Tube Amp PS - Feasible Boost Converter?


2014-12-08 10:28 pm
Hi all,

Has anyone ever explored or heard of someone exploring the idea of isolating, rectifying, and smoothing at mains voltage with a much higher capacitance to get a cleaner DC, and then boost converting from 170 VDC to B+ voltages for plate supplies? I ask because 200V capacitors are cheaper than 450V capacitors in much higher values, and PTs are the most expensive single part in most tube amplifiers.

This is just food for thought for now, to see if this is even a feasible idea.

Thanks in advance!



2014-12-08 10:28 pm
All safety considerations would be made - I did mention isolation in my first post. At first glance from the supplier I usually buy from, isolation transformers are cheaper than step-up transformers and have a smaller footprint, so the idea still seems economic enough to discuss (so far, at least).

The 125V isolation transformer output would be full-wave rectified, smoothed with a very large capacitance, and then sent through both a boost converter to hit B+ voltages and a buck converter to hit heater filament voltages. The idea is to get very clean B+ and DC heaters.

I haven't seen any tube amplifiers using switching DC-DC converters. Do you know any textbook examples or people who've attempted it?
Commercially available high voltage (output 100 to 1500V, 200W) power supply might cost $3000.
PPH220 | 200 Watt Power Supply | Semi Linear Power Supply
Makes a transformer & caps seem cheap!
An SMPS uses high frequency = smaller transformer, small capacitors, complex circuit & for B+ supply, HV components.
Boost convertors for high voltage generally supply a few milliamps, not serious power.