Power supply inductors (what specs?)

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#21
I'm just following Kristijans circuit for Aleph 5 power supply which has transformer, bridges, 2 x 47,000uF followed by 3.9mH followed by 2x 22,000uF

Are you saying the caps should be the other way round?

Why are air cores better than ferrite or iron?
 
#24
Hi,

Some Rdc in the coil takes good care of the surge voltage as the magnetic field collapses.
Keep the final cap 2x to 3x the capacitance of the one before the inductance. Working voltage in a PSU cap is way lower than what it can handle in a ms. We normally find much higher than V+ rated caps in a Zen's suppply anyway. The market is full of 50,63,80V good caps as needed for class AB PP amps and the like.
I recommend to use a 20uf polyprop cap directly on the source mosfet V+ connection with a dedicated return cable to star earth.
Use 1/3 the thickness of PSU wire for V+ and speaker terminals than the one for PSU earth.
Star earth the amp and speaker on the edge of a 10cm long wire tapped off a -PSU caps star subjunction.

Regards

N.S.
 
#26
Bertie said:
Do we know electricaly what differance the air / iron / ferrite cores have in a CLC supply application.

I don't doubt you that "iron cores sound muddy" but I was wondering the technical reasoning.
Click to expand...

I've used really big inductors in a line amp's choke-input PSU (big ol' Hammond 1.5 H chokes) and there hasn't been any trouble at all, sonically speaking. Then again, there isn't a whole lot of current being drawn.

Perhaps in a power amplifier the current is high enough to saturate the core?

Erik
 
#28
Hi,

Here is my proposed wiring scheme.

Nikos
 

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#29
roddyama said:
The effects of core saturation in an inductor are the decrease in inductance (non-linear) and the generation of noise.


Rodd Yamas***a
Click to expand...

But at this point in a power supply we're talking about basicaly DC with some AC noise element.

Are we really suggesting that there is so much AC in the form of noise that the core will saturate? Surely not?

Does the differance have something to do with the change of inductance with frequency? This changes dramaticaly but no one ever quotes the inductance at a particular frequency and anything from 2mH up is deemed to be acceptable.

All of this gives me the impression it's not that critical. Also to get an air core inductor of say, 3mH at 100 Hz with DC resistance below 0.5 ohm they end up like a coke can and I've never seen anything like that in any commercial product.

Does anyone know the innerds of the highly rated Musical Fidelity A3CR choke regulated power supply or is that a totaly different type of thing?
 
#30
Hi,

Musical Fidelity pre amp is the same concept as ours. Filtration of ripple artefacts.
They use CLC PI's with EI core (box transformer type) coils in mono PSUs.
As for metal cores in general, the higher the frequency the easiest the saturation. When we filter 3A of current in a Zen Revisited for instance, we do so because we dont have pure DC in the first place. Ripple current is huge. And its full of HF garbage.
Therefore a non gapped core has its own aural signature.
Tube people know why they pay kBucks for a Tango or Tamura over a plain transformer. Their expensive proprietary cores sound vastly better.
To the contrary Rdc is ok. Check out the cheap speaker coils option as I mentioned in my earlier posts. They are small and effective.

Regards

Nikos
 
#31
As I have mentioned before, I tested a number of
Ferrite and Iron core inductors for loss of inductance
due to DC-caused saturation.

Some of your bigger core types, like the Erse (from Zalytron)
took more than 6 amps DC with no degradation. Of course
they get kind of warm...

😎
 
#32
Bertie,

But at this point in a power supply we're talking about basicaly DC with some AC noise element. Are we really suggesting that there is so much AC in the form of noise that the core will saturate? Surely not?
Click to expand...
The Fairchild link in my earlier post shows that DC current will cause core saturation, and the higher the current the lower the inductance. This is on top of the AC current that salas mentions above.

Also to get an air core inductor of say, 3mH at 100 Hz with DC resistance below 0.5 ohm they end up like a coke can and I've never seen anything like that in any commercial product.
Click to expand...
Look at the link I posted on the first page to the Parts Connexion. They will show an air core 3" indiameter with a DC resistance of .6ohms.

I wouldn't leave the links but sometime I have other things to do.

Rodd Yamas***a
 
#34
Dear Nelson,

No problem with value changes. Any honestly sized core will provide the inductance. I have compared air coils, ferrite coils, iron dust coils, toroid coils. Technically on DC they fare identical when properly sized. Alas they sound different.
In my current preamp I use 3 toroid 20H chokes in stages. 70 Ohm Rdc each...I could easily pick up the sound change of a Holco over a sandcast resistor used as a damper feeding the first cap after the tube rectifier!
The darn things are a pain in the behind to put together based on final sound performance grounds....
And they are barely taxed... imagine 3A or 6A in a common PSU...
They do sound horrible if not being the properly picked ones.
Did you compare the coils soundwise? They even got warm.... they should be screaming aural signatures. 😉

Regards

Nikos
 

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#36
There is an expression that comes to mind when these discussions get far too esoteric. It goes like this "Sometimes a person can be so fixated on a single blade of grass in a clearing that they con not see the forest for all the trees." Interpretations will vary, but basically if we as "Audiophiles" spend soo much time deconstructing the sonics of a system, we forget to feel the music.

I say "feel" the music because I beleive music is far more than just a collection of notes. Really good music can transport you to a different time or place, it can set in motion a series of emotions that can overwhelm you.

I think we should all spend a liittle more time listening to that which brought us here in the first place.

Anyway, that's what I think, now pass me a Hobgolin and put that John Lennon LP on I love so much.

Anthony
 
#37
Audiophilia nevrosa

Hi all,

No! we dont miss the forest for a tree! We DIYers have the big chance to construct the big picture first and then focus on the minute details of the foliage. Cause we have control and access to experiment over our devices. Its a love afair. Some details enhance it and makes it deeper. 'You cant beat love' John Lennon (in a strong hometown accent)

🙂 Nick
 
#38
Can somebody enlighten me on why it is necessary to use more psu filtering on the Aleph. Is it because of a sonic (musical) improvement or just being fanatic about noise reduction. In my normal PSUed Aleph 5 I can barely hear a hum when my ear is next to the speaker so what is it that I can hope to gain by adding chokes and more caps?
 
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