>> Can anyone some it up in a nut shell if possible what
>> the difference in design and output are of class D vs
>> class A power?
>>
>> Thank You!
I believe, from reading the above text, that you asked for an education in class-D vs. class-A design. I do not think that anyone provided that so far. Lacee has vomited a lot of text & bored us w/ his opinions but there is hardly any shred of technical discussion here per what the author of this thread asked for.
I was curious myself about this topic & rather disappointed that not a single member initiated a technical discussion as requested by the author. I did some research & found a very good explanation (NOT IN A NUTSHELL, mind you!) on class-D audio power amps:
http://sound.westhost.com/articles/pwm.htm
class-A amplifiers are more traditional in comparison & are also the most INefficient in their overall power comsumption because the theoretical max. eff. of a class-A power amp is 25% i.e. it burns 4W in order to deliver 1W to the load. Class-A power are, usually, designed with the output power transistors biased at maximum output current bias (hence the heat) whether there is a (music) signal or not. Hence, class-A power amps need to pay a lot of attention to transformer selection & size of the heatsink (to dissipate all that heat from the full-biased output transistors). It is not uncommon for a 100W/ch pure class-A power amp to have its heatsinks measure 54 degrees Celcius. In comparison, the class-D power amp heatsink is as cool as a cucumber. For a class-A power amp, since its current consumption is so high, the transformer size has to be quite large - according to Nelson Pass, 2-3X the calculated value should be chosen from a VA standpoint (if my memory serves me correctly from one of many enlightening white papers). In class-A the designer also has to pay a lot of attention to output distortion by ensuring that the output transistors always remain in the SOA (safe area of operation) otherwise, you'll be SOL ;-) and the amplifier output signal will clip & destroy the loudspeaker either immediately or over (short) time. Needless to say, with the large heatsink & large xformer, class-A amplifiers are very heavy items while the equivalent class-D power amp is much smaller & lighter.
Sonically, class-A & class-D power amps are very different with the class-A sonics being much more appealing TO ME personally but to each his/her own. There is no right or wrong sound - only sound that pleases or does not please YOU, the listener.