The “brightness” of the tubes does not reflect on thier function. The “plate” can surround most of the cathode on most and obstruct the visual light to a great degree. If the actual plate, which is what you predominately see on the power tubes, starts to “glow” (red plate) turn the amp off immediately and have the bias checked. The small signal tubes also will only have a small amount of visual light present. More glow noted in a fully dark room, but again does not relat to function.
McIntosh MC275
Hi all. I recently purchased a used MC275 in very good condition. The original owner said he had it service not too long ago. The amp appears to work fine but the tubes are very dim. I had them tested and they are fine with about 1/2 life still on them. Not sure what to do. Do I need new tubes or is there an adjustment I need to make? If I need new tubes then could someone give me an idea what to get and where to place them on the amp (which slots)? I want quality tubes so please, ANY guidance would be appreciated. Thank you