I am curious as to why i don't see much in the way of turning AC to DC and then filtering it for a low hum heater voltage? What if i just used a battery? I am wanting to build an amp and am tossing the idea around in my head, but I don't want to waste my time designing if it's not a good idea. Yes, I am new to this forum, but not new to electronics. I have seen filaments in amps using DC, but really no filtering. I wish my amp to be different than the rest, the reason for thought. It is too easy to just copy an amp, there are so many diagrams tested and tried, but I find more fun in experimenting.