Simple Symetrical Amplifier

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It works regardless of feedback. I personally dislike trickeries like bootstrapping.
You could consider referring the emitter resistors of the input stage to ground.


Hello,

in this case there would be no more css ?

how would you add a buffer ?

connected to floating or regulated power supply?

yamaha use N channel drain output with a buffer, maybe we should do the same

thanks
 
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UGS-V3RCA-XLR-3.jpg
 
We are nearly there, except two source resistors going to ground in the place of R3.
Complications: JFETs should be operated at low drain-source voltage. You would need four matched pieces of 2SK170BL, a bipolar cascode and two extra resistors.
The 2SK170BL and 2SA1381 are fine.
 
SSA standard 😉

Hi Andrej, i just sim this amplifier and I found 5mA on input, 40mA on vas and 400mA output with 11mA on CCS >> CFA_EVO.asc

that's right ? it seems a lot compared to usual VSSA (2.4mA / 10mA)


696976d1534151525-simple-symetrical-amplifier-ssa-power-amp-1-7-png


https://www.diyaudio.com/forums/att...le-symetrical-amplifier-ssa-power-amp-1-7-pdf


I am interested in this scheme for my circlotron, I do not know if I have to use a differential current feedback or yours with one or two capacitors for more stability


Circlotron Audio
20190506_cfa_circlotron_bipo_mosfet.png


thanks
Best regard
Sébastien
 

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Hi ultimate86
Your VAS current needs to be higher because of mosfet use. The mosfet is highly non linear at low current. Use of higher bias current for output is the designer choice. Personally I target higher mosfet output current to be in class A at higher power level. For input current you want to limit the power dissipation otherwise you will need higher power transistor type normally with lower HFE than low power type.

Fab
 
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