Lieutenant Schmidt's Audiobub: The Great Mystery of Paper Condenser Alchemy

One of the many misconceptions regarding audio components is the approach to the choice of capacitors. So it is known that some part of the audiophile community is highly rated certain types of these elements for charge accumulation. It should be noted here that the use of certain capacitors in amplifiers and crossovers of acoustic systems can indeed significantly affect the fidelity of playback, but ...

Ardent supporters of the “alternative condenser theory” try to prove that certain types of paper capacitors (and in some cases, homemade paper capacitors) are a priori the best that can be used in an amplifier or filter circuit. The argument is categorical and simple - “they have a softer sound”.

Also among those poorly familiar with circuitry, but familiar with the “smell of rosin haze” by inertia, a fashion appeared to replace all capacitors in amplifiers and speakers filters for receiving “divine sound”.

About the absurdity of “listening to capacitors” itself, as well as listening to hangers, cables and warm lamp fractal dodecahedrons, I will keep silence, so as not to offend the feelings of believers. In this post, we burn the paper myth of capacitors, deal with the linearity of these, undoubtedly, important elements and touch upon when necessary. and when not to change capacitors.

The value of oiled paper and the magic of condenser replacements

So let's get started. Unfortunately, the roots of the myth described below could not be found, but I believe that the Honorable Mr. Likhnitsky made efforts to create it (please note that many consider such statements by a respected engineer to be very subtle prank and trolling), having once appreciated the quality of paper-oil condensers the German company Telefunken of the 1930s (the AML also quoted their triodes as the “warmest” and “inspired” very much).

It is argued that, due to technical (physical), and in a number of sources of metaphysical features, various types of paper capacitors are of tremendous value in forming "high-quality sound", since they are more linear compared to other types. Retelling all the myths about the causes of "higher" linearity will take more than one article, and I will allow myself not to bother with it.

In the metaphysical explanations of the effect of these capacitors on sound, arguments are made in favor of the nobility of paper as a material for use in creating the sound path. But all the above arguments are applied relatively rarely, even metaphysical. The main message in the opus of supporters of oiled paper and foil in the “golden hearing” is that the sound with such capacitors becomes “softer”, “more natural” and “more honest”.

I'll touch on another condenser myth. When buying vintage audio equipment or to improve the sound in a budget amplifier or speaker, it is often recommended to replace all device capacitors. In the first case, the replacement can be quite objectively justified by dried and swollen electrolytes. The second case presents a less attractive picture.

Audio maniacs with soldering irons especially often “transplant” the rectifier capacitors, which are responsible for powering the output stages of the UMZCH. At the same time, amateurs studying the “depths of the low-frequency range” are trying to increase the capacitance to the limit. The argument also has:
“I want more bottom, the amplifier can not reveal the low-frequency potential of my speakers. I will put the normal capacitance and the low frequencies will become more saturated. ”

Paper ashes

Hardly this article will force the true adherents of the paper condenser theory to somehow deviate from their views, but at least make those who hypothetically believe this nonsense think.

Some lovers of the “divine” sound talk about linear capacitors. At the same time, in their standard characteristics there is no such thing as “linearity”. Capacitors are characterized by capacity, specific capacity, nominal voltage, energy density.
Parasitic parameters are also distinguished:

It is believed that the parameters described above can affect linearity when used in acoustically significant amplifier circuits and crossovers. And here there is a problem, almost all the described characteristics of paper capacitors worse than other types.

So, the mythmakers say that paper capacitors are a more linear element and, accordingly, it makes sense to use it instead of ceramic, film, electrolytic, etc. I am not the first to ask about the correctness of these conclusions about linearity. So on the forum one of the community members (back in 2008, the year) conducted several tests comparing the types of capacitors for the harmonic distortion factor that they can contribute.

Despite some inaccuracies in the measurement method, which the author warned about, his tests demonstrate quite a realistic picture. To summarize: metal-paper K42U-2 (Kg = 0.0023%, K'g = 0.0078%) turned out to be much more linear than ceramic, but it was inferior to film films. Considering that in comparison of film capacitors with paper linearity differed by thousandths of% Kg, we can safely say that the difference in their linearity is within the limits that can be neglected. In addition, the same author claims (based on the test carried out) that the linearity of the capacitor depends more on the capacity than on the type used. And the problem of linearity in “ceramics” arises in connection with the use of a small volume for large capacity and is not mandatory for all ceramic capacitors.

It is possible to make a rough and indisputable conclusion that metal-paper capacitors (under ideal equal conditions) are probably a more linear element than ceramic, but they do not exceed film and other types in linearity.

In other words, there is no direct relationship between the distortions that a capacitor is capable of introducing and its type. Moreover, in most modern capacitors, the distortions are so small that their values ​​can be safely neglected, especially if we are talking about creating budget equipment.

In addition, paper capacitors have a number of drawbacks, due to which they have been practically ousted from the market by other types. These shortcomings can be reflected both in sound (especially in cases with dividing - interstage elements), and, in principle, on the stability of the amplifier or filter. For example, paper hygroscopicity is peculiar to paper capacitors, which in turn leads to an increase in dielectric losses , a decrease in insulation resistance, and a detrimental effect on thermal stability * (for a number of sources, linearity also depends on thermal stability).

The described drawbacks and the availability of alternatives in the form of various types of film capacitors are enough to forget about all types of “paper” forever. In other words, metal-paper, paper-oil, and other archaic capacitors, so loved by some, do have a fairly low non-linearity until they absorb a certain amount of moisture.

It’s pointless to argue about the changing nature of the sound, since the dispute will occur with people from the category “you don’t understand anything - I can hear it” . To the statement about “softness” in the sound of paper capacitors at one of the amateur radio forums one excellent ironic answer was given:
"Of course! After all, paper is a very soft dielectric)) ”

I guess this is the best answer.

Change not everything or not change at all

The need to replace capacitors when buying an audio vintage really makes sense, especially as regards electrolytes. However, changing everything at least financially unreasonable (one should certainly take into account the age of the apparatus, everything is possible, but not a fact). Moreover, this should be done with an understanding of what and where to change. If there is no such understanding, you should contact specialists who can determine dried and swollen electrolytes, the presence of a breakdown, etc. If the device works without failures and there are no complaints about the sound, nothing is needed.

Regarding the changing nature of the sound through the introduction of "innovation" in the circuitry of the serial device should be said separately. For example, when increasing the capacitance of the output stage power capacitors in pursuit of a “deep bottom”, as a rule, they forget about the increasing charge current. Such carelessness leads to the sudden death of diode bridges as a result of breakdown. Any changes in the serial circuitry is a risk, and a person who rather builds his own amplifier can actually improve it.

Speaker filters also often suffer from transplant abuses, which in the event of a mismatch between the parameters of the capacitor of the filter design leads to disastrous results. Smart people recommend, if you change, the whole filter (with coil, resistors, etc.), counting a new one for the AC parameters.


From all of the above, we can draw some simple and useful conclusions. The spread of the paper capacitor myth is beneficial only to small companies that use them in audio components or produce paper capacitors themselves. In fact, this is the exploitation of the ignorance of the potential target audience and the imposition of a deliberately outdated and in fact unnecessary technology.

Replacing capacitors in old equipment can be a useful preventive measure, but only if performed by a person who understands what to change and what does not. Games with capacitance and types of capacitors in mass-production filters and amplifiers are more likely to lead instead of “divine sound” to an impressive investment in repairs.


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