First, the choice of amplifier circuits produced in the original amp (switching power supply, high-quality amplifier boards, circuit see Figure 1) on the basis of the set into the pitch, volume, balance and 3 D function in a high-quality audio circuit LM4610N ( Circuit see Figure 2) and substantially improve the clarity BBE music circuit XR1075, discard signal switch circuit. LM4610N electrical parameters are as follows: voltage to 9 V ~ 18V (typically for 12 V); distortion of 0.03 percent; SNR 80 dB; frequency response of 250 kHz; volume control 75 dB; balance adjustment 1 ~ 20 dB; pitch adjustment ± 15dB, The largest gain of 2 dB, while a 3 D sound field processing functions. XR1071 to chip at the core of the music circuit definition upgrade for the United States EXAR the company's second generation product, the performance is better than the first generation M2150 and Japan Roma's BA3884, its parameters: voltage ± 5V, enhance clarity of 0 ~ 9.7dB, bass upgrading of 0 ~ 9.9 dB, the circuit board components of the factory finished slightly out of choice.
Second, the specific production: the use of a power amplifier chassis scrapped the "ambitious" 250 W transistor amplifiers chassis, for all devices and removed all the panels, and the other by 3 mm thick aluminum plate in accordance with the mechanism of re-design panel request Processing. The chassis and slightly larger than the standard chassis, the size of 550 mm × 410mm × 145mm, just under the amplifier to accommodate all the circuits and components. Because of the modules are finished plate, it was only in accordance with circuit assembly when asked to make a simple connection, but must pay attention to the current channel should choose high-quality wire, and as far as possible be rough and short and to distinguish between different colors , And small current signal path also should try to select good quality and high capacity wires and signal lines. Signal from the input signal between the start of each board are connected by shielding and shielding net-line termination, to avoid induced noise. Machines that the unit should follow the grounding principle that the board first with stout ground wire (usually black) leads to one point after pooling in the case, the specific location of ground would be after repeated tests, which if done Well be the complete elimination of exchange of sound. As a reminder, most have finished circuit boards have a fixed holes, but there are 12 holes and is connected to power, such as not dealing with insulation, be fixed with screws in metal enclosure, often Formation of the multi-circuit grounding, is prone to lead the exchange sound, which is many enthusiasts in the production of audio and helpless when the source of noise. The correct approach is to use sharp blade ringing fixed holes, with the power ground wire separation, in order to achieve the purpose of that grounding. Because of the power amplifier circuit, as many as 67 units (transformers, switches, power supply), should be fully well the elements of metal and insulation between the floor and preventing earthquakes work. The author's approach is to use a 15 mm thick wooden boards (depending on the size of floor) tiles on the floor, then screw the plate with wooden floor and closely connected together, and then each circuit element Were fixed in the board. At a fixed switching power supply and power transformer before in his next to put the appropriate size of a car inner tubes, to eradicate due to shock arising from the adverse effects. Amp produced a success or not, with a level of quality of power supply has a close relationship. The audio amplifier for the two panels to provide power from one pair of exchanges of high-quality 16 V/35W E-type transformers bear, the 10 A/100V AC rectifier bridge rectifier, 2200 μ F/50V through the filter capacitance from 7812,7912 3 Regulators and NE5532-block composed of servo power regulator after two sound boards to use (see Figure 3 circuit), so high-quality power supply can LM4610N and the performance of XR1071 play to the limit. This amplifier production, give up the production amp commonly used when the connector-even, and the plate connections (including the power input, the amplifier output) are direct welding, such connection is bad and the connector could have been avoided because of the surface Oxidation caused by signal degradation and noise.
assembly, with the multimeter DC voltage measurement amplifier block the mid-point of potential output, should generally be in the 100 mV below.
Third, the trial feelings: Listen, in order not to high-quality signal to cover up the shortcomings of the power amplifier, the first by the author of the JVC TD-W205 cassette blocks to the amp, access to a new two-frequency shelves Granville me. The first two sound boards function switch to pull "OFF" position, I found the amp to-noise ratio high, static, even if the speaker is also close to the ear can not hear any noise. Take a few genuine Yindai disk, the general feeling is that open-market, the balance of good, filled with bass, and Alto bright and clear, crisp and sweet treble is fine. Later, with a new Section 330 super VCD players will JVC TD-W205 deck replaced, take a few quite familiar with their first song, I feel high bass have different degrees of extension, and will XR1071 pull the switch to function "ON" Block, clarity and bass compensation for proper regulation, then obviously wide sound field, increase the density of music, much more clarity, and have heard some never before heard the message. Quite powerful bass, 3 D of the LM4610 will be switched on, with three-dimensional sound field and throughout the entire space, surrounded by a good sense, the trial several classic films, I feel very Guoyin.
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