audio power supply optimizaton

[look&listen]

(from 'Mutec REF 10 Masterclock' thread)

Posted yesterday at 02:22 PM, barrows said:

"Remember, relatively thin aluminum (under an inch thick) has virtually no magnetic shielding ability, so the box itself does very little." 

 

Posted yesterday at 04:31 PM,  JohnSwenson said:

"This actually is not true, I did a research project on this many years ago and found out that thick aluminum (greater than 1/4 inch) actually IS a fairly decent magnetic shield. AC magnetic fields generate eddy currents in the aluminum, which produce their own magnetic fields that oppose the original field. How effective this is depends on the frequency of the original field and the resistance of the metal. For a 60Hz field and 1/4 inch aluminum you get about 6db attenuation, at 1/2 inch it is 12db, and at 1 inch you get about 24db. I would say that is better than virtually nothing, its not huge, but it can make a significant audible effect.

The normal much thinner aluminum plates used for electronic enclosures, are pretty useless for magnetic shielding. For some reason it is common to use the thick aluminum for the front panel, but the top and bottom have very thin plates. If the devices used 1/4 inch for top and bottom plates you would have 12 db attenuation when stacking them. But VERY few companies do that.

John S."

 

@JohnSwenson how would ordinary steel, cast iron, & distance compare with 1/4" aluminum magnetic shielding ?

I have 3 PSU boxes to stack. Many ideas to separate, little data.

Thanks for previous info.

L&L

 

PS. Someones asked for new Power Supply tweaks thread in Mutec thread so Ok, it is here. Listening and measures all good.

 

[JohnSwenson]

Steel has decent magnetic shielding, so you don't NEED the thick panels, BUT magnetic materials also have other problems, they can saturate, which does weird things to their effectiveness. Whether this will be a problem depends on the material type, just normal steel will probably be fine for the fields generated by normal transformers. But you DO have to be careful with special magnetic shielding materials they can saturate if close to the source.

 

There is also hysteresis and energy storage. This can distort the magnetic fields producing higher order harmonics which produce a buzz rather than a hum. 

 

This is why I personally like thick aluminum, you never have to worry about the problems of using magnetic materials.

 

As to what to use, I use 1/2" thick aluminum to put under my components. But that is just me, it is by no means a "this is always is the best"

 

John S.

[Summit]

Much of the difference between Innuos Zenith Statement and ZENith Special Edition seems to be related to its power supply and better enclosure.

• Double-enclosure, linear power supply
• New power supply architecture designed in partnership with Dr. Sean Jacobs.
• AC to DC conversion stage in a separate enclosure to isolate transformer vibration and EMi emissions.
• Regulation stage within main system enclosure to shorten the clean DC power path

https://www.audiologica.co.uk/product/innuos-zenith-statement/

[Ralf11]

which Al alloy is the best one to use???

[look&listen]

21 hours ago, JohnSwenson said:

Steel has decent magnetic shielding, so you don't NEED the thick panels, BUT magnetic materials also have other problems

 

I need stack 3 LPSU boxes vertical (all same dimensions). All have R-core transformer (100VA, 60VA, 30VA) on same end so too close is problem. With high performance PSUs for audio increasing specs to audible millionths, mag. field isolation should be similar range. But equipment space is constrained, and no tools to measure fields.

 

LPSUs Alu. case skin 2.3mm thick. Rubber feet only 8mm high.

Try wood frame (old cassette tray) for 66mm air separation (ugly).

Have 40mm high cast iron (smoker) box, also good heatsink (then all stack one thermal mass).

 

Then think of Alu. slab with rubber feet, copper slab/composite, steel slab, or ?

If they good shields, then problem of source for needed sizes (17cm x 25cm x ??) to solve.

Searching "magnetic shielding" yield conflicting rating of metals of my interest so no direction of solution there. No interest in Mu metal (cost & fickle).

