Choke loading vs. SRPP

HVfanatic · 29th January 2009, 05:59 PM

If I build a direct drive for ESLs, there are 2 possibilities:

1. SRPP
2. Choke load

My very basic understanding is:

SRPP avoids iron, but has the disadvantage of a floating upper heater.

A choke doubles the voltage swing and avoids the upper tube.

While I can calculate the SRPP, the choke load seems a miracle to me.

My question(s):

A: If I use a 12mA current, 3000V classA, how do I calculate the choke? I guess the ohmic resistance should be 2xRa. But how can I calculate the necessary Inductance? A link with theory and exemplary calculations would be wonderful.

B: Because the ESL needs a push-pull signal, I think the choke needs to be done with opposite would coils on both sides of the center tap to cancel the idle current magnetismn. Is this correct? Or would it be preferable to have separate inductors and accept some magnetic saturation?

Regs, Dirk

revintage · 29th January 2009, 06:30 PM

I custom-ordered PP-chokes from Jack Eliano at Electra-Print for my ESLDDs.

Inductance depends on Z at lowest used frequency.

HVfanatic · 29th January 2009, 06:42 PM

Hi revintage,

so Z is the ohmic equivalence at a given frequency. I calculate this value, add it to the ohmic value and can therefore calculate the possible swing for the given frequency?

Can you give me some math? A dgl for calculation? Is the model for this:

variable resistor (valve), modulated in series with inductance in series with resistor?

Which topology you like best?

HVfanatic · 29th January 2009, 06:43 PM

So I guess: The bigger the inductance, the better???? only limited by increasing ohmic resistance???

29th January 2009, 05:59 PM	#1
HVfanatic diyAudio Member Join Date: Feb 2008	Choke loading vs. SRPP If I build a direct drive for ESLs, there are 2 possibilities: 1. SRPP 2. Choke load My very basic understanding is: SRPP avoids iron, but has the disadvantage of a floating upper heater. A choke doubles the voltage swing and avoids the upper tube. While I can calculate the SRPP, the choke load seems a miracle to me. My question(s): A: If I use a 12mA current, 3000V classA, how do I calculate the choke? I guess the ohmic resistance should be 2xRa. But how can I calculate the necessary Inductance? A link with theory and exemplary calculations would be wonderful. B: Because the ESL needs a push-pull signal, I think the choke needs to be done with opposite would coils on both sides of the center tap to cancel the idle current magnetismn. Is this correct? Or would it be preferable to have separate inductors and accept some magnetic saturation? Regs, Dirk

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29th January 2009, 06:30 PM	#2
revintage diyAudio Member Join Date: May 2007	I custom-ordered PP-chokes from Jack Eliano at Electra-Print for my ESLDDs. Inductance depends on Z at lowest used frequency.

29th January 2009, 06:42 PM	#3
HVfanatic diyAudio Member Join Date: Feb 2008	Hi revintage, so Z is the ohmic equivalence at a given frequency. I calculate this value, add it to the ohmic value and can therefore calculate the possible swing for the given frequency? Can you give me some math? A dgl for calculation? Is the model for this: variable resistor (valve), modulated in series with inductance in series with resistor? Which topology you like best?

29th January 2009, 06:43 PM	#4
HVfanatic diyAudio Member Join Date: Feb 2008	So I guess: The bigger the inductance, the better???? only limited by increasing ohmic resistance???