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Tweakers' Asylum: REVIEW: DIY by Jon Risch AC filter according to JR Power Conditioner/Surge Protector by Lukasz F.

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REVIEW: DIY by Jon Risch AC filter according to JR Power Conditioner/Surge Protector Review by Lukasz F. at Audio Asylum

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I have made the famous AC filter as designed by Jon Risch and I was very happy with it. My work was copied and we made 31 units by now. All people love them.
When I first saw Jon's design, I followed it without doubting anything.
After a while, when I saw that peoples interest is increasing and more and more clones are made everywhere, I decided to try to improve it if possible before it is too late (I mean before people make or buy the original version).

Let me cut to the bottom line: the inductors IMHO are made in a wrong way.
Now, my last and by far best filter revision has one inductor per outlet, not two. The live and neutral wires are wired TOGETHER on one ferrite ring. The idea is that the "wanted" current to the device powered via filter is causing magnetic field cancellation in the ferrite ring. For the wanted current the inductance is near zero. Only for the common mode RFI the inductance is doubled.
This approach reduces very much the unwanted choking of the power delivery (to the amps especially). Bass is free and unrestricted as it gets. Much better than from the wall direct. All aspect of the filter got better - the sound improvement is phenomenal in every aspect.

The new filter is a lot easier to make and looks neater too.

THE FINAL RECIPE:
input socket: put one 0,1 uF cap across live and neutral
one 0,01 uF cap across live - earth and one across neutral - earth
Paralell all caps with a MOV varistor 300V (for 220V world, 150V for 110 V world)

Split the signal into as many outlets as desired. Make one extra in case you add a component in the future like a DAC, a DVD or a preamp.

use solid core 2,5 sqmm insulated wire (not the lacquered motor wire). Take a color coded pair (like blue and brown) and hold together. Loop it in and out the ferrite ring three full turns, maintaining wires paralell. So in the end, looking at the ring you will see blue-brown-blue-brown .. etc. This way the magneting field coupling between the phases will be best.

The loose foot at each side of the ring should be twisted
Tie the ring to the box where desired plus secure it with hot melt glue. Wire it to the outlets (one side) and to the input socket (other side).

At the output put a 0,01 uF cap across live and neutral (not ground this time.)
The ferrite I use is 4 cm diameter, thickness of my finger. The bigger the better.

All copper ends must be solder tinted to prevent corrosion !!!

The earth wire should be broken by a switch near the outlets. This way you can switch the earth on or off, depending on hum problems.
I found it to be an absolutely necessary feature!
One outlet must have no switch - just permanent earth. Otherwise the safety can be compromised.

Speaking of safety, I use no power switch and no fuse. The hifi components have their fuses, and the house has its own. No need to duplicate fuses.

The ready filter takes 3 days to sound at its best. It is a good idea to put it on solid, non vibrating shelve, and not on a vibrating floor.

I recommend to use all screened AC cables from filter to hifi. Otherwise the already clean AC will catch RFI again.
I am absolutely sure you will be amazed.
Good luck.
Lukasz


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Topic - REVIEW: DIY by Jon Risch AC filter according to JR Power Conditioner/Surge Protector Review by Lukasz F. at Audio Asylum - Lukasz F. 10:03:53 07/15/00 ( 22)