A guide to building the Pass F4 amplifier

Heatsink

A little advice if I may

There are 6 devices per side running at around 0.43 amps per device so basically the same as the F5 but with 3x the output devices.

I’m hoping to use 2 PC heatsinks with fans and so will need to use a copper heat spreader.

My question is, do the left and right output devices have to be electrically separate or can all 12 share one heat spreader connected to both heatsinks?
 

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as you drew it (phases, not going in details will you burn xformer secondary or not in that way) , you practically have M2 - xformer driving source follower OS





naah

F4 is for Sissies, it's well known that M2 is best FW amp

:devily:

Ok, got the response from Ivan, trafo designer (known as bisesik on this forum): "Such a transformers are gapless and therefore can not handle DC-offset". Too bad ... :( I need to try M2 one day.
 
Ok. So this is the best thing I think I could make with F4 and DAC with trafos on ouput.
One of my builds is based o es9038pro. I/V Trafo on output. Chip itself has high output current thus can produce high quality signal with enough gain to drive F4 directly.
Please take a look whether something like this will work.
 

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as you drew it (phases, not going in details will you burn xformer secondary or not in that way) , you practically have M2 - xformer driving source follower OS





naah

F4 is for Sissies, it's well known that M2 is best FW amp

:devily:

nope

read everything M2, then you will understand what need to be modulated (which point/node)

as you drew it, you made modulated short circuit

edit: find Crippled F4 schm in thread, connect xformer secondary in between GND and amp input , and that's it

Thanks.
I already have this DAC es9038pro connected to F4 standard way and it is fabulous. Just thought whether I could go further with that and skip caps or inputs stage, but apperetntly it is better to live it like it is and just make M2 :)
 
Official Court Jester
Joined 2003
Paid Member
Crippled F4, xformer driven

did't said that - why making M2, when you already have core of it ......

find Crippled F4 and you'll understand it

caps are necessary part of biasing mechanismus, and fussing about necessary parts is nothing more than Audiophoolery

been there, done that, zillion times :clown:

edit: found it, edited for ya
 

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did't said that - why making M2, when you already have core of it ......

find Crippled F4 and you'll understand it

caps are necessary part of biasing mechanismus, and fussing about necessary parts is nothing more than Audiophoolery

been there, done that, zillion times :clown:

edit: found it, edited for ya

Thank you! Just started drawing same thing. Just to clarify is there connection between input signal and inbetween D3 and D4?
 
Official Court Jester
Joined 2003
Paid Member
ZM, D3 and D4 are unnecessary when the JFETs are gone. BUT aren't you going to fret and fuss and worry about a Zobel terminating network for the transformer secondary?



I am the first one to get overly enthusiastic and bang the damn thing on input waaaay above the rails (OK, it can happen to me only on bench, with Dummies on both ends of amp, not when connected to my both precious and efficient spks) ...... so better to leave these diodes on input

Zobel - that's Xformer's Dad job, I don't even know which one is going to be used

though, 47K on input deliberately stays in place
 
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