Single-ended effect tube A-action amplifier production, Class a Power Amplifier
Keywords: single-ended effect tube A-power amplifier production
Since the Amplifier is in the process of signal amplification, there is no dazzling, the music is rich. An important factor in the popularity of the popularity of the enthusiasm of the audio enthusiasts is that almost all single-ended machines need to output transformers; additional machine power consumption is large. The stability of the machine is also affected. General household amplifier, with 6 W power output. It is sufficient to meet the requirements of music appreciation. The premise is that the listener is not too big. In addition, speakers have better sensitivity, from reducing production cost, reducing power consumption, and improving the angle of reliability. There is a need for a simple structure, a relatively low power consumption. The PASS ZEN series amplifier has a simple structure, sound quality, etc. The PASS ZEN1 amplifier is much smaller than the amplifier of Pass Zen4, A5. The circuit is very simple, and the static power consumption is much smaller. Since Pass Zen1 adopts capacitive coupling output, the DC output can be avoided to damage the speaker, so the speaker protection circuit can be omitted when making; do not worry about the low-frequency problem of the capacitor output amplifier, from actual testing and listening situations, sound It is relatively flat in the range of 20-20000 Hz, and due to the VMOS amplifier, the sound is like an electronic tube amplifier. The PASS ZEN1 amplifier schematic is shown in Figure 1. From the circuit, Zen1 can be seen from the primary constant current source load, using IRFP9240 as a constant current pipe, working in the matrix amplification state. Due to the fact that the model MOS tube marked in the schematic is more difficult to purchase, the unit is actually produced. The MSA92 is replaced with A1013, and IRFP9240 is replaced with IRFP9640. IRFP 140 is replaced with IRFP640, and of course, it is also possible to select a VMOS tube to do alternative experiments, but due to the difference between the foot and the opening voltage, the K series and J series Effect tube are not applied. Here is a few key issues during the production process.
(1) The power supply circuit is due to the work of the Pass Zen1 amplifier, and the static current is about 4 a, if the power supply is powered by a single transformer, the transformer capacity is large, otherwise it will be Each channel independent power is a good choice. This machine uses 1 500W ring cattle to power supply; due to the larger current, the capacity of the rectifier bridge, the quality must be guaranteed, the two-channel power supply should be used in the 50A rectification bridge, otherwise the pressure drop is too large, the rectifier bridge is serious Heat, even burned, should ensure that the supply voltage is around 34 V; the filter capacitor must have sufficient capacity due to the load capacity of the power supply circuit, otherwise it may cause communication. If it is difficult to eliminate communication without using regulated power supply Simple RC filter form can be used, the effect is also very good, and R should use the resistance of the resistance below 0.1 Ω, and use multiple step filter forms.
(2) Amplification circuit Debug PASS ZEN1 static working current is set by R1, and the appropriate increase of R1 can further reduce power consumption, but the maximum output power of the machine also decreases. In the case of a small amount of heat sink, the above method can be used, but this is generally not recommended. When the circuit connection is incorrect, power is applied to the machine, and the S, D foot voltage of Q1 is measured, and the P1 is adjusted, so that the voltage of S and D is half the supply voltage.
(3) Machine tone has a large device that affects the sound of this amplifier, mainly IRFP140 and output capacitance C3, C4, and capacitance should be selected as much as possible, and 1 UF CBB capacitor can be used in parallel 1 UF CBB in parallel with 1 UF CBB in parallel 1 UF CBB Instead of C3, C4.
(4) The fixation of the machine's heat dissipation and power tube is due to the high heat generation of the Class A machine, and a large external heat exchanger should be used. The power tube can be directly fixed to the heat sink, since the heat sink temperature is high, the circuit board should be slightly farther away from the heat sink and through the wire connection power tube. Pass zen1 is a small gain of pure post-level, which needs to connect the pre-serial amplifier to reject the CD and other players. If there is no campaign, a front-type field effect tube 2Sk30 can be used. Since 2Sk30 belongs to the depletion field effect tube, the bias circuit becomes simple, take into account the power supplied with the pass Zen1. The actual pre-magnifier schematic is shown in Figure 2. Figure 2 2SK30 pre-stage schematic note, when the 2SK30 pre-stage is not used, since the signal is reversed, the speaker should be connected in FIG. After the 2SK30 is added, the 2Sk30 also constitutes an inverted amplifier, Figure 1 The connection phase of the speaker is reversed. At this point, a single-ended effect tube amplifier having a strong electronic pipe tube is completed, the circuit is simple, the sound is balanced, and the analytical force is also quite good.
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