Propeller Head Plaza Technical and scientific discussion of amps, cables and other topics.

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RE: I posted.............

Posted by jrlaudio (P) on November 3, 2012 at 06:57:05

In Reply to: I posted............. posted by unclestu on November 3, 2012 at 04:09:15:

Please understand, I am over-simplifying my explanations. I could get very technical but that is not important for the discussion here and would easily bar those less technical from joining in. My hope is those interested enough will do some personal research, away from audiophile blogs, advertising, and magazines. I hope they instead delve into the reams of knowledge contained in papers prepared by academia in this field.

While I personally haven't directly measured the affects of plating what I can say is from what I have gleened from others research. The primary reason for their use is the fact that precious metals do not oxidize easily. Oxides increase resistance, and cause intermittent connections. Otherwise, the only difference between precious metals electrically is conductivity. And the differences in conductivity between gold, silver, and nickel are so low as to be non-audible in most applications for connectors. Again, its the lower oxidation potential and improved reliability that brought about precious metals being used on connectors. The alleged audible differences are techno-babble trained into the brains of audiophiles by companies over many many years, successfully trying to increase perceived value and therefore raise prices.

Another more important issue is the fact that plated connectors may in fact be worse than a single metal. For a gold connector to be perfectly consistant and reliable it needs to be solid. The point where the plating meets the underlying metal substrate is a joint of disimilar metals, both of which exhibit different conductivity values. At that junction you in effect have a semiconductor. Also due to the electrostatic differences you have a junction that may be susceptible to electrolysis causing corrosion at the junction, underneath the plating. A solid silver connector, or even solid nickel, is most likely better than a gold plated copper one for these reasons. All this comes from an engineers understanding of metalurgy and electro-chemistry, however I have no first hand test data to support this theory.

The problem I have is I have seen numerous manufacturers make the false and deceptive argument that the cost saving approach of using plated connectors instead of solid is actually attributable to "skin effect". This is a bold faced lie. They claim because of skin effect gold only has to be on the outside of the connector. As I said before skin effect does not occur at or even near audio frequencies. These are physical constants that cannot be disputed. It is a tested, measured and well understood fact. The lowest grade wire does not show skin effects until about 65kHz. And purest wires made of gold or platimum exhibit the same properties in this respect. And since audio is passed equally throughout the entire structure of any wire at the same speed over the entire audio spectrum (as a factor of velocity), the differences between stranded wire and solid of the same gauge in regards to passing signal are identical at audio frequencies. In fact, a solid wire puts slightly more metal in the same volume of space, since a stranded wire has air between all the conductors. Also stranded wire has a minutely higher capacitance, but again to low to have an audible affect. However, the primary advantage of stranded wire is flexibility.

Cardas ... hmm ... Cardas. Mrytlewood blocks. Wood is used in musical instruments because it transfers acoustical energy very well, and it resonates nicely. Why would we then use it to "isolate" gear. I haven't a clue. Cardas does though. And besides, if equipment is so susceptible to micro-phonics as to be audible, there is something seriously wrong with the design. That is a serious design flaw and completely avoidable (with the exception of vacuum tubes proper). But CD players and DAC's. Nope ... sorry. Not real. But it is perceived to be true ... hmm. I'll accept Walkers HDL concept as something real though. A zobel network designed to remove RF from a signal to reduce intermodulation artifacts is certainly something real and quantifiable ... and measurable.

The CJ knob calibrations are of low level electrical signal either dBu or dBv, not dB SPL. These are two totally different things that share a common nomenclature (dB). This ambiguation between the two different descriptives leads to assumptions like you just made. One (dBv) describes a relationship of electronic voltage, the other (dB SPL) describes a quantity of a logarithmic measure of the effective sound pressure of a sound relative to a reference value. For sound in air, relative to 20 micropascals, the quietest sound a human can hear. (Another limit of human perception which measurement can surpass in scope). That knob does not relate to sound pressure levels. If the gain structure follows standards, a 3dB change in signal gain on a that preamp relates to about 6dB change is SPL. (However, the amount is dependent on many variables i.e., power, speaker efficiency, gain structure, etc.) So yes it makes sense you wanted to fall between the detents. Each click was well within the human perception limit.

