Author Topic: how much current do I need to drive the grid for a 6v6gc tube?  (Read 1460 times)

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Offline ELS122Topic starter

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how much current do I need to drive the grid for a 6v6gc tube?
« on: January 27, 2020, 01:27:00 am »
specifically 4 6v6gc tubes.
 

Offline T3sl4co1l

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #1 on: January 27, 2020, 02:32:48 am »
In what class, and to what bandwidth?

Tim
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Offline ELS122Topic starter

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #2 on: January 27, 2020, 02:38:58 am »
in an af amp, push pull class AB2 but I'm also adding a switch to switch it to class AB1 and class A so I want to know really what current at most it can draw
 

Offline T3sl4co1l

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #3 on: January 27, 2020, 02:43:49 am »
What would you be switching that would give any advantage between those two cases?

Class 2 operation typically needs a drive transformer, or cathode followers, to avoid distortion from the nonlinear current draw.  There's very little benefit to running 6V6 in class 2, and doing so is a huge bother, so it's basically never done.

Tim
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Offline ELS122Topic starter

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #4 on: January 27, 2020, 02:52:00 am »
well than I think I have mistaken what is class AB2.
so my design is a differential Gomes amp, with 8 6v6's as the output tubes, I switch the 2nd grids to either the plate, the output transformer tap, or the plate trough a screen resistor.
I guess it won't change much but I put it there so I can experiment with different stuff later maybe

edit:  I mean 6L6GC's not 6v6
« Last Edit: January 27, 2020, 03:11:47 am by ELS122 »
 

Offline schmitt trigger

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #5 on: January 27, 2020, 03:28:32 am »
My trusted old RCA Receiving Tube Manual, lists the grid 2 current at maximum signal from 4 and 7 mA, with a plate voltage of  180 and 250 volts respectively, operating class A1 and connected as a pentode.
With no signal, it drops to 3 and 4.5 mA with 180 and 250 volts respectively.

It doesn’t show any grid 2 current when connected as a triode. 
 
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Offline T3sl4co1l

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #6 on: January 27, 2020, 05:47:17 am »
Yeah, screen grid doesn't count for amp class when it's connected to the plate circuit.

I guess Gomes is a SEPP configuration (ref: TubeCAD article), not really amenable to class AB operation.  Is that really what you're looking at?

Tim
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Offline ELS122Topic starter

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #7 on: January 27, 2020, 06:29:21 pm »
I'm using the design in this picture:

but I have ditched the original phase splitter circuit for a totally different one I'm working on.
I really have just 8 6L6GC's connected to a power transformer and like 500 switches  :-DD
I am gonna probably run it at like 800V or a bit more to utilize every bit of those pentodes.
also, I wanted to use fixed bias (grid bias) in this circuit but I don't think it would work properly. I mean putting a negative bias voltage on the lower tube grids yes. but would doing the same thing to the upper tubes would need a different bias voltage. but now thinking about this more I won't need a voltage that is negative from the ground since the cathode for those tubes is at like 300+V.

also, I intend this for a guitar amp and probably gonna use only 4 of those tubes, I just had too much excitement seeing the price of the Russian 6P3S (not sure if that's right)
basically the Russian equivalent of 6V6GC.

also, I had the idea of driving the grid from 6P1P (EL90) pentodes just cause  :-DD

I guess the more I talk about it the more it turns into The "Unnecessarily Complex 300B Amp" or something similar.

EDIT: upon further googling, it seems that the 6P3S Russian "6L6GC" equivalent is actually the equivalent for the 6L6 not the GC. :(
I guess I'll have to like with 6L6's not GC's
« Last Edit: January 27, 2020, 06:41:12 pm by ELS122 »
 

Offline T3sl4co1l

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #8 on: January 28, 2020, 12:59:18 am »
:-DD Oh man, that circuit has so many things wrong with it...

Such is par for the course in tubophile land.

Tim
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Online langwadt

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #9 on: January 28, 2020, 01:25:45 am »
might consider a bit more learning before you start playing with something quite as deadly ...
 

Offline Johnny10

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #10 on: January 28, 2020, 02:36:35 am »
I don't get it?
Tektronix TDS7104, DMM4050, HP 3561A, HP 35665, Tek 2465A, HP8903B, DSA602A, Tek 7854, 7834, HP3457A, Tek 575, 576, 577 Curve Tracers, Datron 4000, Datron 4000A, DOS4EVER uTracer, HP5335A, EIP534B 20GHz Frequency Counter, TrueTime Rubidium, Sencore LC102, Tek TG506, TG501, SG503, HP 8568B
 

Offline ELS122Topic starter

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Re: how much current do I need to drive the grid for a 6v6gc tube?
« Reply #11 on: January 28, 2020, 11:57:53 am »
Well, then I'll probably stick to something more common.
 


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