• 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.

Vacuum Tube SPICE Models

Hi Jan
You asked me what the contact voltage is.
This is a voltage caused by different materials used for different electrodes. It is typically 0.55V or so, for sure less than a volt.
It offsets the triode's Plate current curves, in same manner as there would be a voltage source connected between the grid pin and the actual grid.
To get your measurement fitted, I had to tune the contact voltage to a very unusual high value. So I suppose there's something wrong...
BR Adrian
PS: I will send you the (most probably not accurate due to this issue) spice model code in a private message, ok?
 
I have got intrigued by using triode part of EM84 for audio purposes to see how it behaves. I cannot find EM84 plate characteristic, datasheets show just length of column plotted depending on grid voltage. I am aware there are commercial devices but I do not want to invest into them. It surely could be possible to do it old fashioned way as in the fundamental course p.44.

In order to spare myself the effort I was wondering if someone already made the measurements or better yet has the model available to share.
 
6G2P SPICE Model

Code:
**** 6G2P ******************************************
* Created on 03/02/2024 20:18 using paint_kit.jar 3.1
* www.dmitrynizh.com/tubeparams_image.htm
* Plate Curves image file:
* Data source link:
*----------------------------------------------------------------------------------
.SUBCKT 6G2P 1 2 3 ; Plate Grid Cathode
+ PARAMS: CCG=4.2P  CGP=2P CCP=3.4P RGI=2000
+ MU=95.8 KG1=2179.33 KP=676 KVB=439.29 VCT=0.424 EX=1.355
* Vp_MAX=400 Ip_MAX=5 Vg_step=0.5 Vg_start=0 Vg_count=8
* Rp=9560 Vg_ac=54.45 P_max=0.5 Vg_qui=-72.48 Vp_qui=300
* X_MIN=63 Y_MIN=187 X_SIZE=757 Y_SIZE=376 FSZ_X=1260 FSZ_Y=630 XYGrid=true
* showLoadLine=n showIp=y isDHT=n isPP=n isAsymPP=n showDissipLimit=y
* showIg1=n gridLevel2=n isInputSnapped=n
* XYProjections=n harmonicPlot=n dissipPlot=n
*----------------------------------------------------------------------------------
E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(VCT+V(2,3))/SQRT(KVB+V(1,3)*V(1,3)))))}
RE1 7 0 1G  ; TO AVOID FLOATING NODES
G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1}
RCP 1 3 1G   ; TO AVOID FLOATING NODES
C1 2 3 {CCG} ; CATHODE-GRID
C2 2 1 {CGP} ; GRID=PLATE
C3 1 3 {CCP} ; CATHODE-PLATE
D3 5 3 DX ; POSITIVE GRID CURRENT
R1 2 5 {RGI} ; POSITIVE GRID CURRENT
.MODEL DX D(IS=1N RS=1 CJO=10PF TT=1N)
.ENDS
 
Last edited:
捕获1.JPG
 
@Khron, I am not the modelling expert, but here is 6Z2P aka 6AS6, I hope it helps you

*Triode 6Z2P, 6AS6 03.2024 acamus
*
.subckt 6Z2P 1 2 3
xU1 1 2 3 Triode Cak=0.035p Cga=2.5p Cgk= 4.1p Kg1=656 ex=2.95 mu=32 kp=100 kvb=50 vgc=2 Rgk=2k
.ends
*
*vacuum tube triode model
*K - cathode
*A - Anode
*G - Grid
.subckt Triode A G K
C1 A G {Cga}
C2 G K {Cgk}
B1 A K I=(pow(v(e1),ex)/kg1)*(v(e1)+abs(V(e1)))/V(e1)
C3 A K {Cak}
D1 G K DGK
B2 e1 0 V=(V(a,k)/Kp)Log(1+exp(Kp(1/mu+(v(g,k)+vgc)/sqrt(kvb+pow(V(a,k),2)))))
.model DGK D(Vfwd=0 Ron={RGK} Roff=100meg)
.ends
 

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I have got intrigued by using triode part of EM84 for audio purposes to see how it behaves. I cannot find EM84 plate characteristic, datasheets show just length of column plotted depending on grid voltage. I am aware there are commercial devices but I do not want to invest into them. It surely could be possible to do it old fashioned way as in the fundamental course p.44.

