Tweedle Dee PI LNFB vs 470k grid stop

[jph118]

Just curious, for anyone who’s built a Tweedle Dee, what’s your take on the 3.3M/2n2 LNFB versus just using a 470k grid stopper on the cathodyne PI input? Pros/cons? I’ve had no problems with just using the single resistor, but always looking for a better mousetrap.

[pompeiisneaks]

I can't compare the two, nor have I built a stock 5e3 before, but I can really feel how much clean headroom this amp has, it starts getting really grindy up near like 6 or 7 on the volume, but up til then, it sounds outstanding and the move into drive is smooth and sounds stellar. On mine anyway. I'd think the grid stopper is going to just balance things out a bit, whereas LNFB will always increase clean headroom. It's a staple on any HIFI system for that reason.

~Phil

[jph118]

Thanks Phil! I’m gonna check it out on a new build. On a common cathode stage, it would theoretically give much more NFB than the 22m/.047uf network we see on some ODS builds (which I really love)... curious to hear it on the cathodyne split load.