John Curl's Blowtorch preamplifier part II

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#51,907
jneutron said:
However, if the shield completes a loop, shield currents can induce voltages along the current path.jn
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JN, I would think it will be extremely difficult, if you connect two pieces of equipment, to avoid a current path through the shield.
That is why it is very important to make sure that the hot and return wire inside the screen have equal geometry, capacity etc against the screen so that the differentially induced voltages are zero.

Jan
 
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#51,910
TNT,

I am not at all convinced that steel reinforcement in concrete will make any difference to the sound you will have. To think through the possible impacts may be a nice thought experiment, but there will be no real life consequences I can think of that couldn't be remedied with some easy fixes.

What I would invest in is in non reverberant surfaces. If you can have a concrete slab floor California style, poured directly on good mother Earth, that would be a good beginning.
 
#51,912
Anybody know what this is? Found it soldered in series with AC line to the transformer.
 

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#51,919
hitsware said:
Don Juan and Carlos take an evening walk through the dessert.
Carlos sees an animal ahead ..... And tells Don Juan.
They draw closer and on closer inspection Carlos
tells Don Juan that it is just a stump.
Don Juan says that is sad because it was so much more interesting
when it was an animal .....
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We actually paid serious money to have Carlos speak at MIT ~1970. The sold out house was captivated.:hypno2:

EDIT - As I have said before, why they do it... "Castañeda withdrew from public view in 1973 to work further on his inner development, living in a large house with three women ("Fellow Travellers of Awareness") "
 
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#51,920
jan.didden said:
JN, I would think it will be extremely difficult, if you connect two pieces of equipment, to avoid a current path through the shield.
Click to expand...

If you can avoid trapping time varying field, it's easy. The problem is avoiding that. That is why I chuckle when people are told to keep their IC's far away from their line cords. That is the worst thing to do. (stay away if the line cord does not have a twist to it, or better yet, twist the line cord if it's a two prong zip.)

jan.didden said:
That is why it is very important to make sure that the hot and return wire inside the screen have equal geometry, capacity etc against the screen so that the differentially induced voltages are zero.

Jan
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Agree there. Both wires have to see the exact same environment.

Even then, a twisted pair is NOT impervious to nearfield magnetic induction. It cancels if two consecutive loops trap the same thing. If an odd number of loops trap, there will be induction. If it is near an agressor with the same twist pitch, there will be coupling (this is a point that Tom Van Doren missed when he presented here, I detailed this to him offline instead of doing the Horshack).😉

Even a coax is susceptible to nearfield magnetic induction, especially if the field has a high gradient at the coax, like leakage from an E core

vacuphile said:
TNT,

I am not at all convinced that steel reinforcement in concrete will make any difference to the sound you will have. To think through the possible impacts may be a nice thought experiment, but there will be no real life consequences I can think of that couldn't be remedied with some easy fixes.
Click to expand...

The only thing I could think of is if the reinforcement current is sufficient to induct voltage into the ground loop. If one were to use two independent AC circuits to power a system and the system loop includes the grounds to panel, then that could really play whoopie with noise.

jn
 
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