Who tried Class D only to return to S/S or Tube

Your link shows a cap input supply, by the way. Put a choke between the rectifier and cap and you get a choke input supply.

Ait, I think it is possible to place very large coil in front of capacitors in order to obtain constant charging current in form of sinewave.  The problem I can see with this scheme is size of the coil (huge inductance with low resistance) and the fact that voltage on the capacitor will depend on the load.  Voltage with load should be roughly 2/3 of peak voltage, but without any load it could climb up to 100% (peak value). I guess it should be possible in class AB amps to provide minimum load with additional resistor (if necessary).   Interesting concept, but I suspect seldom used because of the cost and size.  On the other hand high end audio is never practical.  Thanks for the info - I will find some articles to read on this subject.

[quote]Atmasphere made no big logical mistake - his assumption is valid, though the result of the technological evolution is by no means guaranteed. In other words, class D amps might get a little better and then exhaust their potential, or they might keep improving more and more with no end in sight.[/quote]

Exactly.

One can assume that since there is a 3rd gen out there, that there will be a 4th gen sometime too. This thread and others like it exist as proof that class D is still not a mature technology as the improvements that have appeared in just the last few years are made out on those threads and this one to be pretty profound. If the technology were mature, the improvements would be incremental, possibly taking a decade or more before the improvements accrued really meant something important.

Mature or not, it has arrived, and is already making major inroads in the amp market. Many, as mentioned, have replaced their big name tube and ss amps with class d. It’s here, it’s thriving, and it can only get better, which is scary to think about...especially for those invested in tube and ss tech...

Kijanki,

The choke needs to be of "critical inductance" at minimum, for this type of supply to work properly.

Lcrit = V(dc) / I(mA)

So higher voltage and/or lower current require a bigger choke. This type of supply was often used decades ago when capacitance was expensive compared to chokes; once capacitance became cheaper it fell out of favor in the mass market, but it retains its unique advantages to this day.

Happy reading!