John Curl's Blowtorch preamplifier

[andy_c]

Originally posted by Corvus corax
It is my job to question my observations, and assumptions, as well as those of others. I know what I can hear, I know what the boss can hear

That's clearly a contradiction. You claim your job is to question your own observations and those of others, and yet you say "I know what I can hear". If that is so, you're not doing your job.

[Bonsai]

Amplifiers do sound different - hell, I can say tha t categorically because I HEARD IT. Many times.

The problem, gentlemen is we do not know exactly wha t makes them sound different, all other things being equal.

Some people have developed a view and a body of practical knowledge that aids and steers them in the creation of their products - many examples in this forum e.g. topolology, layout, component selection etc.

Other individuals come at this from a heavily engineering perspective and the viewpoint that, if it measures well, that's a good starting point.

Both are perfectly rational, understandable positions.

Where the tw0 communities go off the rails is when one or the other claim that the oppopsites approach is flawed, and therefore th e end product is fatally flawed (notice how these discussions always quickly become polarized with extreme views on both sides). Well, like I've said before on this forum, there are many great sounding amps with feedback and there are many great sounding amps without feedback, to quote but one example.

So, attacking each others starting viewpoint when in the majority of cases the end result is a 'fine' sounding amplifer is just pointless.



Audio Audio Audio
Subjectivist >>>>> Rationalist <<<<<<<< Objectivist

There should be a sensible rationalist position to all of this!

[Bonsai]

One other point.

'Sound' is a very subjective thing.

somelike it tight clean (most likely solid state with f/back)

some like it looser and airer (most likely tubes or ZGFB)

Take your pick

[AndrewT]

are three pages of off topic "listening and hearing" discussion what we really need to build a better pre-amp?

[x-pro]

Originally posted by john curl
Just because we think that the ear comes first, does not mean that we throw measurements out the window. I have limited means, but over the years I have accumulated perhaps $50,000 in test equipment that I actually own, and can use when I want. I can measure 1 part in a million fairly easily, both IM or THD, and signal average as well. That should account for something. IF ONLY the measurements directly correlated with the listening, then it would be easy. I NEVER deliberately add distortion to a circuit, as well.

Exactly my thoughts as well. Thank you, John.

Alex

[PMA]

Yes, well said. I do not know why some would suspect us to add "nicely sounding" distortion. Nonsense.

[syn08]

Originally posted by PMA
Yes, well said. I do not know why some would suspect us to add "nicely sounding" distortion. Nonsense.

suspect US This plural again

Mind you, nobody said you are adding on purpose "nice sounding" distortion. I should probably add self victimizing to the big picture.

But regarding measurements, the common attitude follows a certain pattern:

1. Avoid as much as possible talking about measurements.
2. When talking about measurements, always mention how unimportant for a good sound and deceptive they can be.
3. When some measurements have to be displayed, show either simulations results or irrelevant data.
4. Correlating measurements with subjective/listening results is always somebody's else job.
5. Never disclose the entire measurement setup, this will make measurements dangerously reproducible.

I think it's time to move on.

[SY]

are three pages of off topic "listening and hearing" discussion what we really need to build a better pre-amp?

In a sense, yes. To build a "better" preamp, one has to decide the definition of "better." For me, a preamp that switches sources, raises/lowers the volume, and does nothing else is the definition of "better." In my mind, if I can't hear the difference between the preamp being in and out of the circuit, it cannot be made "better."

Others seem to want the preamp to do something marvelous and mystical. Nelson Pass would say that they want their preamp to provide entertainment. I think that's what the fuss is about.

[Corvus corax]

Let me state it a different way, Andy, one that wont have any inferred meanings for you: My job is to take the same circuit we've used for the last 20 years, and changing none or few of the values present, and make it sound correct through trial and error. That is how we voice our products. Every time the artist comes up with a different box, the circuit that worked well the last time will refuse to give good sound. Its my job to figure out why. Seldom does a new creation sound the way we want it to. Its my job to fix it. Whether that means moving a component out of an e- field present in the equipment, or manipulating the ground buss noise levels to balance out internal noise by changing the size of a conductor, what we do is less science than it is art. Some of the effects I deal with a very hard to correlate with measurements, most are obvious.

I suppose the fact that 90 percent of my work is done sitting in front of a distortion analyzer and watching the results is lost. Funny, though, how I can't seem to get that fella to show me the results of changing a piece of wire, yet the results are clearly audible to the man in charge and myself, even though he has no idea what I've done to change the sound…

Enough of this. I have actual work to do. CES shipping deadline approaching.

[JPV]

This is not science, this is not art, this is black magic.

JPV