100W Ultimate Fidelity Amplifier

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#9,461
SX8

Simple amp idea.
 

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#9,462
APEX AA9

Mr. Mile,
I have added rail decoupling near the o/p device and also ground lift.
Is it recommended?
+some reduced the PCB size to 68mmx75mm

reg
Prasi
PS; many revisions, but i want to make it as good as possible.

edit: the black jumper is optional jumper to reduce the trace length from C7 to C of T6.
 

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#9,467
apexaudio said:
Simple amp idea.
Click to expand...
You can't use the output stage diamond buffer in a power amp that way.
It's basically two symmetrical SE stages that go to current clipping very fast (if you don't bias it to pure class A) . Simple version from your sch. works for small signals but if you want to make it push-pull you'll have to use a big cap to connect the bases of output transistors. Then it will work but not very good - pair of lateral MOSFETs will do much better job, and then you get old F5-gone-BJT with addition of source follower output stage...
 
#9,469
juma said:
You can't use the output stage diamond buffer in a power amp that way.
It's basically two symmetrical SE stages that go to current clipping very fast (if you don't bias it to pure class A) . Simple version from your sch. works for small signals but if you want to make it push-pull you'll have to use a big cap to connect the bases of output transistors. Then it will work but not very good - pair of lateral MOSFETs will do much better job, and then you get old F5-gone-BJT with addition of source follower output stage...
Click to expand...

Little improvement.
 

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#9,475
olafk said:
Hi, here are some measurements. I've corrected the offset by changing the 470R resistors. But I think now the amplifier is underbiased.
Advice are welcome 🙂

But the sound is very, very good. Deep, powerful bass, well balanced mids and transparent beautiful highs.

Regards Olaf
Click to expand...

hi i also have made fx12. sounds just as olaf described, and i have vssa to compare. 😀

how do i increase the vas current tho? change out 22k resistors or the 220ohm?

550893d1463940838-100w-ultimate-fidelity-amplifier-apex-fx12.jpg
 
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