Historical look at amps

Thanks again Ar_t, I do agree with Unsound that you are the MVP here (Most Valuable Poster.) The most honest and straightforward answers I’ve seen here from the manufacturing community.

I followed your last post OK except for your conclusion about Ayre amps. What caught my eye about Hansen’s response was the fact that he is using the term "zero feedback" in a marketing campaign aimed at your average audiophile, and then justifying the use of it by quoting data sheets that are aimed at electrical engineers. All of this smacks of “baffle them with BS” and it is preposterous on Ayre’s part to expect the average audiophile to pick up on this. Not only that, he defended his position by selectively quoting the Maxim data sheets and ignored the part about their use of local loop feedback that both of us caught and quoted in previous posts.

So my question to you is this; since I am not privy to the Ayre’s schematics and I doubt they are interested in releasing them, unless I misinterpreted your comments, you agree with Ayre’s description of their amps as using zero feedback.

Oops, that wasn’t a question. The real question, why do you feel Ayre is justified in using the term zero feedback? No loop feedback?? If so, do you know this as a fact or just based on listening to them?

i, too, thank Ar_t for his candid & informative posts. Such info sharing has been a long time coming (we got a lot of this in the speaker forum from Roy Johnson when one member 'innocently' asked what the diff between time & phase coherence was & which one was more important. Many of you might remember that valuable thread) & much appreciated by us. The glimpse of the real inside scoop.

Herman, well put in your last post. I join you in asking your question.

"The issue here seems to be concern that Ayre is the one playing fast and loose with buzzwords, created just for marketing measures. I disagree. I believe that is others who are guilty of it, and perhaps Ayre is being cast in with them."
True, "others" have coined these terms. however, these "others" were EE & maybe even the IEEE! They were *not* engineers/designers making audio equipment to the general consumers. Amongst the EE, who are schooled in the art of ckt design, it is fine to use these terms. One is amongst peers of similar knowledge bases. But.......the consumer?
what i was insinuating in my last posts re. Ayre & other manuf loosely using the feedback terminology is that Ayre has done nothing to educate their clients on negative feedback, done nothing over time to dispel the doubts on this topic, done nothing to educate them on the types of feedback, done nothing to show them how their products are any diff from the others in a way that the layman comprehends it. All of this while they seemingly have been the longest term practising proponent of "zero feedback". good companies are responsible for not only good products but also for educating their customer base. Great companies are even reformers.
With audio hobby in a decline, the companies surviving in this realm should think of this (honestly educating the customers) as a self-preservation act.

Bombaywalla,

Ar_t may have topologies of tube, and solid state down, but his "bright" characterization of D amps is off the mark. I don't know of any owners of sophisticated class D amps complaining about HF.

Muralman1,
i'm afraid that I'm unable to make any concrete comments on class-D amps. i've not heard one yet.

Vince......don't start again, ok?? I have too much research on this subject to be off my rocker. Remember, I have building stuff commercially for around 20 years. I am not some young upstart just getting his feet wet. We all know that Henry's amps sound just wonderful on your Apogees. Great. We are happy for you. I doubt that you have dragged a half dozen or so amps, of varying topologies, to as many different systems as we have. Trends emerge........

Well, I can not speak for C. Hansen. I do not know his motivations. I can only surmise that his inclusion of the Maxim part was to show that there really isn't any dictionary accepted definition.

As for how I know.........

At one time, they had the schematic silk-screened on the inside of the lid. I listened to it. Confirmed what needed to be confirmed. Besides, you see someone at CES or RMAF......you talk; you know someone who used to work there; you seem to have a lot of dealers in common; lots of ways that stuff gets around. None of us design in a vacuum, and secrets have a way of not staying secret. I had a dealer in Chicago once call me and 'fess up that he may have been the one who gave Mark Brasfield the idea for a transimpedance amp as an I/V stage. After he heard mine, and I 'splained how it worked. I dunno.......maybe Mark came up with the same idea on his own, just 6 moths later.

Is that both clear and evasive enough? I'm thinking of running for office! Actually, I am fixin' to head out into the hot Texas sun, and bake what little is left of my brain. If I don't return, you will know why. Just look for my dry, withered body..........

Listening to all those bright Class D amps has made me bonkers to start with. It's a joke.......you're supposed to laugh, ok. It won't kill you. Try it.

Maybe when I return tonight, I can relate a story about a buddy in the speaker business, who had a hard time deciding on the tweeter level on his new creation. Seems that he had to change it 0.25 dB depending on what brand of SS amp he listened to it on. And this was before Class D! Wonder how is faring now........I'll have to send him one and drive him over the edge! (Yeah, another attempt at humour.)