• 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.

Interesting linestage optimizing ideas

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Hi
I am not sure of the origin of this interesting circuit however I have had it in my system for some time now and do love the sound however as always we would like to see if it can be improved upon. Perhaps add a ccs etc. Your ideas and input would be greatly appreciated in modifying this schematic and perhaps identifying its origin?

Cheers
Greg
 

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  • cathode follower schematic.jpg
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This input signal is completely bypassed to ground through both
the 470uF and/or the battery. If this is the same circuit you claim
currently to have a working example, then I suspect you might
not have drawn it out accurately.

Were those two components perhaps in the cathode leg of the
circuit instead? And why a battery instead of an LED??
 
Hi kenpeter
Thanks for looking at the schematic. I have double checked the board and it is on pins 2 & 7 which are the grid. They definitely go to the two components and then to ground. The only reference that I have found of a similar circuit without the 470uf cap is in "Valve Amplifiers: Morgan Jones" he states that the valve is biased by superimposing the bias voltage onto the grid via resistor 221K, which prevents the battery from short circuiting the signal. The coupling cap prevents the signal from shorting the battery. Resistor 70k is the output resistance of the signal.

Cheers
Greg
 
PixelPlay said:
I have double checked the board


Then you should do well to triple check. The only way this circuit makes any sense is with the 70k in series with the battery, not with the signal source. Otherwise, the circuit is a big yawn - fixed battery bias common cathode feeding a "Miss Piggy" done with a most unsuitable tube.
 
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