* 12AX7/ECC81 Triode PSpice Model
* copyright (c) 1999 Guilherme F. Ribeiro -- all rights reserved
* Based on the 12AT7 model by Mithat Konar
* Model used: "Improved VT Models for SPICE Simulations,"
* Norman Koren, Glass Audio 5/96.
* Plate parameters determined by computerized optimization, March 24, 1999.
* Plate data from Philips Receiver Tubes Manual.
* Interelectrode capacitances are based on data given for Philips ECC83; however,
* the reliability of the HF characteristics for this model is probably not
* very high. It is likely that that additional complexity will be required
* to better model the HF behavior--including the inclusion of heater terminals
* in order to explicitly incorporate grid, plate, and cathode to heater
* capacitances. And don't forget to add parasitic capacitances of ~0.7 pF
* for adjacent pins and ~0.5 pF for others (see Koren's article) as well as for
* the effects of a shield (if used).
* No guarantees of any kind are made regarding the accuracy or suitability
* of any part of this model. Use at your own risk.
*
* Connections: Plate
* | Grid
* | | Cathode
* | | |
.SUBCKT 12AX7 1 2 3
+ PARAMS: MU=107.6 EX=1.03 KG1=851 KP=682 KVB=8837
+ RGI=2000
+ CCG=1.6P CGP=1.6P CCP=0.33P ;
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
G1 1 3 VALUE={ (PWR(V(7),EX)+PWRS(V(7), EX))/KG1 }
RCP 1 3 1G ; TO AVOID FLOATING NODES IN MU-FOLLOWER
C1 2 3 {CCG} ; CATHODE GRID
C2 2 1 {CGP} ; GRID-PLATE
C3 1 3 {CCP} ; CATHODE-PLATE
D3 5 3 DX ; FOR GRID CURRENT
R1 2 5 {RGI} ; FOR GRID CURRENT
.ENDS 12AX7
.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N)
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