Hope experience of CA can help

 

[Cornan]

I use EMI foam under selected components, but have a temporarily stalled mind-project where I want to wrap top, sides and bottom with cooper mesh and run 1-4 drain wires from from the tube ends like a giant JSSG or a open back/front Faraday shield if you like.

 

(Picture is just to show the mesh)

 

I would be very interested to hear other peoples thoughts about it! ?

[auricgoldfinger]

8 hours ago, Cornan said:

I use EMI foam under selected components

 

Do you have a link?

[Cornan]

15 minutes ago, auricgoldfinger said:

 

Do you have a link?

 

Here you go! ?

https://hollandshielding.se/Ledande-skum

 

 

[tims]

Heres a good diyaudio link discussing magnetic sheilding:

http://www.diyaudio.com/forums/tubes-valves/154198-magnetic-shielding-aluminum.html

 

In it they discuss a product called "Giron"; an alternative to mumetal and sold here:

http://www.lessemf.com/mag-shld.html

This LessEMF shop appears to sell everything related to magnetic field shielding from MuCord (low EMF wiring) to an Upper Body Shield!

 

 

[auricgoldfinger]

45 minutes ago, tims said:

Heres a good diyaudio link discussing magnetic sheilding:

http://www.diyaudio.com/forums/tubes-valves/154198-magnetic-shielding-aluminum.html

 

In it they discuss a product called "Giron"; an alternative to mumetal and sold here:

http://www.lessemf.com/mag-shld.html

This LessEMF shop appears to sell everything related to magnetic field shielding from MuCord (low EMF wiring) to an Upper Body Shield!

 

 

 

I actually put Giron inside one of my bedroom walls because the electrical sub-panel is on the exterior wall directly opposite my head when I sleep.  It works pretty well in reducing the EMF.  (I have a meter.)

 

I put MuMetal across one of my audio shelves.  It does an excellent job of reducing EMF and made an audible improvement by blocking radiation from devices and cables on the shelf below.  It's not an elegant solution but that is not an issue given its location. 

 

Giron is more expensive than MuMetal.  Neither is very attractive.

[look&listen]

1 hour ago, tims said:

Heres a good diyaudio link discussing magnetic sheilding:

http://www.diyaudio.com/forums/tubes-valves/154198-magnetic-shielding-aluminum.html

 

Thanks all for good links!

 

Here is one I found;  https://www.magcraft.com/permeability-and-saturation

about - Permeability and Saturation

pro - good at communicating concepts. very readable.

con - missing graph images (inet rot)

 

[RickyV]

What about this one. 

https://www.vitalitools.nl/yshield-mcl61-folie-voor-afscherming-magnetische-wisselvelden

 

or Google yshield mcl61, is a sort of mumetal but with cobalt. 

[Superdad]

2 hours ago, tims said:

... an Upper Body Shield!

 

Perfect for we knights on the quest for the holy [audio] grail!  

(Now I can't help but whistle the theme song from the Monty Python movie...)

[JohnSwenson]

On 4/30/2018 at 11:42 AM, Ralf11 said:

which Al alloy is the best one to use???

The best magnetic shielding happens with the highest electrical conductivity, good choices are:

 

6101

6063

1100

 

The very common 6061 is not as good as these, but still quite a bit better than the high strength alloys.

 

The effectiveness is a combination of the alloy and the thickness, the result is that it is usually cheaper to go with a slightly thicker piece of 6061 than a thinner piece of the above alloys.

 

I'm using 1/2" thick 6061 in my system.

 

So if you are poking around ebay for some slabs of aluminum for shielding, don't go with the 7075 or "aircraft grade" good old 6061 will work better.

 

John S.

 

[Albrecht]

39 minutes ago, Superdad said:

 

Perfect for we knights on the quest for the holy [audio] grail!  

(Now I can't help but whistle the theme song from the Monty Python movie...)

Next we'll be telling each other that our father's smelt of elderberries. 

