I was 'servicing' my amp recently ie. cleaning off dust, checking tubes for discolouration, microphonics etc. and I began to wonder: what is the point of the metal covers around the preamp tubes? What are the pros and cons of having them on or off?

Anybody know?
they are tube retainers, and they help keep thm from getting loose, but mostly they are an xtra step to get your tubes out.
Your amp will work fine without them.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
They're also faraday cages. They help prevent electromagnetic interference.
Ah, ok! Faraday cages, another thing I learned in physics coming back into real life!

Also, I noticed a very slight bit of brown discolouration on one of the power tubes. Is this a problem? It doesn't seem to be blown.
Last edited by conor-figgy at Aug 14, 2011,