to all greedy boyz

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Great :cool:

Our great Philbyx is experimenting a version ;) Follow links from here : http://www.diyaudio.com/forums/showthread.php?postid=1167632#post1167632

The schematic is a bit outdated, and a "Vbe multiplier" (a BJT based one, since the used output mosfets begin to conduct before a Mosfet bias control becomes active ;) )

The first channel has been tested de auditu (wow,great, etc...:D) and the second channel in on the bench for testing. I think there'll be more to come quite soon.
 

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CheffDeGaar said:


Where did I go wrong ?



Nelson appears to be pulling the old switcheroo, going back to the older Aleph push-pull output stage. The top devices are Ns, biased pretty decently. The bottom is a little more complicated. There are P-ch devices, biased lightly, running in parallel with a current source, biased heavily. What modifications he might have made to the older output stage, I do not know.

Grey
 
GRollins said:
The top devices are Ns, biased pretty decently. The bottom is a little more complicated. There are P-ch devices, biased lightly, running in parallel with a current source, biased heavily. What modifications he might have made to the older output stage, I do not know.
Grey

Grey, even if only the upper fets were heavily biased, it "only" would halve the dissipation, leading to 600W at idle, or 300W per heatsink. To reach 25° above ambient, this assumes a Rth of 0.08°K/W... Pretty cool :D

But I really doubt P and N fets are biased differently, and I do not see any arrangement looking like the Aleph 0 topology...

I need enlightenment :)
 
Hi Nelson,

Thank you very much for posting the X5 service manual. It is very much appreciated. This is a really big deal. It is the first time that service/schematic manual/info for a SuSy based power amp has been disclosed.

There is a wealth of information in this handful of pages.

After two pages of posts I just figured it was time someone said thank you.

Thank you again.

Graeme
 
Nelson Pass said:
The N's are biased somewhat higher than the P's.
Thanks Nelson :cool:. And thanks for putting the document online ;) And apologies to Grey for my boldness (not sure of the english term, but it may sum up to "me little grasshopper") :)

So I do not have to trust the schematics saying "0.47V bias" in front of the source resistors, both for the P one and the N ones... I'm confused, to say the least.

And after a careful reading of the "adjustment" paragraph, I still can't figure out what happens here. The bias is to be adjusted by monitoring the voltage on a source resistor. But the N ones, or the P ones ?

I surely miss a point here...
 
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