Current Measurement Concepts vs. Perception

[Rick Turner]

I'd be very interested to see how many folks here think that current, available, "state of the art" measurement techniques can explain all that we can hear or perceive with regard to pickups.

On the one hand we have the "Mojo" crowd. On the other we have the "Maxwell" crowd. Can Maxwell explain...or absolutely debunk Mojo?

My own feeling is that we can perceive things we've not yet figured out how to measure. That has certainly been the case throughout my professional involvement in audio. And yet I do have somewhat of a skeptical attitude. I know that a lot of high end audio is utter bullshit.

And then I go to the NAMM show and try out VoVox cables...which whether used with a high impedance passive instrument OR a low impedance active instrument sounded absolutely better under horrible circumstances, and sounded so to everyone who "heard" them. Whazzup wit' dat? The damned things SOUNDED BETTER. And I didn't want them to... And they're not stupidly expensive. Not cheap, but they cost less than a lot of people would pay for equivalent improvement somewhere else in their signal chain.

Hunh? Well, I got some hookup wire from them, and I'll try it out. I'd love to get some magnet wire made to whatever their mojo is...

[David King]

Well I must say I get a warm fuzzy feeling when I hear that someone, somewhere is making something that does something useful or good. Then again I'm on my second G&T of the evening..

I did see this in their FAC:
"Solid core conductors: Conductors made of solid wires of silver plated, oxygen-free copper " Ha!

[Steve Conner]

Well, the cardinal rule in these kinds of investigations is that the test doesn't mean shit unless it's conducted blind. When proper blind tests are done, you find that what can be heard is the same as what can be measured.

In short, some subconscious part of you wants to believe that those cables sound good. Or maybe you have a need to see yourself as the kind of golden-eared guy who can detect the differences. (I imagine there would be a lot of peer pressure in that direction, in the NAMM setting.)

Where it really gets interesting is blind testing musical instruments. How on earth do you do it? They feel different, so you're going to know which one you're playing. And the player's feelings toward the instrument make a real, measurable difference to the performance. Maybe some sort of line has to be drawn that isn't worth trying to "science" your way past.

Of course you can take a blind test any day by listening to an album and trying to hear what brand of op-amps they used in the studio. Mmm, I'm getting autumn colours... brown... That's it, must be Burr-Brown. The good shit from before TI bought them.

[MWJB]

"When proper blind tests are done, you find that what can be heard is the same as what can be measured." Hi Steve, can you point us to a proper blind cable test, with methodology & results. What would you measure on a cable to determine performance...& just as peer group pressure may be responsibl for skewed results, assuming humans are equally fallible in this respect, why wouldn't it be the case that somebody would "want" cables with a specific measurement to sound better/match measurements & "results" to be just as skewed?

Cables, like tubes, are not uniformly constructed, with identical materials...potential for tangible differences may exist based on this factor alone?

[Mike Sulzer]

I'd be very interested to see how many folks here think that current, available, "state of the art" measurement techniques can explain all that we can hear or perceive with regard to pickups.

Of course not. But that suggests we need to understand better how pickups and human perception work. You are suggesting a goal.

[Steve Conner]

MWJB: I was referring to hi-fi cables, speaker cables and so on. Lots of tests have been done on those, there was a link posted over in the cryo pickup thread.

When it comes to guitar cords, they do indeed sound different because of their different capacitances. But an instrument with an onboard preamp should nullify that.

One important thing: I said that what can be heard is the same as what can be measured. Every audible difference must correspond to some change in the output of some measuring instrument. But often the change in the data can be too subtle to be obvious. I don't know of anyone who can look at an FFT waterfall plot and say, "I see cedar and koa", but the data distinguishing a cedar and koa wood guitar from a spruce one are in there. The Mama Bear DSP thing proves that, because it uses that same data to recreate the sound, by means of impulse responses, convolution and so on.

But the physics of guitar cords forbid any subtle resonances like you might find in a soundboard. Signals travel in them at the speed of light, so their "fingerprint" is in the MHz range.

[FunkyKikuchiyo]

My own feeling is that we can perceive things we've not yet figured out how to measure. That has certainly been the case throughout my professional involvement in audio. And yet I do have somewhat of a skeptical attitude. I know that a lot of high end audio is utter bullshit.

