John Curl's Blowtorch preamplifier part II

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People can just copy a LP to a CD, but they usually aren't too impressed with the results, from the accounts I've heard, anyway.

You're now hearing different. It's a pain to do, but the results are indistinguishable by my ear from the original. The results were impressive, but as I've mentioned before, ripping all my vinyl to CD or hard disk is a process requiring patience that I lack.
 
All true, but there are cognitive psychology researchers, and then there are psychoacoustics researchers. The latter have a much better idea of what happens in our ears and between our ears, because they don't waste much time trying to figure out the rest of what's going on in our heads.

J.J. Johnston has given many intriguing talks at local AES meetings. One important result of this research is the discovery that distortion increases the perceived loudness without increasing the dB level on standard meters. He has research showing the ear+brain response to loudness based on frequency content, not mere RMS levels. Although the VU corresponds quite well to perceived loudness, it's far from accurate enough to calibrate levels for a valid A/B/X comparison.

One conclusion from this research is that vinyl sounds 'better' than the same music on CD because the amplitude-dependent distortion inherent to vinyl makes it sound louder in the higher level passages, and thus increases the perceived dynamic range, even though output meters would not show any difference in the average VU level or peak-reading level. My assumption is that if we could meter the perceived loudness more accurately, then we could adjust the vinyl listening level down to more closely 'match' the CD listening level, and then we'd hear that the digital source sounds 'better' due to lack of distortion (or, at least, significantly reduced distortion).

I hope to develop a new meter technology which leverages this research to display a value which more closely tracks perceived loudness. Thus, it would be easier to compare the subjective performance of two amplifiers without the old "louder is better" phenomenon taking over.

The loudness matching argument is specious because the loudness of vinyl and cd cannot be matched unless the same dynamic compression, limiting, and FR balance are applied to the cd that are inherent in the vinyl. The only way to get that is to dub the cd using the same preamp that the vinyl will be played through for the ABX test. Otherwise matching at one frequency and one instantaneous level will invariably result in mismatches in loudness one way or the other at different frequencies and different instantaneous levels.

Even matching the level between two speakers driven by the same amplifier won't work because differences in their FR will make one speaker or the other sound louder depending on spectral content at any given moment.
 
J.J. Johnston has given many intriguing talks at local AES meetings. One important result of this research is the discovery that distortion increases the perceived loudness without increasing the dB level on standard meters. He has research showing the ear+brain response to loudness based on frequency content, not mere RMS levels.
That's interesting. what sort of distortion did he mention? Harmonic? Or also time domain artifacts and noise?

(I've always thought my "bad" speakers sounded louder than my "good" ones though the SPL meter didn't seem to indicate that).
 
7th harmonic - crossover distortion indicator

I hope John would like to see this measurement. The output stage runs at slightly less idle current than optimum. We can see the 7th harmonic starting to occur.
 

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One important result of this research is the discovery that distortion increases the perceived loudness...

One conclusion from this research is that vinyl sounds 'better' than the same music on CD because the amplitude-dependent distortion inherent to vinyl makes it sound louder in the higher level passages, and thus increases the perceived dynamic range...
Perhaps this is responsible for some of the "magic" of low powered SET amps. I've noticed that folks who haven't heard them often express the opinion that they "can't" have any dynamics due to their severely restricted output power, while folks that use and love them praise the fantastic dynamics they're capable of.

This effect, together with the fact that valve amps tend to overload gracefully, might also explain why a valve amp often seems to be able to play louder than a higher powered SS amp without sounding terrible.
 
You are technically correct, but that causes problems when talking about even and odd harmonics....
I've reseigned myself to calling the double freq of the fundamental the 2nd harmonic...

jan didden
Dictionary definition of harmonic: "a component frequency of a complex wave (as of electromagnetic energy) that is an integral multiple of the fundamental frequency." So don't be resigned, be happy.:D
 
You are technically correct, but that causes problems when talking about even and odd harmonics....
I've reseigned myself to calling the double freq of the fundamental the 2nd harmonic...

jan didden

Then you'd be wrong. Does it really matter what the accepted convention of defining them is? Well it does when you start talking about even and odd order harmonics. Unlike the usual nitpicking that seems to me to go on around here when there seems to be a mistake, this one matters...but not in audio. In power distribution systems where harmonic components can wreak havoc, it matters a lot. Here it's really just so much of the usual audiophile chatter IMO. :)
 
This harmonic vs overtone business is completely 'Sophomoric' in nature.
A word definition is used in a certain practice, and in this case, engineering and physics. The definition is made and should be used consistently.
A different definition, let us say, in music theory, is irrelevant and confusing, when used in the wrong context.
This reminds me of the 'Sophomoric' individual who might argue what the word 'dry' means to mixing a Martini. Here is another ambiguous word, that must be used in context, to have any meaning. Surely, you understand this. '-) hint: Shirley
 
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Although slightly confusing, I've NEVER seen the harmonic above the fundamental called "1st" in audio. It's always 2nd. Which might sort of imply that the fundamental is first, or that we just like giving the octaves even names. (Maybe it comes from "second order" or something.) As far back as I've known about the terminology, it's been that way. That's only the 70's for me, but still.

Maybe time to learn the jargon of the discipline?
 
This harmonic vs overtone business is completely 'Sophomoric' in nature.
A word definition is used in a certain practice, and in this case, engineering and physics. The definition is made and should be used consistently.
A different definition, let us say, in music theory, is irrelevant and confusing, when used in the wrong context.
This reminds me of the 'Sophomoric' individual who might argue what the word 'dry' means to mixing a Martini. Here is another ambiguous word, that must be used in context, to have any meaning. Surely, you understand this. '-) hint: Shirley

I only brought out this point to demonstrate how these rediculous trivialities are used to obfuscate the crux of an argument so frequently among audiophiles and often in these discussions. For example whether a component of harmonic distortion is one part in ten thousand or one in ten million does not alter the concept of whether or not there is a threshold below which it is inaudible no matter what its nature and that further improvement in electrical performance is in practical terms worthless but only serves those who advertise it as otherwise to sell a product.
 
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.J. Johnston has given many intriguing talks at local AES meetings. One important result of this research is the discovery that distortion increases the perceived loudness without increasing the dB level on standard meters.

While interesting, I thought this was very old news. Maybe not. It certainly seems to be known in the music biz.

One of my father's favorite stories dates from the late 1950's when he was at a friend's house who was a "Hi-Fi Nut" and had a giant system. They were playing the music loud enough that the neighbors called the cops. Cops arrived, listened to the speakers and declared "That's not loud!" And they left.
Of course it was loud (SPL), but it was clean.[/b] The cops had always heard loud with tons of overdriven distortion. That's what loud sounds like, right? They didn't recognize the sound of "loud" without the distortion.

Adding harmonics and distortion makes things louder to the ear. Just ask any guitar player.
 
You're now hearing different. It's a pain to do, but the results are indistinguishable by my ear from the original. The results were impressive, but as I've mentioned before, ripping all my vinyl to CD or hard disk is a process requiring patience that I lack.

janneman said:
We should talk. I've done it often, and in all cases I was not impressed. Meaning, the darned CD sounded just like the LP

jan didden

Well, I kind of expected that opinion from you two.

Now Jan, that's not what you've said about the LP earlier in this thread.

janneman said:
I bought a turntable and some records, first time in 30 years. I love it!

jan didden

I do plan on getting a PCM recorder in the near future and make some recordings for some of my high quality LP recordings. This is because the CD counter parts absolutely suck. Not, due the CD format but because the recording industry has it's head up it's a$$.

So, I'll be trying this experiment for myself.

John
 
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