Found Power Line Filter - Any Good?

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mfrimu

Member
Joined 2004
Hi,

[newbie learning]

My friend has a few of these Fax Machine Power Line Filters. Rated 360W. Seems like a big choke or coil + some capacitors. The usual MOVs

What do you think? Is it worth using? I'd scrap the phone line side of the PCB.

I was thinking it would work both ways, keep some digital noise from going in the power line and keep noise from coming into my amps....

I was also wondering if it would be feasible to use 4 of these in parallel to feed a power bar. It would be less bulky.

Thanks !
 

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M

mfrimu

Member
Joined 2004
Thanks, but [newbie] what's a CNC ? Are you referring to the coil ?

Agreed that the quality of the components is average, in a normal situation I would not bother, but I have a few of these on hand, if they would make a difference... Would not hurt (make things worse) to put them to use, either as is or by using only some components such as the coil.

I have no experience or clue where to start looking. I assume its a RFI filter.
 
A

AndrewT

R.I.P.
Joined 2004
RFI/EMI is emitted by the filter.

The BEST way to minimise this emitted interference is to enclose the whole filter inside a screening case.
That screening case should be electrically connected to the Chassis where the mains cable feeds in.
The gaps in the electrical connection of screen to chassis let in interference. The gap length determines the frequencies that leak past the screen into the Chassis.
Keep the gaps short. There are many 1Ghz to 4GHz transmitters in a house !
 
M

mfrimu

Member
Joined 2004
3

31697B

Disabled Account
Joined 2012
They can be quit useful and effective.... but usually the filtering is at too high a freq to be of max benefit for music system apps.... larger Cap values would help some. The CM coils look to be good for loads other than a power amp. The 'surge' protection is a bonus. With several on hand, you can string them in series and plug the noisiest products at the end of all the filter line furthest away from any rfi sensitive gear. [metal enclosures are preferred, as already said]

THx-RNMarsh
 
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M

mfrimu

Member
Joined 2004
So I could plug my DAC and CD player on 4 of these filters each?

If I understand correctly, they will stop RFI from going into the power line?

Thanks !

RNMarsh said:
They can be quit useful and effective.... but usually the filtering is at too high a freq to be of max benefit for music system apps.... larger Cap values would help some. The CM coils look to be good for loads other than a power amp. The 'surge' protection is a bonus. With several on hand, you can string them in series and plug the noisiest products at the end of all the filter line furthest away from any rfi sensitive gear. [metal enclosures are preferred, as already said]

THx-RNMarsh
Click to expand...
 
Destroyer OS

Destroyer OS

Member
Joined 2005
CMC's when correctly sized don't no exhibit a negative effect. The problem is a bunch of geniuses have used incorrectly sized/spec'd ones that might be low noise, but are not correct for audio power necessities that exceed most things in terms of current, peak, and end result from them.
 
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