TR Power Amp Module, 50 watts Pure "class A" output at US $ 100.
Matched input pair transistors and symetrical output power transistors.

       "Maiko TR Power Amp"   

Specifications : 

Rated output 50 watt class A with 8 ohm load at +/- 35 DC supply volt.
Max. output 80 watt class AB with 4 ohm load at +/- 40 DC supply volt
Freq. response 5Hz to 100 kHz at -1dB to -3dB.
Total harm. dist. 0.001% at 1 kHz 8 ohm load.
Input sensitivity 800 mv at 50 watt output power.
Gain 20 times (26 dB)
Slew rate 33 volt per uS.
Input impedance 10 kilo ohm / 100 PF.
Damping factor 250 under class operation.
Heat sink temp 55 degree C. @ normal operation.
Output offset Output offest voltage less then 5 mV.
Board size 100 mm x 170 mm.
Features minimum external wiring: input,output & DC supply.

TR Power Amp module :

All stages in the TR Power Amp is totally biased at class A operation.

The input stage, the driver stage and the output stage, those prime function transistors are all biased at its best linear operation region. Thus avoiding the distortion caused by the non-linear characteristic of bi-polar transistors. Since each stage is designed with its own feedback plus the system closed loop feedback, a 100 % 'Pure Class A' amplifier is defined and achieved.

Those low noise transistors are selectively picked from hundreds for the front stage.
All transistor pairs used for the input differential stage are matched , thus the output offset voltage can be minimized. The complementary output power transistors are selectively cross checked and matched with the transistor curve tracer to ensure the signal is enlarged symetrically.

The inductance coil of the output stage L-C-R is custom wound to suit the circuitry and different type of speakers tested, assuring no over shoot or under damped occur.
The large heat sink together with the well spaced power transistors are applied for dissipation of heat generated.


To DIYer We suggest :

The sensitivity of the TR Power amp module is 800 mV and the output of a CD drive is 2 volt. Thus using 2 TR Power amp modules and a LV Power Supply as picture shown, a CD drived 'Class A' 2x50 watts stereo amplifier with 0.01 % distortion is built.