[bmichels]

interesting. I just hope it is not one more "black magic" item !

 

[DeeKay10]

You have got to be shittin' me...

 

[Zapp_Fan]

Active noise cancellation is suggesting that it is not filtering anything, but rather injecting its own noise in the form of the inverse of the deviation from a clean sign wave, hoping that the injected noise cancels out the already present noise, much like noise cancelling headphones do.

That means it first measures the current noise, then generates the opposite noise and injects it into the system, but by then the noise will have changed slightly, so some noise remains, even if it otherwise works perfectly. Again, much like noise cancelling headphones, which suck at cancelling sudden sounds.

I'm wondering whether this thing can effectively cause noise echo, where it's trying to cancel out noise it injected itself...

Hmm, again my ignorance is probably showing, but ANC requires the signal and noise to be separate, otherwise you don't know what signal to flip. This device only sees one signal coming in, the power from the wall. Since we know it is not regenerative (?) it's not generating its own 60-cycle wave to compare the noise to.

So maybe it's actually using common mode rejection or something? Does that generally work on AC power? I actually don't really have a clear idea of what the signal and noise waveforms coming out of an electric socket look like.

 

[Alcophone]

Hmm, again my ignorance is probably showing, but ANC requires the signal and noise to be separate, otherwise you don't know what signal to flip. This device only sees one signal coming in, the power from the wall. Since we know it is not regenerative (?) it's not generating its own 60-cycle wave to compare the noise to.

So maybe it's actually using common mode rejection or something? Does that generally work on AC power? I actually don't really have a clear idea of what the signal and noise waveforms coming out of an electric socket look like.

I am not an electrical engineer, so I don't know for sure, either. But Jason said this:

To, er, "contribute," we recently had a discussion about "power regeneration" for the smaller AC-powered products (you know, Magni, Modi Uber, stuff that uses wall-warts.) It's technically feasible to do something like feed a 60Hz sinewave into a Jotunheim and use it to output a perfect 60 Hz, 14VAC wave to power our smaller products.

(There's more after, but this is the relevant part)

So if you measure the voltage, you can lock on to the phase of the underlying 60 Hz signal. Then you know what you should be measuring and what you are measuring, and the difference between the two is noise.

 

[Alcophone]

What I like about this approach is that it makes A/B testing super easy. Just continue to listen, as you insert/remove the power conditioners. No need to turn your main equipment off.

 

[iFi audio]

First, we need to assure everyone that no snakes were hurt in the making of the iPurifier AC and no snake oil is contained in the product, the only oil in the production chain is crude oil that provides the basics for the plastics used.



Is there a scientific basis for the function of the device? Certainly and we can measure significant attenuation of noise on our 2.5GHz RF spectrum analyser between the AC iPurifier inserted and removed.

Indeed using additional plug in capacitors to filter HF noise is not exactly new and tends to be fairly effective at higher radio frequencies. However both practicality and safety agency requirements mean the values of these capacitors have to be fairly low and their effect is thus limited to higher frequencies, often > 1MHz.

In modern EMC (electro-magnetic compatibility) testing, typically frequencies below 150kHz are not included and frequencies below 500kHz allow relaxed levels of noise emission.

So many power supplies (even linear ones) release fairly large levels of noise in these frequency bands while passing all EMC standards. And it is often these lower RF noise components that cause trouble in audio systems and that are not easily filtered inside of audio gear either (no matter how diligent the designer is).

Going active allows us to address especially this < 500kHz noise rather effectively. This way the AC iPurifier achieves very wide bandwidth compared to simple passive capacitor based plug in devices.



Our ANC uses a simple analogue forward circuit, which is very fast and is backed by and hands over to capacitor based passive filtering for high frequencies. So there is no "noise echo" or any such problem.

Where the active circuit is fast enough to provide the opposing noise it kills noise, where it becomes too slow passive filtering through capacitors takes over.

The use of active noise suppression in mains powered systems is not exactly new, it has been used in large scale industrial applications for a while. It's application in domestic power systems to reduce mains born noise at frequencies much lower than possible using passive means and specifically to improve audio systems.

===========================

A single AC iPurifier is fine to use and provides significant objective noise reduction. More than one unit in use increases the noise reduction in our measured tests more than the expected simple doubling/tripling etc. and provides wider bandwidth of noise suppression as well.

Further, as any noise has to "pass by" the AC iPurifier placing it between "noisy" devices and "noise sensitive" devices improves the situation more for noise sensitive devices than placing it at the beginning or end of a power extender strip.

