iFi audio AC iPurifier - Let no noise go unsilenced!

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

  3. Mediahound
    I'm certainly anxious to give it a try. :)
  4. Mediahound
  5. iFi audio
    Yup, updated. Thanks!
    Alcophone likes this.
  6. iFi audio
    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.
  7. thyname
    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?
  8. Matias
    Alcophone likes this.
  9. Mediahound
    I wonder if I can still benefit from this if I already have a MOV-less Furman surge protector that attenuates EMI/RF?
  10. Alcophone
    Thanks for the hint! Been checking for a while. Ordered one to try out.

    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).
  11. Mediahound
    Nope. This iFi one only filters above 10kHz. Granted, perhaps that is lower than others, I don't know:


    from: https://ifi-audio.com/portfolio-view/accessory-ac-ipurifier/
    Last edited: Jan 1, 2018
  12. iFi audio
    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:


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

    Yeah, I think one needs to find a good balance because too much AC filtering could actually hurt the audio.
  14. Alcophone
    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.
  15. iFi audio
    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.

    Last edited: Jan 3, 2018
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