Preliminary: The emotional side is deliberately omitted here. So if you like nice-looking devices and cables and are willing to dig deep into your pockets for them, here you go!
After this clarification, the way is clear for technical arguments. The vast majority HiFi-Devices rely on mains power and first of all it is obvious that the quality of the mains power could also affect the quality of the audio signal being played. An accessory industry is based on this basic assumption, which with the help of special power cables, power strips, line filters, audiophile fuses, etc. wants to ensure that the audio components are supplied with mains power of optimal quality. The prices charged for this can put the prices for a hi-fi component in the shade and one wonders whether that is in any reasonable relation to the profit.
My answer to that is no, with a few exceptions, the gain is not worth the effort. It is not uncommon for manufacturers and sellers to crassly exaggerate the effects in their descriptions and generalize in an unacceptable manner.
Here is the rationale:
In our latitudes, the mains current consists of an alternating current with a frequency of 50Hz and a voltage of 230V. No hi-fi device uses this supply directly. Internally, direct current with (almost always) lower voltage is needed for the function. More than one internal voltage is often required, so digital circuits usually work with 5V or 3,3V, while analog circuits often need two voltages of +15V and -15V. Output stages need even higher voltages. It is the task of the power pack in the device to generate these DC voltages from the mains current.
There are two basic types of power supplies: the switching power supply and the conventional one Power Supplies. The name already suggests that the conventional power supply is the older and still more widespread variant. Its most striking feature is the mains transformer, which can take on impressive dimensions, especially in the case of power amplifiers. Switching power supplies also have a transformer, but it's considerably smaller and lighter, because a kind of chopper chops up the mains current at a much higher frequency than 50Hz. The higher the frequency, the smaller a transformer with a certain Performance be. A switching power supply is more complicated than a conventional power supply because of the additional chopper, but it can still be cheaper because of the saved transformer size. Since the required components are becoming cheaper and cheaper, the switched-mode power supply is also becoming increasingly popular in the hi-fi sector. In computers, it has almost completely replaced the conventional power supply.
The power supply itself is not directly involved in processing the audio signal. These are different circuits and they only get the energy they need from the power supply. Even if you ideally don't want any interference in this energy supply, not every interference in the power supply automatically ends up in the audio signal.
A reasonably constructed analogue amplifier for example, also has a low sensitivity against fluctuations in the supply voltage. With power amplifiers, it is regularly so good that you can do without a separate stabilization in the power supply. With digital circuits, disturbances on the power supply are usually completely inconsequential as long as they do not exceed a maximum specified in the data sheets. If you exceed that, malfunctions are usually the result, which have more glaring effects than the mere impairment of audio quality.
In principle, then, disturbances in the mains power should not have any consequences as long as they remain within limits and one cannot assume a direct relationship between the quality of the mains power and the audio quality - contrary to what accessory manufacturers like to suggest. That does not mean, however, that such influences cannot exist under any circumstances. In fact, there are many ways that a disturbance on the mains can affect audio quality, but because of the many possibilities, it's difficult to make generalizations. Device design addresses and eliminates many of these possibilities, and a well-designed device should be immune to the types of interference that can normally be expected, so additional measures will not help.
For a closer look, it is necessary to dissect the most important sources of interference and influencing mechanisms, so that one can judge whether countermeasures are advisable or not.
We are only interested in interference if it affects the quality of the audio signal, all other interference can safely be ignored in our context. So some circumstances have to come together:
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There must be a source of interference
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There has to be a way or mechanism for the noise to get into the audio signal
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The interference must be of such a nature that it degrades the audio quality
Countermeasures can therefore attack at all three points, and we must consider the different cases separately.
sources of interference:
Some sources of interference are beyond the control of the HiFi system owner. These include e.g. B. Radio transmitters in the vicinity or industrial companies or devices in the neighborhood that pollute the power grid. As a rule, such sources of interference cannot be eliminated (or not legally eliminated). Some of them have already "fed" their interference into the power grid outside their own home, others can also be added in the last few meters (radio stations). Some sources of interference also have an intended function and therefore cannot be eliminated, e.g. B. the ripple control signal in the power grid, which is used to switch between night and day power.
