Competitive class D amp suggestions

Ralph, thank you for the explanation. One thing I’m still not clear about is why people describe class a and high bias a/b as being warm sounding especially if their overall distortion is on the higher side?

I'd like to ask Ralph two questions about class d in general but I will use his class d to ask the questions:

1.  How do I equate a class d amplifiers power output with its power draw.  So for example, your class d amp is capable of producing 100 watts at full power...at full power, how many watts would it draw?

2.  It seems that most class d amp designers are going for the lowest distortion possible. I think I've read correctly that Nelson Pass said that if 2nd harmonics are dominate, an amplifier will sound very musical for music that is not complex and 3rd harmonics are probably preferable for complex music.  I also believe I've read that your goal was to get distortion as low as possible and to have 3rd harmonics be the dominate of any remaining distortion.  Is there a particular reason for 3rd vs a blend of 2nd and 3rd?

I hope I've represented all of the above correctly..

Good for Ralph...life can't just be about music and Gear 🤣.

I can't seem to find it now but I think Ralph said that his goal with the Class D Monos was to get the distortion as low as possible and be sure that any residual distortion was dominated by the 3rd Harmonic....and based on how you describe the sound, I wouldn't be surprised if this is exactly what Tommy Obrien was doing at Cherry Amp...although he never actually said it.

What about the wattage draw question...if a class d amp is 90% efficient, does that mean that it draws 110 wats to produce a 100 watt output?

@niodari 

I suspect that the difference between the Set and the Megaschino is both the amount of distortion and the profile of the distortion with the SET amp having more 2nd and 3rd harmonic giving it a tonal difference.  In my case, with the 2Cherry, I've never owned an amp that was as clear, tonally correct and presented music in a life like way.

I pretty much change my system up every 2-3 years...I guess because the gear is as much fun for me as the sound.  Most of the time, I sell the current piece to make space for the next piece, although lately I've just given gear to my son as his interest in the hobby seems to be growing.

I've got my eye on a couple of amps and as such, will sell the 2Cherry...and usually there is an overlap of the old with the new so a comparison may be possible.

Speaking of 2nd and 3rd order harmonics and their influence on what we hear...this is an interesting post/analysis.....

I'm not an engineer but I suspect that the Purifi is similar to the Benchmark....drive the distortion as low as possible...period, the end...and obviously a ton of people really prefer that sound.

Since very few designers talk at length about what their 2nd or 3rd harmonics strategy is...you don't know for sure what you are getting unless the amp has been tested or the designer will tell you.

I have a buddy who posts here pretty often...he has a Purifi amp and a few other amps as well.  He says that the Purifi actually sounds fantastic...strong low end, really nice top end...good sound stage...BUT...he says that compared to his other amps, it is emotionally uninspiring which to him means that while it technically sounds good, it doesn't seem nearly as musical as his other amps that are know for actually having some 2nd and 3rd degree harmonics.

Is this real?  Is this imagined?  I don't know but since there is more and more being written now about something that Nelson Pass identified 20 years ago...maybe we will all learn more in the years to come?

The interesting thing from the March Audio review/test is that although the distortion is very low, the remaining distortion is mostly 2nd and 3rd.  The question  becomes "although it has great bass and an extended top end, is it musical"...or is possible that the distortion possibly too low for optimal musicality?

Of course "musical" means different things to different people...from lush harmonics to no fatigue to open and airy...and then there is the whole issue of how much influence is being put forward by the specific speakers and room.

The important thing is that with more of these tests, people can begin to draw their own conclusions at to what might be more appealing to them individually.  In my case, I never really understood what CherryAmp was doing to get a less sterile and more musical/harmonic/lush sound...now, I have a suspicion that since Tommy was an admirer of Nelson Pass, he got the 2nd and 3rd harmonics where he wanted them while driving total distortion low.

@niodari 

the numbers might get you in the right theater but you will only find the perfect seat by trial and error because the amp has to mate with the source or preamp and speakers in a way that sounds great to you. 

So for the trial and error process you either buy new and return or preowned and resell if the amp ends up being a bust.  The key is to enjoy the journey knowing that perfect is the ultimate unobtanium.  

Ralph, your distortion discussion is very helpful. What can you say, generally speaking about the distortion make up for class A and highly biased Class a/b solid state amplifiers?  Are they generally the higher distortion 2nd harmonic type or the lower distortion 3rd harmonic type.. or have I missed the mark completely???