iFi AC iPurifier - Video Mini Series - The look, the tech, the lowdown. MORE ADDED!
Dec 28, 2017 at 5:02 PM Post #46 of 312
AC iPurifier
Part 2/5: Mains noise. A real bane.

Power supply noise is the bane of every audio system. There are always multiple sources of noise and they come from two main sources – inside and outside.

External noise is all around

This chart shows that noise is anywhere and everywhere and some of it inevitably ends up in the mains that supplies the audio system, due to the mains wiring acting as aerial. Most of the sources, we can do little about as they are found in everyday life such as radios or mobile phones.



The next chart shows the ‘local’ noise sources found in and around an audio system.


Local noise comes from hi-fi components

These sources of noise are found in hi-fi systems and come from three main sources:
  1. AC mains power supplies
  2. Switch-Mode Power Supplies
  3. Digital circuitry.


From left to right:
  • The first set of noise sources (10k > 10MHz) relate to AC supply rectifiers and their harmonics caused by Linear Power Supplies (LPS). Yes, they make a noise!
  • The second set of noise sources (67k > 200 MHz) is caused by Switch-Mode Power Supplies (SMPS). By comparison, these harmonics run in the higher frequencies.
  • The third set of noise sources (8 MHz > 500 MHz) is caused by digital circuitry, clocks and their harmonics. And this type of noise exists in the most upper frequencies.
  • You can see from the chart that the concentration of noise is from 30kHz upwards (the lower the dB, the less influential is the noise).

LPS vs SMPS

It is worth noting that, as much as LPS designs get a good reputation and SMPS designs get a bad reputation, the reality is somewhere in between. And the situation is dynamic.



First, LPS designs are on the whole, good and, on average, are quieter than poorly designed SMPS power supplies (which tend to be more for charging mobile phones and are not optimised for noise). This is why LPS is often perceived as superior to SMPS.

Hybrid and electric cars used to be shunned, yet they are now all the rage. We believe the same is happening for SMPS. These are now more environmentally-friendly and consume far less power. Whereas all SMPS used to be ‘noisy’, we are one of the few companies who have broken down the SMPS into its constituent parts and fundamentally re-designed it for audiophile use ie super low-noise. The iPOWER is the ‘Model 3’ of SMPS power supplies.

Nevertheless not everyone has an iPOWER at their disposal. It is therefore important to be able to effectively deal with normal SMPS noise which can be quite severe.

The next section explains which aspects of the AC iPurifier target the different groups of noise and how this compares to the common approach.

Stay tuned, there's more!
The images should probably say "Hz" on the X axis instead of "MHz", since the values themselves have the k/m qualifiers for kilo and mega.
 
Dec 29, 2017 at 6:20 PM Post #47 of 312
Because I know people are gonna state it, I'll be the first: I wonder if this is snake oil.

We'll just put it here: 2 PCBs and 109 parts in total.

A.jpg
B.jpg
 
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Dec 29, 2017 at 7:31 PM Post #48 of 312
Dec 29, 2017 at 8:20 PM Post #49 of 312
Dec 30, 2017 at 5:01 PM Post #51 of 312
BTW, this type of product and form factor is not new. Nordost has had their QRT line for a while:

http://nordost.com/qrt/qv2-ac-line-harmonizer.php


Lg-Qrt-Qv2_550.jpg

Our AC iPurifier was designed and build differently. It uses our proprietary ANC technology and serves as a useful diagnostic tool.

Besides, our policy is to not comment on other manufacturers' products. Plus, we know and respect the Nordost people and their products.
 
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Jan 1, 2018 at 8:41 AM Post #52 of 312
Has anyone actually purchased and tried these?

So, if I already have a power conditioner (in my case Isotek Solus), I would still benefit from this? Do I need two? One for the wall plug adjacent to the one that Solus is plugged and one on the Solus itself?
 
Jan 1, 2018 at 11:36 AM Post #53 of 312
Jan 1, 2018 at 12:23 PM Post #54 of 312
I wonder if I can still benefit from this if I already have a MOV-less Furman surge protector that attenuates EMI/RF?
 
Jan 1, 2018 at 2:49 PM Post #55 of 312
Thanks for the hint! Been checking for a while. Ordered one to try out.

I wonder if I can still benefit from this if I already have a MOV-less Furman surge protector that attenuates EMI/RF?

Probably, apparently they usually only filter higher frequencies, while this iFi one also tackles lower frequency noise (which I'd expect to be more audible, but I'm still new to all this).
 
