Four Hour Tube Amp Warm-Up

Dozens of tube components later, the only ones I ever had concerns about a warm-up time longer than (say) 15 minutes were the hybrid electrostatic amps with lots of high-voltage transistor CCS on their outputs.

Never really experienced that with any pure tube components. They should sound really good very quickly. Unlike transistors, tubes need heat to operate at all, and they have filaments for that very purpose - which efficiently heat up so the tube operates at spec very quickly. Transistors are however affected by heat, and can take a relatively long time to reach their final stable operating temp - because heat sinking is used to pull heat out to keep them at a safe operating temp under maximum load conditions. There’s no such heat tug-of-war with tubes, so they get stable quick.

The only aspect of tube amps that has a slowly heat-accumulating element would be the transformers, and maybe silicon rectifiers and voltage regulators in the PSU. Though only large transformers should take hours to fully warm up. I don’t know if that significantly affects their performance - maybe. That could be the "4 hour warm-up" in your case.

I’m becoming more open to the idea that sound quality could improve up to 4 hours, which seems to be around the amount of time for the big transformers & their potting to fully warm up. However, it is very difficult to separate any such sonic differences from psychoacoustic explanations (without 2 of the same amp), and I still posit that if an doesn’t sound good within 10 minutes of power up, something might be wrong or "off" with it.

4 hours -- wow. So, tube life is, in effect, one quarter of their expected life for good listening? That will sound like an argument for solid state to many.

@hilde45  As per above, I would never wait 4 hours to start enjoying the amp. And as for solid-state, there’s another thread floating where a very well regarded SS amp blew and took out the unlucky owner’s JBL speakers. I think tube amps are a lot more reliable than many audiophiles give credit to, and SS are not the infallible devices either, perhaps with even more potential for downstream damage (direct coupling!). A lot can go wrong with transistors; they’re mechanically robust but don’t take electrical trauma well - the reverse of tubes!!

Never experienced anything like that with pure tube amps. In fact I always find them quick to warm up. I once had a hybrid electrostatic headphone amp (grounded grid EL34 with solid state CCS outputs) that took like an hour to sound its best -- but I'm pretty sure that was from the transistors.