F6 Amplifier

[kasey197]

melonhead: good point and fair enough but effect should be small one would think and also applies to both halves...

meantime ... re biasing - would this work ?

 

[Melon Head]

I will need time to think about all of this. It takes time getting my 1.5 brain cells going.
I have a new conspiracy theory. Nelson provides these basic circuits and makes us guess and use our dumb creative minds until one day one of us by pure fluke, accident, or dumb genius has a brilliant idea that Nelson has not thought of before. The best way to get new ideas is to talk to a child. Haha

Or maybe he is just evil and enjoys watching us suffer. Haha

 

[Melon Head]

Voltage divider should work just not sure what other effect it might have on the circuit. It might create a new feedback loop. Is Nelson using depletion or enhancement mode jfets, I think I remember someone saying enhancement?
What about diodes?

 

[taisho_daniel]

I think Nelson mentioned in a thread somewhere that he's using the Semisouth R100s for the F6.

 

[Zen Mod]

OK guys

Papa is somewhat intimidated with noise in this thread (too much questions directly addressed to him ) , so he sent me sch to share with you ;

he said - "later , when gunsmoke is gone ..... "

 

[Zen Mod]

.....
I have a new conspiracy theory. ........

I told ya he's having redish eyes

and , while we at it , there is also a story about 12 monkeys , one typewriter and possible book

 

[buzzforb]

I am not falling for this again.

 

[Melon Head]

OK guys

Papa is somewhat intimidated with noise in this thread (too much questions directly addressed to him ) , so he sent me sch to share with you ;

he said - "later , when gunsmoke is gone ..... "

 

[buzzforb]

Melon,
You need to put a leash on your girls. Everybody has pics of them and they always seem to be taking something off.

 

[Vix]

There is only one thing for sure: Papa killed more than one bird with just one stone. Or, a transformer...

 

[flg]

...and the reason of course is that there is NO source degeneration going on.

It's a simplified schemo

Keeping in mind the mantra I inferred from reading pass articles 10x ... the FET knows nothing about the world apart from what it sees between the gate and the source and will attempt to react accordingly...

No, you left out the Vds? Without it, you only have a capacitor g-s

... That makes the current flowing through the load push UP the source voltage and this reduce the VGS accordingly and this denegerates VGs (creates 100% NFB) and makes the voltage gain drop to 1x.

Hold on, the current only does what the gate signal tells it to. The Gate pulls up the source. There may be interactions between the load if it is'nt just a resistor.

The fet doesn't know anything else apart from VGS and so it blissfully just conducts away based on what it sees between gate and source.

Remember, the Vds?

Just tryin to help

 

[Antoinel]

The circuit is just are Nelson said in http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-9.html#post3102389. The hard part is figuring out how the bias voltages are generated

Semisouth R100 is an enhancement device; like a bjt. The bias network which is found in the pdf of thread #38 will be applicable. The schematics of Mr. Pass are highly effective and usually simple [e.g. F6].

 

[generg]

I learn from this discussion that building amps is much more complicated than I thought.....
So many qualified people and one simplified schematic and so much interpretations are possible..... Crazy!
It really shows the great freedom designing electronics gives to the constructor .....

 

[bobodioulasso]

melonhead: good point and fair enough but effect should be small one would think and also applies to both halves...

meantime ... re biasing - would this work ?

This one allows to choose the bias. It's a classic. Recalls to me transistorized radios from the sixties, using germanium devices.

 

[Zen Mod]

what !!??

Papa's schm is downloaded 98 times (by now) and nobody commented !

 

[Melon Head]

It really shows the great freedom designing electronics gives to the constructor .....

Spot on. There is always more than one way to skin a cat. That is exactly why it is fun. You can let your imagination run wild with ideas.

 

[Zen Mod]

...... You can let your imagination run wild with ideas.

but ..... same as with any sort of art (music , for example) - you need first to spend ridiculous time on your a$$ , developing technique ......

my wilderness is on much higher level than my technique

 

[Melon Head]

That is another reason why it is such a great hobby. When I understand something I lose interest in it fairly quickly. This hobby always makes me feel dumb because there is so much to learn. So I stay interested, and it is amazing reading some of Nelson's articles for the 100th time and still learning something or discovering something Nelson has said that you did not remember him saying.

 

[Antoinel]

The bias network which is found in the pdf of thread #38 will be applicable

The attached pdf shows a possible bias network [OTLAmp3] . Please note that the name I gave this file did not use F6 in it; because F6 is a name which exclusively belongs to Mr. Pass.

 

[flocchini]

OK guys

Papa is somewhat intimidated with noise in this thread (too much questions directly addressed to him ) , so he sent me sch to share with you ;

he said - "later , when gunsmoke is gone ..... "

Cant wait for this. I know my F4 headphone amp with the interstage Jensen transformers sounds outrageously good and the F6 looks like it will be a lot of fun