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So has anyone measured how the IFI Audio AC Purifier is supposed to work?

Yviena

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#1
And does it even do anything, I'm considering buying it if it actually does clean up the mains power from dimmer, refrigerators etc.
 
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Yviena

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Thread Starter #3
I briefly tested one. It had no effect whatsoever on performance of a Dac. It does get warm and wasted power however.
Hmm i see, so it doesn't do anything at all to mains power, emi/rfi, common mode noise etc?
 

solderdude

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#4
It probably does do something about EMI/RFI, common mode noise etc.
That does not mean this has audible consequences and that measurements/performance is 'improved'.
Amir mentioned it did not have any influence on the performance which is very, very likely.
That does not mean the connected gear did not receive 'cleaner' power.
The tested device just had more than sufficient PSRR and works equally well on 'normal' mains power as on 'clean power'.
When one has fairly normal mains such a device does nothing as the components aren't triggered.

In MOST cases audio equipment is designed so it is at least tolerant to FCC/EMC rules and the rest of the equipment in the house is too.
Provided the equipment is used and connected as prescribed.
This is easily measured but NOT with the AP with standard audio tests.

I some cases ground loops can cause garbage to enter the audio path and reach audible or detectable levels.
 
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Yviena

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Thread Starter #5
It probably does do something about EMI/RFI, common mode noise etc.
That does not mean this has audible consequences and that measurements/performance is 'improved'.
Amir mentioned it did not have any influence on the performance which is very, very likely.
That does not mean the connected gear did not receive 'cleaner' power.
The tested device just had more than sufficient PSRR and works equally well on 'normal' mains power as on 'clean power'.

In MOST cases audioequipment is designed so it is at least tolerant to FCC/EMC rules and the rest of the equipment in the house is too.
Provided the equipement is used and connected as prescribed.
This is easily measured but NOT with the AP with standard audio tests.

I some cases ground loops can cause garbage to enter the audio path and reach audible or detectable levels.
I do get some rare buzz/humming sound when the dimmers are used, do you thing it will help then?
 

solderdude

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#6
The best thing to do would be to address the origin of the generated mains crap.
Dimmers and FL or cheap Chinese LED ligthing can be sources of huge mains polution.
Equipment SHOULD be immune to this.
This means one should use a dimmer with a better mains filter (some only have a common mode coil) or filter the wires to and from the dimmer as close as possible to the dimmer.

The ifi device appears to be a MOV (over voltage protection device) that can limit overvoltage.
Combined with a capacitor + lower voltage MOV's (Voltage Dependent Resistors) so it could lower crap on the mains by dissipating it in 'heat'.
It also has some fancy LED's with associated electronics to let them light up.
It won't filter crap < 10kHz anyway so all audible range 'crap' is not addressed anyway.

It is possible that some of your audio equipement may not be connected 'correctly' to mains.
Try this before you invest in all types of devices. maybe this could already solve the issues. If not one needs to look further.
 
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Matias

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#7
The conditioning part measures the noise in your AC line and injects it back counter-phase to null it. Plus test LEDS, overvoltage protection and fancy grounding features.
 
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Yviena

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Thread Starter #8
The best thing to do would be to address the origin of the generated mains crap.
Dimmers and FL or cheap Chinese LED ligthing can be sources of huge mains polution.
Equipment SHOULD be immune to this.
This means one should use a dimmer with a better mains filter (some only have a common mode coil) or filter the wires to and from the dimmer as close as possible to the dimmer.

The ifi device appears to be a MOV (over voltage protection device) that can limit overvoltage.
Combined with a capacitor + lower voltage MOV's (Voltage Dependent Resistors) so it could lower crap on the mains by dissipating it in 'heat'.
It also has some fancy LED's with associated electronics to let them light up.
It won't filter crap < 10kHz anyway so all audible range 'crap' is not addressed anyway.

It is possible that some of your audio equipement may not be connected 'correctly' to mains.
Try this before you invest in all types of devices. maybe this could already solve the issues. If not one needs to look further.
Hmm my country's power network doesn't really have polarity (Norway) I believe they run it balanced with 120v on each leg for 240vac.
 

solderdude

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#9
Then the trick does not work.
As you can easily check for the effect you can try plugging in some mains plugs 180 degrees rotated and check if things improve or not.
Maybe experiment with grounding ?
 
