F4 power amplifier

it deserves dedicated thread ......... biasing ( depletion mode parts ) is what's most complicated

however , when made properly , you'll not hear so easily difference between boutique parts and plain vanilla mosfets based follower stage

so , if name of the game is fun - why not ....... but if you expect some miracle , it's just throwing money and time through window
 
Sheafer -

I agree with ZM; using unobtanium rare parts in a follower is gilding the lily. One of the (many) reasons to use a follower stage is that the devices themselves impart very little of their sonic character on the signal. You will get as good results with more commonly available parts.

You want an amp where the signal makes it through the output - an F6-style would be fantastic in this regard, and be a good place for your parts.

If you have the F4 PCB, build a 'normal' F4... It's a fantastic amp in it's own regard.
 
Is there any consensus about the choice of MOSFETs in the F4? I have the following to choose between:

FQA28N15/FQA36P15
IRFP240/IRFP9240
FQP19N20C/FQP12P20
FQP16N25/FQP17P10

I suppose I could give them all a try, but I was hoping for some comment on experiences others have had.
 
I see the Fairchild 19N and 12P parts are much cheaper a 1/3 of the price of the IRFP parts.
As I have not bought yet.....what should I buy? Why did you use the Fairchild parts 6L6?

So you have good luck... they are unobtainable normally...

the 19N and 12P haver a brighter and more detailed sound, but of course less relaxed than the IRF, matter of taste....and speakers and room .... and CD-player.....and .... and ....🙂