In order to spare myself the effort I was wondering if someone already made the measurements or better yet has the model available to share.
I have found the model here, just reposting with asy file

EM84.sub

  • EM84 Indicator Tube Spice Model
  • Author: Zabb Csaba
  • Date : 10/1/2021
  • The following parameters are not modelled:
  • (1) Filament and filament warmup time
  • (2) Limiting values
  • This model is valid for the following tubes (within max. ratings):
  • 6FG6, EM85E, 6FG5 EM84 6E2 6E3P
.SUBCKT EM84 K G A L D
X1 1 G K EM84x
V1 A 1 DC 0
H1 4 2 V1 54k
E1 D K Value{IF{V(4,K)>0,V(4),0}}
V2 2 K DC -3.21
G1 L1 K A K 4.36u
R1 L1 K 299k
D1 L L1 DMOD
R2 D K 1MEG
.MODEL DMOD D
.ENDS
*
.SUBCKT EM84x P G K
+ PARAMS: Mu=57.99996 Ex=1.421792 Kg1=997.5376 Kp=62.31465 Kvb=9849.735
E1 1 0 Value={V(P,K)/Kp*Log(1+Exp(Kp*(1/Mu+(V(G,K)-2.33)/Sqrt(Kvb+V(P,K)*V(P,K)))))}
G1 P K Value={(Pwr(V(1),Ex)+Pwrs(V(1),Ex))/Kg1}
Rcp 2 K 4.3MEG
D1 P 2 DMOD
Bg G K I=(URAMP(V(G,K)+5.95E-1)^1.5)*1.15E-5
.MODEL DMOD D
.Ends
*

EM84.asy

Version 4
SymbolType CELL
LINE Normal 48 -16 48 0
LINE Normal -48 -16 -48 0
LINE Normal 20 0 12 0
LINE Normal -12 0 -20 0
LINE Normal -28 0 -36 0
LINE Normal 24 12 -24 12
LINE Normal 32 48 32 20
LINE Normal 24 12 32 20
LINE Normal -24 12 -32 20
LINE Normal 28 16 -28 16
LINE Normal -15 -17 -29 -17
LINE Normal -15 -13 -29 -13
LINE Normal -15 -17 -15 -13
LINE Normal -29 -17 -29 -13
LINE Normal 16 -80 16 -48
LINE Normal 23 -48 9 -48
LINE Normal 23 -44 9 -44
LINE Normal 23 -48 23 -44
LINE Normal 9 -48 9 -44
LINE Normal 64 -32 32 -32
LINE Normal 32 -25 32 -39
LINE Normal 28 -25 28 -39
LINE Normal 32 -25 28 -25
LINE Normal 32 -39 28 -39
LINE Normal 36 0 28 0
LINE Normal 40 5 36 0
LINE Normal 40 16 28 16
LINE Normal 40 5 40 16
LINE Normal -32 -32 -32 -64
LINE Normal -22 -32 -32 -32
LINE Normal -22 -17 -22 -32
LINE Normal -48 0 -36 0
ARC Normal 48 -64 -48 32 48 -16 -48 -16
ARC Normal 48 -48 -48 48 -48 0 48 0
WINDOW 0 -8 -80 Right 2
WINDOW 3 24 64 Right 2
SYMATTR Value EM84
SYMATTR Prefix X
SYMATTR Description 6FG5 EM84 6E2 6E3P
SYMATTR ModelFile EM84.sub
SYMATTR SpiceModel EM84
PIN 16 -80 NONE 0
PINATTR PinName L
PINATTR SpiceOrder 4
PIN -48 0 NONE 0
PINATTR PinName G
PINATTR SpiceOrder 2
PIN 32 48 NONE 0
PINATTR PinName K
PINATTR SpiceOrder 1
PIN -32 -64 NONE 0
PINATTR PinName A
PINATTR SpiceOrder 3
PIN 64 -32 NONE 0
PINATTR PinName D
PINATTR SpiceOrder 5