The reason for measurement is to verify accuracy and quantify design criteria beyond that which our senses can determine. For instance, I can measure the THD of two different amplifiers, one tube based the other solid state. Obviously the Solid State would measure much lower THD. Same goes for IMD. But which one sounds better is a matter of the aesthetic and is not directly quantifiable. While the Solid State would be deemed more technically accurate, the higher THD in the tube amp sounds warmer. Why? Added harmonic content that is not in the recording, but instead is an artifact of distortion that happens to be rich in even harmonics. Harmonies in music are even harmonics and are naturally pleasing to the ear. But those harmonics produced by the tube amplifier are not on the recording. Therefore it can be said tube amplifiers, even ones close to being the theoretical perfect design, are less accurate.

After leaving the audiophile electronics game, I settled into making the recordings we all enjoy. I worked for a time on co-engineering Sheffield Labs recordings, working for Doug Sax. I was at the sessions and I know how those recordings sound. It is rare I hear those recordings sound correct on most hi-end systems. Funny thing is the more esoteric the system, the farther away is the reproduction from the sound of the recordings I know so well. I have the advantage of a true reference. I know the actual recordings, since I either worked on them or actually mixed them. I was the person responsible for deciding just how they were to sound. So my aesthetic is of course skewed towards a preference for accuracy, primarily because I have a legitimate reference. A starting point at the recording itself.

What constitutes a proper sound system is one that meets certain criteria for transparency. These are measurable and quantifiable parameters. Ideally, what comes from the source is reproduced with no artifacts from the system itself. A loudspeaker with a flat amplitude response, proper time alignment, and perfect phase coherency will be more accurate. An amplifier with the lowest practical distortion characteristics at the highest gain will be more accurate. A system with low noise and the highest possible dynamic range will be more accurate.

Now I mention this for two reasons. First, I have found myself in the dubious position of listening to a recording I sweated over for months. Fine tuning gobos and diffusers to capture a specific ambient field in the recording. Changing multitudes of microphones and microphone placements to get the right tone and placement in the image. Plus a multitude of other details. And the system I am listening to, some in the hundreds of thousand of dollar price range, are not even close to being able to resolve any of the details in the recording, or even maintaing tonality. And the proud owner turns to me and says, "So. What do you think?" Do I tell him? Most times I bite my tongue.

One circumstance like this was on a system featured in an article in a major audiophile magazine as one the best systems out there. All the big huge cables sitting on their respective telephone poll insulators, the machined aluminum chassis glistening in the special lighting set-up to show off the system. The reproduction of my recording was so poor I nearly pee'd myself. I'm thinking to myself, is this guys listening to the art, or the gear? Which leads to my second reason ...

Audio manufacturers and the people who worship their teachings will decsribe what they hear as "transparent" or "wholly accurate" or best still "musical". This last term really keys into the thinking, both to the purpose of profiteering companies or the justifications of gearheads. A piece of gear that "sounds musical" implies it is making music itself. A truley accurate piece of audio equipment shouldn't sound like anything. It should be transparent. So what we hear in this description are manufacturers cleverly disquising the less than accurate performance of their gear. The term being used by the audiophile desribes his desire to create a sound rather than to listen to the sound the artist created. The latter being a matter of hobbyist fun and aesthetic, which is fine. The former however is a simple deception for extreme profit which is unethical by nature. In other industries, it would be deemed criminal. Strong words, I admit. But honest ones. If it isn't we'd be paying $500 per gallon for gas. Come to think about it, that's way to low by comparision to audiophile margins. $5000? ... yeah that's about right.

My real peeve here is that claims are made that are outright lies. Problems that do not exist are fabricated, then products are designed and marketed at high prices to solve these non-existant issues. And what happens. People buy them and perceive some change. I know of at least three products that came on the market, as a joke by some of the manufacturers, just to see how far they could push the envelope. I was at the meeting for one of them. It is now an accepted thingee amongst audiophiles as a real essential tool, and it is a gag. A fabrication. What is known in the biz as a "guyver". Several other manufacturers no produce this thingee, some charging 1000 times for what was originally discussed as a wim around this table. I wish I could say, but it would violate my non-disclosure agreement I signed when I was hired. Most of you may have some of them. And many have perceived an "improvement". Proving the point that perception can be transient and open to suggestion. I assure you this thingee does absolutely nothing. And if I measure it, it would show nothing, regardless of the aural perception.

As audiophiles it is very easy for us to get caught up in hype, the gear and the next cool thingee. We sometimes forget about the music and art we are supposed to be listening to. The creative effort of the artists and engineers take a back seat to the sound of the system it's being played on.

OK ... I'm biased ... but honest. :-)

JRL

Edits: 11/03/12 11/03/12 11/03/12 11/03/12 11/03/12 11/03/12 11/03/12

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