Bryston, Canada, high-power amplifier circuit, High-Power Amplifier, HIGH-POWER AMPLIFIER
Keywords: discrete component amplifier
Author: Wang Huanzhang
Bryston, Canada is mainly used in professional and recording, etc., and the products have a high reputation in the world, and the power covers the range of 60 ~ 1000W, but almost all of the power amplifier circuits are the same, most of which use this output stage. The complete main circuit of this amplifier is described below with 3B (150W, 8Ω) of the home, as shown in the following figure. The circuit seems to be more complicated because Bryston, Canada as the world's top products, promised 20 years of warranty. Its protection circuit is set very complete, and each power tube has a separate overcurrent protection circuit. In fact, the principle of amplification circuit is very simple, all of which are the most basic criticism amplified or shared (see below). Q1 ~ Q4 forms complementary differential input stage, Q5, QL0 is the second-level co-push-off level, Q15, Q16 (constitutive UBE multiplier to provide appropriate bias voltage and temperature compensation. Here you can see that due to The output level is unusual, the setting of the UBE multiplier is also different. The latter circuit is the structure of the famous "quadruple complementary parallel" output stage, with a relative to the aforementioned circuit architecture, one-stage driving tube Q7 and Q13, the output stage In addition to the aforementioned asymmetry distortion, there is a certain gain. Canadian Bryston's design philosophy is that the magnitude of the voltage is not full, more beneficial to reduce distortion. Input stage and main electricity voltage amplifier circuit It is also a full complementary amplification, so that the existing transistor is not symmetled as before, it may be more advantageous with single-ended amplification. But this world has no perfect amplification circuit, and the single-ended zoom is in short, and the positive and negative half-week signals. The rising rate is not easy to consisten, especially in the high swing high-power applications. From a overall perspective, the dissemination of the transistor amplifier output tube dominates the main position. And this problem has been resolved in this circuit. The small power tube symmetry of the front stage circuit is relatively good. After the circuit principle, let's take a look at the excellent performance indicators brought by this inconspicuous circuit: 8Ω, 150W or 4Ω, 250W is exceeding the power output The total harmonic distortion and intermodulation distortion in the 20Hz ~ 20kHz full frequency band are not more than 0.007%, the loss rate of 10kHz is only about 0.001%, the conversion rate is greater than 60V / μs, the power bandwidth 1Hz ~ L00KHz, 8Ω / 20 Hz The number of series is greater than 500. It can have such a distortion indicator. In addition to the value of the circuit components, the four-yuan complementary circuit configuration is naturally functional, and this circuit is naturally lifted, and the transistor is fundamentally eliminated. The intrinsic distortion. The "ALA circuit" (with the aircraft "(by op amp providing distortion correction voltage) has essentially distinctive differences with the depth negative feedback circuit and the previous prestigious" ALA circuit ".
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Trial adjustment adjusts the entire circuit is commonly used components, which is very beneficial to self-control and low cost. The input stage differential pair 2N5210 / 2N5087 can be used in 2 n5550 / 2 N5400 by 2 N5550 / 2N5401 by 2N5551 / 2N5401. It should be noted that the 2N551 / 2N5401 on my country is very flooding, the quality is uneven, it is best to use the original tube of Ansen, or 2SC2705 / 2SA1145 can be used instead. The frequency compensation setting of the amplifier is very complete, and there is enough phase margin without self-excitement. The MJE180 can be replaced with 2SC3423 or 2SC3419. The passive tube and output tube must make the original model, and require strict pairing, preferably within 10%, this pairing error will directly affect the distortion indicator. The resistance is not labeled with 1 / 4W, the precision is 1% of the metal film resistance, and the small capacitance capacitance preferably selects a high-frequency characteristic polyphenylene capacitor. The importance of the circuit board design and the overall layout of the high-quality amplifier is not in the circuit design. At the time of actual production, the high current pulse is rectified, the filter power supply portion, the two-channel small signal aggregate voltage, the quadritical complementary pair output stage and the speaker protection section, separately designed separately, such as shown on the right, a total of 4 Circuit board (small signal front stage voltage amplifies each of the left / right channels). The speaker protects the use of high reliability UPC1237 integrated circuits, separate 26V power supplies to avoid symmetry of positive and negative power supplies. The whole machine is welded to complete the test, and the static current is adjusted to 50 mA per tube, and it is in the high efficiency AB class amplification. When I actually audition, I found that the sound quality and ordinary amplifier were not in the same day, the most obvious is that the tail of the instrument is completely a lot. Low frequency is loose and there is no shortage, the high frequency is soft and delicate, and the overall tone is extremely pure. Moreover, the machine protection circuit is very reliable, and it has never been faulty for a long time.
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