Tube top caps

[REDDOG45]

In both of my D&A amplifiers, and in many others, the final tube caps are connected together at the top via wire and resistors. Also in the phantom, the drivers are too. I was just wondering what the purpose for this is. When I test my tubes in my tester, the meter reads the same with the lead on or off the top of the tube. Just wondering?

['Doc]

That contact at the top of some tubes is the contact to the 'plate' of the tube, where you get the output from that tube(s). Tube testers only measure a few aspects of the elements on the inside of the tube. Won't normally tell you anything about the rest of the circuit the tube happens to be in.
- 'Doc

Just for grins.
Some tube plate connectors have a ceramic cover over them, not just a bare connector. The reason for that is so that you don't inadvertently touch the @#$ things. Usually means a nasty shock or burn, and you don't have to worry as much about if your life insurance is paid up...

[Night Crawler]

In both of my D&A amplifiers, and in many others, the final tube caps are connected together at the top via wire and resistors. Also in the phantom, the drivers are too. I was just wondering what the purpose for this is.

The resistors with the wire wound around them are Parasitic Suppressors.

This is what they're used for [Please login or register to view this link]