aluminium as electromagnetic field shielding ?

[djboomstick]

any one with any experience in installation or insulation ?

I am finding this sheet of 1/8" thick aluminium is amplifying the field rather than damping it .

the electric field reading is negligible either way

But , according to the meter i have . My magnetic reading is up to .11 microtesla (μT) without the shielding and up to .5 μT with the sheet in place .

at .41 the "unsafe" alarm goes off with blinking lights and a buzzer .

the main thing is , i'm using the aluminium for a shelf with a non rack mountable cassette deck in a rack with other typical rack mounted stuff .

with " 24 μT being the strength of magnetic tape near tape head " maybe it doesn't matter either way

perhaps i'm better off with wood ? or steel ? or forgetting it and having a drink and just recording those drums .

i suppose i could try recording the field itself to the tape , if i don't hear anything i guess it isn't there .

if i do hear something would it make a good sample pack ?

have i been social distancing too much ?

does it need to be grounded ? or why would that matter for the magnetic field anyways ?

what do you think ?

[BertKoor]

Does your meter tell you whether it's a static field (like earth magnetical) or not (hence oscillating)
Static fields are silent. Could the shield create a reflection of EM fields already there? Or even work as an antenna? Grounding it would be mandatory.

What EM / RFI source are you shielding it from? Or is this purely a theoretical counter measure?

I'd expect a consumer cassette deck to be shielded sufficiently. Especially at the places where it really matters, which is the head itself. And the case itself is metal sheet already, right??

So personally I would not even bother with measuring 'n all.

[djboomstick]

The meter displays in either average or peak a range of magnetic field from .01 - 99.99 μT and electric field from 1 - 1999 Volts per meter. updating about every half a second.

The manual says it has a testing bandwidth of 5Hz - 3500Mhz but the meter does not display any info regarding this.

I just started metering stuff for the fun of it and i need a shelf to put the nonrackmountables on. i needed to make a shelf i might as well make a snazzy multipurpose ultra shelf . i'll up-cycle it into the walls for my time machine if i get some real damping from it .

Currently the rack is set up with power conditioners on the bottom , then the amplifiers , then the shelf. all with one empty space between each for convection cooling. it's a very tall server rack .
about 10 spaces or so above the amp is where the field drops to zero , either with or without the sheet . I started racking outboard processing there . normal studio stuff, pres , comps , ect ..


Messing around with it today i was able to find a hot spot around the top center of the power amp witch was damped by the sheet from around 1.2μT to about .75μT . still dropped to 0 at the same distance of about 10 rack spaces up from the top of the amp.

I think , the sheet is changing the shape of the field . between what is being damped but still going through the sheet and what is going around the edges of the sheet .

So... i'm assuming , the space i was measuring yesterday near the front edge of the shelf had an increase because of the changed shape of the field .

Now i'm wondering if i made it worse with the aluminium sheet ? or just different ? or if it could be better if i find a better combination of materials ?