But don’t get too carried away, because with increasing R14, the depth of the environmental feedback decreases and the unevenness of the frequency response and SOI increases. It is better to measure the output voltage level of the source at full volume (amplitude) and calculate what Ku is needed to operate the amplifier with the full output voltage swing, taking it with a margin of 3 dB (before clipping).

For specifics, let’s say the maximum to which it is tolerable to raise K is 40-50. If you need more, then make a preamplifier.

If you have any questions, write to the appropriate topic to the forum . Happy building!

Amplifier Lanzar. The repetition of the same questions on every page of discussion about this amplifier prompted me to write this short sketch. Everything written below is my idea of what a novice radio amateur needs to know who decides to make this amplifier, and does not claim to be the absolute truth.

Let's say you are looking for a good transistor amplifier circuit. Circuits such as “UM Zueva”, “VP”, “Natalie”, and others seem complicated to you, or you have little experience in assembling them, but you want good sound. Then you have found what you were looking for! Amplifier Lanzar It is an amplifier built according to a classic symmetrical circuit, with an output stage operating in class AB, and has a pretty good sound, without complicated settings and scarce components.

Amplifier circuit:

I found it necessary to make some minor changes to the original circuit: the gain was slightly increased - up to 28 times (R14 was changed), the values of the input filter R1, R2 were changed, and also, on the advice of MayBe I'm a Leo, the resistor values of the base divider of the thermal stabilization transistor (R15 , R15') for smoother adjustment of the quiescent current. The changes are not critical. The numbering of elements has been preserved.

Amplifier power

Amplifier power supply- the most expensive link in it, so you should start with it. Below are a few words about IP.

Based on the load resistance and the desired output power, the desired supply voltage is selected (Table 1). This table was taken from the original source site, however, I personally would strongly not recommend operating this amplifier at powers of more than 200-220 Watts.

For supply voltages below ±45 V/8 Ohm and ±35 V/4 Ohm, the second pair of output transistors (VT12, VT13) can be omitted! At such supply voltages, the Lanzar amplifier receives an output power of about 100 W, which is more than enough for a home. I note that if you install 2 pairs at such voltages, the output power will increase by a very insignificant amount, on the order of 3-5 W. But if “the toad is not strangling,” then in order to increase reliability, you can install 2 pairs.

Transformer power can be calculated using the PowerSup program. A calculation based on the fact that the approximate efficiency of the amplifier is 50-55%, which means that the power of the transformer is equal to: Ptrans = (Pout * N channels * 100%) / efficiency is applicable only if you want to listen to a sine wave for a long time. In a real music signal, unlike a sine wave, the ratio of peak to average values is much smaller, so there is no point in spending money on extra transformer power that will never be used anyway.

In the calculation, I recommend choosing the “heaviest” peak factor (8 dB), so that your power supply does not bend if you suddenly decide to listen to music with such a p-f. By the way, I also recommend calculating the output power and supply voltage using this program. For the Lanzar dU amplifier, you can choose about 4-7 V.

More details about the “PowerSup” program and the calculation method are written on the author’s website (AudioKiller).

The circuit itself of the simplest bipolar power supply looks like this:

The circuit itself and the details for its construction are well described by Mikhail (D-Evil) in TDA7294.
I will not repeat myself, I will only note an amendment about the power of the transformer, described above, and about the diode bridge: since the Lanzar amplifier can have a supply voltage higher than the TDA729x, the bridge must “hold” a correspondingly higher reverse voltage, no less:

Urev_min = 1.2*(1.4*2*Uhalf-winding_of the transformer) ,

where 1.2 is the safety factor (20%)

Amplifier parts

A list of parts for one channel is attached in the archive in the file

Some denominations require special explanation:

C1– separation capacitor, Lanzar amplifier must be of good quality. There are different opinions on the types of capacitors used as isolation capacitors, so those experienced will be able to choose the best option for themselves. For the rest, I recommend using polypropylene film capacitors from well-known brands such as Rifa PHE426, etc., but in the absence of such, widely available lavsan K73-17 are quite suitable.

The lower limit frequency, which will be amplified, also depends on the capacitance of this capacitor.

In the printed circuit board, as C1, there is a seat for a non-polar capacitor, composed of two electrolytes, connected with “minuses” to each other and “pluses” in the circuit and shunted by a 1 μF film capacitor:

R3, R6– ballast. Although initially these resistors were chosen to be 2.7 kOhm, I would recalculate them to the required supply voltage of the amplifier using the formula:

R=(Ushoulder – 15V)/Ist (kOhm) ,

where Ist – stabilization current, mA (about 8-10 mA)

L1– 10 turns of 0.8 mm wire on a 12 mm mandrel, everything is lubricated with superglue, and after drying, resistor R31 is placed inside.

