Ok, so it's not really a "recall" as there is nothing wrong with your TRUMPET STEP-UP. What happened is that I discovered an improvement to it. I was working with a customer on a hum problem (happens all the time). Each system is different, installation issues such as racks, cabling, placement, other machines, tubes, everything can make a difference. First off, we solved the NOS tube mismatches, as he also has a VACUTRACE. That solved half of it. But here was still some hum when the STEP-UP was plugged in. Ok, some environments are more harsh than others.
So I played with my new GOLD STEP-UP here in the shop to try and recreate the system. Was able to get find ways to increase hum to what I would term unacceptable. Anyway, even though we had found a working solution, I had an hunch. So I did an experiment.
You see, there is a small, residual ground loop made up of the coax shields that connect to the inputs of the TRUMPET. This makes for a one-turn transformer secondary and it can pick up stray magnetic fields. I found a way to break this ground loop inside the STEP-UP by re-wiring and adding a new ground lead. Well shoot, it worked really well. It immediately turned a bad environment into a quiet one.
So there it is. The fix is not easy or straight forward, and involves new parts and a new cable. Therefore, the upgrade can only be done at the factory, but it is plug and play. Anyone who owns a STEP-UP can send it in for a free upgrade. All of them are still under warranty - even if you are not the original owner.
jh
