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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.
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Plate Curves
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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 |
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VG=[0, -0.5, -1, -1.5, -2, -2.5, -3, -3.5, -4, -4.5]
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Recently I have designed a small stereo PCB for this monotube amplifier. Look at the following for its "artistic" representation:
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