I love jfet input

[Tekko]

Heres another one of my ideas for a amplifier with jfet input and a frequency response flat from dc to 1MHz.

I'm bold enough to call this one a HIGH END(a wire with gain) kinda poweramp even though its a rather standard circuit:
http://i.imgur.com/PjwPsh.png
http://i.imgur.com/ZeWnvh.png

 

[Tekko]

Some loop gain stuff:

http://i.imgur.com/RdxSgh.png
http://i.imgur.com/ZKyLDh.png

 

[AndrewT]

Would you be prepared to post a more detailed schematic so that we can share component values and types?

 

[Tekko]

Heres a larger and also updated version:
http://i.imgur.com/xDqfi.png

 

[dadod]

THD20k with 21ppm. Could you show FFT?
Here is JFET input too, look at the link:
http://www.diyaudio.com/forums/solid-state/182554-thermaltrak-tmc-amp-3.html#post2751316
dado

 

[Tekko]

No i cannot show a FFT because i cannot get that part to work properly, and i set my spice directives to not visible to get the window smaller, so i can no longer change any of those settings.

 

[dadod]

No i cannot show a FFT because i cannot get that part to work properly, and i set my spice directives to not visible to get the window smaller, so i can no longer change any of those settings.

You don't need to change anything, just click with right mouse button on Voutput diagram and then choose View and then FFT.
dado

 

[Tekko]

And all i get is a line with a stair step down to a lower level.

 

[Tekko]

Heres something that has me stumped, the amp is not unstable with signal, but it is during startup, see the red ring:

http://i.imgur.com/qKIfe.png

 

[jechentau]

i think it probably has to do with C1 and/or C8, for now ;p
i suspect C1 most direct. what happens if you make it 47µ?

i'd like to add that it most likely does not show up like that in the real,
and, that c6 and c9 might need a resistor involved somewhere, basestopper perhaps or maybe
between each collector-capacitor node and the powerrail, very low value (could try).

 

[Tekko]

It seems this is about as small as i can get it without beeing back at the 0.0x% THD my current amps in use measures in at.

http://i.imgur.com/tIn27.png

http://i.imgur.com/VTeXG.png

I'll find out when i actually build this thing, if this will actually even exist in the real world circuit or if its just a simulation thing.