Lately i am experimenting with various diy opts for use as line output transformers intented to be driven by trioded pentodes with Rp from 2k to 5k. My target is something around 5:1 and the best banwidth possible. I am able to wind any type and got alot of time and experience. I have tried so far 2p-2s 3p-3s and also split bobin 1p-2s + 1p-2s and 3p-3s+3p-3s. All of these with no luck yet as resonances seem to fall inside the audio band or near it. Mostly i use around 3000 to 4500 primaries with paper interlayer insulation and sized EI75 and EI84 grain oriented cores. Any help would be appreciated.