Jan 1, 2018 at 2:57 PM Post #56 of 312
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Jan 1, 2018 at 3:30 PM Post #57 of 312
I wonder if I can still benefit from this if I already have a MOV-less Furman surge protector that attenuates EMI/RF?

Our return policy is generous, hence we strongly suggest to try it out for yourself.

Has anyone actually purchased and tried these?

So, if I already have a power conditioner (in my case Isotek Solus), I would still benefit from this? Do I need two? One for the wall plug adjacent to the one that Solus is plugged and one on the Solus itself?

As above, it's for the best to try it in your setup. As a starting point, one works just fine, but it all depends on how many products (and on what PSUs these are based) you have in your setup.

Please see here for further details:

https://ifi-audio.com/portfolio-view/accessory-ac-ipurifier/

In the following days we'll explain where AC iPurifier should be used.
 
iFi audio Stay updated on iFi audio at their sponsor profile on Head-Fi.
 
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Jan 1, 2018 at 3:31 PM Post #58 of 312
Our return policy is generous, hence we strongly suggest to try it out for yourself.



As above, it's for the best to try it in your setup. As a starting point, one works just fine, but it all depends on how many products (and on what PSUs these are based) you have in your setup.

Please see here for further details:

https://ifi-audio.com/portfolio-view/accessory-ac-ipurifier/

In the following days we'll explain where AC iPurifier should be used.


Yeah, I think one needs to find a good balance because too much AC filtering could actually hurt the audio.
 
Jan 1, 2018 at 3:41 PM Post #59 of 312
Nope. This iFi one only filters above 10kHz. Granted, perhaps that is lower than others, I don't know:

AC-2-2.jpg



from: https://ifi-audio.com/portfolio-view/accessory-ac-ipurifier/

I was looking for surge protectors the other days. I saw the Furman SS-6B, which just says "RFI/EMI Filtration". Then I saw the Furman PST-8 DIG, a total beast compared to what I'm used to, which says "> 40 dB from 150 kHz - 100 MHz, > 80dB from 100 kHz - 1GHz", which seems to start much higher. Though looking at it it more closely, that spec makes no sense. It probably should say 15 kHz - 100 kHz for 40 dB, unless it's somehow worse at filtering between 150 and 100 MHz than before and after.
The power conditioner Furman ELITE-15 PF I for instance says ">40 dB from 10Khz. - 100 kHz, >80 dB from 100 Khz. - 1GHz."

I was thinking of the 150 kHz spec when I mentioned "higher frequencies", but that looks funny to me now.
 
Jan 1, 2018 at 4:59 PM Post #60 of 312
AC iPurifier
Part 3/5: Active beats passive.


Passive filtration is the most common approach seen in aftermarket power supply accessories.

However, it is not without its limitations:
  1. It filters only in the very high frequencies in the high MHz region.
  2. To be effective, the capacitors must be large and this means bulky and costly.
Given these drawbacks, the AC iPurifier had to be different, more thorough and more comprehensive.

The solution for the AC IPurifier is active + passive sections for the most complete purification over the frequency range.

1. Active Noise Cancellation (ANC) - covers high KHz and low MHz ranges
2. Passive Noise Reduction (PNR) - covers the high MHz range
3. Intelligent Earth - connects to devices without earth to drain mains leakage noise to earth

The chart below illustrates the impact upon noise.



The black line represents normal noise found in a system with no remedy for it. It runs across the frequency range at 0dB as it is not reduced.

The red line represents typical mains accessories that have passive circuitry – these typically start to work at around 1 MHz.

The green line represents the AC iPurifier impact by starting at 10k and then reducing noise by up to 40dB all the way up to 100 Mhz! By comparison passive filtration starts much higher in the frequency range at 1 MHz so misses out on filtering two-thirds of the noise.

AC iPurifier against generic passive filters

As explained earlier, external sources of noise, from radios to TVs to mobile phones, are not concentrated in just one area as they contribute to noise across the frequency range.

The graph below shows how the AC iPurifier nullifies external noise sources across the frequency spectrum.

By comparison, the generic passive filter does not deal with certain radios and walkie-talkie type products.



With local sources of noise, these range from linear power supplies (yes they make noise!) to switch-mode power supplies to digital circuitry and all the related harmonics.

It should be no surprise that, with the AC iPurifier actively covering the frequency range, far more noise is reduced – by an impressive -45dB or so!

By comparison, with a generic passive filter, noise from linear power supplies and switched-mode power supplies remain with only some digital circuitry being attended to.

 
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