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Tube heat covers... to use or not to use?

Joined
Apr 26, 2018
Messages
93
So I was replacing the tubes on my Fender Tonemaster head today and noticed that the tube housings have mounts at the top of them for heat coverings... you know, that little metal condom that slides over the tudes. All but one other amplifier I own has these covers; at least for the power section. I've never really given it a second thought, I've always just remove them, replaced the tube, and placed the cover back on. But after noticing the mounts I've begun to wonder if I should install them on this head. I'm assuming the previous owner of this head removed them and never reinstalled them? Or maybe Fender never put any on to begin with? I read some information online including one website that sells these covers stating that they allow the tubes to run at a more ideal temperature when installed. Not at the website that sells these covers would be biased or anything, but is that true? I've heard some other stuff regarding increase tube life and less electromagnetic interference in the amps sound. Any truth to this?
 

PaulD

Active member
Joined
Jun 25, 2007
Messages
671
The shields are nothing to do with heat, they act as a Faraday cage around the preamp valves to shield them against RF and EMI interference. It is somewhat debatable as to whether they have any significant effect but they certainly do no harm and the added advantage is that they also act as valve retainers and ensure the valves are securely retained in the sockets.
 

rick c

Active member
Joined
May 28, 2016
Messages
282
My Marshall one have springs inside that push down on the top of the tubes when fitted to better secure the valves in their sockets.
 
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