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RE: What tubes to use with this Interstage Transformers?

I am a little rusty on the filters and I stand corrected on the roll off points.

However, I want to standby my own account of increasing Vin proportionately to the attenuating Slope passing Fc point to remain the constant Vout from a low pass RC filter circuit. Since R is fixed value, it can only supply a maximum current to the shunt C when Xc is effectively becoming a short at very high frequency. R is always been fixed and Vin is fixed so how much maximum current (Imax) it can supply through the R is fixed too. The only thing changes is that the load current demand which is based on the Xc. It's just that Xc comes into play based on how much current it gets from series R and how often it gets charged.

Even though Xc is the reactance components, it still is really a cap and the charge across the cap at various frequency.

Before the Fc point, the Xc is high so it does not present a very current demanding load to the R. Voltage drop across R is small or none due to the Xc being high.

Passing the Fc point, the Xc value gets smaller and smaller thus shunting more current to the Ground. This creates a bigger voltage drop across the R and smaller voltage appears at the C.

But When the series R reaches the max current it can supply due to the Fixed Vin divided by it's own value, the Imax is reached regardless of how lower Xc goes.

To overcome this attenuation, you need a larger Vin passing Xc point since the R is fixed to supply more current. You can't get more current through a Fixed value R and a fixed value Vin / Vsource regardless of how much current is made availalbe at the Vin / Vsource or anything in front of the R. The R value itself it the limiting factor here when Xc is effectively becoming a short circuit to Ground.

So, let's get back into the RC filters and shunt cap drive requirement.

In RC series filter, R is usually fixed. And the C is fixed as well since it's inside the tube.

To get more current into the C, you can either increase the voltage (resulting more current flowing through the R) or lower the value of R (as your suggestion).

Lowering R sounds good if it's possible since it's the simplest and easiest. But this defeats the whole point of this thread which is to find the usable tubes with the 1:4IT.

Or we can reduce the C value for a fixed R value? Since the R is fixed in my case, we can find the tubes with low gain since the open loop Gain has the most effect on the total C. It's exactly what I am hoping to find.
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