[Jiffi32]

9 hours ago, Albrecht said:

Next we'll be telling each other that our father's smelt of elderberries. 

And our mother's were Hampsters

[look&listen]

Saved tab to read link from CA thread "Excerpted  from The Sound of the Machine
The Hidden Harmonics behind THD" by  Lynn Olson, 1997.

http://www.nutshellhifi.com/library/FindingCG.html

Interest in sounds of distortion info good, but last 1/3 page has writing about Power Supplies & Noise Spectra. Please read to explain some LPSU (optimization!) issues. Remind me of good John Swenson post. Seem think similar - sound engineering!

sample below,

"The current demand for Class AB fluctuates a great deal, especially for transistor amplifiers that typically idle at a few watts. This means the noise spectra of the power supply (which extends into RFI frequencies) is always changing with the music.
This might be the single greatest advantage of choke-fed supplies; at least the current pulse through the rectifier is much wider and not significantly affected by current demand. It also looks like folks who are stuck with bridge-capacitor supplies (the worst kind) for heater supplies and solid-state amplifiers might be wise to slow down the bridge with modest values of resistance, rather than leave the damping to the unpredictable value of ESR in the first filter cap. This is probably the reason why adding a film bypass cap makes this type of supply sound worse; as a result of the film bypass decreasing the effective ESR, the current pulse is speeded up and EMI emission increased."

[sandyk]

31 minutes ago, look&listen said:

This is probably the reason why adding a film bypass cap makes this type of supply sound worse; as a result of the film bypass decreasing the effective ESR, the current pulse is speeded up and EMI emission increased."

 

 Yet many people use low ESR main filter capacitors.

Personally, I find this has a tendency to "harden" the sound with Solid State amplifiers.

[look&listen]

Just finish 3 stage ultra low noise LPSU of new & old parts, so show pictures & description. Also mark 100th post ?

Got nice black anodized Alu. case & hardware (match other LPSUs) (from Slovenia via Singapore to US!).
New 30VA China r-core transformer replace old EI type.
Add John Swenson transformer snubber (JSTS) circuit.
1st stage regulator is Audiowind LT1963 PCB, but replace old fast recovery rectifier diodes for Schottky's, wire power status LED at front panel.
2nd stage is ldovr 1A LT3045 PCB, with Kemet A750 560mfd Alu. Polymer output cap.
3rd stage is ldovr 1A LT3045 PCB, with Kemet output cap (thx to Stammheim/Cornan)
Add switch & wire to choose Swenson Ground Tweak (JSGT)

 

 

Notice Waco ‘Lever Nuts’ (32A) for heavy multi-primary wiring. Keep 1 PCB screw terminal for heavy secondary wire & snubber mount. 1st stage PCB mounts on drilled standups, 2nd & 3rd stage PCBs suspended to good 18g wire & foam blocks. Also drill careful holes & scrape paint/copper to mount caps to PCB. Important must heat sink Alu. Polymer caps for soldering to keep properties good.

 

Regulator #1 adjust output +8.90V, reg. #2 fixed output +8.02V, reg. #3 fixed output +7.12V, to power USB device.

 

 

DC cable; 2C microphone connector, Beldon #9418 15g star-quad wire, Oyaide right-angle 2.1mm barrel connector. Shield is wired for JSSS (‘John Swenson Shorted Shield’ (JSSG is not sense to me, so not use it!)). I wait & see on POE/360 experiments.

 

 

Now needs time for burn-in & listening to many things in many ways. Later maybe try to put hearing experience to feeble words.

 

[sandyk]

1 hour ago, look&listen said:

1st stage regulator is Audiowind LT1963 PCB, but replace old fast recovery rectifier diodes for Schottky's,

 

Did you notice any obvious improvement from replacing the HER303 diodes ?

[Cornan]

1 hour ago, look&listen said:

Just finish 3 stage ultra low noise LPSU of new & old parts, so show pictures & description. Also mark 100th post ?

