My thoughts on my first Class D amp

Why I really like this forum.  So many good points made. 

@desktopguy Wyred for Sound.. Heard of them, turns out there is a distributor on Canada, Reverb, who sell new and refurb units. Makes me want to buy a pair, just to try them.

I am now realizing how difficult it is for me to do a blind listening test, as my gear is next to impossible to access.  

@ozzy62 Bel Canto, another brand I know I have seen in a shop, and I think I liked their sound.  It must have been over 5 years ago.

@decooney You are most likely right.  The weakest link shows up.

Some speakers (like 86dB Magnepan's) need high current to shine.  I replaced an vintage entry 50 WPC Levinson amp with a high power 500 WPC class D and it was better sounding but I think that was because the caps on the ML were worn and it could not deliver the current needed.  At high dB's the sound of the Class D got unpleasant, I think because the Maggies were starving for current or the Class D I used wasn't right for my speakers.

I replaced the Class D with a 60 WPC Pass XA60.8 with less than 20% of the rated output of the Class D and night and day difference for the better all around but especially at louder (not loud) levels.  With the Pass the sound swelled as the loudness increased, it's like listening to waves crash on rocks at the beach from 30 yards out and then moving to standing on the rocks.  The Class D did not do this but rather took on a harder honking character as the volume rose.

I found an interesting paper on output filters of Class D amps.  

https://www.eetimes.com/understanding-output-filters-for-class-d-amplifiers/

Apparently the design of the low pass output filter is critical and is referred to as "the heart of a Class D amplifier". Class D amplifiers generally use a low-pass filter to attenuate the switching noise in the output waveform while passing the audio signal to the loudspeaker.

While the paper is above my head in general it does make the statement that the output filter's "Inductance" and "Q value" need to be designed around the impedance of the speaker!  If you change the Impedance (the Speaker) the optimum Inductance and Q value of the filter changes also changes.  It then goes on to describe what to me are compromises to work with a range of impedances.

I suspect that speakers that provide a difficult load will not shine with Class D amplifiers just like Maggie's don't shine without high current amps.  Class D likely sounds best with simple loads centered around the designed output filter's selected optimum speaker impedance.

Of course I am no engineer and I have limited experience with Class D and this is just what makes sense to me.

Interesting answers you guys are giving on class d amps.

@robeffy 

Always happy to hear happy news and reviews when someone gets some new equipment. Here’s to many many hours of listening!

My wife and I sat down last night, and played a variety of music, from the Baetis server. 

@curiousjim Thanks... we are enjoying the tunes.  Today was super busy, got in an hour or so of listening and reading.  My wife is doing an art show on next Saturday, and today she was interviewed for another show.  Oh boy, what started out as a 1 night event 10 years ago has resulted in over 2600 paintings, and around 5-6 events she is involved in at the moment...