A Zen/Schade-inspired driver for the two output devices. With PP, current can be set lower than SE for the same Pout. Could this go very wrong🙄?
The choke could be substituted by a voltagecontrolling AC-CCS. And how the floating bias voltage should be arranged I don´t know. Global feedback shouldn´t be needed as the PP SF is 100%feedbacked already.
This was just a fantasy in the car on my way home from work today....
The choke could be substituted by a voltagecontrolling AC-CCS. And how the floating bias voltage should be arranged I don´t know. Global feedback shouldn´t be needed as the PP SF is 100%feedbacked already.
This was just a fantasy in the car on my way home from work today....
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Nice idea!
I would prefer using a DN2540 instead of a sk170 j-fet. The Supertex DN2540 can run a 100 - 200 mA.
Why not a White cathode follower type of output arrengemant? I dont like mixing N and P devices as complimentary pairs. The output should run in class A anyways to lower distortion...
I would prefer using a DN2540 instead of a sk170 j-fet. The Supertex DN2540 can run a 100 - 200 mA.
Why not a White cathode follower type of output arrengemant? I dont like mixing N and P devices as complimentary pairs. The output should run in class A anyways to lower distortion...
Hey Johannes,
The 2SK170 has a Ciss of 30pF and the DN2540 about ten times as much. To get a descent Zin the first one must be the choice. About the output stage one still wonders: Can it be that simple😕?
The 2SK170 has a Ciss of 30pF and the DN2540 about ten times as much. To get a descent Zin the first one must be the choice. About the output stage one still wonders: Can it be that simple😕?
Did some adjustment to the circuit above. Now the driver is a JFET mini-Zen with an AC-CCS that controls the drain-voltage. This way we can also simplify the PP-follower by getting rid of the floating bias supply.
By using a PP-follower we also get an environment friendly simple amp that theoretically only needs 50% standing current compared to a standard SE SF. Or with (std) 2A we should get an amp with more muscle for lowZ loads.
By using a PP-follower we also get an environment friendly simple amp that theoretically only needs 50% standing current compared to a standard SE SF. Or with (std) 2A we should get an amp with more muscle for lowZ loads.
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Why not just use another 2sk170 for the current source it sure would be easier.
I notice you are not using any thermal compensation to prevent the output stage
going into thermal run away.
I notice you are not using any thermal compensation to prevent the output stage
going into thermal run away.
Hey Woody,
A current source wouldn´t fix a stable voltage. This one is a gyrator with fixed and stable midpoint voltage for the outputstage. Also the MOSFET in the gyrator helps tempcomp, so that one is undercontrol(I hope😉). I get indications of -100mA from 25-100 degrees C.
A current source wouldn´t fix a stable voltage. This one is a gyrator with fixed and stable midpoint voltage for the outputstage. Also the MOSFET in the gyrator helps tempcomp, so that one is undercontrol(I hope😉). I get indications of -100mA from 25-100 degrees C.
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