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HA-PRO Class A MOSFET IRF61 Single-ended OUTPUT Headphone Amplifier Kit for DIY
- Operating voltage:IN AC24V to AC28V
- Gain of 13 times
- IQ Quiescent Current 60MA * 2 work in single-ended CLASS A.
- SNR> 125 DB
- Distortion <0.015% 20K HZ
- HA-PRO is the new LJM development for a variety of high impedance, low impedance headphone amplifier design.
- HA-PRO is not the most widely used differential circuit, and differential amplifier circuit of double power supply similar.
- But in recent years saw the former circuit all designed in accordance with operational amplifier circuit inside the form, but its application in audio on whether to DC differential circuit can not?
Application of operational amplifier in audio, actually reflected the designers more and more lazy:
The op amp input infinite output impedance, infinite small, so it is convenient for example frequency equalization, filter circuit design.
But the general preamplifier are no frequency equalization, magnification is only a few times, circuit so complex to do is really put fine timber to petty use.
The main purpose of 1 differential circuit is to realize the DC characteristics of a good, but not much good for the AC characteristics, even harm;
2 general audio output, behind the public houses by the input capacitance isolation, so the preamp you until the frequency response will not widen the whole system of DC 0Hz of bandwidth.
3 similarly, front, behind have capacitance isolation amplifier, then the positive and negative double power will not play any role, then directly with single power supply.
4 differential circuit less elegant, but you're not a measurement applications, and only a few times magnification, even 25 degrees above the temperature changes, the output end of the amplifier circuit of DC potential drift is less than 1V.
The 5 difference noise sub circuit is twice as tall as single end
Why amplifying circuit now are no longer used circuit is simple and effective, and not to pursue no effect on AC characteristics of the differential circuit?
Single end electric circuit HA-PRO each level are used to work on the CLASS A, the output stage uses a single Duanheng current source circuit.
In order to reduce the input of the amplifier noise, HA-PRO ultra low noise, high HFE signal amplifier BC547C, BC557C.
Output using the German VISHAY original IRF 610 MOSFET fet.
Using three terminal voltage regulator IC 7824 as a power supply filter, a power supply ripple rejection ratio up to 93DB.
Coupled with excellent PCB wiring technology.
No matter how high sensitivity make HA-PRO drive earphone, headphone performance makes no AC noise interference.
(recommend installing chassis, the potentiometer circuit shell with PCB ground conduction, avoid potentiometer inductive interference)
Wiring technology of military grade PCB process and LJM quality first-class.
Is an important means to solve the interference.
HA-PRO to drive more difficult to push the earphone, the earphone impedance is generally low, or low sensitivity. The need of the current output larger
HA-PRO in the output stage uses IRF610 good linearity FET as the output stage. Using single end with constant current source mode.
The output pipe and a constant current tube adopt IRF610. working current is 30MA, so that HA-PRO can have a very good driving performance.
Because the IRF610 working current is higher, the temperature is relatively high. Be careful not to be burned.
Note: DIY kit only,you need to weld the components and board by yourself(schematics will be attached), the pictures above are finished board for your refference. DIY kit installation requires some basic electronic production and practical ability, there is the risk of damage during installing. Once the parts are installed we are not responsible for the components. Thank you for your understanding.
- HA-PRO Class A MOSFET IRF61 Single-ended OUTPUT Headphone Amplifier kit for DIY X1