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Old 7th October 2012, 08:35 PM   #28011
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Wood!
Better still, ironwood.

se
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Old 7th October 2012, 08:38 PM   #28012
morinix is offline morinix  United States
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Now you only have to use it.
A sphere with no openings. what rating on the practical scale is this?
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Old 8th October 2012, 12:33 AM   #28013
gpapag is online now gpapag  Greece
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A sphere with no openings. what rating on the practical scale is this?
Congrats Morinix.

The highest rating!
Itís the price one has to pay if he is looking for theoretically perfect solutions.

Now, start thinking how this construction can become usable.
With every step you make, one elementary condition of theoretical perfection will be violated and itís effects will be canceled.
Consider the importance each canceled effect has on your goals.

George
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Old 8th October 2012, 12:38 AM   #28014
gpapag is online now gpapag  Greece
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However, that said..Amperes law states the magnetic field (B) around an electric current is proportional to that current. And Faraday's law states that the voltage generated in a loop of wire is proportional to the rate of change of (B) flowing through the loop.

Neither law invokes H, so if H is a non linear function, it does not directly impact either Ampere's law nor Faradays. So that's how I'd explain it, if I knew what I was talking about...

The non linearity of a BH curve will certainly impact the inductance of the system, and when you start to saturate, that inductance will drop. All these factors will come into play with the primary current, so the IR drop and varying impedance of the primary to its driver can cause all kinds of nasties..

BTW, I looked up hyperphysics to confirm what I've said w/r to Ampere and Faraday..really nice site, University of Georgia I believe..


jn
Jneutron
I really hadn’t noticed this part of your post.
I am surprised that I see H and B changing roles.
Maxwell refers to the entities of:
H as the magnetic force of the field and to
B as the density of the lines of force of the field. It names B also as magnetic induction.
Both are vectors.
Vector of H functions over lines. Line integral denotes work.
Vector of B functions over surfaces. Surface integral denotes flux.
He explicitly stated that magnetic force produces magnetic induction. (A Treatise on Electricity and Magnetism Vol I, Preliminary, Forces and Fluxes, page 11, see attachment)

On BH diagrams, H is the abscissa on the horizontal axis.
B the ordinate, is on the vertical.

In modern terms, B is the degree of magnetization a material obtains in response to an applied magnetic field of strength H.
The factor of proportionality μ (B= μH) is not a constant. It is an attribute of the medium through which the lines of magnetic force travel.
Any variation or non linearity of μ distorts B.

George
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Old 8th October 2012, 01:03 AM   #28015
fas42 is offline fas42  Australia
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However, the usual engineering solution would be to use a relatively thin steel case. BUT I will NOT use a steel case, because I can hear them when they are in physically close contact with my designs. I last tested this the the JC-3 phonostage design.
What distance from steel reduces the effect to audibly zero? Find that, make a cube of thin steel with double those dimensions and use spacers to position the components to be in the middle of the cube.

May look awkward, but certainly cheaper ... !

Frank
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Old 8th October 2012, 01:03 AM   #28016
RNMarsh is offline RNMarsh  United States
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Aluminium and copper for chassis are the two best non-ferrous materials. Cant get lower cost either. It cost what it cost.... wall street has figured it out -- commodities are the way to make the most money. Watch out for metals and food and the like. Thus smaller physical builds are the way to go for lowest cost of chassis/materials. Thus, iPOD/PAD et al. For the Highest-End its practical to physically seperate/isolate or move noisy elements/circuits away from sensitive circuits.

You need to worry about both field-coupled as well as direct-coupled modes of unwanted signal/noise pickup. -RNM

Last edited by RNMarsh; 8th October 2012 at 01:09 AM.
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Old 8th October 2012, 12:35 PM   #28017
gpapag is online now gpapag  Greece
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Originally Posted by gpapag View Post
Congrats Morinix.

The highest rating!

George

Sorry Morinix. I misread your post. (non practical scale)
So on the practical scale, the rating would be very low (for this application).
The congrats and all the rest remain the same.

George
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Old 8th October 2012, 01:12 PM   #28018
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If the chassis is a cost driver I would expect there to be plenty of data showing the detrimental audio effects, and supporting evidence that a thick chassis is the best solution.
Its not apples to apples but all the low signal level instrumentation (HP analyzers etc) seem to get by with thin multiple electrostatic shields, and I would expect these are often used in a harsher EMC environment.
There are also always practical trade-offs, an electroless nickel plated aluminum chassis may be discarded by some for its magnetic properties, ignoring the improved contact impedance and resistance to oxidation.

I really do like the look of a thick aluminum chassis, very different from the cheap Bud box experiments which may have housed the equivalent prototype.

Thanks
-Antonio
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Old 8th October 2012, 01:30 PM   #28019
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Jneutron
I really hadnít noticed this part of your post......George
Well written.

I try to keep the explanations as simple as possible, but no simpler. You'll drive others nuts if you push E/M theory too far here.

But then, I'd have company, no??

jn

To quote the maravingian.. there is only cause...and effect..
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Old 8th October 2012, 02:17 PM   #28020
morinix is offline morinix  United States
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Sorry Morinix. I misread your post. (non practical scale)
So on the practical scale, the rating would be very low (for this application).
The congrats and all the rest remain the same.

George
The first rule in design - S$!t Happens
Corrections duly noted.
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Last edited by morinix; 8th October 2012 at 02:19 PM.
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