PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc

Im thinking it works, for me in my setup, because the safety ground, aka analog ground is floating to my DAC, balanced.
And an two way active where I have an MA12070 at HF which dont't like long speaker cables and I have 5 meter coax to my to DAC:s...
That 5V power that is bad and an amp that have an SMPS without any ground give ****.
And then this clean up amazingly!
It sounds stupid I know.
But never had so good HF!
It just cleaned up the sound.
 
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I built some of these for some years agoe and tried them around but never heard any difference but today I tried one
beacause I had some whining sound from my new DAC and it lowered it remarkabel!
I don't say it all disappeared but it payed of this board now. :)
Thanks!
And Merry Christmas!
To address whatever is left, I'd recommend checking out @Mark Johnson 's post earlier in the thread about how to test the output to see where the switcher's noise is centered around and how to measure if the filter is squashing it or not.

--Tom
 
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One wrinkle -- with some of the little "brick" DC-DC converters, more than a few tens of uF on the output will trip the overload protection. I found this to be the case with the recently arrived PO89ZB kit bought from the DIYAUDIO store.

The image below is of a XP Power 24V 6 Watt unit. Probably won't make a difference with a higher output DC-DC converter.
 

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For those you could redesign the circuit. Increase inductance by 100X , and also decrease capacitance by 100X: Bob's your uncle. Now instead of 2 x 470uF you've got 2 x 4.7uF. Check to make sure the new inductors are rated for 3 amperes DC or more. You may need a new and different PCB layout to accommodate the physically larger inductors. If so, while you've got the layout on your drafting table, you could shrink the PCB footprint for the tee-ninecy capacitors.

It might be cheaper, or simpler, or both, to merely buy a different DC-DC converter. Members have mentioned good success with Triads and MeanWells, hooked up to PO89ZB, here on this thread. Review the old messages for specific model numbers.
 
One wrinkle -- with some of the little "brick" DC-DC converters, more than a few tens of uF on the output will trip the overload protection. I found this to be the case with the recently arrived PO89ZB kit bought from the DIYAUDIO store.

The image below is of a XP Power 24V 6 Watt unit. Probably won't make a difference with a higher output DC-DC converter.
What you are likely experiencing is that the capacitance the power supply brick you are using cannot handle and that is either in part because of the caps in the filter, but could also be what appears at the input of the device you are powering (or both). @Mark Johnson posted on this earlier in this but suffice to say, if the PSU doesn't list these values it likely cannot push through much input capacitance and thus will cyclically trip the over-current protection. Try a different PSU like a Triad or a Meanwell. Also keep in mind that higher Amperage ratings on these will not necessarily fix your issue.

What I've found after some painful experience with this is to take Mark's advice and only use PSUs that will reveal their max capacitance. This is why you will find that most if not all of the store kits now only supply reputable / well-known brands like Triad Magnetics or Meanwell, to name a few.

--Tom
 

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I’ve found it’s on a wall-wart by wall-wart basis. Not all of the big names are guaranteed to make it past hiccup, and the “cheap” ones might do just fine. You have to try and see.

Generally speaking though, the bigger name wall-warts have lower noise overall and are worth using for that reason.
 
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For those you could redesign the circuit. Increase inductance by 100X , and also decrease capacitance by 100X: Bob's your uncle. Now instead of 2 x 470uF you've got 2 x 4.7uF. Check to make sure the new inductors are rated for 3 amperes DC or more. You may need a new and different PCB layout to accommodate the physically larger inductors. If so, while you've got the layout on your drafting table, you could shrink the PCB footprint for the tee-ninecy capacitors.

It might be cheaper, or simpler, or both, to merely buy a different DC-DC converter. Members have mentioned good success with Triads and MeanWells, hooked up to PO89ZB, here on this thread. Review the old messages for specific model numbers.
What is the max current the PCB/traces can handle (assuming appropriately scaled components)? We've been using 48V @3A as the max (which is printed on the PCBs too).

--Tom
 
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At the moment, I don't know of any active high current (> 3 amperes) SMPS filter projects. Keep in mind that higher current SMPS manufacturers include cooling fans, to ensure reliable operation of their SMPS. The acoustic noise from the fan may be unacceptable to some builders. In that case you don't need a high current filter because you won't be using a high current SMPS which includes an acoustically noisy fan. Possibly two fans if your amplifier has a bipolar supply.
 
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Hi @Mark Johnson ! To power the Topping E30II I use Mean Well RS-50-5 and of course PO89ZB which significantly improved the sound quality which fascinated me. This filter is a perfect device. Whoever recommends a smartphone power supply for the DAC should definitely use the PO89ZB.
On the other hand, you have many mini (???) amplifiers (ayima, fosiaudio, topping ...) which use SMPS power supply and which with a good filter would give a much better sound. Let's take the V3, which has built-in excellent components from world-respectable companies, but the power supply. With a better power supply it can give a much better sound. But there is no way to find a "good soul" who will offer these users a quality filter on the power supply. A whole series of these filters is offered on AliExpress, but I am not an expert to assess their quality according to the image, and I have neither the knowledge nor the desire to play with them.
So it's constructors' turn! There is room for a businessman!!!