If you like, you can think of it like a “bias monitor” of sorts, which wouldn’t require opening the amp at all.zhivago wrote: ↑Sun May 08, 2022 2:10 pmGood advice there, Brad...I contacted a tech earlier and I am waiting to hear back...I will check youtube to see if there are any videos showing the process using that gadget. It sounds pretty straightforward, but I do get nervous whenever I open an amp!øøøøøøø wrote: ↑Sun May 08, 2022 1:39 pmYannis, I'd really recommend getting a Bias-Rite or similar. Then you can check bias without even opening the amp... it might be pretty close to in range already, and that'd save you a trip to the tech. And if it does need adjustment for the new tubes, it's just about being comfortable adjusting an internal trimpot
Insert the device between tube and amp, read plate current, cross-check against online references (or calculator).
If it looks out of range, then you can decide whether you want to learn an easy DIY adjustment or delegate to a professional—but it would save you a trip to the tech just to find out if bias needs adjustment or not
Full disclosure—I monitor my bias “the hard way” and so don’t own a bias-rite, but for people who don’t have the inclination for a lot of tech work, it really is the way to go