Burning Amp BA-3

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#246
generg said:
...

F5 and BA-3 have p and n types just opposite!

...
Click to expand...

:rofl: You're killing me ! :rofl:

It's all in the F5 article - common Source, common Drain, common Gate topologies, explanations and drawings...

Just remember that every FET with 2SJ prefix is a P-channel and every 2SK is a N-channel device.

Few simple things more:
- every N-ch device has its Drain more positive than the Source in order to work
- N-ch depletion mode device (f.e. JFET, like 2sk170) will not conduct the current only if its Source is far more positive than its Gate
- N-ch enhanced mode device (f.e. HEXFET, like IRF610) will conduct the current only if its Gate is more positive (few volts) than its Source

-With P-ch devices everything is the opposite
 
#247
Zen Mod said:
naah ......

do not worry ........

what's little smoke , between friends .......

:rofl:

(disclaimer - as long someone is still sane in our musings )

:cheers:
Click to expand...

You are right! Juma is invited!
 

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#252
I was looking at the BA-3 idea and I realized that an alternate connection may be possible?
What if you remove R125 & 126, P102 and C101. Insert the drain connection of Q3 and Q4 in their place.
Would this work? I see where the TL part would then be dealing with 45mA and that would probably not be good. maybe we could lower the values of R127 and 128 to correct for that?
We would possibly be benifitting from the removal of C101 and maybe a reduction in power supply noise getting into the signal?
Any comments?
😀
 
#254
Hmmm, yes I think something should be done there? Also the 45mA can't all go through the TL part so maybe we could incompass the loading and the large portion of the Q3 qnd Q4 current through a seperate set of Rs and a third to ground?
P1, 2 and 3 would still be useable.
This only works of coarse on the comp (BA-2) version.
 
#255
tinitus said:
I don't understand why new BA-3 driver/gain amp and BA-2 power amp module can't use individual seperate supply, unlike the F5

so, I ask again, any reason not to use individual seperate power supply ?
only connection really needed is common signal, yes?
Click to expand...

My amp uses a separate shunt regulated power supply for the input board with just the ground tied together with the follower supply. I’m running this at about 5 volts higher than the output section at +-28V.

🙂
 
#256
tinitus said:
I don't understand why new BA-3 driver/gain amp and BA-2 power amp module can't use individual seperate supply, unlike the F5

I thought the driver/gain amp was more like a seperate preamp
and that you could use any other preamp, like say a tube pre
and the BA-2 is more like a power buffer, with its own bias curcuit

so, I ask again, any reason not to use individual seperate power supply ?
only connection really needed is common signal, yes?
Click to expand...

there is similarity between BA3 FE and F5
for these two means that you can't use separate rails for input and output parts

BA3 FE and adjacent power stage are two different entities , so there you can use different rails ,whatever that means
 
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