Join Date: Oct 2004
Location: Arizona badlands
Originally posted by kmtang
I am just wondering why you employed a RC filter in the last stage of your power supply. I added a RC filter of 250-ohm 100uF for the last stage which forms CLCRC so that I could lower the B+ from 455V to 430Vdc for my 300B SE amp.
With this change, my 300B amp sound rather differently. It has more sweet and detailed sound.
Hi kmtang, In my case the voltage at C3 is the B+ split off for 415V and the RC provided the 410V for the input tube, in this case a mu-stage, 6AC7 - 6SL7 combo. This is what the schematic specified. So the extra 'R' was used to drop the voltage 5V and 'C' provide a little more smoothing as well. I tried some more simulations over the weekend and noticed a smoother supply from a 5H + 5H over the 2.5H + 2.5H. One more note, the DCR of the different componets plays a big difference simulating the output in Duncan and it can be interesting chasing down the value for them but crucial in trying to make Duncan work. Has anyone seen a good tutorial for Duncan out there?
Also, anyone have some thots of choke mounting? I assumed that the top was fine and you just needed to turn the power transformer 90 degrees from the output trans. but I have been reading this thread and was curious about it?