F6 Amplifier

[Zen Mod]

yeah

nasty Pa ......

 

[generg]

yeah

Papa's Kung

is funniest

Fu

So nice Zen Mod, it comes in my special folder!

 

[Zen Mod]

entire thread can go in your special folder

http://www.diyaudio.com/forums/pass-labs/198589-papas-pubs.html

 

[generg]

you are right, I forgot it.....

 

[Antoinel]

entire thread can go in your special folder

http://www.diyaudio.com/forums/pass-labs/198589-papas-pubs.html

Zen Mod. You did a great job in that special folder.

 

[Zen Mod]

it is not even finished

ya can call me World's Biggest Mithrandir's Fan .........

(or never accepted adoptee )

 

[Antoinel]

Threshold days?

One more step to STASIS[R] for lhquam's schematic. Is a minimal current fluctuation in the amplifying MOSFETs needed?

 

[Nelson Pass]

Of course it all depends on what you mean by the word needed''

My remark about Ihquam was to mean that he anticipates some of the same
variations that I do....

 

[Nelson Pass]

Papa's Kung

is funniest

To put it in context, that is about 35 years old.

 

[Antoinel]

Of course it all depends on what you mean by the word needed''

My remark about Ihquam was to mean that he anticipates some of the same
variations that I do....

[We] are looking forward to your variations on F6 that you wrote about earlier. You taught the world that STASIS[R] is an amplifying conditition whereby a constant voltage is put across the amplifying transistor [cascode it] and a constant current is enabled to flow through the transistor. Constant must mean needed

 

[Zen Mod]

that would be #4107619

is that Stasis ?

 

[lhquam]

that would be #4107619

is that Stasis ?

That looks like Stasis. Note that the drive fets are used as source followers. Is there a patent for a common-source cascoded output stage?

 

[Zen Mod]

read #5343166

 

[lhquam]

Simulations of a circuit based on post #4540 http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-454.html#post3527968 suggest that it would perform very well with NO FEEDBACK, having an open-loop gain of about 70 into 8 ohms and -3dB at 67kHz.

The artwork is finished and I intend to order PCBs tomorrow.

 

[kasey197]

And this is how to get bias vs. temperature stability with ordinary MOSFETs:

any problems if + leg of V2 is connected to junction of R4/Q3 and - leg of V1 to junction of R5/Q6 ? Eliminates the coupling cap ?

 

[lhquam]

any problems if + leg of V2 is connected to junction of R4/Q3 and - leg of V1 to junction of R5/Q6 ? Eliminates the coupling cap ?

Yes. Doing what you suggest would eliminate any need for R4 and R5, but those resistors are important for bias current stabilization. As MOSFET temperatures rise, the MOSFET current will increase for a given value of Vgs, but the voltage drop across R4 and R5 will increase, thus reducing Vgs. Thus, R4 and R5 provide negative feedback for the DC bias of the MOSFETs.

 

[kasey197]

Thanks n keep us posted

 

[tmegaard]

Does anybody know where to get the Lovoltech LU1014D jfets?

 

[nr12]

Have a look at Bulk Cable, Network Cables, Audio Video Cables, Cat5E, HDMI Cables, Computer Cables, Networking Cables and Structured Wiring, Fiber Optic and more!

Ulf

 

[Antoinel]

Simulations of a circuit based on post #4540 http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-454.html#post3527968 suggest that it would perform very well with NO FEEDBACK, having an open-loop gain of about 70 into 8 ohms and -3dB at 67kHz.

The artwork is finished and I intend to order PCBs tomorrow.

Please count me in for 2 PCBs if that is possible. -3dB by your simulation is ~10 times that observed by Mr. Pass for F6. This is a remarkable improvement. Pass Feedback from this high Zo output port to the inverting port is expected to give your amp triode-ish instead of pentodish characteristics.