Other disturbances, on the other hand, arise in one's own home and can certainly be turned off. It's important to mention this because removing the disruptor is often the easiest, cheapest, and most effective course of action. Unfortunately, there are more and more potential disruptors, parallel to the increasing "electrification" of the household. Some devices act as disruptors because they are simply defective. Some examples of such potential disruptors are: light dimmers, electric motors in household appliances, electronic halogen transformers, power packs for electronic devices (especially switching power packs), powerline modems (for using the power grid as a computer network). Clicking noise can also come from simple switches, especially when switching inductive loads.
Power supplies of electronic devices as a disruptive factor? Yes, indeed, and that means that hi-fi devices can sometimes interfere with one another or themselves. The chopper of a switching power supply is a potential source of interference, and so are the rectifiers in all types of power supplies. If they are not sufficiently suppressed, both can emit frequency components well above 50 Hz both into their own device, i.e. into the DC power supplies in their own device, and such interference into the supplying power grid. Because this has led to more and more problems over time, there are now regulations that a device manufacturer must comply with in order to be allowed to sell the device.
A device that interferes with itself is of course incorrectly designed in a certain sense and as a buyer you can hardly do anything about it, apart from complaining. A device that disturbs others can only be reproached if the permitted limit values are exceeded, i.e. it may wrongly bear the CE mark. If it stays within the limit values, you have to demand a higher immunity from the disturbed device. That brings us to the second point:
Interference path or interference mechanism:
Sources of interference are irrelevant if they don't manage to degrade the audio signal. If you cannot get rid of a source of interference, you can try to make the hi-fi system immune to it. There are also regulations for immunity in connection with the CE mark, failure to comply with which means that a device cannot be sold.
These regulations state that a device must be able to accept a certain amount of interference without failing and that it must not exceed a certain limit of the amount of interference emitted to the mains. As a side effect, you can roughly estimate the extent of interference in the power grid that you as a device manufacturer have to reckon with and can design your device accordingly. A minor drop in audio quality does not count as a malfunction, so it cannot be assumed that a device you buy will be completely immune to interference, just that it will not stop working properly because of it.
There are two principal ways interference can enter a device: through the air as an electromagnetic wave or through a connected cable. We are particularly interested here in the way of that power cable, and we are interested in the way in which a disturbance coming through the mains cable can get into the audio signal in the device. A look at the typical power supply circuits suggests that such interference is suppressed there by the already existing filtering and screening. Since interference is already generated internally by the rectifier, it is necessary to provide a certain amount of filtering internally. An external filter would be in the wrong place. Another possibility would be a non-optimal grounding, which could cause an interference signal to get past the filter and into the audio signal. However, ground routings are usually done very carefully in audio equipment.
If a device has an immunity problem, the first thing to do is to know what type of interference is causing the problem, because there is no filter or accessory that will address all types of interference at the same time. When a device is sensitive to DC components in the mains current, a very different type of remedy is required than when it is sensitive to radio waves. Since not all interference is coupled via the mains cable, it may also be necessary to attack it at a completely different point.
In general, the devices cannot be lumped together, i.e. each device has a certain immunity and one cannot assume that experience with one device can be transferred to another. It would be a task for product testers to determine if any immunity issues exist, i.e. if the device responds to certain types of interference with reduced audio quality. From this one can then derive which external measures may be necessary or promise success.
Degradation of the audio signal:
Not every interference that couples into the audio signal also causes a noticeable deterioration in the audio quality. On the one hand, the influence could simply be too weak, so that it might be measurable but no longer audible. On the other hand, it could play in frequency ranges that are inaudible anyway and leave the audible frequency ranges unaffected. An unmodulated broadcast carrier signal has z. B. often no audible consequences, only when a modulation is added (a broadcast program), this becomes audible. Powerline modems have z. B. Often a modulation, which is audio-wise like noise, so you might add some noise to the audio signal, but you won't produce any coloration in the sound.
Procedure for suppressing system interference:
From what has been said so far it should be clear that there is little that can be done with blanket statements and measures. Because devices have their individual characteristics of immunity and interference generation, experience with one device cannot be extrapolated to another, and since the interference present is not the same in every home, even experience in one home may not necessarily be extrapolated to another , even if the system should be identical. Statements like: "Power cord A sounds better than power cord B" or "Line filter X improves the Klang their investment” are therefore worthless because they are too general. In the vast majority of cases, the use of such special accessories does not change anything at all, either because the accessory has no appreciable effect at all, there is no corresponding interference, or because an existing interference does not match the accessory's suppression mechanism and is therefore not reduced becomes. In view of the multiplicity of the problem and the targeted disinformation that is operated here, success is often pure coincidence.
