Anyone use an IEC line filter plug??

[djn]

I came across this and wondered if it would do anything to increase the sound quality of the pre-amp I'm building.


https://www.arrow.com/en/products/0...UFaQod4zIMvw&gclid=CI6ltPj36coCFQUFaQod4zIMvw

 

[lcsaszar]

Yes I use the same in my tube preamp, but I can't comment on the sound quality, since I haven't done an A/B test. I think it does not harm, but does not improve anything either, because RF interference is not an issue at my place.

 

[ericj]

They are mainly about common-mode rejection. It's basically a P-I filter.

If you have an sq issue that doesn't sound like RFI, it probably won't help.

Well, not more than a boutique power cord anyway

 

[Wavebourn]

When I do, I open it and cut off Y-caps.

 

[Shoog]

If there is a lot of RF interference from external sources such as radio stations, or if you have a lot of cheap Switch Mode Power supplies the power line can be carry ultra high frequency noise into you amp. This might be audible or not depending on the circuit and the build, it will just sound harsh and fatiguing. It will shine a spot light on any shoddy build practices by forcing them into instability and oscillation. These IEC filters are designed to isolate the circuit from the line and prevent these issues.
I use them when I have ones to salvage, but I have never gone to the trouble of actually buying one. They are much more important in digital circuits where the noise will actually introduce gross distortion into the data carrying signals.

Shoog

 

[mcandmar]

When I do, I open it and cut off Y-caps.

You probably already know this, but most manufacturers make "medical grade" versions which omit the Y-caps.

 

[Wavebourn]

You probably already know this, but most manufacturers make "medical grade" versions which omit the Y-caps.

Do you mean to buy them? Nope. I mean salvaged from computer power supplies. They are needed for UL certification, if you use SMPS.

 

[ArtG]

When I do, I open it and cut off Y-caps.

When you get them cut open, do you usually find metal film caps or ceramic "Y"caps? Metal film types are more likely to fail open.

 

[Wavebourn]

When you get them cut open, do you usually find metal film caps or ceramic "Y"caps? Metal film types are more likely to fail open.

They are always ceramic. I remove them because they add garbage to the chassis. Such filters are not for protecting the amp from the garbage in the power line. They are for protecting the power line from the garbage caused by a SMPS of the device where they are installed. Try for yourself such a filter in a preamp with unbalanced inputs. Connect a notebook as a source, and listen to the noise generated by a battery charger.

 

[Refugee1]

The capacitor across the supply can fail causing smoke and grime inside the equipment. I replace these with a "pulse" type that fails open circuit without producing the mess if you hammer it with 800V P/P pulses. They are rated at 1700V.

 

[DF96]

All X and Y caps are supposed to fail open. It seems that some do not, but at least they are designed to do it; you can't assume other caps will do this reliably.

 

[Max Martin]

I use Schaffner FN9262B-6-06 medical iec units bought from digikey. Very good quality and tight comnection. Other iec inlets from oter european countries and china have had issues. Plug would pop out for example. Also use RIFA 840 polycaps X2 10nf over the switch and 100nf over the secondary before rectifier.
Been using also Wima X2 mkp caps before and worked perfectly for over 10 yrs.