Does heat effect tube ?

[kldguitar]

when amp worked more than 2 hours, the inner of amp case is very hot. Does it effect sound of amp, Certainly, we know it would effect other component such as CAP, so some people add fans on amp. But it will cause noise.
we know force cold ( from wind like fans) is best cooling way. But it will cause noise, do we have other way cool down amp? such as using metal case. ?

[Wilder Amplification]

when amp worked more than 2 hours, the inner of amp case is very hot. Does it effect sound of amp, Certainly, we know it would effect other component such as CAP, so some people add fans on amp. But it will cause noise.
we know force cold ( from wind like fans) is best cooling way. But it will cause noise, do we have other way cool down amp? such as using metal case. ?

Not something I ever worried about. I just keep the backs off of my heads and call it a day.

[Merlinb]

But it will cause noise, do we have other way cool down amp ?

Yes, passive cooling fins have been around since the 60s: Pearl Tube Coolers
Make your own: http://www.diyguitarist.com/GuitarAmps/Tubecool.htm

[booj]

Use ventilation to allow the hot air to escape. In doing so it will draw cooler air in.

[mooreamps]

when amp worked more than 2 hours, the inner of amp case is very hot. Does it effect sound of amp, Certainly, we know it would effect other component such as CAP, so some people add fans on amp. But it will cause noise.
we know force cold ( from wind like fans) is best cooling way. But it will cause noise, do we have other way cool down amp? such as using metal case. ?

well, it could. I've read some opinions saying the fan could inject a high frequency noise into the power supply. But, I would always recommend using one. Just because a tube runs hot does not mean the tube is happy to run hot. The 9 pin tubes have a pretty good glass seal, and don't think heat would be so much a problem. But, any of the 8 pin octals is different. You have a seal at the base, and I've pulled a fair share of upsidedown 6L6's out of Fenders where the seal failed, and the tube lost it's vacuum. As such, I would always recommend using a fan for the power tubes. As for myself, I use the 4 inch AC fans, and feed from a RFI filter network, and a series resistor for the job. The series resistor just cuts the fan speed in half because all you need is just a little air moving around the tube to bleed away most of the heat.

-g