Shielding Capacitors

[CJ]

never seen this before, Mesa Dual Rect Blue Angel

 

[JohnRoberts]

more likely to be a coil/inductance.

JR

 

[Brian Roth]

It kinda looks like both ends of that purple wire are connected to the same circuit trace....

Bri

 

[CJ]

That is correct sir.

 

[[silent:arts]]

I'm also always amazed at the shielding of C3 in the Neumann PMV70 preamps:

 

[nashkato]

found this in a pr&e mixer , too
https://groupdiy.com/threads/thermally-coupled-electrolytis.85742/

 

[Disco Volante]

The QUAD II has metal-housed coupling caps, the housing connected to chassis..

 

[tomas.borgstrom]

The film input capacitors on Crane Song Flamingo is covered with metal tape that's grounded with a wire.

 

[Matador]

That is correct sir.

I bet Mesa has a patent on the coil of wire too.

 

[musipol]

Just for grins, did you try unshielding it? I have heard some talk on certain geetar amp forums claiming that orienting film cap outer foil side to the lowest impedance circuit node improves the tone(more so for drive tones) . It's pretty easy to test noise pickup using a scope and your fingers squeezing the cap(lowest signal when outer foil side is connected to gnd side of scope probe) ..............but I don't know that I believe it improves the overdrive characteristics. Anyone have any thoughts on this?

 

[Cqwet Dbdfte]

Typically film caps have a line on the body towards the end connecting the outer foil. This should be the grounded side in decoupling caps.
In coupling caps there is no clear choice, but as stated, shielding the cap should help against electrostatic fields.
Older metal can paper/oil caps had
case ground lugs.