so, this is my new amp, mu cf with ecc88 for input stage with gain up to 20 and SE power stage with gain 2 in A class with mosfets. Bias is around 3 A per channel , heatsinks reach around 45 degreees C, output power is around 18 W on 4 ohms...it sounds.....OHHHHHHHHHH........i'm in love....no hum, no buzz....
thank to Federico and mr.Pass for concept
thank to Federico and mr.Pass for concept
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Re: schematic???
here is one pic more...
lp
I must find a time to transfer schematic from my head to paper, but actualy, basic concept for power stage is mr. Pass Zen ver1, with some modifications (higher bias and higher input impedance), line stage is common cathode follower with ecc88, they are coupled with cap. Actualy i want to get gain from line stage, current stage should have gain 1 (now is 2, but sounds o.k.)AudioGeek said:
here is one pic more...
lp
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how about...
ok... the BEST SS amp I ever made was just a source follower mosfet with irfp240n mosfets running at 3.25A bias.
why not configure one as a source follower, one as a CCS with MPSA18a as current sense transistor.
bias to source follower on the neg lead of a IT tranny, other lead connected to gate of mosfet.
then run like a ECC99 on input side of IT.
I think this is what I am going to do anyhow.
comments?
ok... the BEST SS amp I ever made was just a source follower mosfet with irfp240n mosfets running at 3.25A bias.
why not configure one as a source follower, one as a CCS with MPSA18a as current sense transistor.
bias to source follower on the neg lead of a IT tranny, other lead connected to gate of mosfet.
then run like a ECC99 on input side of IT.
I think this is what I am going to do anyhow.
comments?
voltages?
what voltages did you use for the output stage, regulated?
also input stage?
I am thinking of 32v on the output....
OOORRRRR...............
what about choke load the source follower with say a LARGE 50mH 5A choke.
It will get rid of the other mosfet and I can bump the voltage or current up a bit.
hmmm....... starting to sound like the pathos designs.
p.s. If I really regulate the bias voltage on the source follower, the output power supply doesn't need to be that well regulated.
what voltages did you use for the output stage, regulated?
also input stage?
I am thinking of 32v on the output....
OOORRRRR...............
what about choke load the source follower with say a LARGE 50mH 5A choke.
It will get rid of the other mosfet and I can bump the voltage or current up a bit.
hmmm....... starting to sound like the pathos designs.
p.s. If I really regulate the bias voltage on the source follower, the output power supply doesn't need to be that well regulated.
voltages are regulated, mucf has transistored rectifier, power part rectifier only biiiig caps , PS is 36V, one of the fet-s is 9240 for current source, second one is n type.....no choke....
yesterday i made some modifications (on input resistance of power stage, and now sounds even better (for me)....
Now I'm thinking about simple circuit with power tubes to get as much gain as I can and then instead of transformer, I want to use something else....maybe fet-s or trannies....or.....I dont know yet.......
My opinion is, that the amps with output transformer had "trafo sound"and its slow, only with tubes and without trafo is true tube sound....but this is only my opinion.....
yesterday i made some modifications (on input resistance of power stage, and now sounds even better (for me)....
Now I'm thinking about simple circuit with power tubes to get as much gain as I can and then instead of transformer, I want to use something else....maybe fet-s or trannies....or.....I dont know yet.......
My opinion is, that the amps with output transformer had "trafo sound"and its slow, only with tubes and without trafo is true tube sound....but this is only my opinion.....
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