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Page 2: Circuit Description
January 4, 2007
Given the fact that the 832 asks for push-pull type of amplifiers, I had a look at the following circuit defined by TubeCAD. Of Course I would need to change the design in a way and make a mix between the Coldwar and some other designs but it was a start.
The idea started with this design which is not quite common as both halves of the double triode share the same cathode.
The circuit above is just a braindump which I'll have to simulate in order to test its feasibility. There are not at all many amps built with this tube and as none of them is a headphone amp. And as I will not build this amp with an output transformer, I wonder whether I need the extra swing provided by the push pull architecture. And apart from that, the architecture does not offer the befenits of cathode followers (as these are shared). So the alternative is to use both halves in parallel like I did with the Headline.
For the moment I'll make some calculations with a parallel architecture. Needless to say that using one halve per channel of one 832a tube is not possible since the cathode is shared between the two halves of the tube.
Since the grid current is 6mA, we may need another driver tube to provide the required amount of current. And also I want to recalculate the grid voltage of both the 832A tubes.
According to Remco's datasheet:
Class-A audio push-pull
Anode voltage 250 V
Anode current 40 mA
Grid voltage -17.5 V
Grid current 6 mA
Screen current 2 mA
Anode dissipation 15 W
Screen voltage 200 V
Power output (2 tubes) 14 W
I've decided that should I not find over the next few days a very good reason to use a push-pull architecture with this tube that I'm not even gonna bother about any other architecture than a cathode follower (which can be either resistor or FET load).
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