So what do you think of Class D amp for subwoofers

"My advice to you is to start listening to your ears, accept the fact you can't afford the most expensive gear, and quite accepting reviews as gospel. In the long run, you will have a better sounding stereo and more money in your pocket."

Tell the truth Spatialking, I was tempted to forge similar language for your own benefit. . . but then, naaah. . . I would not do that, would I. On the other hand, you seem fixated on the issues you verified on a Marantz amp, and you are performing a somewhat bold yet unorthodox induction step, which is leading to potential fallacy. Remember the old bad syllogism:

Socrates is a man.
Socrates has bad breath
All men have bad breath.

Well. . . 'tis probably almost true, but.. . you know what I mean (grins!). Thus, instead of expending furter energy in the futile attempt of associating the scurge of audio halitosis to all class D amps, why not take a moderate pinch of your own free advice. . . get out of the house, and listen to some true high end switching amps. . . with and without switching power supplies. Chances are, you may find some pearls. G.

PS. The only part I am not sure of. . . is the one about the very un-audiophile solace of finding more money in your pocket.

Spatialking - what quantization error you talking about? Quantization happens only in sampled system - this is purely analog. Imagine perfectly linear ramp generator that converts voltage to duty cycle and filter that converts it to average value. That way you can get absolutely any value - therefore unlimited resolution. Oh yes - it is also very linear. Nonlinearities come from errors in switching times and feedback corrects it. Other classes of amps also use feedback to correct nonlinearities - even in class A. Icepower of course is more complicated than that. Modulator uses sine wave and not the ramp etc. but principle is the same.

When I mentioned -140 dB idle noise shown on FFT it is the noise of amplifier in 20Hz-20kHz bandwidth and not the wider bandwidth noise. My point was that if other audio gear is affected by switching noise (since you stated that it must be audible)in audible band then why Icepower doesn't affect itself? Maybe simply because carrier is way outside of the audible band.

Please read carefully what I wrote. I didn't say that digital implementation of 16 bit and 20kHz is not possible. I said that digital class D is not possible with 20kHz and 16bit. Each period of 20khz would have to have 65536 individual codes - so the width of the smallest pulse in PWM would correspond to 20kHz*65536.

Same about careful reading applies to even harmonics. I did't say that Icepower plays only even harmonics - I said exactly "Harmonics produced by class D are mostly even" - completely different thing. Produced simply means that amplifier exaggerates mostly even (like tube amp) and not odd harmonics. Class AB amp tends to exaggerate odd harmonics because of TIM (overshoots pulses).

As for the radio - I did exactly what you asked. I set portable AM radio less than a foot from the amp and set to different frequencies where there is no station. Then I plugged and unplugged my amp - no difference in noise. I even tried lowest frequency 540kHz assuming that it will be closest to the carrier - still no difference. As I mentioned before my TV that is foot above and has antenna cable running next to power cables shows no difference on any of the analog channels - even very weak ones. I just cannot detect if my amp is ON.

I'm very happy that you agreed that class D is analog because I was about to say that if everything that switches is digital then FM radio is digital radio. Perhaps in future I will be lucky to convince you that it is as linear as class A and doesn't suffer from TIM. Just perhaps.

Guido - I like your Socratese example of bad logic. Let me offer you one from "Alice in Wonderland"
"I see what I eat" is not the same as "I eat what I see"

I'd like to keep open mind about audio since I've learned that not everything can be explained by specifications and electrical engineering (and that's the beauty of it).
Person with negative attitude toward particular construction of an amp has no chance to fully appreciate it because of it (placebo effect). Trying to convince, as I found, makes it worse since it creates avalanche of counterarguments and fortifies hate toward the subject.

I have never said that class D is perfect - no class is but just in my humble opinion it is pretty good (and good for the money). I like neutral and open sound but I also really enjoy sound of good tube gear and cannot understand why people have to be so polarized about it. Our discussion here took turn toward technical side and I think I should perhaps sign off this thread.

Cheers,

Bingo Kijanki, I have heard marvellous amplifiers of every class under the Sun. . . and a few more not so marvellous ones as well. I do so adore the open, linear, and harmonically textured sound of my system for the long run, but readily admit that I have been occasionally enraptured listening to sound that is radically different from my more typical target. The task of audio engineers is a daunting one: they are dealing with the complexities of electronic engineering, the vagueries of psycho-acoustics, and the imponderables of human emotions. . . my hat's off to all of them for managing to come up occasionally with something that even vaguely resembles music. Guido

I have H2O monos. I have had them for 7 years. First I had them upgraded to Signature level. The second upgrade came from the ICE people themselves when they improved their ICE 500 A module. The third upgrade, and the most significant, was the add on of Sonicap Platinum bypass caps. Now, these amps are ready for anything.

During those 7 years, I had what some may call a foolhardy belief I could get close to perfection with these amps. No preamp was a decent match. H2O solved that problem by creating the Fire preamp, a perfect match to the H2O, and a big bonus to any amp.

Through trial and error, I learned the amps need fully shielded power cords, and naked speaker cables. Spelz cables proved to be wonderful for these amps. I did a lot better, though, when I replaced them with very thin copper ribbons.

I also learned only non oversampling DACs are appropriate to the class D on the whole, but especially for the H2O. My amp builder took AN DACs and created a full spectrum DAC. The depth is phenomenal. Macro dynamics are tremendous, while micro dynamics add life to players and singers. Bass is fully controlled, but that is a well known attribute. Mids are life-like, highs are fully spread out evenly over the spectrum. This gives a marvelous naturalness to the music. There are no hot spots. No frequency is spotlighted. Every musical instrument is tone correct and I mean all.

Finally, the speaker is of importance. If you have a hot speaker, this system will show your ears no mercy. That is what happened when I had one of my two pairs of Apogee Scintillas fixed with import ribbons of a different design. The sound was unacceptable. The frequency curve reached all over the place. The highs were piercing. Luckily I still had my stock Scintillas.

My point of all this is to let class D owners not to give up trying to better their sound. Persevering paid huge dividends to my amp's over all sound.