Hi folks,
Can anybody help me with this schematic, Yamaha says that is a D class power amplifier, is a Stagepas 500 250W+250W RMS power amplifier 4 ohms, (+46V -46V).
With only two 2SK3607 N 17amp mofests (70W mas power disipation) how it works???
![](http://imageshack.com/a/img923/7602/12tC3j.jpg)
Thanks
Regards
This is a very good commercial amplifier to clone and diy its based on the Philips UCD self oscillating patent.
A) Forms a simple differential output stage, the output will have a differential output swing which is identical to an op-amp with a complementary output stage. (you could replace A with a high speed op-amp with complementary outputs )
B) A simple DTR fast turn off mosfet driver, this method is a cost effective technique to drive mosfets
by taming them for slower propagation turn on (to avoid turn on mosfet cross-conductance) yet allows fast turn-off response, turnoff is essentially grounding the gate almost instantaneously.
C) Switching pair of N-channels, these will form a switching stage switching at the rate of least twice the audio frequency (using Nyquist Theorem) then feeding a LC stage used to demodulate the signal to audio.
D) Forms are simple asymmetrical current sense trip for both +/- rails, if the amplifier is driving heaving speaker loads at high output levels it will signal a trip signal and shut the amplifier down.
E) The most complex part, a pole/zero feedback system is used to create a phase/lag with compensation, its used to create feedback loop and get the amplifier to oscillate, the carrier residual used as a reference to create a PWM signal based on the difference between the two signals, note this system uses post feedback to obtain the carrier.