I don't think there is too much to say beyond that. I don't have any anti-math or anti-science philosophies; I love both. But, they just can't explain what I hear a lot of the time. What we hear is data. Science is based on data, not data on science.

The best luthiers/pickup makers/etc., I think, are artisans rather than engineers. Who makes a better loaf of bread - a biologist who understands the bacteria and the yeasts, or a baker? We've been baking bread for a lot longer than we've understood anything under a microscope. And more than that, we didn't need to understand yeasts in order to "invent" leavening bread. Of course it makes the life of a baker easier to have that information and technology available, but in the end it is the baker that knows how to make bread and not the scientist.

As for double blind tests, I think the ability to listen without personal bias is simply an acquired skill. I hear things all the time that I'm sure I wouldn't want to hear, so I can blame little on psychological bias. In fact, I get extremely frustrated with my pickups because I keep hearing things I don't want to hear. Just yesterday I swapped cables because I wanted a right angle for something else, same brand, same length, same everything, and it changed the sound. That annoyed me. If I simply heard what I wanted to hear, I'd have a final version of my pickup design months ago, but I keep going with it.

People try to debunk stuff all the time because there isn't empirical evidence, but this is a logical error. Why is the sky blue? Well, we know vaguely that it has something to do with refractions of the gases in the atmosphere, but really won't don't have a definite idea. So, if I lie and say that the sky is made of skittles and someone disproves me, what does that mean? Does it mean that the sky ISN'T blue, or does it mean I'm just horrible at explaining things? This happens all the time. Someone gives a crappy explanation for something in the music world, and all of it goes down the drain, including the original datum, like Rick trying out those cables.

I'll shut up now.

[Steve Conner]

Just because you don't want to hear something doesn't mean that it exists. If you go to your local insane asylum, you'll meet lots of nice people who probably genuinely wish the voices in their heads would stop. Not at all like the basement at NAMM, then.

You mat be right that listening without bias is an acquired skill. But it's one that very many people claim to have, when they actually don't. How can you take a hi-fi nut seriously when he buys speakers that cost as much as a nice car, then puts them in a room with no acoustic treatment? And when they sound wrong he blames the speakers. If he really understood the nature of sound and knew how to interpret what he was hearing, he could get a better sound with some 500 buck ones.

I will leave you with a Gedanken experiment. You have access to the finest minds in science and lutherie, and a budget that would make the Department of Defense weep. Your mission is to make a machine that, when a guitar pickup is placed inside it, will determine whether it has PAF-nature or not.

Your only restriction is that no living organism may be part of the machine. You can't train your trusty pet dog, giant-eared arctic fox, or Seymour Duncan, to do the recognising.

[Jazz P Bass]

Stevie Ray loved the "coiled" instrument cables.
Reason: higher capacitance.

[frankfalbo]

I wouldn't concede that "everything" is in an FFT. I'll say we're not even close to the full understanding with today's methods. And you have to know how to use them of course. But think about something like an FFT. Suppose you were looking for something but it turns out it requires a fingerstyle player with a snappy attack to drive the top and back into something that was audible. Some type of "auto-strummer" or worse-impulse tester won't draw that out. I get what you're saying that the difference has to be in there somewhere, but the degree would go unnoticed or dismissed. The problem would arise when that fingerstyle player found one average and the other "magical". Those staring a the graphs would roll their eyes, say the guy is full of himself, etc.

I've seen guys in house (former employees) swear up and down that two things should be identical that were not. I mean we're talking about dead-on matches of circuits and stuff like that. Or like alloys that "should" behave exactly like one another, etc. You not only had to play them, but you had to play them the right way to find the differences. But once you did, it couldn't be argued anymore. Then they'd just hide behind blanket statements like "well no one plays like that or no one will actually be able to hear that but you know what? In some cases it makes the difference as to whether you get an artist or you don't.

I often liken it to the stock car driver who is told "everything checks out" but he finds a shimmy at around 110mph. After arguing to the point where something IS found that is so minuscule it shouldn't matter, the mechanic goes "yeah but you can't go 110 on the street anyway, you'll get a ticket."

