Current amp vs Voltage amp

...plus I must add that I share the feeling expressed by many others that I do learn things of value from Ralph's posts and I thank him for that as well.

Plus Ralph's paradigm (based around avoidance of use of NF as the best means to avoid those nasty odd order harmonics + the rest seems to stem from that), FBOFW, is more unique and "radical" and a huge minority relative to the norm these days, so I think he has more work to do to gain mind share overall accordingly.

A lot of people think that this Power Paradigm thing is something of my doing. Its not. The Power Paradigm is what existed as the means of design test and measurement in the old days, pretty much everything before about 1958 or so, which EV and Mac lead the charge to move to a Voltage model.

For evidence of that I direct you to Google:
https://www.google.com/search?client=ubuntu&channel=fs&q=fisher+A-80+amplifier&ie=utf-8&oe=utf-8

The Search is for 'Fisher A-80 amplifier'. The first hit has a YouTube image, a photo of the Damping (feedback) control on the amp. If you look at it closely, you can see the range of control goes from 'Constant Voltage' to 'Constant Power' and finally 'Constant Current'.

IOW I didn't make this stuff up. FWIW it appears that there never was a current drive paradigm, although Nelson Pass has done a lot of experimentation in that area.

I also found that the means of measuring output impedance has changed- the Radiotron Designer's Handbook, which dates from the early 1950s shows a very different means of doing so, with different math, than the techniques typically used today. It did take me a while to sort out why, and the why is that as an industry we went from using power measurements to voltage measurements.

You can see this in the recording studio; older studio equipment is based on the power model, for example older microphones are often set up to drive 150 ohms, while modern mics are set up quite a bit differently!

Another way of looking at this is output impedance- many SET designers are accustom to building amps with higher output impedances and choose speakers accordingly.

This is that equipment matching conversation that all audiophiles hear about sooner or later. All I did, FWIW, was to gather these tidbits from all over and put them in the same place at the same time, and gave them a name so it would be easier to have a conversation about them. But many people have confused this with it being something I came up with, which is obviously not the case, if you look at that YouTube image.

The fact that negative feedback does what it does is also not a matter of debate. It is knowledge that has been documented since the 1950s- I refer you to Norman Crowhurst, who outlined many design parameters of audio equipment in his many writings.

(If we were able to build amplifiers with absolutely zero propagation delay as the signal propagates through the amp, then the feedback would work correctly with no ill effect. FWIW, most amplifier design theory that involves feedback actually assumes that this is the case. Unfortunately the real world does have have such examples, and being pragmatic, I figure since that is the case maybe we should look elsewhere for fidelity, since the feedback model clearly fails.)

I persist in this is only because I want to forward the art. I don't see any amplifier technology as having the answers, all amplifiers have weaknesses and tradeoffs. I am simply pointing to What Is; what you want to do with the resulting knowledge is another matter.

Now Mapman tries to make it look like I might be tilting at windmills; the evidence that I am not is very simple: If the Voltage Paradigm really worked, there would **be no vacuum tube industry**. Its really that simple. But here we are, over half a century after tubes were declared obsolete, and tubes are still being made (they are the easiest way to create an amplifier on the Power model).

FWIW normally how it works is when a superior technology replaces the prior art, the prior art dies out. How many of you still use a rotary dial on your phone?

Atmasphere,

For the record, I never said you made this stuff up.

I would say you are its most vocal champion these days, at least in these parts.

Just making an observation. You offer a way that works and these days at least is different than most. Plus you are willing to spend time talking about it and educating others in the process. Kudos to you for all that!

On of the pivot points of the argument would seem to revolve around how how well a good local NF implementation implementation in a SS amp these days can work in comparison. That is something I have seen discussed here as well by some who are quite knowledgeable about NF and SS amp design, but I would like to learn more.

Meanwhile, I have to trust my ears, which largely thanks to you are tuning in more and more these days for those nasty odd harmonic side effects of NF. My ears tell me that use of NF these days does not necessarily have to be the road to audiophile hell, as perhaps it can be and has been perhaps in the past.

ISn't there a threshold below which all kinds of distortions become insignificant? Pick your distortion, all amps have them. The goal is to make them as unoffensive as possible.

Odd order harmonics from NF might be quite nasty relative to others as suggested, but that does not mean there is no way to get the negative effects into a range that is not significant, at least for most. No amp is perfect, I think we would agree on that?

But I am not convinced distortions from NF is such a pox on good sound necessarily these days as perhaps it was in the past. Seems like a curable disease to me, but I have no data to support that, only a gut feel from what I read and hear, only what my ears are telling tell me after years of listening.

Time will tell. WHat technologies will dominate 20 years from now I wonder? How will they sound compared to today?

Mapman, thanks for your comments.

I think there probably is some sort of point where the odd ordered distortion is not detectable. The problem is, we can hear that which is very difficult to measure! So how do we tell?? Test instruments don't seem to be able to help us.

Odd order harmonics from NF might be quite nasty relative to others as suggested, but that does not mean there is no way to get the negative effects into a range that is not significant, at least for most. No amp is perfect, I think we would agree on that?

We do indeed.

I think it can be cured too... BTW you might want to read Nelson Pass's article on distortion: https://passlabs.com/articles/audio-distortion-and-feedback

I think this article is a wonderful tutorial in what the amplifier designer is up against.

Most of us here have been listening for decades. I've been into audio since the 7th grade (1970), and playing in bands and orchestras since the 6th grade (string bass). I run a recording studio, have three solo albums and play keyboards with a band on two more albums. I've cut LPs for commercial release on our own LP mastering lathe.

Regarding the lathe: we cut a lacquer when testing the lathe that used the same cut repeated 4 times on one side, each cut with its own lockout groove. The way the cuts differed was by the kind of amp that was used for each cut. The first was using the stock transistor amps for the cutter head, the rest were using three different tube amps including our own. What was nice about this lacquer is we could play the differences between the amps for anyone, on any system (FWIW the solid state amp being obviously brighter and less detailed than the other amps...). Several people have suggested putting this out as an audiophile demo LP. I'm not so sure about that- might be a small market...