Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on August 21, 2022, 07:18:31 am

Title: Amnesia, didn't remember how to guess load in SE & PP .... ????
Post by: kagliostro on August 21, 2022, 07:18:31 am
Some time ago somenone explained me how to gues the correct load for SE & PP

this using the tube plate max dissipation and the voltage of B+

to me seems that for SE the formula is Zout = Va/(Pa/Va)

I remember that DummyLoad and PRR gived some explanations to me but, unfortunately, my brain don't want to collaborate

Please can someone help me to remember ?

Many Many Thanks

Franco

Title: Re: Amnesia, didn't remember how to guess load in SE & PP .... ????
Post by: sluckey on August 21, 2022, 08:31:51 am
Maybe this...
P = E2/R so R = E2/P

example...

    plate voltage = 300V and PdMAX = 15W
    3002 / 15 = 6000Ω

Title: Re: Amnesia, didn't remember how to guess load in SE & PP .... ????
Post by: kagliostro on August 21, 2022, 09:26:06 am
Ciao Steve

Thanks

Seems that for SE Class A

P = E2/R so R = E2/P

&

Zout = Va/(Pa/Va)

Gives te same result

R = E2/P  ....... 300x300/15 ....... 90,000/15 ..... 6.000

Zout = Va/(Pa/Va) ..... 300/(15/300) ..... 300/0,005 ..... 6.000

Beautiful .... and for PP what we do ? we moltiply by 2 to estimate aa value ?

Thanks

Franco
Title: Re: Amnesia, didn't remember how to guess load in SE & PP .... ????
Post by: sluckey on August 21, 2022, 10:27:55 am
Quote from: kagliostro on August 21, 2022, 09:26:06 am
P = E2/R so R = E2/P

&

Zout = Va/(Pa/Va)

Gives te same result
Of course. They're the same equation, except yours has not been simplified.  :icon_biggrin:
Title: Re: Amnesia, didn't remember how to guess load in SE & PP .... ????
Post by: kagliostro on August 21, 2022, 12:15:31 pm
😁😁😁😁

OK, my brain Is officially lethargic

Franco