Hello. I bought Marshall DSL40 CR from the local dealer (BON STUDIO- Greece) in 2019. Since the first time that I turned it on, I noticed that the amp makes aweird scratching soun when I'm using High Output. I 've contacted the dealer and he told me that it is normal and the amp is doing a format. I accepted this information and I was using the amp like this. I still have the scratcing sound for 10 minutes, every time that I'm using High Output.
A week ago I desided to check the tubes and the BIAS and I found 11mA at the first EL34 and 17,5mA at the second. I'm trying to adjust them and increase them at 35mA but the trimmer stops when I reach at 20mA. I'm trying to understand what is the problem. Is it normal?
Thank you in advance