Class D is just Dandy!

"Tim,
Ofcouse I have read all this info before,I appreciate you taking the time to post all of this pertinent info so others can read it too."

Hi kdude66,

     Thank you, but I actually really enjoy reading the Audiogon and other audio and video forum threads on-line and contributing my version of the truth especially when I believe I have useful input based on personal knowledge or experience related to the subject being discussed.  
     Unfortunately, I had emergency open-heart surgery about 8 yrs ago and suffered a stroke immediately following the surgery when I was relatively young at 51. I recovered my cognitive and speech abilities rather quickly but I’m still trying to coax my paralyzed left limbs back into action. I decided to retire early after consulting with my cardiologist and neurologist and am currently on SS Disability Insurance with a reasonable but fixed income until I reach my actual retirement age in about 8 yrs.
I wasn’t prepared for how much I actually missed my job as an operations manager at a very large (1 million sq. ft), high volume, fast paced and highly automated distribution facility and the people I worked with, Oddly, my dreams often revolve around work and my former colleagues. I’ve even awakened many times in the morning thinking I need to still solve fairly complex problems or employee situations I was dealing with a few minutes earlier in my dreams.
     So, while I feel grateful I’m still on ’the right side of the grass’, I’m also grateful for this forum that enables me to keep learning from other members about this hobby I’ve enjoyed for decades and post my thoughts when I think I can contribute constructively on certain subjects.
     As my typically overly long posts indicate, I now have plenty of spare time to read and respond when I may be useful to forum threads, too.

     Like this thread for example. I initially learned of class D amps from positive comments on various audio threads. I purposely began researching all I could on the subject here and on other sites and I credit my own quasi-scientific readings on the over 60 yr history of class D amp development along with the forum posts of class D guru Guido Corona and a few other members with exceptional knowledge and experience.
After my older class A/B amp went belly up due to leaking caps a few yrs ago, it was the perfect time to take the plunge and start gaining some personal experience with class D and I bought my first amp, a Class D Audio SDS-440-CS stereo unit that was superior in virtually every aspect that audiophiles care about in an amp. I was so impressed that I replaced the other 2 class A/B amps I used in my combo 2-ch music and 5.1 HT surround system with relatively inexpensive class D amps; a Emerald Physics EP-100.2 stereo unit and most recently a pair of D-Sonic M3-600-M mono-blocks.
     When I read posts from members like georgehifi and randy-11 about a theoretical issue with class D amps switching frequencies needing to be dramatically raised to avoid affecting frequencies in the human audible hearing range without presenting any semblance of even anecdotal evidence that it’s true, makes me seriously suspicious of their true motives for spreading and trying to validate something that I highly doubt 99%plus of humans could even begin to detect, although I believe at least georgehifi has heard a good class D amp and acknowledged how good they currently are but is going to wait for his view of perfection. I’m not even sure if either one of these guys has personally heard any sonic anomalies from a class D amp.
As far as I’m concerned, they’re in my doghouse until they can cite a SPECK (as in Peewee Herman’s dog) OF EVIDENCE.

Tim

When I read posts from members like georgehifi and randy-11 about a theoretical issue with class D amps switching frequencies needing to be dramatically raised to avoid affecting frequencies in the human audible hearing range without presenting any semblance of even anecdotal evidence that it’s true, makes me seriously suspicious of their true motives for spreading and trying to validate something that I highly doubt 99%plus of humans could even begin to detect

By saying this, a little better explanation is needed.
It’s the output filter to rid that switching frequency completely, that is the problem, not the switching frequency by itself.
As that output filter has phase effects down to 5khz, the upper midrange and highs. And by moving it (output filter) and the switching frequency much higher, takes those effects at 5khz upwards by the same amount, hopefully passed 20khz.
Why I ask then are these transistors developments happening, if not to do anything good? Forest and trees.

Cheers George

Hi Erik,

Well, It is not rated doesn’t mean it can not drive it. It is just that the designer didn’t test it with such a load. The same goes for the NCore. And to be fair, Apogee is no more for many many years and very few own the 1 ohm scintillas. So it is not a very popular speakers so there iI can see why there is no point in testing the amp with such a load. No worry about impedance, it is low enough, besides lower output impedance is not necessarily better or conversely, high output impedance is necessarily bad as you can have too much of a good thing knowhatImean :-)? I think you read a bit too much into spec at time. Don’t get me wrong. I am not saying that spec is not important It all depends on the system as I have alluded to. No I have not measured the Scintillas with these amps.

Kenny, Thanks for the good wishes. And yes I will keep you posted as long as no one here thinks that I am here to sell products :-). The H2O Special Edition uses the icepower modules 500A. has 1KW transformer and lots capacitance filtering reserves. I have implemented with many other goodies which is too long to list here. These are rated at 250Watts/8 and double that into 4 ohms. Don’t let the power fools you though. These will put the biggest boat anchors from Krell, Levinson and the likes into shame when it comes to liquidities, smoothness, extension, control subtleties, dynamic, composer when push hard :-). And should I go on? Oh even some class D too. LOL.

BTW, I spent 2 hours wrote about 3 pages long. Took a break and came back to continue and everything I wrote disappeared. This stupid computer. Not sure what happens.

Henry

@h2oaudio

What you do with your amplifiers is between you and your part supplier, but these are high current outputs. Unless specifically rated for such low loads I would never encourage anyone to attempt this without further input from the manufacturer. :)

Um, as a guy who makes loudspeakers, no, I don’t know what you mean, but measurement and experience trumps theory. It would be interesting to examine what happens to the output response on those scintillas, as they are pretty much the worst case scenario. :)

Honestly, those speakers were absolutely brutal. If ICEPower modules can drive them as well as you say they do that’s pretty astonishing, even for me, an obvious fanboy. I think the biggest, most lasting impression they have left on the audio industry was to give Krell a raison d’être. I think without Apogee loudspeakers the history and viability of Krell might have gone a different way.


Best,

E

There is no way an Apogee Scintilla will sound anywhere near it's best driven by ANY class-d, and they could just switch off or blow up.
 
Not only is it 1ohm @100hz, but it has a massive -90 degree phase shift at 100hz also, these two together mean almost a dead short as see by the amp.
Only the biggest heaviest Refererence Monoblock Krells of yesteryear can drive those sort of loads and sound good.

To quote a great Australian movie (The Castle)
"Tell'im he's dreaming son."
https://www.youtube.com/watch?v=dik_wnOE4dk

Cheers George