Electrolytic capacitors C8, C11, C16, C17 must be designed for a voltage no lower than the supply voltage with a margin of 15-20%, for example, at ±35 V capacitors of 50 V are suitable, and at ±50 V you need to choose 63 Volts . The voltages of other electrolytic capacitors are indicated in the diagram.

Film capacitors (non-polar) are usually not made rated for less than 63 V, so this should not be a problem.

Trimmer resistor R15 – multi-turn, type 3296.

For emitter resistors R26, R27, R29 and R30 – the board provides seats for wire-wound ceramic SQP resistors with a power of 5 W. The range of acceptable values is 0.22-0.33 Ohm. Although SQP is far from the best option, it is affordable.

The Lanzar amplifier also requires the installation of domestic resistors C5-16. I haven't tried it, but they might even be better than SQP.

The remaining resistors are C1-4 (carbon) or C2-23 (MLT) (metal film). All except those indicated separately - at 0.25 W.

Some possible replacements:

Paired transistors are replaced with other pairs. Composing a pair of transistors from two different pairs is unacceptable.

VT5/VT6

VT8/VT9

VT7

(VT1 and VT3), (VT2 and VT4)

Another illustration of the beta measurement process:

Printed circuit board

The corrections on my part were mainly of a cosmetic nature; some errors in the signed values were also corrected, such as mixed up resistors for the thermal stabilization transistor and other little things. The board is drawn from the parts side. There is no need to mirror to make LUTs!

IMPORTANT!

Jumpers to avoid accidental short circuit. It is better to do it with insulated wires.

Transistors VT7-VT13 are installed on a common radiator through insulating gaskets - mica with thermal paste (for example, KPT-8) or Nomakon. Mica is more preferable. VT8, VT9 indicated in the diagram are in an insulated housing, so their flanges can simply be lubricated with thermal paste. After installation on the radiator, the tester checks the transistor collectors (middle legs) for the absence of short circuits. with radiator.

Transistors VT5, VT6 also need to be installed on small radiators - for example, 2 flat plates measuring about 7x3 cm, in general, install whatever you find in the bins, just don’t forget to coat it with thermal paste.

For better thermal contact, the transistors of the differential stages (VT1 and VT3), (VT2 and VT4) can also be lubricated with thermal paste and pressed against each other with heat shrink.

First launch and setup

Once again, we carefully check everything, if everything looks normal, there are no errors, “snot”, short circuits to the radiator, etc., then you can proceed to the first start.

IMPORTANT! The first startup and setup of any amplifier must be carried out with input shorted to ground, power supply current limited and no load . Then the chance of burning something is greatly reduced. The simplest solution that I use is incandescent lamp 60-150 W, connected in series with the primary winding of the transformer:

As already mentioned, the amplifier is easy to configure: you only need to set the quiescent current (TC) of the output transistors.

It should be set on a “warm up” amplifier, i.e. Before installation, let it play for a while, 15-20 minutes. During installation of the TP, the input must be short-circuited to ground and the output suspended in the air.

The quiescent current can be found by measuring the voltage drop across a pair of emitter resistors, for example on R26 and R27 (set the multimeter to the limit of 200 mV, probes on the emitters VT10 and VT11):

Respectively, Ipok = Uv/(R26+R26) .

Next, SMOOTHLY, without jerking, turn the trimmer and look at the multimeter readings. It is required to set 70-100 mA. For the resistor values indicated in the figure, this is equivalent to the multimeter reading (30-44) mV.

The light bulb may begin to glow a little. Let's check the DC voltage level at the output again, if everything is normal, you can connect the speakers and listen.

Other useful information and possible troubleshooting options

Self-excitation of the amplifier: Indirectly determined by the heating of the resistor in the Zobel circuit - R28. Reliably determined using an oscilloscope. To eliminate this, try increasing the ratings of correction capacitors C9 and C10.

High level of DC component at the output: select transistors of the differential stages (VT1 and VT3), (VT2 and VT4) according to “Betta”. If it doesn’t help, or there is no way to choose more precisely, then you can try changing the value of one of the resistors R4 and R5. But this solution is not the best; it is still better to choose transistors.

Option to slightly increase sensitivity: You can increase the sensitivity of the amplifier (gain) by increasing the value of resistor R14. Coef. gain can be calculated by the formula:

Ku = 1+R14/R11, (once)

But you shouldn’t get too carried away, since with an increase in R14, the depth of the feedback decreases and the unevenness of the frequency response and SOI increases. It is better to measure the output voltage level of the source at full volume (amplitude) and calculate what Ku is needed to operate the amplifier with the full output voltage swing, taking it with a margin of 3 dB (before clipping).

For specifics, let’s say the maximum to which it is tolerable to raise K is 40-50. If you need more, then make a preamplifier.

Download: Printed circuit board
Download all files in one archive: