Mohican question, capacitors.

[jebem]

(01-22-2016 07:00 PM)Geoff Quickfall Wrote:  P.s. Would it not be better to have the wire be a three piece part, two internal for the speaker and one shielded surround which would be grounded to the chassis by circuit and the second grounding point at the chassis by the speaker?

Hi, Geoff,

It was common in those days to connect one of the two speaker coil terminals to its metal frame (those speakers had in fact three terminals, where one of them was riveted to the metal frame - example in a Toshiba receiver that I restored recently).

The shielded cable would then have its shield connected to the speaker metal frame connector, and at the other side of the cable its shield would be soldered to a chassis ground terminal.
This arrangement only makes sense when the speaker have a large metal area and it is close to sensitive components.
Also the radio enclosure, being metallic, should form a single ground surface (or shield).
This is not only about hum (audio interference) but also about RF interference caused by people touching the metal parts of the radio, for instance.

Killing hum/RF interference is kind of a art on its own.
Too much shielding sometimes leads to great hum, for instance when we create ground loops (without even knowing it).
Basically experimentation is the key, along with some best practices.