That's right!
A transformer, whether an isolating transformer or a low-voltage transformer, has a 230V primary winding and a galvanically isolated secondary winding. Current is transferred from the primary to the secondary winding by induction. The secondary winding is always a separate circuit.
A transformer, whether an isolating transformer or a low-voltage transformer, has a 230V primary winding and a galvanically isolated secondary winding. Current is transferred from the primary to the secondary winding by induction. The secondary winding is always a separate circuit.
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Most that try a good industrial or better medical one will not take it out of their system. Relatively light systems to playback at normal levels that is.
The audiophile stuff I don’t know. The ones I tried generally were large, expensive, bombarded with many marketing blah blah and full of useless features that seemed to be there to shorten their lifetime. Very good experience with an old Belkin type though.
As usual taking it back to the essence clarifies things. It helps to take a look at the other side of home installations too. No nanocrystalline coils or common mode coils there. What many not see is that their mains is polluted by the stuff they plug in 😉
Tip for those wanting to try: EI types have better natural filtering but their efficiency is lower and they very often hum. Toroids by the usual suspects are more efficient but they filter less good. Hum depends on brand and mains but with sub 500VA types rarely is an issue.
The audiophile stuff I don’t know. The ones I tried generally were large, expensive, bombarded with many marketing blah blah and full of useless features that seemed to be there to shorten their lifetime. Very good experience with an old Belkin type though.
As usual taking it back to the essence clarifies things. It helps to take a look at the other side of home installations too. No nanocrystalline coils or common mode coils there. What many not see is that their mains is polluted by the stuff they plug in 😉
Tip for those wanting to try: EI types have better natural filtering but their efficiency is lower and they very often hum. Toroids by the usual suspects are more efficient but they filter less good. Hum depends on brand and mains but with sub 500VA types rarely is an issue.
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I don't know how high-quality your system is or to what extent you've already dealt with line filters. I do agree with you on one point: the line filters available on the market are completely overpriced and not really tailored to the needs of individual customers. I also have no doubt that an isolation transformer can be the better solution. My intention wasn't to refute your experience with isolation transformers. I simply wanted to explain the reasons behind it. When I started dealing with line interference suppression over 20 years ago, I experimented with isolation transformers myself and achieved good results. Over time, I familiarized myself with the subject and came to the conclusion that the coil-based line filter was the better choice for my needs. Just like you, I was completely frustrated by the market offerings and the lack of research on the topic! Then I started building line filters myself and discovered that this was exactly the right path. My line filter took some work and cost me €175.
So far my setup is 200 for variac (20 pounds china) and 25$ for the DC blocker filters, add 10$ for inlet outlet, and 20$ box,
250 which is the price of some power bars alone, a variac made in USA of same size is 3000.
Belkin is good but they use very bad metal slag for their connectors, it is not copper.
250 which is the price of some power bars alone, a variac made in USA of same size is 3000.
Belkin is good but they use very bad metal slag for their connectors, it is not copper.
I had used this adjustable isolation transformer before. The noise suppression was okay, but the 3.2 ohm impedance also caused a loss of dynamic range.
This is the DC and EMI filter I built myself. It has two filtered outputs with different filters, one for the network player and one for the amplifier.
Never have an opinion based on just 1 case. That is an isolation transformer/variac combination used by the Romans. Something totally different from just an 1:1 isolation transformer.
The mechanical indicator in the switch (instead of a lamp or LED) indicates early seventies.
The mechanical indicator in the switch (instead of a lamp or LED) indicates early seventies.
I've heard various variacs in front of stereo systems. They all have their advantages and disadvantages. For me, the line filter is the best compromise. The device in the photo is a German variable transformer from the 1980s. I sometimes use it behind a generator.
Why add a high impedance variac? That is something different from a 1:1 transformer. Simple. A variac has a wiper. Variacs are generally also not meant to be used continuously in a circuit.
If we start to discuss stuff like is done now it becomes a question of taste and opinion instead of facts.
If we start to discuss stuff like is done now it becomes a question of taste and opinion instead of facts.
I played a lot with inline AC filters and decided not to use them. I felt pretty much everything that was stated in this test (as pros..??), word for word:
However, I do segregate all appliances with crap SMPS to one mains outlet, and all important hi-fi gear to other outlet... the segragation is the house wiring of some 20 meters long between two mains outlets, which works beautifully. Natural dynamics is preserved, but I also get improved spacial presentation, better bass and high frequency definition and extension, and everything sounds more natural and easy on the ear.
... but ultimately, the raw dynamics were affected too much, so I stopped using them.
However, I do segregate all appliances with crap SMPS to one mains outlet, and all important hi-fi gear to other outlet... the segragation is the house wiring of some 20 meters long between two mains outlets, which works beautifully. Natural dynamics is preserved, but I also get improved spacial presentation, better bass and high frequency definition and extension, and everything sounds more natural and easy on the ear.
it is in German and I can't see anywhere they measured the reduced dynamics.
It would be great if someone measure the dynamic reduction of the said variacs/transformers
It is like THD in amplifiers, there is barely no measurable difference with 10, 40, 80 watts on typical home loudspeakers, it is not measurable and even less audible. (given they all drive properly with accurate frequency)
The only real impact that could be measured well is the noise of the power supply contaminating the signal from impulse to stop. And it had nothing to do with THD.
the ear can determine a very slight difference in db. it could be so easy to measure it with a voltmeter and see a deviation of linearity of signal at various powers. Or with a sweep a reduction in loudspeaker performances.
