Historical look at amps

I did not say that I heard them at a dealer.

I sent them to guys who had aleady brought one of those models in to audition. And sent them back, unsatisfied. There are a few times when I found someone who actually owned one of those brands. There is a big difference when doing a serious side-by-side comparison, as opposed to a "shootout", where there has to be a winner and a loser.

Actually, you may recall, I didn't buy their explanation why they preferred ours over the others. Some guys get carried away exaggerating minor warts. The guys that I placed the most faith in their reasoning was the ones that said they all sounded very close, but chose ours for other reasons. Features........ease of use and interfacing.......looks, whatever. As grateful as I am when someone thinks ours sounds better, I tend to dismiss their enthusiasm when it overflows with superlatives.

I know the Gallo isn't planar. Strangest looking thing I have ever seen.

No, I am not doing a Google search, because I know the truth. I have to.......I build this stuff.

Honestly, I do not see why you seem so defensive. I have not maligned Henry's, or anyone else's, efforts on this genre of amps. I may have a different opinion wrt their pros and cons. They may be among the best we have to work with at present, but I seriously expect that we will have many other options in the near future. And you can rest assured that I will be just as honest and forthcoming about them, at that time.

Guys,
Oh no! You all have got Muralman started again!
To Muralman the H20's are the perfect amp, and can do no wrong...let him continue to live in his fantasy world.

Let's not jump all over Muralman without the consideration of his rather unique situation. How many of us are driving one of the most difficult loads (Apogee Scintilla 1 ohm) in all of home audio? Very very few I'll bet. I had Apogee Calipers and although they are easier to drive than Scintillas they are still a bitch. OTOH I am not endorsing the H2O as I've never heard it but I suspect there are only a limited number of amplifiers that will drive the Scintillas properly. He found one. So what? Let him have some fun.

Audio Girl, we all live inside our heads, don't you know? There isn't a thing you feel, touch, hear, that isn't a product of your brain activity. :)

Ar_t has said, repeatedly, tucked into his long winded lectures, ICE highs are wrong. I say, the ICE module is a chameleon. Actually, I'm borrowing that from another thrilled H2O owner. It can be made to sound like just about anything the designer wants.

Henry's amp has a full kilowatt high quality transformer, and over 70,000 mƒ of capacitance. These figures far exceed that of competing amps. There are other devices that I'll wager is unique in class D amp design.

Whether that is bad or good, one can debate. One thing is for sure, Henry builds amps his own way. No one should assume what they sound like.

It might be a little late to comment on this, but here at Atma-Sphere we use an old school means of defining feedback:

A cathode or emitter resistor is a form of negative feedback called *degeneration*. This form of feedback occurs in real time and also has the effect of increasing the output impedance of the circuit. A secondary form of degeneration is the type where a push-pull amplifier can cancel even-ordered harmonics in its output. In any case the feedback is characterized by being in exact real-time opposition to the output signal.

The second type, the 'bad' kind IMO, is *loop* or *global* feedback and is the more common variety referred to loosely as negative feedback. In this form, a portion of the output signal of an amplifier circuit is applied back to the input of the circuit (and can be tube, transistor or opamp). Due to propagation delays in the amplifier circuit itself, the weakness of this approach is to be increasingly less correct as the frequency increases, and/or less accurate as the propogation delay through the circuit is increased. IOW it is not in real-time opposition to the signal. Generally the output impedance is said to be lowered with this type of feedback.

I personally do not like loop feedback as it increases odd-ordered harmonics (depending to certain degree on the amplifier circuit too) in the range at or beyond *about* the 9th harmonic up the 17th- the area that the human ear (over millions of years) has evolved to use to detect loudness. Obviously we cannot change our ears! IOW, these harmonics make an amplifier sound louder and harsher, and they only need be in vanishingly small amounts to be noticed. Humans are *very* sensitive to this type of distortion.

I feel that the appearance of low and 'zero' feedback amplifiers ('zero' meaning zero loop feedback) in the last two decades is a good thing. Negative feedack is a character of the ruling Voltage test and measurement paradigm, which has been in place for some 50-60 years. It has been responsible for a lot of foolishness over that time, negative feedback's acceptance being one of them.

The opposing paradigm, the Power paradigm, uses slightly different rules of test and measurement, which conform more closely to the rules that the human ear has developed over the millennia. Horn speakers, ESLs and magnetic planar speakers all operate according to the power paradigm. So these zero feedback amplifiers that have appeared have some venerable company...

Back to our regularly scheduled flames, already in progress :)