I have way more to say on the subject but I'll be late for church. Say what you want but until a scientist can turn nothing into something, and then make it alive I'll take the artist over the scientist.LOL

[Steve Conner]

Frank, I kind of agree with you. That is an example of what makes differences so hard to measure objectively. Two different players, even the same player in a different mood, can make noises that measure so differently that they swamp the real difference you're looking for. But human sound perception can flip the data into a completely different dimension where the thing you're looking for sticks out like a sore thumb. We have this wonderful passive-sonar kind of system that is tuned to guess the physical properties of an object from the noise it makes. It will ignore room reflections, whatever. You could spend months training an artificial neural network to tell two acoustic guitars apart, then move the mic 6 inches and it would be helpless.

My day job is writing DSP algorithms to tell healthy machines from sick ones based on the vibrations they give off. It's really the same problem.

And one last thing: artists can't make something alive any more than scientists or engineers. They all make cold, dead lumps of stuff, it's just that artists weave better stories around them. Unless you count Dr. Frankenstein as an artist.

[Mike Sulzer]

Why is the sky blue? Well, we know vaguely that it has something to do with refractions of the gases in the atmosphere, but really won't don't have a definite idea.

Of course we know why the sky is blue. We just do not know why blue is blue. But that is another question altogether.

[Jazz P Bass]

Off topic: Why Is The Sky Blue?
Link:Why is the sky blue?

Quote:"Why is the sky blue?

The sky appears blue to us on a clear day, because the atoms of nitrogen and oxygen in the atmosphere separate the suns white light into its many colors, and scatter them throughout the atmosphere.

The wavelength of the blue light scatters better than the rest, predominates over the other colors in the light spectrum, and makes the sky appear blue to us.

The scientific name for this phenomenon is the Tyndall effect, more commonly known as Rayleigh scattering.

This phenomenon describes the way in which light physically scatters when it passes through particles in the earths atmosphere that are 1/10th in diameter of the color of the light. The light spectrum ranges in wavelength from red to violet, and, since the wavelength of the blue light passes through the particles with greater ease than the wavelengths of the other colors of light, the sky appear blue to the naked eye.

The human eye has three types of light receptors, known as cones, located in the retina. The cones are either considered to be red, or blue, or green, based upon their strong response to light at these wavelengths. As light stimulates these receptors, our vision translates the signals into the colors we see.

When gazing at the sky, the red cones respond to the small amounts of red light scattered, and even less strongly to the orange and yellow wavelengths. Although green cones respond to yellow, their response to scattered green and green-blue wavelengths is stronger. Finally, colors near the strongly scattered blue wavelengths stimulate the blue receptors.

In short, the skylight stimulates the red and green cones almost equally, while stimulating the blue cones more strongly. For these reasons, our vision naturally adjusts as clearly as possible to separate colors."

[salvarsan]

... until a scientist can turn nothing into something, and then make it alive I'll take the artist over the scientist.LOL

Several technical points:

Ya can't turn nothing into something. It's a Conservation of Mass violation.

If you reliably perceive a difference that you are unable to measure instrumentally, then the test method is at fault.

VoVox is pretty clear about how they make their cables. They use highest purity materials, thickly insulated conductors that are twisted, then given a polymer web jacket. Compared to most coax, this minimizes capacitance and microphonic susceptibility. EMI noise susceptibility is surprisingly adequate for twisted pair.

The other elephant in the room is that gross variation in right+left hand techniques guarantee that different players sound different on the same gear. A particular guitar+pickup+amp combination is an accomodation to physiological differences as well as preferences. Gimme a wide fretboard with a compound radius, thanks.

A stomp box maker I know blandly states that the greatest source of noise in the signal chain is usually found holding the guitar.

[FunkyKikuchiyo]

Of course we know why the sky is blue. We just do not know why blue is blue. But that is another question altogether.

I seem to remember hearing someone say that the data was unsatisfactory; perhaps he had his own agenda. Who knows.

My main point is that if we don't know WHY the sky is blue, it doesn't dispute whether or not the sky IS blue. In audio, if two things sound different and we have no good explanation/empirical data to explain or show that it is different, it doesn't mean that they don't sound different, it simply means we don't have the data. That is an error in thinking that seems to come up a lot.