Linlai 6SN7

atmasphere. Good to hear that. I saw a video from Kevin at Upscale Audio that if tubes run cool then one needs to worry. Naturally I needed to confirm that. I do not know why if tubes run cold we should worry.

The Linlai E 6sn7 are the coolest tubes I own. Thank you @atmasphere for explaining this.  

I posted basically what Ralph noted, but it didn't take.

In addition I mentioned that if the Psvane 6SN7's also have large ST shapes bottles, but also feel hotter, they may have thicker glass.

Guessing that thicker glass would be less efficient @ dissipating heat as the added mass would also increase heat storage over hours of usage (like a cast iron pan VS a thin tin/copper pan).

I have/had numerous ST shaped 2A3/300B tubes with varied bottle/glass thickness, but have never monitored how hot they get/got (also never touched them when hot unless by accident).

The worst burn (under forearm) I ever got was from early JJ 2A3's which had very, very thick glass envelopes.

My old 300B amp (power switch on the back) was located on the bottom shelf of my rack, which is squeezed into a hall linen closet, and it's the same with my current Bottlehead 2A3 mono blocks (so burns do happen on occasion).

Curious if the hotter Psvane's have thicker glass.

DeKay

@dekay, interesting question about glass thickness and heat. I’m  also curious about this. I never really thought about that,until this thread popped up. 

Just checked my Psvane CV181 tubes in front positions (warm) and TJ Full Music 6SN7s (slightly warmer) in rear positions in my Cary SLP-98 preamp. Can hold my fingers on both, neither are "hot" or burn fingers.  Put my tongue on them, no issue there either - just kidding, yak yak 🤪.   Power transformer is separate/external on mine, and not heating up the whole preamp top plate surface area either.  It's going to vary by design with each preamp, transformer locations, and casing, venting too.