Manufacturing a quality capacitor is more difficult than one initially suspects, especially if low cost is your primary goal in the hopes of selling a bajillion of them. After all, if you can't sell a bajillion for peanuts, why bother? Everyone must eat and to do so profits must be made.
My favorite Woody Allen movie is "Midnight in Paris" where Gill, a struggling screen writer, is engaged to marry his girl friend. His mother-in-law to be has a saying that applies to the issues of this lowly search for profits; she "always says cheap is cheap." Indeed it is.
No one can sell a quality made product for the same price as a thrifty product. Those who try to sell quality at low cost (try to compete with the thrifty lot) will inevitably go out of business because of the huge differences in fixed costs. Even if you buy a bajillion tons of Teflon, it still costs a far more than the equivalent amount of Mylar. The economics are just not on the side of quality, at least as far as capacitors go.
Plate, lead, and dielectric material choices all influence not only the cost but also the life expectancy and built-in signal degradation of a capacitor. It's a wonder that any affordable capacitor works at all with so much stacked against them. But yet numerous manufacturers find creative ways to lower costs and here are just a few examples of how that is achieved.
One way to lower fixed costs is to make the surface area of a plate appear larger than it is. In doing so, you can use less plate material and therefore less dielectric to make the same value capacitor. A trick called "etching" increases the effective surface area of the plate by roughing up the surface (creating ridges and valleys). This 3-D etched plate has more effective surface area than its 2-D counterpart however the resulting capacitance value varies because of the hill/valley dimensional differences (less/more dielectric between the plates at any given point).
Another way to lower costs is to "print" a conductive plate onto a dielectric sheet and stack these printed dielectric sheets on top of each other. By rotating even-numbered sheets 180 degrees, edge terminations to each layer can be made on opposite sides of the stack.
Lead bonding techniques also vary from direct soldering, to welding, to crimping, to chemical layering, and many more. Lead material composition also varies from steel, to copper, to tin-alloy, and many, many others all aimed at an optimum cost-to-performance point.
The methods chosen to mass-produce standard-quality capacitors vary significantly from those used for esoteric capacitors. You can view in-depth videos on how one example of volume-based capacitor manufacturing is achieved for ceramic capacitors at http://www.youtube.com/watch?v=gFEYuaY35Vo, tantalum capacitors at http://www.youtube.com/watch?v=8F1XMOE4kAU, aluminum electrolytic capacitors at http://www.youtube.com/watch?v=PkLG-_S5yl8, and film capacitors at http://www.youtube.com/watch?v=s39HCu7Zs2U.
Manufacturing processes vary by company and for esoteric brands their manufacturing processes are proprietary and well-kept trade secrets. For example, it is common knowledge that Mundorf uses two capacitors in series to lower (literally halve) the inductive property of their Supreme series capacitors. This means that two capacitors each twice the value of the actual capacitance desired are required to make one capacitor (two 50uF capacitors in series make one 25uF low-inductance capacitor). This doubles the cost of making that capacitor style but results in a capacitor that sounds different (faster, more detailed) from others that do not use this technique.
Other manufacturing techniques exist that focus primarily on the quality of plate and lead materials (high purity copper, gold content, silver content, etc.) each changing the sound while measuring exactly the same (or with minor differences) as their budget counterparts. Each time a variant of low-cost production materials is used, the price of its use increases. Plus the number of capacitors produced in a production "run" is also smaller so the economic benefits of volume purchasing are not achieved.
Although this is not a thorough exploration of why capacitors sound different, it does give you an idea of why they could potentially sound different. There is a saying that applies to high-end anything (auto racing, photography, audio, etc.): the devil is in the details. It is at this highly detailed level where the differences between the state-of-the-art are and it is why a good quality capacitor costs what it does.
I hope you have enjoyed discovering how capacitor designs vary and why esoteric capacitors, if nothing else, cost more to make than the mass-produced varieties. When considering which style to buy and which to avoid, that is another whole can of worms beyond the scope of this series.
The Vishay 1837 Review and Modification
Bypass Capacitors
Mundorf Supreme Capacitor Review - Part 1
Mundorf Supreme Capacitor Review - Part 2
Capacitors: All Things are NOT Created Equal - Part 0
Capacitors: All Things are NOT Created Equal - Part 1
Capacitors: All Things are NOT Created Equal - Part 2
Capacitors: All Things are NOT Created Equal - Part 3
Capacitors: All Things are NOT Created Equal - Part 5
Esoteric Shunt Capacitors - Part 1
Esoteric Shunt Capacitors - Part 2
Esoteric Shunt Capacitors - Part 1
Esoteric Shunt Capacitors - Part 2
Philip Rastocny
Skeptics are essential to keep us sane; skeptics do little to keep us inspired. Philip Rastocny, 7-16-2014
Skeptics are essential to keep us sane; skeptics do little to keep us inspired. Philip Rastocny, 7-16-2014
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Copyright © 2015 by Philip Rastocny. All rights reserved.
Copyright © 2015 by Philip Rastocny. All rights reserved.
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