• 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.

lowish voltage (110V) tube HP amp/preamp idea...

kodabmx

Member
Paid Member
2011-10-31 1:00 am
Toronto
It uses a 6N6P and a 6P43P loaded with a TL783. I think it will work as a headphone output for my 470R phones, as well as being a line stage.

Does anyone see any glaring errors?
 

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kodabmx

Member
Paid Member
2011-10-31 1:00 am
Toronto
"Active pull down"
It's actually push pull.

"It is a push-pull buffer design that allows the delivery of up to twice the idle current into the external load impedance, twice as much as a conventional cathode follower can deliver."
"The White cathode follower belongs to the family of push-pull, class-A circuits that includes the SRPP and SRCFPP, as all three circuits use a current-sense resistor to create the needed anti-phase signal for push-pull operation."
Variations on the Theme of the White Cathode Follower
 
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1µA current noise is way above anything else in the circuit I suspect. Remember its over a 10kHz BW, so its 10nA/√Hz, current noise is normally measure in pA or fA. A 10k resistor has 1.3pA/√Hz thermal current noise for instance, 60dB less.


Of course that noise spec in the TL783 datasheet is probably only a rough/ready thing, perhaps a worst case including bad flicker noise, but still its high - most voltage regulators are not low noise amplifiers. Worth trying to see how bad it is in practice with a real part - can always substitute a 1k5 resistor as a load to compare.