I cannot emphasize enough

[Doc B]

that you MUST use the rubber feet supplied with the wood bases in our kits. If you leave them off there will be inadequate air intake under the chassis for the vents to properly cool the circuitry.  Kelvin has just repaired an amp that had a channel go out due to failed semiconductors after playing fine for some time, and unfortunately it now has a noisy power transformer. There did not seem to be any miswiring, but there were no feet on the amp. The only conclusion we can draw is that it overheated.

 

[faskenite]

A word to the wise guy.  This is why tube amps are usually not enclosed and why the traditional approach, if a top enclosure is used, involves a tube cage with ample ventilation or a case which is vented and has lots of clearance above the tubes.  Although there are some preposterously expensive cones etc for the bottom of the wood base, there are lots of inexpensive options which will increase the elevation and the ventilation provided.  And they look cool.  Impress your friends!

 

[Doc B]

Yup the tubes get hot and need room for airflow. But the specific thing I am addressing here is that the solid state components under the chassis panel overheat with no air flow. There are big resistors dissipating a lot of heat as well as transistors that have heat sinks requiring air flow under there. The feet are a part of the cabinet design and the amp's performance will suffer without them. Pointy feet and all that is cool, but the stock rubber feet are perfectly adequate for the job.

 

[faskenite]

Dear readers, if I were you I would listen to the President For Life.  I’m still figuring out the solid state parts of Bottlehead designs, so go to the source!