But why use systematically LT spice?
I don't know how.
Are my load lines wrong ?
I will tst the transformer of course.
No, it is not if optimum supply voltage and plate current is used.
But in general GU50 is not optimum tube when triode connected.
But in general GU50 is not optimum tube when triode connected.
In class AB pentode mode, a pair of GU50's would be good for about 35 watts output power into 3.5 kohms plate to plate impedance at a plate supply voltage of 350 Vdc. Screen supply shouldn't exceed 250 Vdc in this case.
Best regards!
Best regards!
I believe that we are re-opening an old debate on the gu 50, namely the OPT and the screen voltage. I read on this site that in triode mode and in BF the screen could take 500v ... On the other hand, I have seen very complicated OPTs with several windings. I am not sure of my 1.75KΩ (Raa3.5kΩ) load line but at vg = -20v, P = 26w (215v, 120ma) which is 0.65xPmax.
Now the question I ask myself is: is a current of 0.3 amps enough to feed a channel composed of 2 GU50 in push-pull and 2 6n8s tubes (4 triodes)
How much power do you need?
What are your speakers and do you listen at loud levels or not?
Maybe that's what you have to define first, otherwise you'll have hundreds of answers and still don't know where to go.
What are your speakers and do you listen at loud levels or not?
Maybe that's what you have to define first, otherwise you'll have hundreds of answers and still don't know where to go.
You can not get more than some 20 W from a pair of triode connected GU50 if using 3k5 load impedance.
400 V as +Ub and some 100 mA plate current produce the plate dissipation power that can not be exceeded.
With these conditionds, especially with +Ub = 215 V you get very little power out, maybe 5 W, which is a bad joke for a pair of GU50.
400 V as +Ub and some 100 mA plate current produce the plate dissipation power that can not be exceeded.
With these conditionds, especially with +Ub = 215 V you get very little power out, maybe 5 W, which is a bad joke for a pair of GU50.
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Maybe I'm somewhat blind, but I don't see any reason for this »triode connected« postulation?
Best regards!
Best regards!
Big power doesnt mean good sound. What do you need? Big power or good sound? If good sound, you can use 2A3 or television tubes
Damned! i calculated 6w. I mistakenly thought that an amplitude of 145v would be comfortable. But with a transformation ratio of 20.91 it gives 12w per channel (unless I'm mistaken). maybe I should choose -30v to get slightly more.What a misery!
However, there are a lot of schematics with 400v or near. And there is not much difference between 3.5k and 5k for example.
How many times you need to be told that 3k5 OPT with 400 V +Ub is fully OK for a GU50 triode connected pair?
And how many times do I have an itch to say that there ain't no need for an unefficient triode connection?
Best regards!
Best regards!
Dear sirs if you need to fight go running or biking but don't stay in front of your screen.It bring nothing.
That's no good.
The bias needs to be -50V or more (GU50,triode,400V), demands to much drive for the concertina.
And with the right drive only somewhat over 20W out.
Mona
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