large triode for PP

archeus68

archeus68

AK Subscriber
Subscriber
I have a PP transformer rated at 65 watts. Primary runs 3300 ohms.
It's intended to run something like 6550 in Ultra Linear. But I'd like to try to find a triode.
Things like 845 can run around 4500 ohms at 850 volts.
Maybe the Russians have some big triode with a lower plate load?
Thought ???
 
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archeus68 said:
I have a PP transformer rated at 65 watts. Primary runs 3300 ohms.
It's intended to run something like 6550 in Ultra Linear. But I'd like to try to find a triode.
Things like 845 can run around 4500 ohms at 850 volts.
Maybe the Russians have some big triode with a lower plate load?
Thought ???
Click to expand...
A triode connected 6550 ?
 
archeus68 said:
I have a PP transformer rated at 65 watts. Primary runs 3300 ohms.
It's intended to run something like 6550 in Ultra Linear. But I'd like to try to find a triode.
Things like 845 can run around 4500 ohms at 850 volts.
Maybe the Russians have some big triode with a lower plate load?
Thought ???
Click to expand...
A quad of 845 will run you about a thousand bucks. The driver tubes for that will be expensive as well since people usually drive an 845 with a 2a3 or 300B! The power supply for all these tubes will also be humongous and take up a lot of chassis space. Check out the Audio note site for some examples. Be sure to wear protective eye wear to keep your eyes from falling out of their sockets, ala Saturday morning cartoons.
 
You could look at some sweep tubes. A few have gotten trendy (EL509, EL519) but there are plenty to choose from.

primosounds said:
The driver tubes for that will be expensive as well since people usually drive an 845 with a 2a3 or 300B!
Click to expand...

There is no reason why a driver for an 845 needs to be DHT or an expensive tube at all. There are very successful designs using 6AU5, 6AV5, or relatively inexpensive triodes.
 
With a 3k a-a load, that deserves some load line calculation. In Class A, draw 1k5...for the AB amp above 2x idle current draw at 750 Ohms. That is a fairly steep load line for an 845. It is a pretty steep load line for any tube actually...:)
cheers,
Douglas
 
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