Class D aka digital amplifier is a switching amplifier that utilises PWM (pulse width modulation) to drive an H type bridge with the appropriate filters and to reach up to 97% efficiency. Only problem is that simple designs like this wont give high fidelity results. Recently i read about a new kind of class D amps that can reach very high efficiencies yet deliver a comparable to class A amps sound with 0,002% at even 200w. It blew my mind but i cant remember their names. So to sum it up:
Advantages:
- Greatly improved efficiency over every kind of amplifier classes.
-Very easy to understand and to make your own amp unlike the other kinds of amps. I mean cmon here there is no mind boggling bias calculations no impedance matching no nothing. Well maybe the filters are harder to construct
-Because of the high efficiencies they can be constructed in a more compact design that doesnt require enormous transformers or big filters and stuff.
-Because of the high frequencies used the high efficiency and the fact that the power transistors are on just half of the time class D amps do not require the utterly enormous heatsinks that are usec in lets say class A amps.
Disadvantages:
- They are not as Hi-Fi as the class A or AB amps and to be honest they sound kinda flat. This is why they are not very used in high fidelity systems but are used in High Power systems because the the produced sound is less subjective to distortion at high power levels unlike some other types of amps.
- Oh and something i totally forgot to mention. Due to the high frequency used to sample the signal they often need extra shielding to counteract the high frequency emmisions through large parts of the circuit that may act as an antenna (wires,heatsinks etc.)
- They are demandant of the power supply in such way that the supply must be able to withstand returning energy from the load (inductive capacitive)