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solderdude

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#10
The conditioning part measures the noise in your AC line and injects it back counter-phase to null it. Plus test LEDS, overvoltage protection and fancy grounding features.
As can be seen it does nothing in the audible range (below 10kHz) acc. to their own plot:

No attenuation below 10kHz.


The active noise cancellation is a very old trick that was already used by JLH called the ripple eater.
This was for DC and did work in the audible band.


You can't do this for AC as that already consists of AC with lots of harmonics.
Funnily enough in their manual it shows a picture that shows 40dB noise reduction even at 1Hz.
This is a pretty nifty feat to suppress the 50/60Hz mains with 40dB.

One would normally call that a 100:1 transformer.
 

Matias

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#11

solderdude

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#12
Yes I know...
one big 470V MOV (Varistor that clamps at 775V) in series with a fuse and some 2kV capacitors.
A capacitor that supplies DC voltage to some LED's and the ground current detector (no idea what that could do other than let an LED light up).
Nothing high-tech fighter yet stuff.
 
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Yviena

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Thread Starter #13
Yes I know...
one big 470V MOV (Varistor that clamps at 775V) in series with a fuse and some 2kV capacitors.
A capacitor that supplies DC voltage to some LED's and the ground current detector (no idea what that could do other than let an LED light up).
Nothing high-tech fighter yet stuff.
So that opposite Phase Cancel they tout is BS?
 

solderdude

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#14
It seems to be for anything below 10kHz anyway.
There are small value capacitors in it so lower frequencies (below 10kHz) cannot possiblly be 'injected back'
One would need to have a look at the schematic to see what they are doing.
 
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pozz

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#16
So that opposite Phase Cancel they tout is BS?
It would really amazing if they accurately use phase cancelling at those frequencies.

@DonH56 Do you have an opinion from your RF days?
 

DonH56

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#17
Phase cancellation can work to many GHz but I have no idea exactly what this thing does and have not read their description (long day, just home and practiced a bit after dealing with a dead car battery on the way home :( )... I can think of several ways to suppress noise but wouldn't bother as most power supplies do just fine on their own. I suspect the actual noise suppression is not that flat to 100+ MHz but too many unknowns, including just how high a noise level it can handle. At its simplest, you just need a wideband unity-gain inverter, so a few transistors will do it. I built a circuit like that in the primordial past to suppress dimmer noise, but naturally all I learned was the noise was radiated and not coming over the power lines, something I should have known without wasting time on a fancy active suppressor circuit (that was definitely not UL-approved at the time!) It was a fun project based on a simple idea that worked OK (though was not designed for >10 MHz).

Anyone have a schematic?

FWIW, my current day job deals with 10+ GHz signals and sub-ps jitter. I no longer do mW/mmW stuff; most of the harmonics are dead somewhere over 20 GHz though we characterize to 40 GHz just to CYA and because some specs require it. Still, higher than most audiophiles can hear, and than most speakers can reproduce. ;)
 

Wombat

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#19
Phase cancellation can work to many GHz but I have no idea exactly what this thing does and have not read their description (long day, just home and practiced a bit after dealing with a dead car battery on the way home :( )... I can think of several ways to suppress noise but wouldn't bother as most power supplies do just fine on their own. I suspect the actual noise suppression is not that flat to 100+ MHz but too many unknowns, including just how high a noise level it can handle. At its simplest, you just need a wideband unity-gain inverter, so a few transistors will do it. I built a circuit like that in the primordial past to suppress dimmer noise, but naturally all I learned was the noise was radiated and not coming over the power lines, something I should have known without wasting time on a fancy active suppressor circuit (that was definitely not UL-approved at the time!) It was a fun project based on a simple idea that worked OK (though was not designed for >10 MHz).

Anyone have a schematic?

FWIW, my current day job deals with 10+ GHz signals and sub-ps jitter. I no longer do mW/mmW stuff; most of the harmonics are dead somewhere over 20 GHz though we characterize to 40 GHz just to CYA and because some specs require it. Still, higher than most audiophiles can hear, and than most speakers can reproduce. ;)

10 GHz plus. Are you now a soprano? :eek::facepalm:

;)
 
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