• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Spice model for 811a A2 Grid

Hi!

Glad to be back after almost a decade, any one has a good spice model for the grid circuit of a 811A?

I'm using this at the moment and the grid current draw in A2 mode doesnt seem right.

At 430v @ 100ma, Vg +22, the model only draws 3ma, I believe from reading tubelabs comments in 2007, Ig should be like 20ma or there abouts.

any help is greatly appreciated


.subckt 811a 1 2 3 ;
+ params: mu=160 ex=1.317 kg1=1350 kp=100 kvb=1400 rgi=2000
+ ccg=2.3p cgp=2.4p ccp=.9p
+ a=1.6667e-10 b=-.0000002875 c=0.0001758333 d=1.275
e1 7 0 value=
+{v(1,3)/kp*log(1+exp(kp*(1/mu+v(2,3)/sqrt(kvb+v(1,3)*v(1,3)))))}
re1 7 0 1g
e2 8 0 value=
+{a*v(1,3)*v(1,3)*v(1,3)+b*v(1,3)*v(1,3)+c*v(1,3)+d}
re2 8 0 1g
e3 9 0 table {v(2,3)} =
+ (-1 1.1e-16)
+ (0, .6e-4) (20, 5.38e-4)
+ (40, 6.25e-4) (60, 7.41e-4)
re3 9 0 1g
g1 1 3 value= {(pwr(v(7),v(8))+pwrs(v(7),v(8)))*v(9)}
rcp 1 3 100k
c1 2 3 {ccg}
c2 1 2 {cgp}
c3 1 3 {ccp}
r1 2 5 {rgi}
d3 5 3 dx
.model dx d(is=70u rs=1 cjo=1pf N=180)
.ends