Got nice black anodized Alu. case & hardware (match other LPSUs) (from Slovenia via Singapore to US!).
New 30VA China r-core transformer replace old EI type.
Add John Swenson transformer snubber (JSTS) circuit.
1st stage regulator is Audiowind LT1963 PCB, but replace old fast recovery rectifier diodes for Schottky's, wire power status LED at front panel.
2nd stage is ldovr 1A LT3045 PCB, with Kemet A750 560mfd Alu. Polymer output cap.
3rd stage is ldovr 1A LT3045 PCB, with Kemet output cap (thx to Stammheim/Cornan)
Add switch & wire to choose Swenson Ground Tweak (JSGT)

 

 

Notice Waco ‘Lever Nuts’ (32A) for heavy multi-primary wiring. Keep 1 PCB screw terminal for heavy secondary wire & snubber mount. 1st stage PCB mounts on drilled standups, 2nd & 3rd stage PCBs suspended to good 18g wire & foam blocks. Also drill careful holes & scrape paint/copper to mount caps to PCB. Important must heat sink Alu. Polymer caps for soldering to keep properties good.

 

Regulator #1 adjust output +8.90V, reg. #2 fixed output +8.02V, reg. #3 fixed output +7.12V, to power USB device.

 

 

DC cable; 2C microphone connector, Beldon #9418 15g star-quad wire, Oyaide right-angle 2.1mm barrel connector. Shield is wired for JSSS (‘John Swenson Shorted Shield’ (JSSG is not sense to me, so not use it!)). I wait & see on POE/360 experiments.

 

 

Now needs time for burn-in & listening to many things in many ways. Later maybe try to put hearing experience to feeble words.

 

 

Very nice and well thought of piece of work L&L! ? I would be very interested to hear your subjective impressions after your thorough listening session. You might even want to add another Kemet right at the DC output (soldered to the back pins of the outlet). It is clearly worth a try IME and easy to remove if you do not like it! ?

[look&listen]

22 minutes ago, sandyk said:

Did you notice any obvious improvement from replacing the HER303 diodes ?

No, only one of many changes together. No fun to try each alone. Did listen to LT3045 PCB (deeper detail), then Kemet A750 cap (subtle) for positive SQ changes on old LPSU. For new build LPSU initial impression to soon for talk.

 

26 minutes ago, Cornan said:

You might even want to add another Kemet right at the DC output

No, only 50mm wire difference. Think better to put one inside powered device after all cable & close to end use, but different problems. Also, not happy with sensitive PCBs and caps outside metal case in EMI soup!

 

[Cornan]

4 minutes ago, look&listen said:

No, only 50mm wire difference. Think better to put one inside powered device after all cable & close to end use, but different problems. Also, not happy with sensitive PCBs and caps outside metal case in EMI soup!

 

My point was also to put it inside the case and not outside the case (even if one Kemet on each side of a ~80mm cable without shielding but with distance between the -Ve & +Ve wires improves on the outside as well). As close to the inside pins on DC output as possible. Unless you will use this LPSU specificly for ethernet devices the removal of JSSG might actually improve SQ.

[chauphuong]

On 5/1/2018 at 12:36 PM, Cornan said:

I use EMI foam under selected components, but have a temporarily stalled mind-project where I want to wrap top, sides and bottom with cooper mesh and run 1-4 drain wires from from the tube ends like a giant JSSG or a open back/front Faraday shield if you like.

 

(Picture is just to show the mesh)

 

I would be very interested to hear other peoples thoughts about it! ?

Where can I find that wrapping material? Thanks

[Cornan]

2 minutes ago, chauphuong said:

Where can I find that wrapping material? Thanks

 

This project is still temporarily stalled, so I have´nt actually started to look for the material. But after a quick Google for copper mesh  I found this https://www.amazon.co.uk/Mallard-Metals-Copper-Mesh-approx/dp/B00XGMCRX2

There is a lot more out there!