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

[rtate]

Was there ever a consensus on a substitute for the 2.2uH coil that is on back order ?

[ClaudeG]

Thanks Kasey

Do you perhaps have a schematic showing how you connected both SMPS at the input/main and at the output?

I had a look at the Mean Well you mentioned. My knowledge of SMPS is limited. My understanding is it might be feasible on some to connect + of one unit with - of the other to form the ground / amp 0V.

I would have thought though it depends on the technology used for the SMPS and would per definition only apply if not connecting any part of the SMPS to ground, that is having only on the side of the mains L and N connected with 120 or 240V AC depending on the country... and no ground.

Is that correct?

If so, how to ground the units? I know my old amps only have L and N but when dealing with a big Class A or AB amp with heavy dual voltage (say +40 and -40V and over 10A per phase and channel) I guess knowadays people would for safety reason have a ground at the mains?

Thanks again for your help, SMPS could open a brand new field of possibilities, if only it were quality dual phase...

Claude

[ClaudeG]

Re coils, mine are due in 2 weeks, and (chicken, I know...) I perfered to stick to what I knew and was recommanded. Enough variables and risks running my company - when dealing with hobbies they have to be quite straightforward :-)

Plus I would probably have the parts lying around, in time indeed but me not being available LOL - what are 2 extra weeks on MY audio projects?

Will though introduce a new variable in form of the latest caps... and report

Claude

[rtate]

Looking forward to your findings !!
Great info as usual !

[wg45]

I ordered the boards from JLPCB. It couldn't be any easier. Got them in a week or so.

Components came from Mouser. Yes, the coils are on back order, but I'm in no hurry. Figured I'd just get all the components on the same BOM as opposed to a Mouser/Digi Key split order.

It's easy to add the components and you can complete a board in 5-10 minutes.

[Mark Johnson]

oooooh. The super low ESR Nichicons. excellent.

[Monk55]

I bit the bullet & bought from 2 sources...got plenty of parts....waiting on boards to arrive...even have several different boxes.

[jean-paul]

Originally Posted by kasey197

Fwiw, here are some interesting measurements from stereophile between amps using linear vs smps supplies for your enjoyment.
Not at all a scientific comparison, but it seems at least plausible that some of the differences are due to the use of switching supplies.

This is a also a nice five min watch: Audio Myth - "Switching Power Supplies are Noisy" - Benchmark Media Systems


On another thread i also did measurements on some supplies and the effects of a SMPS filter..I didn't know at the time that there was already a project cooking on this else i'd have waited for an expert designed one! I'm really looking forward to trying out the design from Mark when its published!

post #41:
Mean well vs generic power adapter vs audio oriented smps

Cheers,

The Benchmark video is advertising and it is also not exactly the standard cheap SMPS as generally found.

What often seems to be forgotten is the pollution many SMPS produce at the mains side of things. And the RF emission .... the short life of many of them ... the wearing out of caps at the higher frequencies... the wining noise they often make ....

It is like class D, when that started people were complaining of cold sound, non musical blah blah. Nowadays class D is the new standard according to many The details are somewhat forgotten like lower weight when shipping from China, very little or no costly heatsink....

[Monk55]

These are so nice! Thanks Mr Johnson

[rikiheck]

There seem to be two pages at Mouser for the inductors. This one shows them in stock.