Tube coolers?

Laptop fans will do the trick, especially with a wall wart power suppl. These usb powered fans, often available for $5 would be the first stop. Most are pretty quite and you can add a few to get the air flow you need in all areas of the amp. I've done this and it works well.

Check out Parts Connexion. They sell these Pearl Tube Coolers. In discussing with some folks a few years back, it was recommended to add some grounding cable from each of these to the chassis to drain any static that could occur.

FrankC

BTW, the fan I linked to above is rated 8.7 db. That's pretty quiet.

Thanks everyone for the advice. I am trying to place a pair of 6NS7s in a space where there is only about 3-quarters of an inch to 1 inch from the top of the tube to the shelf above. (The rack is open on all 4 sides, though.) So I will give the Pearl coolers a try and see what happens, and try a fan later if I need to.

I am not sure how much heat 6NS7s generate, as I have not used them before. (I have some 12AU7s in a headphone amp that are pretty cool, so I was hoping the 6NS7s were cool also.)

Herbies tube coolers are very nice. I use them in all my equipment to get rid of heat from my tubes.

Http://www.herbiesaudiolab.net

And he and his wife are nice people to boot...Can't beat that and his prices.