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PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
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Old 23rd January 2021, 09:20 AM   #351
ClaudeG is online now ClaudeG
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I will let Mark respond, but my guess would be no issue from an electrical POV.

On the other hand, it has a dedicated high Fc, appropriately for HF SMPS vs LF harmonics with conventional linear supplies, so not its best performance range...

Idea...perhaps Mark will have the ultimate filter answer for conventional PS aswell :-)
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Old 23rd January 2021, 09:38 AM   #352
jean-paul is offline jean-paul  Netherlands
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Point being that a good linear PSU does not need such a filter It is meant to polish SMPS as these are very noisy. When going for a quality linear PSU this drawback does not exist and adding a filter meant for SMPS is simply superfluous. This filter is meant to improve mediocre cheap ready made SMPS power supplies as these are apparently more suitable for beginners or something like that. It is not the best thing since sliced bread. The generic SMPS has hundreds of ÁV to even tens of mV of noise, a simple linear PSU often fewer than a few tens of ÁV. The lower the better so normally one tries to design a linear PSU with lowest noise possible which directly defies the use of an extra filter while even the best SMPS will improve from adding this PO89ZB.

Simplified: linear PSU are generally low noise by design, SMPS are generally high noise by design. The best SMPS have linear regulators in them to solve that .... or an extra filter at the output.

It would be OK to add a mains filter in any case. SMPS have their habits there and linear PSU's also benefit from filtering mains voltage.

* As a challenge I obtained new old stock military linear PSU's made in 1998. No replacement of caps and only powering them on and leaving them for a few hours. Well, these were directly better than the polished SMPS.
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Last edited by jean-paul; 23rd January 2021 at 10:02 AM.
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Old 23rd January 2021, 09:44 AM   #353
JohnnoG is offline JohnnoG  United Kingdom
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I have a Question about the Mains Filter.
I don't do EE or tinker with electronics

A board I sent to a Friend has been built and is being passed around a few friends.
I am now in possession of it, but can't use it on a loaned KB1 I have, as it has a internal Power Supply, so no external Jack Plug.

As an alternative usage for the filter,
I have a Valve Hybrid Phonostage which has a Jack Plug - Walwart Power Supply - Motorola - Input 240V - 2A / Output 12V - 3.5A .

Can the Filter be used on this Phonostage ?

Could the new 6A Filter be used on the Phonostage ?

Thanks in advance of any info supplied.
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Old 23rd January 2021, 10:03 AM   #354
SuppersReady is offline SuppersReady  United Kingdom
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PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
I understand that it doesn't require the filter with a linear psu. The question arose due to aesthetic considerations. Do I have a little box at the back of all my preamps or fit them inside as a permanent fixture? For now, I can continue with my test boxes until the linear psu is made.

So the question could be rephrased as 'Would it create any problems if used with a linear psu?'
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Old 23rd January 2021, 10:05 AM   #355
jean-paul is offline jean-paul  Netherlands
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It wouldn't make anything better unless you have the absolute crappiest of linear PSU's. With any good quality linear PSU it won't help anything and possibly make it even slightly worse. It would be better to build them in the casing of devices as outside stuff is not the most mechanical stable in most cases. When reversed: what is the benefit of keeping it outside? Nothing.

Quote:
Originally Posted by JohnnoG View Post
I have a Question about the Mains Filter.
The PO89ZB is an OUTPUT filter for filtering the noise created by SMPS in low voltage DC applications. A mains filter is to filter RF out of mains voltages so either 115V or 230V AC. The mains filter filters incoming RF (and also outgoing RF in the case of using an SMPS).
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Last edited by jean-paul; 23rd January 2021 at 10:33 AM.
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Old 23rd January 2021, 10:06 AM   #356
ClaudeG is online now ClaudeG
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Yes, mainsfilter was what I meant (it was just joking BTW), as good old CRCRC don't need any extra output filter :-)
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Old 23rd January 2021, 10:07 AM   #357
jean-paul is offline jean-paul  Netherlands
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A good old CRC without regulator is only used by the tube guild/class A devices etc. In any low power solid state device or any precise low power piece of electronics a CRC is followed by an ultra low noise regulator for let's say a low impedance low noise stabilized 5V. Adding an filter to that is like most things extra simply superfluous and not based on technical reasoning.
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Last edited by jean-paul; 23rd January 2021 at 10:34 AM.
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Old 23rd January 2021, 10:15 AM   #358
ClaudeG is online now ClaudeG
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Hmm... Jean-Paul, I was refering to my solid state power amp, 40V and many amps... I prefer don't to think about the correspnding regulator set up ;-)

There are still Class A and A/B amps around, and they aren't tubes - I know heresy in Class D times :-)

EDIT: having said that I am about to redesign the PS of my high biased Class A/B and want something quite definitive re quality, so would welcome any comments. Time permitting will be posted in the FSSA thread and inputs are very welcome Jean-Paul.

Last edited by ClaudeG; 23rd January 2021 at 10:20 AM.
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Old 23rd January 2021, 10:19 AM   #359
jean-paul is offline jean-paul  Netherlands
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Exception to the rule while the thread/discussion is about PO89ZB meant for low voltage low power DC and meanwhile mains filtering (often forgotten but also important).

Again a side step so allow me: actively regulated linear PSU's are also good for power amps but that is difficult when class A or heavy amplifiers are built. Also the losses and thus heat are significant. Since I don't play more than 1W I decided to try out very simple low power amplifiers with oversized transformers regarding current, ideal rectifiers, uLDO so regulation as this now is manageable. Recommended!
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Last edited by jean-paul; 23rd January 2021 at 10:27 AM.
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Old 23rd January 2021, 10:30 AM   #360
ClaudeG is online now ClaudeG
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Very interesting
To avoid polluting this thread, any link perhaps?
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