More than 10 years ago on hamfest I found big MV power supply from 40's with two WE MV rectifiers . I put it in the middle of the back yard , used extension cord and hidden behind chestnut tree turned on the switch. It surely had a beautiful blue glow and I was turning it on during nights but filament transformer was buzzing terribly. 866A looks like a sensible choice for die hards ....
Good looks is a must for a boat anchor amp...
Good looks is a must for a boat anchor amp...
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3b28s or 872a mercury vapor rectifiers may not work so well for this.
This is mostly a +- 150 volt supply and the 3b28s or 872s have a critical voltage of about 50.
You may get away with some other lower voltage mercury vapor rectifier though you would need more than one transformer.
You could use one transformer for the bottom pair of diodes where the cathodes are tied together. You would want all four diodes to be the same though so both the negative and positive supplies come up at the same time.
Voltage drop would also be a problem as you replace .7 volt drop for about 10 volts X2.
It shouldn't "sound" at all. If it does, then something's wrong. Both the 3B28 and the 872 have the same problem: both depend on a glow discharge for their operation, and that means a negative resistance characteristic that can lead to RF noise. Not only does that radiate interference, it can also mix other RF noise into the audio spectrum. That would cause sonic performance to degrade.
Otherwise, the two types share the same disadvantages: low Isurge capabilities that pretty much limit then to use with L-input ripple filters. They need another hole, and a filament PTX. They have higher forward voltages than Si diodes. The only advantage is glowey bottle coolness.
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