Class D is just Dandy!

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

George,
If I'm not mistaken,do you still have a pair of ref600m.
If so what amps do you like better and what speakers do you use.
Just curious.

Kenny.