Is the red glow normal for 845 tubes?

The Bel Canto amp is designed to run the 845 tubes at the NOS RCA standard dissipation of 100w, therefore, you are running the Sino (70w) low dissipation tubes 40% over their optimal operating rating, which accounts for the red hot spots on the plate. Red hot spots on the plate are a sign of an over driven 845 tube. You will not harm the amp, but the tube life will be significantly shortened. You have 3 options 1) run the current tubes until they expire 2) change the tubes to a higher dissipation 845 3) have the amp modified. I would opt for #2.

Thanks again Brf. I just run into an article in VTV (vacuum tube valley) where it says "graphite es heat-resistant (in fact, it can operate with a dull red glow for a long time without failing)" in power tubes like the 811 o 845. However a new set of 845 tubes is coming my way.

Red glow in morning, audiophile take warning! Sorry, sometimes I just can't help myself.

I just got an answer from Mathew Cramer from Bel canto. He says that "the red glow is normal for this type of design" (SETi 40). So that settles everything down. Thank all for your help. Tiofelon.

What did he say about using a low dissipation (70w) 845s in the SETi40? That is the real question you should ask. If the SETi845 is auto biased for a standard 845, then the amp is over driving the Sino.