• 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.

single tube to drive 300ohm headphones

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Stixx

Stixx

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Joined 2003
original-ton.net
You could also try something along these lines...(see attached schematic).
It is the low voltage headphone amp by H. Ahammer that I converted :)o ) to use
the 6N6P instead of the pricey E288CC.
You can use 6N23P instead of the E88CC.
Output impedance is around 50ohm which is a far better match to your phones than 700...
(assuming Gordy's math is correct, didn't check ;) )
 

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sparkle

sparkle

Member
Joined 2003
tnd-pipes.com/
Gordy said:


No. CCS as the anode load will give an output impedance (at the anode) equal to the internal Rp of the tube. Hence not lower, but about 700 - 800 Ohms (at the operating point that I estimate for your application).

However, the output impedance of a single triode will drop lower if you configure it as a 'mu follower'. Perhaps that is what you meant.
Click to expand...



i am sorry - i am one big stupid guy.... i completely forgot about the high impedance of the ccs ... this way the output can't be lowe (in resistance) than Rp..... i don't know with what i am thinking with :D
sorry...
i will try input with tube and output with some kind of buffer for a start....
 
sparkle

sparkle

Member
Joined 2003
tnd-pipes.com/
Stixx said:
You could also try something along these lines...(see attached schematic).
It is the low voltage headphone amp by H. Ahammer that I converted :)o ) to use
the 6N6P instead of the pricey E288CC.
You can use 6N23P instead of the E88CC.
Output impedance is around 50ohm which is a far better match to your phones than 700...
(assuming Gordy's math is correct, didn't check ;) )
Click to expand...


Stixx - thanks,
i have sen this amplifier - i was giving a thought if i should do that too. 6n6p is a good tube, also 6n23p - i have some at my stock too...
well, i will think about it for sure - thanks for the sch.
 
G

G

Member
Joined 2002
sunrise said:



Stixx - thanks,
i have sen this amplifier - i was giving a thought if i should do that too. 6n6p is a good tube, also 6n23p - i have some at my stock too...
well, i will think about it for sure - thanks for the sch.
Click to expand...

Why not try a 5687 anode follower into a 12b4a cathode follower? That should do the job nicely.
 
sparkle

sparkle

Member
Joined 2003
tnd-pipes.com/
i am scared of getting to much gain... not sure how much i need - i assume up to 5 times is enough - and i do not want to have global feedback here.
the problem is also space... i have to minimize the circuit in order to have it small and to be able to put it inside the 20*20*5cm box - if possible with psu too. Also i would be very hapy to have a tube in that circuit. So i am trying to include everything that i want in what i can do :D crazy - i know.
but the idea of having a tube like 12B4A for a gain device together with some nice mosfets in voltage follower (i was testing yesterday some nice followers with N.Pass ccs - looks promissing). and also i have some 2sk/2sj mosfets at my home that i do not know what to with ... if not - maybe some IRF510 will do.
i am still thinking.
 
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