All FET Symmetric HP-Amp, LSK170A+LSJ74A

[lineup]

JFET Symmetric HP-Amp, LSK170A+LSJ74A

JFET input,
BJT VAS,
IRF610+IRF9610 output.

Supply = +/-16VDC, 2x12VAC Transformer.

Simplified schematic here to begin with.

 

[donovas]

Subscribed

 

[Mark Johnson]

For a headphone amplifier, I'd recommend a 2x16VAC power transformer and voltage regulators on the supply rails. That'll get you well regulated ±16VDC rails, even with 10% mains sag and, at the same time, "high Vin to Vout voltage drop" regulator circuits.

 

[Andersonix]

Is it like a cascoded F5?

 

[bogdan_borko]

Is it like a cascoded F5?

Where do you see cascodes? It's classic (like F5) circuit, with complementary source follower..
Btw I dont think offset will be stable without cap in the feedback loop or servo.

 

[EUVL]

2A & DIY Zenquito
DC stable if done right.


Patrick

 

[EUVL]

> DC stable if done right.

By that I meant not 1:1 as shown in post #1.
But then it is also a "simplified schematic".

And using IRF610 & the like will mean you lose 5~6V output headroom from rail either side.
Which is why laterals or 2SK2013 / 2SJ313 are more attractive in this particular application.


Patrick

 

[BesPav]

And using IRF610 & the like will mean you lose 5~6V output headroom from rail either side.

But we can add bootstrapped gate drive like attched.

My library lacks of ZVP's, so BJT shown just for example.

 

[Mark Johnson]

Woo hoo, recovery after a clipping event might be seriously "entertaining" thanks to those 470 microfarad capacitors.

 

[EUVL]

And too complicated for me.


But just me,
Patrick

 

[BesPav]

Woo hoo, recovery after a clipping event might be seriously "entertaining" thanks to those 470 microfarad capacitors.

Ah, no, this capacitors mostly is just a way to jump over the rails for a gate drive.
Clipping behaviour are very nice to my eyes, just stick to rail at any depth.
Potent bandwidth for used FETs and bias current.

And too complicated for me.

But with a LatFETs this approach easily allows to fully saturate OPS devices, it naturally jumps over power rails without additional windings, diode bridges, regulators.
Which instead becomes too complicated for me.

 

[EUVL]

As long as you are happy, that is the most important.


Cheers,
Patrick

 

[BesPav]

As long as you are happy, that is the most important.

Yes, Patrick, that's the most valueable and most oftenly underestimated.