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I simply use ordinairy line filters. The can be found everywhere.

Hi Theo,


Yes I still use this 10:1 ratio. But there is no real calculation or knowledge behind this ratio. I just copied values that I red in 2 documents on decoupling (the Murata paper and the Altera paper).

> I would like to see a link to these devices to understand them better. <

Nothing special about these filters. They all have the same schematics and they are widely used. You will find them everywhere. Since they are cheap, it’s an easy way too combine 2 chokes in a handy enclosure onto one can easily solder the PSU wires. I don’t connect them too a real earth. It’s just the chokes I’m interested in. It’s easy too create a 3 order filter with them. I place caps before and after chokes so I can experiment with much higher capacitance values.

Ontstoringsfilter 0,6 A (Conrad Electronic)
http://www.produktinfo.conrad.com/datenblaetter/525000-549999/534625-da-01-en-Printfilter_0_6_A_5500_2000.pdf

On the 12 V DC power line which powers the Pico, I use one which can handle 1,6 amps. On the P4 12 V DC power line I use one which can handle 0,6 amps. I chose hight mH values. The Voltage drop across these filters is about 0,3 – 0,4 Volts. But this is easily corrected through raising the output voltage of the linear PSU’s a little. I’m really amazed that these filters give a profoud positive SQ effect on the 12 V DC power line which powers the Pico. Not in my wildest dreams I would have expected this. It was audiodan who suggested trying this.
7 or 8 ferriets on the 12 V DC power line to the Pico have no effect. I expected this. But I didn’t expect 2 x 6mH chokes + caps placed BEFORE the Pico too have such an effect.

So the last stop, before the top (an all linear PSU) is no longer a hybrid PSU solution (P24: Linear PSU + Pico and a Linear on the P4)
The last stop before the top is: a hybrid PSU solution with heavy filtering. What filters and what way is the most easiest DIY solution, still has too crystallize from experiments. So far I found:
- caps + (much)ferrites + caps give a nice sound quality improvement and is easy to do. But It only effective in the mega Hertz regions.

- The Pico uses the LM2642 chip from National Semiconducter which has switching frequency of 300 kHz. This frequency (and harmonics) should also be filtered. So chokes have too be brought in.
Using ferrite based coupled chokes which can be found in these ready made line filters is an easy way the experiment with chokes in the P4 12 V dc power line.
Too my (big) surprise these filters also had big effect on SQ when placed on the 12 DC power lines that power the Pico on the P24. So cheap linear bench PSU’s (50 – 90 euro’s) may give a nice SQ pop, but the output of cheap linears appears to be very noisy somehow. I see no other explanation for the very significant SQ improvement when ferrites, caps and/or chokes are used on the outputs of a linear.

My overall conclusion is:
A hybrid PSU solution is no longer the last stop before the top (an all linear PSU).
The last stop before the top is: a hybrid PSU with heavy filtering.

I hope other inmates with more skills and knowledge will join these filter experiments.
When done right: ferrits + caps give a real significant SQ improvement, but will not deal with the 300 Khz swithing frequency from the Pico.


> What really baffles me is that with my old mobo I got a significant sq pop but not on my new mobo. Maybe it needs more breakin time, maybe its the difference between an ES2L and an S2L Ga-G31m mobo.<

I’m not a member of the ‘breakin school’. I don’t ‘believe’ in it the way audiophiles handle the subject.
I also don’t think it’s the difference between mobo’s types. I used several brands and types and the difference are very little too none.
I really have absolutely no clou on what is wrong and what might be the cause, as all details about your setup and connections matter very much.


Mark

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