Class A Headphone Amplifier
 
Class A Headphone Amplifier


 

Class A Headphone Amplifier

 


Presented here is a Class A headphone amplifier built around OPA134 opamp and IRF510 MOSFET power transistor as output stage and current driver. Quality, sound engineering applications, the most important criterion. Although many criteria used in the definition of quality for Class A amplifier. The most important feature, new crossover and work conditions and very low intermodulation distortion characteristics of a sound is very close to nature. Audio gurus know very well that the sound of a class A amplifier is the best one you can ever get.


Class A Headphone Amplifier

Bottom of the signal, in general, sine input signal, the output signal of the left in the floor of the Class A refers to a amplifkatör. A standard Class A amplifier in the middle of the floor of the curve gives the response curve.

In this way, class B, or AB-class response curve with a more accurate terminology. Transistor is only one signal in accordance with the characteristics of alternans are cut other alternansta strengthened. Naturally, this curve is for NPN transistor. Signaling is used to complete the komplemer PNP placed at one under and the other half of the signal is amplified. The result and the result is two amplified signals are combined to obtain the alternans.

The biggest handicap of the EU class, while the transition between the signal alternansları (zero crossing) signal is interrupted by the transistor semiconductor structures "other" parts of the very poor, this is precisely at this point to form a peak. This peak is directly proportional to the frequency of signal. So it is a harmonic of the signal is like. You are pleased that the cutting point. This is called crossover distortion. To prevent this, but it kind of made a kind of solutions was not possible to completely disappear.
Let us come to a class and at the same time şemamıza circuit;

Application is very simple in design and has been completely one-out double A-class bias ... ..
A class of applications, the output signal (+) and (-) for alternanslar is done via the same transistor group. In other words, zero-crossings of signals is not felt.

Application diagram, OPA134 input buffer Integration and VAS (Voltage Amplifier Stage) used. HEXFET IRF510 is used as output stage and current drive. Constant current source, this application-specific health 2W 120ohm resistor and the feedback as a simple direct injection) used two pieces of resistance. Op-ampın inlet and outlet of the 100 ohm current limiting resistors metal film took place. Introduction to the load as the savings element is made by using the volume potentiometer.

Serenity of the circuit current is 100mA. Only a very high current for an amplifier rather 100mW health. But this is a class property. Inefficient and warm-blooded! Wasteful, such as a woman ...

Power output for class A and class AB for 1W of 100mW. A headphone amplifier is to say very good figures. 32ohm headphones have been in this state, but for Circuit diazyn la 64 ohms 8 ohms headphones and speakers from all kinds of works.

The quality of the amplifier, and only depends on the quality of parts used. Metal film resistors in the circuit except for R2 should be chosen, and certainly the match.
In addition, the output MOSFET to be match, and they certainly should be original. Op-amp at the entrance, but naturally I would choose the track he is the most important quality. Shipping costs $ 16 a can get this integrated with the currently accepted best audio grade op-amp combination and JFET input. Instead of starting from a wide range of all kinds of TL071 op-amp can be used ONLY. But be sure to capture the same sound quality, use OPA134.

In practice, a regulated power supply certainly be used. OPA No. 4 s and 7 and between the legs like I did with the chassis, additional capacitors 100nF health eklenmelidir.Devre following form + / - 9v from + / - 18V regulated supply to up to accept all kinds. I am in my application + /-12v used.

For this, health 2x12v and a 25W transformer, a bridge to quality of 2A, 2 4700uF 25V Low ESR capacitors for high quality and used the 7812 and 7912. LM317 and 337 pairs of people who want to use a quality power supply. Catch a performance of the circuit as desired with unregulated power supplies, constant current source can not be created as soon as you mevta ICN will have stable work and MOSFET. Here is a very simple circuit diagram for the circuit will not supply.

Implementation details about the future if the notes. Circuit efficiency is very poor in terms of power consumption of approximately 24V x 200mA = 4.8 W per channel and two channels at the level of about 10W. And almost all of this power MOSFET s by s and R2 as the air temperature being taken. Although there is no need to cool for Resistance (130 °) for the MOSFET s certainly will need a very solid coolants. I have a cooler in my application I used approximately 5 cm x 10 cm, the size of the complex. An estimated 2 ° C / W coolant level in the form of standby amplifkatörümü 65-70 ° C, but could hold stable. Full power output of up to 80 °, this value is listening on. Can be considered as a proportional value. But it may be preferred to a larger cooler.

Own design in terms of sound quality is not saying, but really I can say I'm satisfied. Until now, detailed midrange and treble that of any EU amplifkatörde class had a chance to listen. In particular I would strongly recommend headphone enthusiasts.


Class A Headphone Amplifier


Class A Headphone Amplifier


Class A Headphone Amplifier

Class A Headphone Amplifier




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