A planned approach starts with thinking: "Do I even have a problem?quot;?. Debugging a system so that it performs at its best is a detective game. Everyone has probably had doubts about the perfect condition of their system, but the first thing you should do is try to narrow down what indications of a fault problem actually exist. If you want to solve a murder, you should perhaps first make sure that there is no body at all. It is necessary to separate the hot from the false leads, and the facts from the deceptions.
Helpful indications or questions can be, for example:
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Does the system play differently well at different times of the day or days of the week? Can you spot a pattern there? Or does the pattern have less to do with the plant and more to do with how you just “on” it? is
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Is the sound somehow related to the operation of other devices, i.e. specifically: is there a specific device, either in the system itself or elsewhere in the household, that changes the sound when it is in operation?
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What do the loudspeakers say when the system is in operation but nothing is being played? Is it hissing, humming, buzzing or can you even hear a radio program very quietly? Neutral, steady noise is probably harmless if not too loud, but anything else indicates a source of interference. If the volume of the noise increases as soon as a certain device in the area is switched on, that is also an indication.
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Does the system produce pops or clicks when nearby bystander devices are turned on or off?
If the above questions do not yield any clues, then there is very likely no corpse either, which means the use of additional interference suppression devices such as shielded mains cables, mains filters or similar. will most likely have no noticeable effect and you can safely save yourself the investment.
If the above questions have actually brought clues to light, then it is either already clear where the error is or you can "harass" an expert with the knowledge you have gained, who can either recommend further investigations or advise you on a specific antidote. At this point it can also make sense to get a few different filters and try them out in the system.
As a rule, fixing a problem isolated in this way is easy and relatively cheap. Complex and expensive solutions are only necessary in extreme cases and it would often be better to simply replace the sensitive components with non-sensitive ones. Contrary to popular belief, it is not a mark of quality for an audio component if it is particularly sensitive to interference, quite the opposite. The particularly sensitive diva is a myth, insensitive divas can sing just as beautifully. The manufacturer of a device can design immunity into the device for a small fraction of the price that the end user would have to pay for external filtering measures. Therefore, an overly sensitive device is a sign of the manufacturer's carelessness or his willingness to compromise.
Disinformation:
Therefore, when I hear comparative tests of interference suppression accessories in the trade press, not to mention the statements made by the manufacturers on their websites, I regularly notice a few things that I don't like:
- The tests are often carried out on a "reference system", with the implicit assumption that it would "resolve" the differences particularly well. If it actually does that, that's confirmation of the quality of the system, but to me it means that the system - or its components - are not sufficiently immune to disturbances. The ideal reference system would be one that is very immune to interference even without special accessories and would therefore be unsuitable for testing interference suppression accessories.
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If a tested interference suppression component is particularly effective for a certain type of interference, but that type of interference did not occur during the test or does not belong to the types of interference to which the installation is sensitive, then the test will erroneously show that the component is ineffective.
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Sonic effects found during testing are often directly attributed to the tested accessories, notwithstanding the fact that the effect on a different installation or even in a different failure situation can be vastly different, including the possibility that the component has no effect at all.
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As a result of the test, a ranking between the individual components is established, regardless of the fact that the differences are often minimal from the outset and are also so dependent on the circumstances that another test at a different place, at a different time, with another system, or with other testers would have to come to a completely different order.
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What you still don't know as a potential customer is under what circumstances which product can be expected to improve on your own system. As a rule, such a test is not a useful aid for a purchase decision and the question arises as to what the point should then be.
In my opinion, it would make much more sense if normal hi-fi components were also tested for their immunity to interference. When testing one final stage could you e.g. B. couple a radio signal into the LS cable and see how the amplifier copes with it. Or couple the switching frequency of a switching power supply into the mains cable and see how much of it can still be found in the loudspeaker signal.
The result would be much more practical: if e.g. If, for example, an amplifier is sensitive to radiation in the LS cable, you might not want to buy it if you live near a radio station. The end result might even be that the manufacturers of the devices are already more eager for immunity. Accordingly, it would be less common to have to help the immunity with expensive and dubious accessories.
And what could also come out is that most of today's devices are already quite good in terms of immunity and that the expensive accessories are often used more for the good feeling than for any real improvement.