F6 Illustrated Build Guide

Around hour ago finished one channel PCB and PSU, connect them together and looks that everything is working, but looks like that amplifer produce only less than watt at output (<1watt) :(
Output mosfets are hot, BIAS are 0.5V and offset around zero. I try to play some music via it, but it too quiet...

Look's like first issue when i have trouble with zeners, now i'am using LM329, i cut first pin and use another two like generic zener, resistor are 3.3k.

What problem that may be? Maybe you tell me what measure in control points?
Thank you!
 
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We can't help without photos. If bias and DC offset measure OK you most likely have a wiring error.
https://i.imgur.com/xowP6Jl.jpg
https://i.imgur.com/Hx86NQa.jpg
https://i.imgur.com/PUVStXt.jpg
https://i.imgur.com/HJKnyjn.jpg

Images added, but it's look's like with my first issue when i build my first F6 build, now i'am solder precision components, but again back to the roots... :D

Also, you remind me something, try to connect to DAC instead of the phone and report here.
 
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Yes, but 5.1V may or may not be enough to bias correctly
Thanks, i understand that after that moment when i solder 5.1 v zener, so i cut it and solder to leads 6.1V zener, to avoid damage to PCB holes.
Input JFETs are seems to me fakes.
Or these are LSK ones?
LSJ74/LSK170 Directly from LinearSystems.
IFRP240 from DiyAudioStore.
I absolutely hate fakes.

Now it's time:

1) To understand where is bass and what happen with sound quality (i know that amplifer can deliver exceptional quality), i already swap two pair of capacitors, but that won't solve problem, because very strange that Z-Foil resistors sound worse instead of Vishay / Dale MF60.
2) Think how to mount all inside amplifer enclosure, PCB standoffs, wires, back panel wiring e.t.c

Anyway Vishay / Dale MF60 awesome resistors for their price and they sound nice too!

k43JFgQ.jpg
 
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As i understand R5, R11, R12 (F6 Mosfet version) is only on signal path all other resistors are "third-party".
And again i swap capacitors, i put my lovely Nichicon FG 1000uF 25V.
Maybe i'am wrong but my ears make following conclusion, Z-Foil sound too clinical (sterilely).
So how about PR9372 in sound signal path if no, then downgrade to MF60.
 
Spend around 6-7 hours today for listening tests, desoldering/soldering and i get what i want!
Solder to (R1, R2, R3) Panasonic 3W Metal Oxide Film Resistors and success! Yay! :)

Next try to swap again back R5, R11, R12 to Z-Foil, maybe it's improve sound quality, currently it's PR9372 resistors.

Also i remember one note from vegalab forums member, that mostly all resistors acts same in low's frequencies, but may differently in mid and high's.
 
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