The case made from thick aluminium has great shielding effect (I am serious now) and that shown here is used under very severe EMI conditions.
PMA said:
Pavel,
anyone can put an extra extruded aluminum box inside a case, + close to any drugstore sells them.
Even ones with 1/4" wall thickness.
The sandwich core alloy in my post is not aluminum but 1/8" nickel-iron plate, seams filled with high content silver epoxy.
Low nickel-iron plate (<50% Ni) is much cheaper than Mu metal and fairly easy to obtain.
Talking preamps, this is a preamp thread afair.
jacco vermeulen said:
My experience with any kind of magnetic materials for the enclosures was always very, very poor. The non-linear changes in the PCB traces impedance in the presence of high permeability materials makes the amp behaviour hard to predict and control.
The mutual inductance between the power rails and the signal rails induces even order harmonics, while this effect induces odd order harmonics. Overall, it's much worse in power amplifiers, but I was able to measure it in preamps as well. Any external magnetic field shielding positive impact is masked by these nasty problems.
I'm not saying it's audible, but it's just there and it can easily be minimized by using non magnetic materials for the enclosures. There are a few articles in the AES database on this topic.
If you have the power transformer inside a ferromagnetic case the stray magnetic flux will couple with the case and cause currents elsewhere in the circuit. It's tempting because it shields well, but I'd rather use something non-magnetic.
Grey
Grey
syn08 said:
Exactly. The system I showed works closer than 1m from conductor with up to 100kArms/50Hz steady state, and fast HV transients during circuit breaking. The customer at first insisted on magnetic material. Different samples were produced, but every magnetic material had saturated, resulting in worse interference S/N ratio. I knew that, as I have been working in this field for more than 25 years. But the customer had to be convinced by experiment, not by explanation .....
no one builds amps with tin, and gold is tasteless.
Platinum isn't that great thermally, but a platinum case would sell rather well i think
Platinum isn't that great thermally, but a platinum case would sell rather well i think
brass and certain types of stainless steel
and if not talking about chassis materials (you didn't specify metals), there are few ceramics that conduct heat well, like BeO and SiC
this is like diy trivia - keep 'em coming
and if not talking about chassis materials (you didn't specify metals), there are few ceramics that conduct heat well, like BeO and SiC
this is like diy trivia - keep 'em coming
jacco vermeulen said:
I can see this being popular in certain hummer vehicles that utilize low-efficiency, large-area sound motors and wheels that appear to spin whilst the vehicle is stopped😀
jacco vermeulen said:
I was a trashman in the summers as a kid, I once found a 30's Telefunken radio with a 140lb solid copper chassis. When I went to college my mother threw it away.
john curl said:
SY said:
Carbon/graphite is pretty useful as well, I used it for a few amps by now.
Magura 🙂
- Status
- Not open for further replies.