==============================

A note on the surge suppressor. These devices are in parallel with the mains, they are not resettable circuit breakers - instead their function is to limit any voltage between live/neutral by drawing extra current.



This current drawn to limit the voltage to safe levels may very well trip conventional current based circuit breakers, but the MOV is NOT a circuit breaker in itself. It also needs no re-set, if the surge is over it simply stops drawing current to limit the voltage.

===============================

We'll release our tech notes soon, so stay tuned!

 

[Alcophone]

First, we need to assure everyone that no snakes were hurt in the making of the iPurifier AC and no snake oil is contained in the product, the only oil in the production chain is crude oil that provides the basics for the plastics used.



Is there a scientific basis for the function of the device? Certainly and we can measure significant attenuation of noise on our 2.5GHz RF spectrum analyser between the AC iPurifier inserted and removed.

Indeed using additional plug in capacitors to filter HF noise is not exactly new and tends to be fairly effective at higher radio frequencies. However both practicality and safety agency requirements mean the values of these capacitors have to be fairly low and their effect is thus limited to higher frequencies, often > 1MHz.

In modern EMC (electro-magnetic compatibility) testing, typically frequencies below 150kHz are not included and frequencies below 500kHz allow relaxed levels of noise emission.

So many power supplies (even linear ones) release fairly large levels of noise in these frequency bands while passing all EMC standards. And it is often these lower RF noise components that cause trouble in audio systems and that are not easily filtered inside of audio gear either (no matter how diligent the designer is).

Going active allows us to address especially this < 500kHz noise rather effectively. This way the AC iPurifier achieves very wide bandwidth compared to simple passive capacitor based plug in devices.



Our ANC uses a simple analogue forward circuit, which is very fast and is backed by and hands over to capacitor based passive filtering for high frequencies. So there is no "noise echo" or any such problem.

Where the active circuit is fast enough to provide the opposing noise it kills noise, where it becomes too slow passive filtering through capacitors takes over.

The use of active noise suppression in mains powered systems is not exactly new, it has been used in large scale industrial applications for a while. It's application in domestic power systems to reduce mains born noise at frequencies much lower than possible using passive means and specifically to improve audio systems.

===========================

A single AC iPurifier is fine to use and provides significant objective noise reduction. More than one unit in use increases the noise reduction in our measured tests more than the expected simple doubling/tripling etc. and provides wider bandwidth of noise suppression as well.

Further, as any noise has to "pass by" the AC iPurifier placing it between "noisy" devices and "noise sensitive" devices improves the situation more for noise sensitive devices than placing it at the beginning or end of a power extender strip.

==============================

A note on the surge suppressor. These devices are in parallel with the mains, they are not resettable circuit breakers - instead their function is to limit any voltage between live/neutral by drawing extra current.



This current drawn to limit the voltage to safe levels may very well trip conventional current based circuit breakers, but the MOV is NOT a circuit breaker in itself. It also needs no re-set, if the surge is over it simply stops drawing current to limit the voltage.

===============================

We'll release our tech notes soon, so stay tuned!

Awesome response, thanks a lot! I appreciate that your product is basically vegan
I'll get one just to try it out.

 

[Matias]

@iFi audio when will it be available?

 

[iFi audio]

@iFi audio when will it be available?

The official launch date is already in the past, hence the product is already available. Please feel free to ask your local iFi representative about it.

 

[Matias]

I checked all 4 us dealers on your website, including your own Amazon page, and still not available. I suppose I have to wait a little more for them to list it.

 

[Swetone Audio]

Unless this device has been tested and approved by UL, then anyone using it is taking a big risk.
Extraordinary claims require extraordinary proof, preferably provided by an independent testing laboratory.
I cannot find any reference to "industrial active noise cancelling" for AC power.

 

[Matias]

There are hundreds of power conditioners for audio on the market. I don't know why people are so impressed by this one.

 

[iFi audio]

I checked all 4 us dealers on your website, including your own Amazon page, and still not available. I suppose I have to wait a little more for them to list it.

It might take them a while to do this, hence direct mail is the best shot.

 

[iFi audio]

interesting. I just hope it is not one more "black magic" item !

Please take a look at extensive tech nfo we provide for our products. As we wrote, AC iPurifier will have its own as well. That's neither black magic nor snake oil approach, but proper R&D instead.

 

[sinkr]

Bah, looks like a great way to needlessly eat up power outlets!