That's a good point - I tried a number of logic level mosfets. The one with the lowest drop was the IRL640. With this mosfet, at a load of 1A, the voltage drop was about 2.5V. That total drop includes some (0.3V?) dropped across the passive filter too....
The schematic i used was (post#51): Mean well vs generic power adapter vs audio oriented smps
Built mine on veroboard!
Attachments
Thanks for the book links Mark, I love the subtitles "A Handbook of Black Magic" and "Advanced Black Magic" .
Very good point about the ground being noisy in a poor setup preventing meaningful measurements. I used a differential configuration (pin 2 to PSU+ and 3 to PSU- on an XLR, using blocking caps in both) to feed the ADC it seemed to help reduce common mode noise. I just got the boards from konst so I'll get a couple of filters built for experimenting.
.Very good point about the ground being noisy in a poor setup preventing meaningful measurements. I used a differential configuration (pin 2 to PSU+ and 3 to PSU- on an XLR, using blocking caps in both) to feed the ADC it seemed to help reduce common mode noise. I just got the boards from konst so I'll get a couple of filters built for experimenting.
I've installed it inline with my B1 Korg Balanced version, works very,very well! Mark Johnson even suggested using two in series, I just finished another to try that as well. The B1 Korg is exactly what this filter is for, I have seen external versions inline, and the filter installed inside the enclosure with the B1 Korg.
Quote: Has anyone installed this circuit inside the Korg Nutube B1 pre- amp case or is this a no no? thanks
It is a YES YES!
Absolutely recommended and no problem whatsoever to be in the same casing.
Tried daisy chaining 2 but (perhaps as...) my B1 Korg is already tweaked re PS (low ripple PS + 2200uF caps), it made no real difference - but of course always worth a try.
Next step is to try Mark's enhenced version with the better caps and daisy chaining aswell. Whatever is best will come in the casing permanently with my B1 Korg.
Mark's filters are really good and nonexpensive, it is IMHO always worth to build a few more: you will always find an application sooner or later and of course you can experiment a lot of combos that way.
Have fun
Claude
It is a YES YES!
Absolutely recommended and no problem whatsoever to be in the same casing.
Tried daisy chaining 2 but (perhaps as...) my B1 Korg is already tweaked re PS (low ripple PS + 2200uF caps), it made no real difference - but of course always worth a try.
Next step is to try Mark's enhenced version with the better caps and daisy chaining aswell. Whatever is best will come in the casing permanently with my B1 Korg.
Mark's filters are really good and nonexpensive, it is IMHO always worth to build a few more: you will always find an application sooner or later and of course you can experiment a lot of combos that way.
Have fun
Claude
Hi safesphere,
I have several boards left over from a recent order. Please pm me with your address and I'll let you know the shipping cost. The boards are free.
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I'll be installing the filters inside the nutube case when the bench is clear of its current project. The plan is to use the slots in the sides of the case for mounting them without having to drill any holes.
Which leads me to another thought. The plan is to permanently install these filters in all of my current preamps (AKSA Lender, B1K, ACP+, Starving Student x 2). At some point in the near future I aim to put together a linear power supply to compare with the SMPS.
Is there any issue with using a linear power supply with these filters in circuit? I can't see that there would be, but I'm no expert in these matters.
Is there any issue with using a linear power supply with these filters in circuit? I can't see that there would be, but I'm no expert in these matters.
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
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
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 µV to even tens of mV of noise, a simple linear PSU often fewer than a few tens of µV. 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.
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 µV to even tens of mV of noise, a simple linear PSU often fewer than a few tens of µV. 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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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.
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.
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?'
So the question could be rephrased as 'Would it create any problems if used with a linear psu?'
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.
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).
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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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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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.
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.
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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!
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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