I am damn tempted to use my 1000Va small chinese variac on my amp and see if I can measure anything.
It would be great if someone measure the dynamic reduction of the said variacs/transformers
It is like THD in amplifiers, there is barely no measurable difference with 10, 40, 80 watts on typical home loudspeakers, it is not measurable and even less audible. (given they all drive properly with accurate frequency)
The only real impact that could be measured well is the noise of the power supply contaminating the signal from impulse to stop. And it had nothing to do with THD.
the ear can determine a very slight difference in db. it could be so easy to measure it with a voltmeter and see a deviation of linearity of signal at various powers. Or with a sweep a reduction in loudspeaker performances.
I am damn tempted to use my 1000Va small chinese variac on my amp and see if I can measure anything.
I am not sure if it is possible to measure the loss in dynamics, as perceived by the human ear.
Also, it is apparent that the review/site is a product placement website for that particular filter box they reviewed, so they would not explicitly state a loss of dynamics in the review.
All moot points as mains voltage is fluctuating at the upper side too much for many transformers. This will be even worse with more solar and wind energy.
It will be SMPS to cure that whether we like it or not.
It will be SMPS to cure that whether we like it or not.
The loop resistance of the network can be measured via the voltage drop, of course only with filters, not with variacs! Every coil with a core has saturation behavior, this can be found in the respective data sheets. The harmonic distortion would have to be measured in a special circuit, but is irrelevant as long as the coil core does not saturate! 90% of the filters on the market do not use highly permeable coils, which means that the coils must have very high values and the internal resistance and saturation of the cores increases. In addition, such filters with simple ferrite cores require common-mode chokes for common-mode filtering, which increases Ri and core saturation. In addition, many filters use excessively large Y capacitors; asymmetrical damping should be kept as low as possible. For example, a Chinese ferrite core coil with a push-pull winding of 1.4 mH and 1.4 mm² wire has an internal resistance of approximately 0.16 ohms. A comparable Vitroperm coil from vacuum melting has a Ri of 0.03 ohms with significantly higher permeability and lower saturation behavior at 1.4 mH and 1.6 mm². Combining such a Vitroperm coil with a 4.7 uF X2 capacitor results in a lower cutoff frequency of approximately 2000 Hz (always depends on the variable resistance of the connected amplifier), which is an average value. If I double this filter to a 4th-order filter, I get an attenuation of 40 dB around 4000 Hz, which remains stable up to 100 kHz without driving the Ri high. I listen at home with a Naim amplifier and can't perceive any dynamic loss with this filter circuit, but I do get very good filter performance.
Thel Audio has good explanations of mains filters and there are also simple calculation principles; I have added two links.
https://www.thel-audioworld.de/module/Netzfilter/Netzfilter.htm
https://electronicbase.net/de/tiefpass-berechnen/#rc-tiefpass-rechner
Thel Audio has good explanations of mains filters and there are also simple calculation principles; I have added two links.
https://www.thel-audioworld.de/module/Netzfilter/Netzfilter.htm
https://electronicbase.net/de/tiefpass-berechnen/#rc-tiefpass-rechner
This filter from Puritan costs over €1500. It uses large common-mode coils (the large yellow coils on the right) and simple ferrite coils. This line filter is not suitable for power amplifiers; dynamic losses are clearly audible, which has been clearly confirmed by numerous tests.
Well-functioning line filters are only available through DIY!
Well-functioning line filters are only available through DIY!
It does not help to publish stuff by companies that earn money by selling mains filters. I have yet to read a negative review by them regarding mains filtering. Remember that the stuff we use usually is meant to plug in in a wall socket directly and you can do without. If there is a pollution problem one can persevere in finding the best filter but the situation and the pollution maybe change by the hour. Then it is fighting wind mills with a panzer.
Many in this hobby exxagerate issues so that the issues themselves become the hobby. This can be noticed with (for instance) aversion against caps, aversion against class D, aversion against opamps, aversion against industrial parts without gold lettering and aversion against anything modern.
Never got around to the why of this. The dogma usually also stays for years or decades. The issue of interest can always be fine tuned (never solved) but the setup as a whole may have imperfections that stay unnoticed. Seen it so many times that I take anything and certainly myself with a grain of salt. Then I play an album.
Many in this hobby exxagerate issues so that the issues themselves become the hobby. This can be noticed with (for instance) aversion against caps, aversion against class D, aversion against opamps, aversion against industrial parts without gold lettering and aversion against anything modern.
Never got around to the why of this. The dogma usually also stays for years or decades. The issue of interest can always be fine tuned (never solved) but the setup as a whole may have imperfections that stay unnoticed. Seen it so many times that I take anything and certainly myself with a grain of salt. Then I play an album.
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If you look at the coils in my homemade filter, you'll notice that they have just four turns (1.6mm², 10cm long). The internal resistance is difficult to measure, and the required low cutoff frequency is achieved using a very large X2 capacitor. Dynamic losses are not audible with this filter as long as the amplifier's power consumption remains below 400W.
You talk and talk without ever having built a line filter or even heard a homemade one. You have consistently held preconceptions that you can't substantiate. I'm trying to demonstrate a viable approach to solving certain problems, and you keep arguing against them, even though you've apparently never really studied the subject matter. Thel actually provides good explanations. The link to the refraction principles is also rather non-commercial, and I cited the Puritan filter as a bad example, so it's not really an advertisement either!