Full Bridge Rectifier With Tubes

[Einric]

I have seen a few tubes out there that are called "Dual Diode".
Would it be possible to use two of these in the same fashion as four rectifier diodes?
If so, what would be the practicality of the setup.
I love the idea and look of tubes but I also really like the Gainclone.
I would love to be able to marry the two by using 4 "Dual Diode" tubes to supply both power rails to my Gainclone and use at least a tube buffer preamp with passive attenuation on the front end of the amp.

Feasible?
Practical?
Neat Factor?

Any Thoughts?

Thanks

[TheGimp]

The dual diode tubes have two anodes and one cathode. This is fine for FWB with a centertap transformer, but you can't build a FWB without the center tap unless you incorporate two SS diodes and two Vacuum diodes or a dual Vacuum diode.

[astouffer]

Originally Posted by Einric

I have seen a few tubes out there that are called "Dual Diode".
Would it be possible to use two of these in the same fashion as four rectifier diodes?
If so, what would be the practicality of the setup.
I love the idea and look of tubes but I also really like the Gainclone.
I would love to be able to marry the two by using 4 "Dual Diode" tubes to supply both power rails to my Gainclone and use at least a tube buffer preamp with passive attenuation on the front end of the amp.

Feasible?
Practical?
Neat Factor?

Any Thoughts?

Thanks

Yes you can but keep an eye on the current needed. People can't give away types like the 6AL5, and another quad diode which number escapes me at the moment. If you're just powering a simple gain stage then some of these small tubes could work. Anything bigger and you'll need a 6BY5.

[kevinkr]

A pair of 6BY5 will do about a couple of hundred mA in bridge connection, but the gain clone requires amps, and the forward drop across these makes them impractical..

I suppose you could use a quartet of tungar bulbs - now that is a challenge you probably want to avoid.

Honestly tube rectifiers are not practical at these current levels.

Seems like building a tube amplifier might be just a bit easier.

[Einric]

Wouldn't that be the same as high power diodes of the same configuration?
If that was the case i would need four tubes per bridge just like a standard bridge?
At this point it still doesn't look impossible, just expensive.
Maybe this is an exercise in thoery now.

[kevinkr]

Originally Posted by Einric

Wouldn't that be the same as high power diodes of the same configuration?
If that was the case i would need four tubes per bridge just like a standard bridge?
At this point it still doesn't look impossible, just expensive.
Maybe this is an exercise in thoery now.

Helps to look up the type referenced before commenting.. The 6BY5 contains two completely separate rectifiers in a single envelope so indeed just a pair of them will realize a complete bridge - in your application you could need up to 20 of them per channel depending on the load impedance you need your gain clone to drive.

You could use 6C33 strapped as diodes as well.

It really isn't just a question of throwing money at it, it certainly can be done, but why would you go to the trouble with a gain clone? Better results could be achieved for much less with conventional solid state rectifiers, and even better results with a comparably expensive tube amp. (All those rectifier tubes, and the transformers to run them will cost a lot of money and take up a lot of space..)

[analog_sa]

Originally Posted by kevinkr

Honestly tube rectifiers are not practical at these current levels.

Practical??? Since when is this a consideration?

I have to admit having often played with the idea of using glass rectifiers for SS equipment. It seems mercury is better suited for higher currents but an input choke filter is a must. As it probably is also with vacuum in the case of a GC needing thousands of microfarads. Another issue is of course the voltage drop. The bridge will double it. Why use a bridge anyway?

I would imagine some paralleling of rectifiers is a must for a GC, as is a regulator. And an input choke. Ok, not so practical indeed. With this kind of effort one can build a real amp.

[Einric]

OK, all great information, thanks for all the input.
I just found a 6AL5 laying around my shop and it got me thinking.
This thread was very enlightening.

[Doz]

My Dolby 5.1 amp has two glass bridges using EY500, not practical at all.

[kheper]

http://web.archive.org/web/200712202...rectifier.html