Vbe problems ... I'm going nuts !!

[PMA]

Hi ostripper,

good to hear it has helped, and probably this solution might be useful for other DIYers as well.

Regards,

 

[ostripper]

Hi ostripper,

good to hear it has helped, and probably this solution might be useful for other DIYers as well.

Regards,

I was always "afraid" of any CFP , but this is "tame" (100pF cap just in case). I might try it on a bootstrapped current source VAS to see how it handles the primitive current fluctuations. This test was done with a CCS and separate rails for the VAS/bias generator - most ideal conditions. It (the idea) did more than just "help" , I am pretty much "rock solid" with normal 65-70ma bias , even with ventilation blocked or random program material loads.

It was especially interesting to "cook" the output stage and see this "lock on" to 300+ ma (67mv/.22R) per device (and stay there... "a cookin'" ).

OS

 

[Bonsai]

Good result OStripper. This is the same circuit I am using BTW on my amp with good results but a slightly different physical execution (I use an SMD for the smaller transistor).

 

[ostripper]

Good result OStripper. This is the same circuit I am using BTW on my amp with good results but a slightly different physical execution (I use an SMD for the smaller transistor).

I wondered why you awaited results ... spreader is in your ovation 250 ?? Why BC847c ?, the beta ? and MJE350 ... I just used what I had.


I just completed the long term "no ventilation test" with a target cold setting of 15mV , 2 hours later ... hot as hell , but 14mv. With any "creep" (like before) ,that would of been 25mv+. So it seems I have a slight over-compensation , but that is what my design goal was.

OS