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A 6C45-PE Single Tube Amplifier

    This Amplifier  produces  astounding results in terms of transparency and musicality. The only drawback is  a very low output power (less than 2Wrms in SE mode). Other tubes useful fot this work are :

437A

3A167M

E55L in Pseudotriode

EC8020

 417A (very very low output power) and so on.

    This tubes, excluding 417A, are rare and expensive. During the search (back in the late '90)  I found a wonderful alternative given by the  6C45-PE (ab initio code named  as  VTW to avoid 3A167M-like speculations), a small tube with the following caracteristics:

m=50, gm=50mA/V, rp=1k; Plate Dissipation 8W.

I have designed a compact, easy-to-building, power amplifiers with 2 6C45-PE.

Fig. 1 Full Schematic

 

The 6C45 is also excellent  as driver  for big transmitter triode as VT4C/211, 845. We can easily design a Two Stage Class A2 211 single_ended amplifier for example. Further, a parallel cathode follower of '45s has only 10ohm of output impedance. In the full schematic of Fig. 1 you can observe  a quiet high load; this is detrimental for the output power, nevertheless distortion figures are better and the sonic response more satisfactory.

Plate Curves

 

 

 

 

 

 

 

 

 

Click on it to enlarge

 

Pspice Model

.subckt vtomega 1 2 3 ; plate grid cathode

+ params: mu=47.4501 ex=2.374193 kg1=268.615545 kp=485.735371 kvb=501.503636 rgi=300

+ ccg=2.4p cgp=4p ccp=.7p

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

c1 2 3 {ccg}

c2 1 2 {cgp}

c3 1 3 {ccp}

r1 2 5 {rgi}

d3 5 3 dx

.model dx d(is=1n rs=1 cjo=10pf tt=1n)

.ends

VG=[0, -0.5, -1, -1.5, -2, -2.5, -3, -3.5, -4, -4.5]

 

 

Recently I have designed a small stereo PCB for this monotube amplifier. Look at the following for its "artistic" representation:

 

 

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