2022年AD芯片资料[收 .pdf

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1、Service Manual for Aleph P Version 1.0PRODUCT DESCRIPTIONThe ALEPH P is a high performance Mosfet Class A audio preamplifier,intended formaximum performance in reproduction of music.It is a simple design,having only asingle balanced gain stage consisting of a balanced pair of power Mosfets operatedw

2、ithout feedback.The Mosfets are biased by resistors and loaded by resistors,willaccept either single-ended or balanced input while delivering single-ended orbalanced output.To best understand the operation of the preamplifier,refer to the schematic of basicgain stage.Q101 and Q102 form the active po

3、rtion of the gain stage,with Q101receiving the+balanced input signal,and Q102 receiving the balanced input signal.Reference voltage A of 18.2 volts is used to bias the gates of the Mosfets throughR109 and R110,and the inputs are capacitively coupled through C105 and C106.R111 and R112 are employed t

4、o prevent parasitic oscillation,and Z101 and Z102protect the Mosfets from electrostatic high voltages at the input.The Mosfets amplify the input signals and present them at the outputs,with thepolarity inverted,so that the output of Q101 becomes the-signal,and the output ofQ102 becomes the+output si

5、gnal.The gain stage is fed a regulated 60 volts which is decoupled twice using R101,R102,and C101 and C102.The output is capacitively coupled through C103 and C104.The intrinsic gain of the output stage is set by the ratios of R103 and R104 divided bythe combinations of R105 and R106 in conjunction

6、with potentiometer P101 andR115.Minimum gain is 8 dB,and maximum is 14 dB.The Drain(case)connections of the transistors operate at+40 volts DC.When using the circuit with a single-ended input,the negative input should be shortedto ground for best performance.This is accomplished by shorting plugs be

7、tween pins1 and 3 on the XLR input connector.Referring to the schematic of the power supply,the toroidal power transformerprovides an unregulated 80 volts across C1,which is passively filtered by R2 and C2.Active regulation consists of a 64 volt zener stack driving an NPN follower transistor.查询AD080

8、4 供应商名师资料总结-精品资料欢迎下载-名师精心整理-第 1 页，共 7 页 -Two reference voltages are also provided off the zener stack,Ref A at 18.2 volts,andRef B at 9.1 volts.Q2,R6,and R7 provide a power source for the relays in the volume control whichshuts down when there is insufficient unregulated voltage for the regulation s

9、ystem tofunction properly.The input selection system schematic shows the simple use of relays to switch thefour inputs with four poles of connection each.The volume control system schematic shows the 6 bit binary relay ladder circuitswhich perform precision attenuation of the output of the gain stag

10、es.In order toachieve good common mode rejection performance,the output attenuation must bematched far more precisely than can be accomplished with potentiometers,and sorelays and precision resistors are used.They are controlled by an analog to digital converter(AD0804)which reads the valueof the vo

11、ltage across the volume control potentiometer and converts it into theappropriate binary output.Discrete components surrounding the AD0804 provide regulated supply,clocking,andturn-on time delay for the chip.There are no adjustments in the Aleph P.The Mosfets of each channel are matched to optimize

12、performance and minimizenoise while adjusting the individual gain controls.If it is necessary to replace one ofthese,please obtain a device from the factory which has the same match code(written on the device in felt pen).The last figure is the component placement diagram for the preamplifier.When c

13、hecking operating voltages,look for+40 volts on the case of each gain device,+80 volts on the case of Q1,+62 volts on the emitter(pin 3)of Q1,and 5 volts on thesource(pin 3)of Q3.名师资料总结-精品资料欢迎下载-名师精心整理-第 2 页，共 7 页 -SPECIFICATIONSMaximum Gain14 dB teal in/teal out 14 dB unbar in/teal out8 dB teal in/

14、unbar out 8 dB unbar in/unbar outFreq.Response-3 dB 3 Hz-3 dB at 100 KHzDistortion.1%THD typically fess then.01%Maximum Output20 volts rms.teal out 10 volts rms.unbar outOutput Impedance0-1000 ohmsInput Impedance20 KOhm balanced 10 KOhm unbalancedTotal CMRRmin 40 dBOutput Noise5 microvolts,unweighted 20-20kHzPower Consumption20 wattsDimensions19W x 11.5D x 4H名师资料总结-精品资料欢迎下载-名师精心整理-第 3 页，共 7 页 -名师资料总结-精品资料欢迎下载-名师精心整理-第 4 页，共 7 页 -名师资料总结-精品资料欢迎下载-名师精心整理-第 5 页，共 7 页 -名师资料总结-精品资料欢迎下载-名师精心整理-第 6 页，共 7 页 -名师资料总结-精品资料欢迎下载-名师精心整理-第 7 页，共 7 页 -