Computer Audio Asylum

Posted by hfavandepas (A) on September 05, 2011 at 15:37:30

In Reply to: RE: Improving Hybrid Power Supply through filtering with coupled inductors. posted by theob on September 05, 2011 at 10:44:35

Hi Theo,

“Are you using smt’s or others?”
If smt’s stands for: Surface-Mount Technology, than I think the answer is: yes.
The ferrite based coils I use are inside commode mode filters which are designed for being mounted on a PCB.
Their physical appearance, physical size, circuit designs and specs can be fond in these brochures.
For the 230 AC mains filter block see:
http://www.schurter.com/var/schurter/storage/ilcatalogue/files/document/datasheet/en/pdf/typ_FPP-01.pdf
For the TDK data transmission line filter see:
http://www.tdk.co.jp/tefe02/e971_zjys.pdf

There is no real ration or special thought on my side in using these common mode filters.
The only reason I used these filters is: inside them there are (ferrite based) chokes/coils.
Also I had them lying around, thus at hand.

These filters are relatively cheap.
The Shurter AC mains filter (with 40 mH choke inside) cost: 4,02 euro.
See link: http://www2.conrad.nl/goto.php?artikel=534625
The TDK common mode data line filters are: 3,07 euro.
See link: http://www2.conrad.nl/goto.php?artikel=443410

I don’t advocate use of these filters. I just noticed that the (ferrite based) chokes/coils inside these filters are coupled inductors.
May be, or even probably, there are better coupled inductors available for use in filter with coupled inductors.

May be more knowledgeable inmates should comment and point at better suited coupled inductors for this purpose. But unfortunately most knowledgeable inmates around here on the PCaudio asylum are not interested (or don’t see the potential) of some extra filtering on the output of a linear PSU and or some extra filtering of the output of a Pico.
Pitty, because as you experienced yourself: IF DONE CORRECTLY, the sound quality greatly benefits from these filters.

The effect of these filters can be heard very clearly when applied ontoo the 3,3 DC volt psu line that is powering the digital part of the Juli@.
Minute changes in these filters on the 3,3 psu line, can be heard immediately in sound quality.

I now have applied coupled inductor based filters together with the ferrite+ caps based filters (which where already installed) on the lines that power the: SSD, the digital part of the Juli@ and the P4.
The effect is no less than breath taking. I think I now have some glimp at the ultimate sound quality which guys with an all linear PSU are enjoying.

I will let you know the SQ results when I also finished the P24 with coupled inductors filters.
Pairing the + and – wires are not important ihmo.
There is no saturation effect through DC-bias on the ferrites in this situation.
I just will just bundle all ‘-‘ wires and than simply ground all Lac coupled inductor-sides too it.

More to come.

Mark

fully optimized cMP2 PC -> ESI Juli@ -> Van den Hul Optocoupler MkII-> Lavry Black DA10 -> XLR Mogami Gold -> Klein & Hummel O300

Edits: 09/05/11