*Nutube 6P1 triode model V2.0
*2018/1/17 KORG Inc.
*accuracy improved
*continuity at Vgg=0 improved
*download from https://www.korgnutube.com/, modify to work in SPICE

.SUBCKT Nutube12 A G K
BGG   GG   0 V=V(G,K)-2
BEP   EP   0 V=URAMP(V(A,K)-1.5)
* BEG   EG   0 V=URAMP(V(G,K)) ; This B source does nothing in this model!
BM1   M1   0 V=V(EP)**-0.1129
BM2   M2   0 V=(URAMP(V(GG)+V(EP)/15.4))**1.613
BP    P    0 V=42e-6*URAMP(V(GG)+V(EP)/18)**1.5
BIK   IK   0 V=U(V(GG))*V(P)+(1-U(V(GG)))*45.26e-6*V(M1)*V(M2)
BIG   IG   0 V=25e-6*URAMP(V(GG))**1.5*(V(GG)/(URAMP(V(EP)+V(GG))+1e-15)*1.2+0.3)
BIAK  A    K I=URAMP(V(IK,IG)-URAMP(V(IK,IG)-(22.9e-6*V(EP)**1.5)))+1e-15*V(A,K)
BIGK  G    K I=V(IG)
* CAPACITANCE ; typo corrected
CGA   G    A 2.52p
CGK   G    K 9.08p
CAK   A    K 4.32p
.ends Nutube12 ; missing .ends