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

[Halauhula]

Originally Posted by Mark Johnson

The custom is: when somebody buys a lot of boards and finally manages to sell off the very last PCB,

The very next person who posts "Hey, who will sell me one of these boards?", becomes the organizer and funding manager of the subsequent group buy. That way there's always a group buy underway. Attempting to dodge the Organizer responsibility carries a penalty: you don't participate at all.

Very wise words. I will start to research doing this myself and give away the extras for those in the US.

[strongbow60]

I have two boards left over. That is, I have no components for those. Will send inside Europe only (not sure about GB customs etc).

[Monk55]

[QUOTE=Mark Johnson
Thank you very much...I just placed my first order EVER for PCB's to JLCPCB. Jeez it went fast!

[elwood625]

I completed five of these filters, I have one installed inline with the Meanwell SMPS for my Balance B1 Korg preamp. After listening to my system with it installed last night, I'm very impressed with the change in sound quality.
I think everyone who uses an SMPS with the B1 Korg should have one installed.
To help others, I have seven (7) extra boards. PM me you name and address (USA only), and I will mail you one of the PC boards, no charge. Please, one per member.

[Mark Johnson]

VERY nice build, elwood625! Congratulations. Re-purposing a barrel jack male-to-female extension cord, is a great way to get heavy gauge conductor wires and low resistance molded plugs & jacks. So you're introducing the lowest possible series resistance. So you can (if you want) try the experiment of connecting more than one of these filters in series, between SMPS and audio gear.

[elwood625]

I had not heard of putting them in series. Easiest A-B test I've ever done.

I love your work!
Can't wait for your higher amperage version, I have two ACA's with the Meanwell SMPS,

Thank You!

[Mark Johnson]

Hi amp version is undergoing listening tests right now, in Pass amps neither built nor owned by me. (to avoid "proud parent" bias in the listening results). We are not in a big hurry. Wouldn't it be cool to completely eliminate the power transformer from Pass amps that include a signal-handling transformer from Edcor or Cinemag or Jensen? Like the F6 or the M2x? Yes, IF you could make SMPS work in those amps, it would be cool.

[elwood625]

I am a builder, not a designer, I don't understand why an SMPS would be an improvement for my M2x. Since you mentioned the F6, which also has a signal-handling transformer, there might be a reason the power transformer degrades the sound.
How?

[ItsAllInMyHead]

Very cool builds, elwood625!

My guess is that it may not be an improvement necessarily. However, it could be for some depending on their implementation of the existing linear supply. Big toroids are known to emit varying amounts of EMI at audio frequencies just due to their inherent design and mains AC power frequencies. The signal transformers in the F6 and M2 variants among others can "pick up" that EMI through inductive coupling (I think that's the correct term), and it can produce audible hum that many people have gone to varying lengths to reduce whether it be a potentially more expensive power transformer, a larger chassis, physical shielding for power transformers and/or signal transformers, wiring layout, rotating donuts, etc. etc.

I am not knowledgeable enough to know the relative levels in Tesla of the EMI, but I do think the frequencies of the change in a SMPS are well outside the audible frequency band. So, if there is any inductive coupling to the signal transformer, it might be unable to be heard, and it might be at a much lower level.

I don't have an M2x or F6 in a chassis at the moment, but my next experiment would be to hold a laptop supply near my signal transformer and see what happens. I may try it with a Iron Pre

Separate but related, a builder could have one "power brick" outside the amplifier chassis to add distance and flexibility, which could also allow smaller overall amplifier chassis volume (if desired). It could also be easier to have a much larger distance between the power supply and the signal. It could also be easier and potentially more cost effective for FW clone addicts (self-admitted) to have one power brick to move between amps. If this type of thing were available early on, it may have also made me a bit less apprehensive about my first build. I wouldn't have needed to fret over mains AC power (as much) and its relative associated dangers to me and components. I haven't been in the hobby long. However, I see a lot of questions and (stealing ZM's word) ookups on mains wiring and PSUs in general. Something like this could make a lot of builds more approachable to more hobbyists separate from the F6 or M2 variants.

I'm excited just by the idea even if I don't have a clue how it would all come together or work. This is just a WAG, and maybe a bit of a SWAG, but even if I'm half right re: some of the reasons and associated benefits, it's neato.

[ClaudeG]

Some progress re casings for the 8 units to be build (as additon to 1 directly integrated in the B1 Korg and another already at a friend's).

Gilles did a splendid job finding nice sleek casings from China. Looks good to me, and do far more justice than my jerry-rigged handcraft :-)
Same for cables, plug etc.
The device holding the cable to the casing is a tad bigger than anticipated, but still very nice IMHO. The box is very small, don't get fooled by the pix.

BTW, these is still the "old" filter, with original initial caps. I will keep it so for comparison purposes (vs all other filters with the latest upgraded caps), well noting I have the parts to upgrade it aswell later. So quite confident in the end result, although not really expecting anything mind blowing, it works already great...

Last step is experimenting on the best way to hold the board in the casing: blu-tack, double-sided adhesive tape, scratch... or in fact a combo of these to make it last and safe. Nearly settled by Gilles...

Thanks Mark and Gilles

Claude
PS: Mark, that new high current SMPS filter from yours sounds more and more amazing... and attracting!