I own a modded 6-B which never took more than a minute or so. When I first glanced at the topic, I thought No the tone of my ARC 6-B was always on the colder, analytic side, and couldn't be warmed up by my usual tube rolls LOL!
ARC SP-6 Warmup time
I just bought an Audio Research SP-6 preamp. It takes about ten minutes after powering on for the power lamp to stop blinking and the unit to start passing signals. Other than that it sounds perfect on all inputs. Is this at all normal? Does it indicate something is about to fail? Ten minutes to warm up is more than annoying.