Sorry- I have been extremely busy lately.
The DC filament upgrade eliminates all AC around the audio amplification circuits. AC propagates like RF and can go from the heater to the cathode. DC voltages to not propagate or transmit at all.
If the amp's or preamp's high voltage supply is providing pure DC and there is AC on the filaments, it is possible to hear a hum or buzz in the system. The amount greatly depends on how good a tube's cathode/heater insulation is. It has been my experience that it varies greatly from tube to tube. The best and simplest approach to a cure is to use DC on tube filaments. I have also noticed that even if the noise is mostly inaudible, removing all AC influence maximizes resolution by providing a nearly 100% black backdrop. It can provide a substantial sonic improvement.
Chokes: C-L-C filters can be very good. Chokes even regulate DC to a certain degree. I mainly use R-C filtering since it works just as well and costs much less. Some of my models use chokes when an older power supply design is created.
Will a choke improve sound quality? They would greatly improve sound quality in amps made in the 50's and earlier because filter capacitors didn't have the capacity they do now. Presently- I do not believe there is much benefit. I like to use them in nostalgic builds. They add flare, make an amp look chunky and I can use some nifty smaller capacitors in place of the big electrolytics. Chokes have their place, but not everywhere.
Great post!! Very instrutive, thanks for this lesson.
I fail to understand ''add flare'', what do you mean say with ''flare''??
Do you think the inductive power supply used by Bartholomeo Aloia is better than the regular capacitive PS??
Thanks
