F6 Illustrated Build Guide

But doesn't the choice of R1,2 of 0.56/0.47 vs 0.22/0.22 also influence the composition of harmonics, if I understood Nelson's talk correctly and also the discussion in some of the other threads (a while back, when I wasn't on this forum yet)?

Only if there is degeneration, the pcb design does not permit this type of adjustment.
So having differing values of resistance has virtually no effect, this is why I had instructed earlier, either on this thread or the other one to put in a resistor before and after the junction of the capacitor.
Some members did that and got the results I suggested to them.

This mod is actually better
 
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IRFP250 at Q1 (has to be IRFP250 not IRFP150)
IXTH64N10L2 at Q2
This will get you the sound.


LED Mod + R7/R4 around 3k - Lower noise, better regulation, and adds thermal compensation to the bias circuitry, compared with the stock zener.
Reduce R1 and R2 to 0.22 Ohms (lower if you want) - Not critically important if you have very good resistors, but it does provide some improvement.
Increasing R4 to between 20 Ohms to 23 Ohms - Improves everything a little
 
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ResisterClone
Joined 2011
Paid Member
IRFP250 at Q1 (has to be IRFP250 not IRFP150)
IXTH64N10L2 at Q2
This will get you the sound.


LED Mod + R7/R4 around 3k - Lower noise, better regulation, and adds thermal compensation to the bias circuitry, compared with the stock zener.
Reduce R1 and R2 to 0.22 Ohms (lower if you want) - Not critically important if you have very good resistors, but it does provide some improvement.
Increasing R4 to between 20 Ohms to 23 Ohms - Improves everything a little

Thank you!
 
3k might be a little sissy. As Zen Mod said.
2.5k would be less sissy.

Anything in between would also be ok.

Obviously 3k is perfectly fine, however the performance continues to improve with further current.
I don't think I would exceed 10mA though just to ensure a long healthy life for the led.
 
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This is what F6 has always done.

Transitioning into Class AB from Class A is always better than hard current limiting. This is what F6 has always had over Aleph J and J2, nothing new.
Aleph J and J2 just hard current limit, not good for difficult loads.

Here you can have it all.
Zero degeneration
Similar single ended operation to J2/Aleph J
No hard current limiting into difficult loads

It's a win/win


Just to clarify IRFP250 must be VISHAY

Why must it be VISHAY?